Intake Manifold Gaskets - Chevrolet Forum - Chevy Enthusiasts Forums

Intake Manifold Gaskets

Join Date: Sep 2011
Posts: 11

September 11th, 2011, 8:25 PM   #1  
CF Beginner
Intake Manifold Gaskets

I'm new to the site. WOW! Could spend all day just reading.
Anyway. I have a 2001 Suburban 1500, 175,000 miles. Recently had a coolant leak, mechanic replaced water pump and thermostat. Still have a mysterious problem with disappearing coolant. From everything I've read, it sounds like it could very likely be intake manifold gaskets. How do you know if it's that or a head gasket. How long does it take to change the manifold gaskets

Join Date: Jul 2009
Posts: 52
Ridgeway, Ontario, Canada

September 14th, 2011, 6:31 PM   #2  
CF Junior Member
I had the same problem. Took it to the garage and it would be around $600 to install the new Felpro intake gasket (they do them all the time). Since I only paid a few grand for the truck less than a year ago, I added a bottle of Rislone Liquid Copper Intake Stop Leak. Believe it or not, the steady loss of coolant stopped and after 6 months, I have not had to add coolant. I know there is still and intake gasket issue not fixed but at least it doesn't leak!

Join Date: Sep 2011
Posts: 11

September 14th, 2011, 8:11 PM   #3  
CF Beginner
Thanks. I found stuff on line saying it should take anywhere from 2 to 6 hours so I wasn't sure what to expect. I called the dealer and suprisingly they said to estimate 3 hours. I dropped it off at the shop I go to last night, he's going to look at it tomorrow. If it's a few hundred dollars I'll get it fixed, if not I might try your alternative. Like you say, I'll still have the gasket problem, but maybe I can hold off on the expense for a while.

Join Date: Nov 2008
Posts: 2,955
Bowie, MD

September 14th, 2011, 9:21 PM   #4  
Super Moderator
Professional Mechanic
If you have a 5.3 engine there is absoultly no coolant in the intake. Intake problems were on the 5.7.Below is the mostlikely cause.

Bulletin No.: 06-06-01-019B

Date: June 12, 2007


Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

2004-2006 Buick Rainier
2001-2006 Cadillac Escalade Models
2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models
2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models
2001-2004 Oldsmobile Bravada
2005-2006 Saab 9-7X

with 4.8L or 5.3L VORTEC(R) GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z - RPOs LR4, LM7, LH6, L33, L59)


This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

Refer to the illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

Cylinder head(s) location of the Castech manufacturing casting logo (1).

Close up view of the cylinder head(s) showing the Castech manufacturing casting logo (1).

If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).

If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly.

Join Date: Sep 2011
Posts: 11

September 14th, 2011, 10:11 PM   #5  
CF Beginner
Are there other signs to look for if it is the cylinder head? I thought the classic sign was white smoke from the tailpipe, which I don't have. The low coolant light comes on about every 400-500 miles.

Join Date: Sep 2011
Posts: 11

September 14th, 2011, 10:30 PM   #6  
CF Beginner
Since it looks like replacing the head is a major expense, would a product like Duraseal work?

Join Date: Sep 2011
Posts: 11

September 16th, 2011, 5:44 PM   #7  
CF Beginner
What to do next.

OK ... so here's the update. MDTAHOE was right on the money. The leak is at the head. Obviously don't know how bad it is until you get it all apart. Like I said, I'm not a mechanic so I'm paying for whatever the fix is. Pushing 180,000 miles what do you do, replace the head or replace the motor? Really don't want to replace the truck. Would like to know what people think.

Join Date: Nov 2010
Posts: 21

September 17th, 2011, 10:12 AM   #8  
CF Beginner
If it were my truck I would try a sealant first. No guaranty it will fix it but it's worth a try. I like to use Mendtite by Zecol. Works very, very well and I haven't found it to clog up the cooling system like other products. Otherwise I would recommend an engine replacement. A new head would cost quite a bit of money if you can't do it yourself and that money is out the window if the engine fails.

Join Date: Sep 2011
Posts: 11

September 20th, 2011, 9:14 PM   #9  
CF Beginner
Thanks Spicoli. For the time being the shop I go to put some GM tablets into the system. Not expected to be a permanent fix but maybe slow things down for a while so I can figure out what to do. I'm just going to watch for a while and see what happens. I don't seem to have a loss of compression, mileage is staying the same, no smoke from the tailpipe ... he said it may get worse in the colder weather, we'll see. I think I'm going to let it run its course and if it gets worse I'll try one of the sealers. If it works great, if not then I think I'm going to go for the motor change. If anyone else has opinions about which sealers work or better yet one's to definitely stay away from, please let me know.

Join Date: Aug 2011
Posts: 23

September 21st, 2011, 9:19 AM   #10  
CF Beginner
i have done cars/trucks for 20+ years even the best of the sealants are a band aid on a gun shot wound..with those miles doing a new head while leaving the lower end alone is asking for trouble.Find a good salvage yard that removes the engines with wrench's instead of a cutting torch,one that will give a warranty and go that route.You are only delaying the inevitable.

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