Onan 7000 Generator problems
 

Has anyone had a problem with an Onan Marquis Gold 7000 HGJAB with overheating? If I run my generator for 15-30 min, and shut it off it will not restart, it throws a code 37 (Invalid Configuration Fault) When it cools down it will restart. It only has 95 hrs on it, and it looks like the previous owner had the same issue. I have been unable to find anything on the web, other than possibly a circuit board is overheating, and has to cool down. It is a 2006 model. It runs great and has no other issues unless I shut it off and make a pass, and then try to restart it. Once it is running I can run it for a race weekend without even a hickup.

Thanks for any help.

Sean

Re: Onan 7000 Generator problems
 

Reach out on here for Rich Beibel and /or Matt Shurman.They both race in the Super catogories.They're generator guys.




2 more to go.

Re: Onan 7000 Generator problems
 

Thanks Ed. I contacted Rich and have a direction to look for the problem now.

Sean

Re: Onan 7000 Generator problems
 

Sean.....One other thing you can check...but it rarely happens...

The air inlet for cooling is directly in front and below the aluminum base tray.

If a rag or some paper or something else gets sucked up in there it can block the air flow and cause the unit to get very hot.

There is a fan blade attached to the underside of the generator end. It sucks air up and in for cooling.

We had one racer who had something making a nest up in there and it blocked the air flow. Probably a chipmunk or mice or a bird.....

DON'T put your hand up in there when it's running!!!! and don't leave a rag under the unit for checking the oil.......

The suction will take it right out of your hand when it's running......


and Ed....Please spell my name right....Biebel, like Diesel and Spiegel........and contrary to what the announcers have said for 40 + years.....my family pronounced it......BEE-BULL NOT BIBLE....LOL

I was told that the announcer...probably Dave Mclelland at the time said something like...how can you beat a guy named BIBLE on Sunday......Well you couldn't on that particular day.....that was always very funny to me.....

Re: Onan 7000 Generator problems
 

I bought a new trailer last year and had the same issue, overheating problems. One of the Cummins guys looked under the trailer and told me there was nothing directing the heat away from the cool air intake on the bottom. I made a duct out of aluminum and it solved the problem. Miine did the same as yours, shut it off and would not restart but it usually ran all night. Good luck!

Dennis Breeden

Re: Onan 7000 Generator problems
 

Thanks Rich,

I will look into making sure no obstructions, and no nests or rags too.

Sean

Re: Onan 7000 Generator problems
 

This model Onan does NOT have a high temp shutdown. If they shutdown or won't restart it is not because of any specific safety shutdown built into the machine. It's more like the machine just got too hot and something fails to operate because of the heat.

And yes they do need to NOT suck up their own hot exhausted air.

They had some of these units mounted under the back end of work Vans. They released an air deflector to direct the hotter air away from the front of the machine....I installed a few.

Most larger machines and diesels DO have an over temp shutdown. These would be liquid cooled and have a coolant sensor....

Big generators all have safetys as we call them. L.O.P. Overspeed, Over Temp and more.......all to protect a big dollar unit....

W

Re: Onan 7000 Generator problems
 

Dennis and Rich,

There is not a divider or ducting, so chances are it is recirculating the same heated air, and just heat soaking everything. It looks like when the trailer was built they just windowed a hole under the generator in the plywood. I found info on the web about the ducting kit that was being installed. So definitely a trip under the trailer is in order to rule out what you guys have pointed out here.

I really appreciate the advice and help.

Sean

Re: Onan 7000 Generator problems
 

Checked for rags, nests in the fan. It is clear. With it running, it was definitely recirculating it's own air. Installed baffle to correct. Shut it off and same thing. Code 37. Pulled control module and heat sink was very dirty. Cleaned heat sink and reassembled and still code 37. Looks like the module is bad. Probably too many overheating cycles on it. All wiring connections clean and tight too.

Sean

Re: Onan 7000 Generator problems
 

Part # 300-5047 You can expect to pay over **500 for one.

I have had them fail and can push on the lower right corner of the potting material...... and they work.....

The fuel pump/carb solinoid circuit fails.....usually....

I keep a known good used one around for testing.....

All it is is a PC Board.....in a tray.

The same part number is used for carb'ed models or EFI models.....

Re: Onan 7000 Generator problems
 

Thanks Rich I ordered one and it should be here in a couple of days.

Sean

Re: Onan 7000 Generator problems
 

Resurrecting an old post before we had a separate Generator section.

Well same problem different year and several hundred hours later we are back to a unreliable generator. Here is what has been done since 2012.
New module, new fuel pump.

A couple of weeks ago the same no restart until it would completely cool back down to ambient temperature. So I replaced fuel filters, drained gas tank and verified no obstructions in outlet (gas tank is fabricated out of steel and is under trailer) replaced spark plugs with factory NGK and gaped .028". Re-inspected cooling fan for obstructions. Added more ducting under trailer, as air being exhausted for cooling could be recirculated depending on which way the wind is blowing. The generator cooling intake and exhaust are separated by the trailer floor joists. So I have closed off the bottom side of the exhaust with aluminum to direct the hot air to the opposite side of the trailer.

The generator runs fine until it is shut off and will not restart, until it's back to ambient temp. Same code 37. This weekend at Topeka, I made the mistake of shutting off when we left the track to go eat, came back a couple hrs later and it would not run. Starts runs a few seconds and shuts down. Cylinder heads ambient but where the module resides is still warm. We run the generator with the door open in the trailer, and the outside door open to access the generator compartment, we even have a fan that is used to cool the car blowing on it to blow air across it from inside.

Friday morning it restarted at 7 am ran until 2:30 PM when it was 100 deg ambient. Removed access cover and let it cool. It would not restart until Saturday morning and I ran it with the access door removed all day, but it was only in the upper 80's. We are the 3rd owner of this trailer and when we bought it the generator only had less than 90 hrs on it. Now we have 770 hrs. I am running out of ideas to try, as it is so unreliable. It's hard to concentrate on what we are doing at the track not knowing if this thing is going to shut off. It's not running out of fuel as I top off the tank throughout the day because of the no restart issue.

Another idea is to relocate the module outside of the generator housing and install a cooling fan on it, as this is obviously where the issue is. What am I missing on this thing? Do the modules not last that long?

Help!!!!

Thanks
Sean

Re: Onan 7000 Generator problems
 

Sean, trust me here when I tell you I feel your pain but in this case I have no magic bullets for you. The modules or PC's generally are the reason for high temp shutdowns and if you changed it I would not expect it to be the problem so soon...but here are some things to try...

If the machine gets hot and won't restart....try closing the choke right at the carb while cranking it at the machines switch. These machines are very difficult to restart hot most of the time. If you choke it momentarily they starrt right back up.....Very old style bi-metal spring style electric choke with a vacuum break or pulloff.....

There is a small 2 pin connector on the solenoid at the bottom of the carbs float bowl. 12 volt supply allows fuel to pass thru the carbs main jet....That is the circuit that fails on the PC board. It is the same circuit as the fuel pump. If you can clip a meter to the solenoid leads you can look for 12 volts + and - there anytime you try to start it or with it running. If that voltage is lost it will shut right down. There is also an ATK type fuse for the fuel pump and the connector or wires might be poor....check it.

The machine MUST have a good battery connection both + and - and the + post sometimes gets loose....it is double nutted.....check it. The small white wires power the PC board......

Code 37 is not a normal fault code I see on those....36 yes.....Possibly you misread the blinks? Code 36 points to a loss of fuel......or a shutdown without a command.......Yea I know we already know that....!!!

I have a pretty large contingent of customers that have these units in mobile dog groomer vans......I have seen most everything but they throw me some curves sometimes and I just work to resolve the issues as quickly as I can.....

Re: Onan 7000 Generator problems
 

Thanks Rich,
It is code 37, as I read it several times and had my wife double check me. All I find for code 37 is " invalid genset configuration fault". I may not have described won't restart very well. It will start and shut back down within 5-10 seconds. I will check the fuel solenoid and see if it is the issue. I have pulled the 12 VDC power and grounds and verified those connections.

Thank you for your help.

Sean

Re: Onan 7000 Generator problems
 

Sean remove the brushes and make sure they are not worn enough to lose contact with the surfaces they contact.

1 -10mm bolt.....top of generator end bell....left side, in the rear area. Brushes slide in and out in a plastic holder...

Re: Onan 7000 Generator problems
 

I will check them.

Again Thank you!

Sean

Re: Onan 7000 Generator problems
 

Well the brushes were right at 7/16", so I ordered brushes. I also cleaned the slip rings with scotch bright and now they look like new. We will see how this works. I ordered the brushes from ASAP (Advanced service and parts inc). They sell a replacement module as well, as the one I purchased is an OEM and states origin China, July 25 2011.

Rich,
Any thoughts on this module?

http://www.partsfortechs.com/asapcar...ae-p-1378.html

I do appreciate all the help that you offer.

Sean

Re: Onan 7000 Generator problems
 

I have bought items from ASAP and that replacement is a very recent item. Cummins price is now well over $500 for one. Yes they say Made in China right on them just like so many other "name brand" parts we buy.

I have not used one of the ASAP replacements yet but definitely planned to in the future to offer a better price for one.

If the brushes were still contacting the slip rings and the rings themselves were not in real bad shape, that is probably not your problem.

They will wear down so far the wire shows thru the carbon and the slip ring gets pretty burned from arcing....

I check them routinely on any machine that comes in with at least 500 hours. I have seen them worn to failure at somewhere around 1000hrs.

One brush is always worn more then the other. The lower one. The wire ends have locks on them....you need to use a small screwdriver or something to release the lock......1 at a time so you don't mix them up. It is DC voltage there and will work either way but is shown in the manual a certain way. I have found them wrong a few times....I forget right at the moment which is positive...

Re: Onan 7000 Generator problems
 

Rich,
Well as you stated the new brushes did not change anything. We went to the track Saturday and after running the generator for 7 hrs and shutting it off to leave the track for an hour. We came back and it would not run for more than 10-15 seconds and code 37. We gave up on staying the night at the track and came home. Sunday I pulled it out of the trailer and disassembled. I verified the fan and belt was fine, No debris in the fan, or anywhere. The magnetos had .015" for air gap. I cleaned the rust from the flywheel lands, and cleaned the flywheel magnet with scotch bright. I reset the air gap to .012".

I verified the wiring had the same reading at the pins for P-15 and P-20 on the magneto kill lead with the + lead to chassis ground and - lead to pin P-15 and P-20.

The following readings were taken on each magneto: Left measured 20,100 ohms, the primary measured 326.5 K ohms. The right measured 20,200 ohms, the primary measured 323.7 K ohms.

Windings measured: T1-T2 = .50 ohms, T3-T4 = .50 ohms
Q1-Q2 = 2.60 ohms

Slip rings measured 31.3 Ohms on the slip rings.
Brushes on the slip rings measured 36.6 ohms

Every measurement is close to what the Onan service manual 983-0501D, 01-06 calls for.

So I reassembled the generator and with it outside of the trailer but using the trailer fuel tank, fuel pump and battery, I ran the generator for an hour, shut it off and let it set for 30 min. It restarted and ran fine, Voltage was 120.6 VAC, 60.5 Hz, this is with no load. Shut it off and waited 15 min and same thing. It starts and runs for 10-15 sec and code 37.

So with everything hot, rechecked stator and brushes.
Q1-Q2= 2.90 ohms
Brushes = 36.0 ohms

All readings taken using a Fluke 87 DVM

I am at a loss as to what else to even look at. It runs fine until it is shut off and then will not restart while hot for more than 15 sec before shutting down on code 37. Unit will not restart, and continue to run until everything cools all the back down to ambient temperature. The only thing I come up with is the module is the problem and is faulting from heat. Do you have any other thoughts of what to try or measure?
The generator is an HGJAB 7.0 kW

Thanks for your help Rich

Sean

Re: Onan 7000 Generator problems
 

Sean, this is exactly what happens when I have tested some. I purposely let them run and get hot....I shut them down and let the machine heat soak....The trouble usually starts right after doing this. I swap in a different PC board once the machine starts shutting down.

I have also sometimes just pressed on the face of the potting material of the board and got it to stop shutting down.

You did way more than most people would do and did it all to perfection.

I do the same things and come up with no clear bad readings....

You need to monitor that voltage at the carb solenoid if you really want to say 100% for certain that is what is happening. PC board voltage supply out to carb fuel solenoid fails when hot.

You could.....do what some creative racers have done....and power that solenoid separately with a switch....I think it is also the fuel pump supply circuit and believe it also may need to be fed separately.

Diesel Onans have done the same thing.....fuel pump circuit fails....they added a separate switch fed 12 volts to their fuel pump...

In your case it is the carbs fuel solenoid that is not getting power. It is just a small pin that retracts and allows fuel to be drawn up into the main jet....

Or you could defeat the pin entirely.....cut it or grind it off so it can't shut off the fuel......Think of how many carbs never had a device like that on small engines....What's the worst that could happen....Not much. Ignition magnetos get grounded for shutdown....engine might "run on" or diesel a little but I doubt it......You would still need to power the fuel pump separately so it stayed running anytime you wanted the generator to run.


Just throwing that out there for you. I never tried it as I have to fix these things by the book for customers.....

I have had racers tell me they added separate fuel pump voltage supply switches on diesels that do the same thing....random shutdowns....It is the PC board on those as well....they bypass the PC board and feed the fuel pump independently.....off a switch......

I am not recommending this type of repair but only mentioning it to show what some creative and resourcefull people have done to fix their generators....

Re: Onan 7000 Generator problems
 

Thanks Rich,
I hate throwing parts at things to resolve problems, but I have resorted to it on this problem.

I have questioned the generator battery and had it load tested tonight. It was deemed bad, it was the original 2006 marine battery for the generator. It has not been allowing very many starts and would need recharged. It may have affected the module operation, as a stabile 12 VDC to the generator is needed. I also replaced the Mr Gasket 42s fuel pump that has been on it for 2 years now just to remove it from the equation with the same exact pump.

I ran the unit until it reached normal operating temperature. I then shut it off and let it heat soak the module, and when it would generate code 37. I then manipulated the choke while spaying carb cleaner to keep it running. I monitored the 12 VDC to the carb solenoid and fuel pump, and could never get it to change, always 12.7 VDC while running even with the carb cleaner. This confirms what you suggested, that it is a fuel issue. I removed and cleaned the carb and float bowl. After reinstalling, it restarts and runs easier, but will still code 37 if the choke is wide open when starting while hot. If I manipulate the choke, I can get it to run. After running, I can then allow the choke to go wide open and no issues.

As for the solenoid circuit or pin, I may add an additional gasket/washer to increase the clearance. As I wonder if the expansion from the heat is reducing the fuel volume.

As for the fuel pump/solenoid circuit. Keeping this safery circuit automated would not be that big of a deal. By adding a 120 VAC relay, and the coil energized by the generator when running would close a NO contact. The contact would have the battery 12 VDC + to the line side and the fuel pump/solenoid coil to the load side. The priming circuit would be in parallel. The same operation that is currently used by priming the unit before starting. Once the generator starts and produces 120 VAC the relay would then close and turn on the fuel pump/solenoid coil. When the generator is stopped the 120 VAC relay will be deenergized and the fuel pump/solenoid coil will be disabled.

I will try some of these ideas before reinstalling the genset back in the trailer.

I appreciate your time and help with resolving this issue.

Thank you
Sean

Re: Onan 7000 Generator problems
 

You could come work with me.....LOL

I once fixed an older Onan that had a 24 Volt AC circuit failure in the stator by using the 120 VAC output fed to a small transformer and applied to the control board. Mounted the transformer outside the endbell.....added the wiring and it worked perfect.

The 24 volt ac was used to operate circuits on the control board and keep the machine running. A new stator was not available. Older flathead 1800 rpm machine.

I get creative sometimes if needed and if it makes sense.

Keep in mind if you never lose that 12 volts to the carb solenoid and fuel pump......your issue is NOT the PC board....

These machines are very hard to restart hot and I have not come up with a fix for that. As you see, if you close the choke as you crank it hot.....it will start right up usually. Otherwise they may crank a very long time and or not start without numerous tries or waiting a while.

The engines are Subaru-Robin built I believe. Not sure on that or who may have designed them but they really need to address some serious issues on them.

I am installing a new engine right now on one. 7KW.....6600 hours

Re: Onan 7000 Generator problems
 

Here is a little tip that I thought of today....

Has only happened a couple times but...

The mufflers on some Onan's can get plugged up with carbon and soot...

Back pressure goes up and the engine does not run well once it runs for a while....

I disconnected the muffler from the exhaust pipe from the engine and engine runs fine.

This occured during a load bank test and would not be readily apparent without testing it this way....

Another piece of info I am just throwing out there ....

Re: Onan 7000 Generator problems
 

Heck we might make quite the team! I would not know what to do with racing in the atmospheric conditions you have!

It is somewhat concerning that this thing gets as hot as it does. I will take a look at the muffler, good thought. I can't say I am a big fan of this air cooled design.

Thanks Rich!

Sean

Re: Onan 7000 Generator problems
 

Well same problem again this weekend at the divisional and I pulled the plug and came home.

The generator ran for 6 hrs and shut down in the heat of the day at 101 deg. Code 37. I let it cool down, and it started and ran for about 5-10 seconds and code 37.

Today I ran the generator in the driveway with the same weather conditions. A/C running and Fluke 87 measuring Hz and another meter measuring voltage. The voltage remained steady at 120 VAC, and the Hz was 59.6 to 60.5 as the A/C cycled on and off. At 3 hrs of running it shut down on code 47. I tried getting it running again, and same as always, starts and runs for 5-10 seconds and code 37. I applied 12 VDC directly to the fuel pump and same thing, starts and runs 5-10 seconds and shuts down. I then used carb spray and I can keep it running. What I did notice is the carb is spitting fuel back out of the carb when the generator shuts down. It's as if it is flooding the engine. So a couple of things I am not sure of is happening. The carb even after cleaning is suspect, and only when the generator has been running and has gotten hot, is the module failing? With bypassing the module running the fuel pump, and the generator still failing, eliminates the fuel pump circuit from the module. The carb solenoid is already bypassed. I just question if the module is interrupting the mag circuit? I do not run the generator for more than 20 seconds with shots of carb cleaner, but it runs longer than with the fuel pump alone.
Any idea's?

Thanks
Sean

Re: Onan 7000 Generator problems
 

Sean this is a bad one and I am really sorry to read about all you grief trying to fix it...

Did you ever do a valve lash check yet on this one. I don't recall as it has been a while.

They use solid lifters. Lash is very small at about .003-.004 cold.

There is only one way to do this and it is difficult but I know you can do it.

Under the generator end is a plastic plug. Pop it out....I tape a 15 or16MM socket( can't recall which right now) to an appropriate length extension. There is a bolt in the end of the generators rotor.....straight up from the hole where you popped the plug out of. This is the only way to rotate the engine and to do the valve lash check. Spark plugs out....rotate it in the proper direction and do it like any 4 stroke engine. They are a real pain to do and they get tighter as you lock the locknut....and the studs like to loosen up sometimes. If you watch the valves it's easy to see the proper sequence so you know your turning it in the right direction.
If the exhaust valve lash is tight....once the engine gets hot the valves do not seat and compression is lost and exhaust backs up into the intake....Might be your problem. It is counter clockwise if you were looking up at the rotor bolt your turning....

If you see heavy deposits of oil sludge around your exhaust springs.....you could easily have loose guides. They do it on a regular basis.....I wiggle the springs/valves trying to see if there is movement. The seal might move....if it does.....You need to replace the head or both of them. Now when I find one side bad.....always the left side.....I pull them both and take them apart. If the exhaust guides are loose, I install new heads.....both and have done about 3 in the last 3-4 months....The y are press in guides and loosen up.....and the valves and seats get beat up. High heat is when they really start running bad or may shut off...

Fuel supply is good.....Ignition is good....12 volt supply stays up to the pump and solenoid.....it should not shut down....

Ignition coils get grounded to shut it down. They are magneto style....don't need a battery to make spark...only need to be grounded to shut them down....

Starts to make me feel it might be the head issue....

Re: Onan 7000 Generator problems
 

Thanks Rich,
This thing is really taking all the fun out of going to the track, not knowing if I have power to run fans or charge the battery for the car, let alone no A/C or power to stay in the living quarters overnight.
Checking the valve lash is probably the only thing I have yet to check. I should have checked that before putting it back in the trailer. As the plug you are talking about is not accessible with the generator installed. I was concerned with destroying the gaskets too, but that will be my next step. What is the ballpark cost of heads? Is there a place you would recommend if I have to buy them?

Again thanks for the help,

Sean

Re: Onan 7000 Generator problems
 

I can get you anything you need and have it drop shipped directly to you.

In the past heads came unassembled.
The last few have come complete with everything including rocker arms and hardware.

I will have to check the prices as Cummins has done a lot of price raising.

I will look tomorrow and PM you the cost.

It's a very common failure on these units.We give our customers 3 options depending on overall condition of the generator and hours on it.

2 new heads and various other small parts
complete new engine and all lower end drive parts with new coils
Brand new generator.....

Have done all the above a few times in the last 6 months....

Generator ends are very reliable .....engines and controllers and fuel pumps and carbs are the most common issues/failures. Throw in a few other occasional failures....belt drive or coupler and coils now and then...

Re: Onan 7000 Generator problems
 

Thanks

Re: Onan 7000 Generator problems
 

Sean I just went back and re-read all your posts on this machine and it is a real mystery. It really should not have bad heads as that problem rarely occurs with less than 1200-1500 hours, I don't think I've ever seen it on a machine with less....

Pop the valve covers.....unfortunately you will need new gaskets as they are paper thin and stick and are nearly impossible to reuse.

Just to get a look around the exhaust valves and springs. You can remove the spark plugs and try to bump it over to see if it has some lash. Mostly all your looking for is signs of overheating on the exhaust valve and spring. They can really get roasted....If it's clean.....then I would say with so few hours the heads are fine.....and it's back to scratching our heads....

Re: Onan 7000 Generator problems
 

I should be able to have the valve covers pulled tomorrow night. I will try and get some pictures.
Thanks

Re: Onan 7000 Generator problems
 

Sean I just read a note on one fault code page that says if the fault code shutdowns alternate between 37 and 47 it is a bad ignition coil.

You have said that you get 37 and 47 fault codes I believe.

I have seen coils fail but not very often and they do fail when they get hot. Usually only one.

Another possibility is a failed wire from the coil. It is one piece and molded in. I had one machine mice chewed thru the wire. They are carbon core wires and easily damaged right at the spark plug end....

Yes I know the coils are in the bottom of the machines lower tray.....and totally inaccessible without complete disassembly......


Sean I read some more info and here is where your problem is......

The machines controller senses engine speed from the ignition coils.....it senses generator speed from the generator at what is known as the quadrature windings. That is a small winding that makes a small AC voltage in the stator. If you lose quad output....you lose main AC output.....That never happens on your machine.....If you lose a coil the machine may shut down and does not restart probably because the coil is still not firing.....just a guess but about as good as I can come up with.

Those 2 sensing circuits are what the controller uses to compare engine speed and generator frequency. It will shut the machine down if it does not sense the proper signals from both....

I'd replace both coils....

Re: Onan 7000 Generator problems
 

The only time I have seen the code 47 was Sunday when running it in the driveway. Following checking the initial shutdown code I then tried restarting and then subsequent failures of code 37. At this point coils look to be far less expensive than heads! There are two different coils as the high tension leads are different lengths. I did inspect them both, but that means nothing with high voltage finding a path to ground.
I did order the replacement control module last night from ASAP. Supposedly it ignores all interruptions except for oil pressure and stator voltage. Could you PM the prices for the coils and a way to contact you please. I might as well have valve cover gaskets too.

Thanks Rich!

Re: Onan 7000 Generator problems
 

Yes I will Sean...

Re: Onan 7000 Generator problems
 

http://i569.photobucket.com/albums/s...psf9ac4b44.jpg
http://i569.photobucket.com/albums/s...ps4ccc43fc.jpg
http://i569.photobucket.com/albums/s...psd7584293.jpg
http://i569.photobucket.com/albums/s...ps15457d10.jpg
http://i569.photobucket.com/albums/s...ps30d9e24e.jpg
Well finally some progress. Side by side of the OEM Onan control module and the new ASAP module. Each cylinder head, with no signs of problems other than the valve lash was as follows:
Left (cyl#1) intake .014" and exhaust .013"
Right (cyl#2) intake .014" and exhaust .018"
I adjusted the lash to spec of .004"

The heat sink on the ASAP module is about 1/4" longer than the OEM module.

And finally for those who need to know the safe way of lifting and supporting the generator to remove the bottom structure and access the belt and coils.

I am sure the parts will be here by Tuesday and I can put this back together and in the trailer. Thanks for the help Rich

Sean

Re: Onan 7000 Generator problems
 

Heads look clean..and loose on the lash is noisy but is better than tight.

I use a set of 4 chains with a loop I made up for those machines and have two overhead rolling cranes so lifting anything is easy.

I also have a 4' square all steel heavy work table for a bench....I do all my work on that or use a forklift for diesels......Makes it a lot easier to be able to raise or lower the machine to a good working height.....

Our shop was once a steel tank fabricating business. They made any size tank and the ceiling is 20' high.....and with the cranes they could build some very large tanks....

You'll be an expert on these when your done Sean.......

Re: Onan 7000 Generator problems
 

Rick,
Although spec states .004 for valve lash, as hot as these things run is that pushing it? Should I open up the lash more?

It make all the difference in the world to have the right tools to safely work on stuff. I was half tempted to make a spreader bar for the engine hoist instead of the lifting straps that I am using. But that means planning on having to work on this more in the future! Its sitting on jack stands until I work on it, otherwise it will be lifted 4' off the floor so I can access the bottom. I can't imagine working on this thing if it was last year before I built my shop.

The overhead cranes would be great, heck the fork lift would make this even easier to get this thing in and out of the trailer a lot faster. I am sure this is a tinker toy compared to the large generators that you typically work on!

Take care
Sean

Re: Onan 7000 Generator problems
 

Sean I set the valve lash with a .004" feeler gauge. The studs tend to loosen up from the heat. I always check the exhaust side studs to make sure their tight. The lash gets tighter as you lock the locknut.....Very tedious to get them right and tight....They seem to run much better with the lash set to .004" and I just advise my steady regular customers that we need to check the valve lash every other time I do a full service on them which is at 500hrs....assuming their machines are working well....

The heat transfer from the valves to the springs/retainers etc. is usually noticeable on the exhaust side just by the color of the metal of those parts.....

The exhaust stud can loosen up and a pushrod pops out and maybe damage a rocker......all this from the heat.....

Re: Onan 7000 Generator problems
 

I can set the 16 valves on my stocker quicker than I did on the 4 valves for the generator. It did take some trial and error on where I was and then locking the adjuster down how much more they would move. So that makes sense. Do the valves tend to loosen about .010" after 500 hrs? I could easily see where a pushrod could fall out of place if this maintenance was not performed.

Sean

Re: Onan 7000 Generator problems
 

Sean they do tend to get looser rather than tighter.
BUT if the exhaust does get tighter, the lash is so small it can lead to early head failure as I have described earlier.

This is a fairly common issue on small engines with solid lifters.

It was new to me when I first started working on this equipment.

They run fine cold and after a warm up and maybe some load gets applied they start to run badly.....shut it off....cools down.....cycle starts all over again....

Onan flathead engines did this pretty regularly......They had a very wide exhaust lash spec at .013"

Exhaust valve needs to touch the seat every cycle to shed some heat of combustion from the valve....No touch.....valve overheats and it magnify's the problem.....

Small engines were a whole new world to me going back 15-20 years ago...

Chasing some of these problems has always been a challenge to say the least....