Replacing an Intake Manifold Gasket

robharvey · **Posted:** Sun Dec 18, 2005 6:00 pm

OK....here's the situation.

1999 Chevy Venture van. The intake manifold gasket had to be replace 3 yrs ago (49K miles) after it developed a leak and there was Dex-cool coolant leaking everywhere. At that time, Chevy knew they had a problem with the cooling system (blame it on the coolant, the gaskets, or whatever you want to) and even though the car was out of warranty, they agreed to fix the gasket at no cost to me. So, it's 3 years later and guess what.......the damn thing is leaking again. I've done a good bit of reading on this and found a TSB that was released in Mar 2003 where GM documented not to use the original gasket, but instead to use their newly design gasket. Unfortunately, this came out after the repair on our van had occurred. There are all kinds of class action lawsuits out there in regards to the number issues GM has had with their cooling systems that use Dex-cool.

I went to the dealer on Thur and they confirmed that it is the intake manifold gasket. They said it would cost $853 ($190 parts, $663 labor) to replace the gasket and they recommended the cooling system be flushed (which was another $125). At this point I kindly asked them to remove the van from their service area as I would be discussing this matter directly with GM (as I don't see it as a dealership issue....I see it as a design issue with GM). I've been told that the probability of getting GM to agree to more than one "good will" repair on a vehicle is pretty close to zero. I plan to call GM first thing on Monday to discuss.

Now, here are my questions............

* Has anyone had this type of discussion with GM and can offer any advise?

* As of right now, if GM offers no assistance, I plan on changing the gasket myself. I read through the steps involved and it doesn't seem to be very difficult, just time consuming. However, if the gurus out there think its not a good idea to do this, please let me know.

* Any recommendations on where to get GM parts at a better price than the dealership?

* I looked online at Advance Auto and Auto Zone. They have the gaskets for $50-$60. Would you consider using something other than OEM? If yes, which brands would you use?

* Anyone have experience flushing a cooling system that uses Dex-cool? Is the process any different than a traditional system? I have read about issues with air being trapped in the system.

*Since I will be removing the intake manifold, are there other preventive maintenance items I should consider?

Finally, I ask that the replies to this post be in regards to the questions above. I'm not looking to start a debate on different types of coolant or on Ford vs Chevy, etc. Since, I'm looking to resolve this issue over the next 2 days, I'd like to keep this thread focused on these questions (unless I have left off something of vital importance that needs to be communicated). Thanks

Rich Anderson · **Posted:** Sun Dec 18, 2005 6:25 pm

I would check to see if Victor Reinz has a sealing solution for this application. Often they will make a gasket for well known problems that are designed to compensate for shortfalls in the original design. Chances are the original is either Fel-Pro or Victor as they provide a large percentage of Big Two and Half OE gaskets.

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

What engine do you have in the Venture?

The intake manifold gasket is a common problem with the 3.1, 3.4, and 3.8 liter V6 engine. Most prevelant in the 3.4L but that is only because they made more of them. This problem has been around since the mid-90s. GM has redesigned the gasket twice I beleive. My theory on the leaking is part gasket, partly the machined surfaces, and mostly that the way the manifold bolts down the bolts can't keep good pressure on the mating surfaces where you start to see the leak.

My wife has an 00 Monte Carlo and my daughter has a 99 Grand Am. Both have the 3.4L and both exhibit the leaking gasket. On both cars if you look by the thermostat housing or under the TB area you will see it when it starts. It will puddle in the groove/galley of the intake manifold. Both vehicles have a 100K on them but started to show around 70K. Mine don't leak all over the place. I just have to top them off from time to time.

I never contacted GM as it would be pointless given the mileage. If you want to chase after GM forget the dealership. However you need to contact one of the local ones and find out who the Zone/Area rep is. That is the first part of the escalation process.

As far as the parts. I have a dealer that will get you parts at wholesale + 10%. He is the one I get all the parts from for the Vette, Monte, and GA. The GM gasket as Rich pointed out is probably Felpro. I've used Felpro almost exclusively on GM engines with no complaints. I'll post the dealer info for you.

Now as far as DexCool is concerned it has nothing to do with your gasket problem. I have DexCool in all our GM cars. I won't get into a coolant debate but I have run DexCool for many years and it works fine for me. The biggest thing is if you are going to flush and replace or add to a DexCool system. You NEVER use tap/drinking water. It must be distilled ONLY. If you think DexCool is bad then flush the system and convert to the Green stuff. Once you go to the Green stuff then NEVER go back to DexCool or use it to top off a system with Green.

As far as doing the repair. I would say do it yourself. It is all labor intensive. Doing it isn't horrible. I haven't done it yet but wouldn't think twice about it. Get a Haynes manual or look on the web on any of the forums (W-body, F-body, etc). There are detailed procedures for doing it. If you do it then you'll be pulling a lot of hardware off the top end of the motor. It would be a perfect time to replace the plugs, wires, any distributor parts, thermostat, and any hoses that look bad.

Flushing a DexCool system. I avoid the cooling system flush treatments. When you go to drain the system besides just loosening the drain petcock on the radiator. If you can get at them remove the knock sensor(s). When you remove them you usually get just about all the coolant out of the block. On my Vette I dumped everything. Then filled with distilled water only and ran it for 10-15mins. Then let it cool down and drain some out of the radiator. If it looks nasty then add more distilled water, run, drain radiator, until clean. Then I drained the radiator and added DexCool until I got about 2 gallons in. That was with almost 100K on the engine and the car was 10yrs old. Yours should be cleaner. Remove the overflow jug from the system and clean it out thoroughly.

As far as air trapped in the system. No problem. If your reservoir is the high point of the system then the air will eventually get out anyway. But if you look on the radiator hose coupling and possibly one by the heater hose connection. You will see a bleeder. It's a small brass bolt screwed into the fitting. There are always 1 or 2 on these engines. Get the engine properly warmed up. You need the thermostat to be open. Loosen one at a time just a bit until you hear it fizzle. Leave it open for a minute or so. Then open a tiny bit more and make sure all you get is a steady stream of coolant. Tighen it down. You're done.

Graham

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

Any GM vehicle parts at good prices. Gene Culley is the parts manager. Real nice guy and his parts guys are very helpful.

http://www.fredbeansgmparts.com/

Parts Manager
Fred Beans Pontiac Buick GMC
gculley@fredbeans.com or 610.495.1700

robharvey · **Posted:** Mon Dec 19, 2005 5:01 pm

Thanks Rich / Graham!!!!!

The engine is a 3.4L and the leak is in the exact location that you described. I had already planned on changing the back 3 spark plugs since I changed the front three a couple of months ago and struggled for 3 hours trying to get the damn spark plug boots off of the rear three (with no success). The biggest problem was there wasn't a good way to get to the rear three plugs to get the leverage necessary to remove the boots.

So, I noticed that Advance Auto sells the Fel Pro gaskets. They have two versions but don't give much detail as to what the difference is between the two.

http://www.partsamerica.com/ProductList ... old+Gasket
http://www.partsamerica.com/ProductDeta ... 02&ptset=A
http://www.partsamerica.com/ProductDeta ... 02&ptset=A

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

From the looks of it MS98003T is a complete kit with valve cover gaskets. Might as well replace all old gaskets while you have it apart. MS90565 is just the intake manifold and plenum gasket. Find the the thermostat and gasket also and get one of those.

Forget Parts America. Order that MS98003T kit from Rock Auto (www.rockauto.com). $68 instead of $102 ...

Shame you can't just yank the intake with plenum and all the other crap attached. Would make short work of it.

There is a trick to getting the back 3 plugs and wires but I'm not sure it would work on a van. You can disconnect a couple of mounts and actually rotate the engine forward to get your mitts in there :wink:

Graham

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Replacing an Intake Manifold Gasket

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