Tow Vehicle Question

Pistol Pete · 08-07-2015, 07:30 PM

I have a GMC 6.0L engine.

It has a bad exhaust leak coming from the head to the exhaust manifold ( common problem i'm told ).

It has Aluminum Heads, and they tell me the bolts go bad.

The question i have: Is the 8.1L motor have the same issues ??
Does the 8.1 have Steel or Alum Heads ??

Has anybody experienced any problems with the 8.1 Engine ??

Thanks for any input.

Jim Whitehead · 08-07-2015, 07:48 PM

The 8.1 has the same problem. Aluminum head, stainless bolts, and cast iron exhaust manifolds. All dissimilar metals that expand and contract at different temps. A company called Karl products plus the company Dorman make repair kits for this problem. They work if the exhaust leak is caught early.

Rich Biebel · 08-07-2015, 08:08 PM

http://www.hotrod.com/features/1506-...n-big-brother/

I did not think an 8.1 had aluminum heads. The above article says Iron heads and basically just a somewhat redesigned 454......and a very heavy engine..

My buddy had one in a pickup and it had tons of torque and power.
Fuel mileage was not good.
I had a 96 GMC 7.4 Vortec when he had his 8.1....and I drove his home from Maple Grove once. His truck had more low end power than mine for sure....

Greg Hill · 08-07-2015, 08:18 PM

I have a 2001 GMC 3500 with an 8.1 motor. Iron heads. Mine has 112k miles no exhaust leaks. This is the last generation of the Big Block Chevy.

Alan Roehrich · 08-07-2015, 08:57 PM

My 2003 3500 Silverado 8100 has cast iron heads.

ss3011 · 08-07-2015, 09:17 PM

The 8.1 has iron heads, and cast stainless steel exhaust manifolds. It also has mls exhaust gaskets, and special torque specs on the exhaust manifold bolts, and studs. GM put big money into that system to address warrantee problems with previous generation of Mark engines. My 1995 7.4 L had blown the exhaust gaskets, and sheared the bolts due to manifold expansion. I bought all the upgrade parts to fix it, and so far its worked well.

Rich Biebel · 08-08-2015, 12:34 PM

I sold my '96 GMC 7.4 Vortec with about 80-85K miles on it. Many tow miles and never had any kind of exhaust leak problems.

Only issues on that truck was .....a serpentine belt pulley bolt snapped on one trip and I had to get towed and the P.S. pump shaft snapped in half on a cold winter morning. No Power steering or brake boost.....drove to work anyway and fixed it...and I also had one episode of dirty fuel that cost me numerous problems.

Pistol Pete · 08-08-2015, 03:14 PM

Thanks to all for the information, it has been most helpful.

J&P · 08-10-2015, 11:51 AM

I've got an 05 GMC with the 8.1..... Iron heads. Broke 5 exhaust studs a couple years ago..,. it's not "if" but "when".... they will break. The shop who fixed mine has done alot of em.... not just the 8.1
It only has 60k miles by the way
I've got an 05 silverado with a 4.8 and 190k on it and the manifolds just started leaking....

Pete

08-07-2015, 07:30 PM	#1
Pistol Pete VIP Member Join Date: Oct 2003 Location: Punta Gorda Isles, Fl. Posts: 1,626 Likes: 3,396 Liked 777 Times in 209 Posts	Tow Vehicle Question I have a GMC 6.0L engine. It has a bad exhaust leak coming from the head to the exhaust manifold ( common problem i'm told ). It has Aluminum Heads, and they tell me the bolts go bad. The question i have: Is the 8.1L motor have the same issues ?? Does the 8.1 have Steel or Alum Heads ?? Has anybody experienced any problems with the 8.1 Engine ?? Thanks for any input. __________________ "Pistol" Pete Dutko

08-07-2015, 07:48 PM	#2
Jim Whitehead Member Join Date: Mar 2003 Location: MA. Posts: 287 Likes: 153 Liked 150 Times in 41 Posts	Re: Tow Vehicle Question The 8.1 has the same problem. Aluminum head, stainless bolts, and cast iron exhaust manifolds. All dissimilar metals that expand and contract at different temps. A company called Karl products plus the company Dorman make repair kits for this problem. They work if the exhaust leak is caught early.

08-07-2015, 08:08 PM	#3
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Tow Vehicle Question http://www.hotrod.com/features/1506-...n-big-brother/ I did not think an 8.1 had aluminum heads. The above article says Iron heads and basically just a somewhat redesigned 454......and a very heavy engine.. My buddy had one in a pickup and it had tons of torque and power. Fuel mileage was not good. I had a 96 GMC 7.4 Vortec when he had his 8.1....and I drove his home from Maple Grove once. His truck had more low end power than mine for sure.... __________________ Rich Biebel S/C 1479 Stock 147R

08-07-2015, 08:18 PM	#4
Greg Hill VIP Member Join Date: May 2006 Location: Louisville , KY Posts: 1,995 Likes: 68 Liked 279 Times in 68 Posts	Re: Tow Vehicle Question I have a 2001 GMC 3500 with an 8.1 motor. Iron heads. Mine has 112k miles no exhaust leaks. This is the last generation of the Big Block Chevy. __________________ Greg Hill 4171 STK

08-07-2015, 08:57 PM	#5
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,101 Likes: 1,559 Liked 1,780 Times in 405 Posts	Re: Tow Vehicle Question My 2003 3500 Silverado 8100 has cast iron heads. __________________ Alan Roehrich 212A G/S

08-07-2015, 09:17 PM	#6
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Tow Vehicle Question The 8.1 has iron heads, and cast stainless steel exhaust manifolds. It also has mls exhaust gaskets, and special torque specs on the exhaust manifold bolts, and studs. GM put big money into that system to address warrantee problems with previous generation of Mark engines. My 1995 7.4 L had blown the exhaust gaskets, and sheared the bolts due to manifold expansion. I bought all the upgrade parts to fix it, and so far its worked well.

08-08-2015, 12:34 PM	#7
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Tow Vehicle Question I sold my '96 GMC 7.4 Vortec with about 80-85K miles on it. Many tow miles and never had any kind of exhaust leak problems. Only issues on that truck was .....a serpentine belt pulley bolt snapped on one trip and I had to get towed and the P.S. pump shaft snapped in half on a cold winter morning. No Power steering or brake boost.....drove to work anyway and fixed it...and I also had one episode of dirty fuel that cost me numerous problems. __________________ Rich Biebel S/C 1479 Stock 147R

08-08-2015, 03:14 PM	#8
Pistol Pete VIP Member Join Date: Oct 2003 Location: Punta Gorda Isles, Fl. Posts: 1,626 Likes: 3,396 Liked 777 Times in 209 Posts	Re: Tow Vehicle Question Thanks to all for the information, it has been most helpful. __________________ "Pistol" Pete Dutko

08-10-2015, 11:51 AM	#9
J&P Junior Member Join Date: Sep 2010 Location: Seacoast,NH Posts: 16 Likes: 0 Liked 0 Times in 0 Posts	Re: Tow Vehicle Question I've got an 05 GMC with the 8.1..... Iron heads. Broke 5 exhaust studs a couple years ago..,. it's not "if" but "when".... they will break. The shop who fixed mine has done alot of em.... not just the 8.1 It only has 60k miles by the way I've got an 05 silverado with a 4.8 and 190k on it and the manifolds just started leaking.... Pete