Dreaded GM 3800 intake manifold gasket problem?

[Benzadmiral]

It looks like my '03 Buick with the non-supercharged 3800 (72K miles) might be due for surgery.

Thanks to info here, I've kept an eye on the Dex-Cool coolant since I bought the car in late '07. Two UOAs have shown a hint here and here of higher sodium, but no indicator of a leak, and the oil has always looked fine. Last month I noted the coolant recovery tank was a little low when the engine was cold, so I filled to the FULL COLD line with distilled water. Today, after a swift 10-mile drive, the tank level was a good quarter-inch below the FULL HOT mark.

I don't see any leaks, but I'm not sure I would anyway. So it looks like I have to get this investigated, and maybe repaired, pretty soon. If it's just a minor leak, great, but maybe I might as well defuse this time bomb now. My questions:

1) When I mentioned this to my regular mechanic, he said they've had success in the past using sealant tablets (?) combined with a coolant change. Now I like to save money as much as the next guy -- probably more -- but posts here suggest that this is only a temporary fix, and one which might make things worse in the long run. True?

2) What exactly is the procedure, and what are the names of the parts? I've seen references here to both the lower intake manifold (LIM) gasket, and to the upper manifold and EGR pipe. Which parts should he be planning to replace? Is there a TSB he can reference?

3) I suppose he'll need to change the oil as well as the coolant, and so there's no point in my changing to the Castrol Edge right now. Should I do a couple of short OCIs with inexpensive dino, to make sure any coolant residue is out?

4) How long does the procedure usually take, and about what should it cost?

TIA!

 

[sciphi]

If you do need to change the IM gaskets, here's an excellent reference: http://www.pontiacbonnevilleclub.com/forum/viewtopic.php?f=53&t=3591

Read that, then get a pressure test done. That'll tell you if the leak is internal, external, or if it's a radiator cap.

The cost is about $250 in parts for the DIY. At a shop it will be that plus 4-6 hours of labor. I did my intake gaskets myself, and it cost me about $250 after everything.

 

[Benzadmiral]

Thanks, sciphi. So I should have my guy do a pressure test first, to nail the diagnosis down? And if it's internal, then off we go to the OR?

Both the upper and lower intake manifold gaskets have to be replaced? I might do well to rent a car for a day or two and let get the job done without a rush.

 

[sciphi]

Yeah, do the pressure test to confirm the diagnosis. Then budget your resources accordingly.

It's best to do everything in 1 shot while you're in there. If the upper manifold is leaking, the lower manifold gaskets are not far behind. And the upper has to come off to replace the lower intake manifold gaskets anyhow. It's not much more work to replace the lower intake manifold gaskets once everything is removed.

 

[barlowc]

I loved the NA 3800 V6. My previous car, a 99 Grand Prix GT, had that engine and never once had a single problem (with the engine). I sold the car about 2 years ago at which time it had 175,000 miles on it. Back in those days, drinking the 3,000-mile / 3-month Kool-Aid, I religiously changed the oil and filter every 3K miles. I used whatever 10W-30 brand name conventional that I could get cheap, which was Mobil Drive Clean (the predecessor to Mobil Clean 5000) most of the time because Costco sold it for $12/case. I wonder if it's still running for the 18-year old kid that bought it from me or if he destroyed it.

 

[Bluestream]

I would guess he likey destroyed it...

 

[sciphi]

The 3800 in my 1999 Buick LeSabre had the lower intake gaskets and upper intake replaced this past fall at ~66k miles. The lower intake gaskets were starting to fail, but they hadn't failed yet. We replaced them with aluminum gaskets that aren't affected by the coolant.

While we were in there the lower intake manifold was ported and the openings in the head chamfered. Along with a computer reflash and a lower-temperature thermostat, the ported manifold made the car come alive.

 

[dwcopple]

sleeper LeSabre!

 

[wtd]

I just had the lower intake gaskets replaced on my 2004 Monte Carlo SS with the supercharged 3800. I also had the two plastic elbows replaced as well as the gasket under the supercharger. I supplied the upgraded intake gaskets, plastic elbows, valve cover gaskets, oil and filter. The mechanic bought the gasket under the supercharger. He charged me $342 and I spent about $110 on the parts I provided for about $450 total.

My car had about 90,000 miles when the repair was done and the intake gaskets were beginning to come apart in a few places around the middle ports. It was leaving fluid on top of the intake but nothing in the oil that you could see. I would say change it now before it becomes worse.

Wayne

 

[The Critic]

Mitchell shows 3.3 hours to replace the Lower Intake Manifold gasket. Labor rates are about $120/hr over here, so I would expect to spend about $400 on labor. The Fel-Pro "2nd design" Lower Intake Manifold Gasket lists for $53 on Rockauto.

There is a TSB, #04-06-01-017 issued 5/26/04 which discusses new upper intake manifold service kits. In that TSB, they discuss that some of the newer upper intake manifold gaskets are of a more robust design.

 

[Benzadmiral]

Just spoke to my regular mechanic, and he can run a pressure test on Thursday morning and see what's what. He says if it'll hold pressure, then the GM sealant tablets may be all I'll need. If it doesn't hold pressure, then he can investigate.

He tells me, however, that the coolant can't get into the oil -- that if the manifold gaskets leak, they'll leak coolant to the outside of the engine, not the inside. Say what? Did I misunderstand him?

 

[Trav]

Time to find a new mechanic.Seriously these can leak internally right into the lifer valley.

We do these often,we have had great success with ATP replacement upper manifolds,they come with upper gasket and 2 sizes of EGR chimney to fit all years covered.
They have a metal sleeve around the chimney to prevent burn through,the chimney also has slightly more clearance between the
sleeve.

Use GM aluminum gaskets,these are the latest design and seem stronger and more durable than the Fel-pro ones.

This is a straight forward job be sure to buy new plastic coolant elbows to the manifold with new o rings.
We use GM OEM for these.

We use a new thermostat (GM OEM with pintle valve) and peak green when refilling the coolant with no sealing tabs.

This is a good time to clean the injectors,we use our ASNU machine but doing it at home without this machine is difficult,sending them out for cleaning and new filter baskets is a good idea at higher mileage.

Edit Before we disassemble the manifold we remove the thermostat and heater hoses and flush the system with a garden hose until it runs clear.

 

[Benzadmiral]

Trav, you mean the "lifter" valley, right? In any event, if the system holds pressure, I shouldn't have to do anything just yet.

I've been going to this guy since 2002, and he's not steered me wrong yet. It's true his major focus is on Benzes and Jaguars, but a lot of his customers are also Ford and GM owners. Is it possible he just isn't aware of this -- that giving him a TSB number, as The Critic kindly posted above, will make him realize it?

If he won't do it, what sort of shop should I look for? My local dealer would be fine, but more expensive than I'm ready for.

 

[Trav]

Correct,lifter valley,my bad spelling sorry.
There is a TSB i believe refers to leaking from the throttle body which would be an external leak.

Its been my experience that this TB leak is far less common than LIM gasket failure.He maybe thinking it is a dry manifold with just coolant passages at the throttle body which is common on many vehicles.

Point out to him that this is a "wet" manifold with a long history of internal gasket failure.
EGR chimney to coolant passage burn through is also common.

Any decent shop should be able to do this with ease.

Pressure testing will tell if there is a leak,if its not external then almost 100% its the LIM gaskets.

 

[10bears]

Originally Posted By: Benzadmiral
Trav, you mean the "lifter" valley, right? In any event, if the system holds pressure, I shouldn't have to do anything just yet.

I've been going to this guy since 2002, and he's not steered me wrong yet. It's true his major focus is on Benzes and Jaguars, but a lot of his customers are also Ford and GM owners. Is it possible he just isn't aware of this -- that giving him a TSB number, as The Critic kindly posted above, will make him realize it?

If he won't do it, what sort of shop should I look for? My local dealer would be fine, but more expensive than I'm ready for.


Paul,

Part of what might be confusing the issue for your mechanic is that there was supposedly a class action lawsuit verdict **in Canada** whereby GM was required to pay for some of these repairs on the 3800 V-6's.

But what was required were the sealing tablets and a throttle body gasket. I don't personally consider that to be an adequate fix.

As Trav pointed out, the Upper Intake Manifold (UIM) has an EGR stove pipe that sticks up into it from the Lower Intake Manifold (LIM). That stovepipe slowly "cooks" the plastic of the UIM... and near that passage is the coolant passage for the throttle body.

I recently DIY'd the UIM with the improved APN (Auto Parts Network) part and used the metal framed LIM gaskets. In my case, I used the Fel-Pro metal framed LIM gaskets though most people prefer the GM aluminum framed LIM gaskets. I agree with that.

What I found:

In advance, my car's coolant recovery tank would go down about 1/2" in roughly an hour of use. Confounding things, sometimes it wouldn't use at all. And, the pass side front water port was leaking externally, so this mislead me into believing it was entirely external.

Upon disassembly, I found the aforementioned EGR passage to be badly eroded and the first hints of leakage internally. Also, I found most of the wet LIM bolts threads seeping.

The tensioner elbow was cracked and leaking externally, but these are cheap and should be done whenever the UIM/LIM refit is done.

I'd call the job "intermediate" skill level though that's probably influenced by working in a freezing garage while fighting the flu.

One additional note: I had to replace the oil pan gasket due to leakage. On my car, I found that there was over half a quart of oil still in the oil pan when I took it down.

So since I suspected some coolant contamination, the following 3 oil changes I made sure to vacuum out the remainder in the bottom of the pan. Kitchen experiment with a shaker showed me that oil quickly stratifies on top of water in just a few seconds after shaking (not stirred)

Anyway, Sciphi gave the link to Bill Buttermore's good article on this job and that's what I followed during my DIY job on this. Also, another enthusiast named Bob Naylor in Texas sent me a zipped folder of pictures and files for this job. My ISP is stingy, but if you want that folder of info, feel free to PM or email me and I'll try to send it to you.

My car's coolant recovery tank stays perfectly full. I used Zerex G-05 antifreeze mixed 70% strong due to the sometimes very cold environment here.

Out of superstition and because of all the things previously leaking, I did add the coolant sealing tablets... but only AFTER the UIM/LIM refit was done. That's controversial even as such.

Once again, I don't personally consider those sealing tablets a fix for the badly pitted EGR passage, the cracked LIM plastic gaskets, the cracked tensioner elbow...

FWIW, on one of my Dad's Gen II cars, he tried Bars Leaks for a few months and thought he had it licked on his 1998... but then a cylinder filled with coolant and he got "WHUMP" one morning when he tried to start it. Fortunately, that somehow didn't wreck the engine and the UIM/LIM refit brought it back from the dead. No guarantees on that, though... ballooned cylinder, broken rod or worse are all obviously possible upon "hydraulique".

Well, that's my 2 cents worth.

Kind regards,

Larry S.
10*b

 

[Benzadmiral]

Larry,

I've copied the essentials of your post and some of the earlier ones into a text file, and will print it out and bring it to Kevin on Thursday. To be clear, then: If the pressure test shows no leakage, then the project is not yet urgent, right? Or should he open the engine up to inspect anyway?

And when I have this done, it would be a good idea to do a couple of short OCIs to get rid of possible contamination?

 

[sciphi]

Benz, if it's already leaking, get it done, and do some short change intervals. If the pressure test is fine, then consider it a long-term project, to do when you get the chance and money.

I did a fairly short interval when I did mine. They were not leaking, but were close.

http://www.bobistheoilguy.com/forums/ubb...235#Post1647235

The above link shows what my lower intake gaskets looked like when I changed them. The coolant ports were close to breaking through. Note the mileage, too.

 

[10bears]

Originally Posted By: Benzadmiral
Larry,

I've copied the essentials of your post and some of the earlier ones into a text file, and will print it out and bring it to Kevin on Thursday. To be clear, then: If the pressure test shows no leakage, then the project is not yet urgent, right? Or should he open the engine up to inspect anyway?

And when I have this done, it would be a good idea to do a couple of short OCIs to get rid of possible contamination?


Paul,

That is my understanding.

I've only done one of these refits and saw 2 others at arms length on my Dad's cars... and read the internet a bit about it. So I'm no expert on this.

It appears there is the possibility of a fast leak starting suddenly in the EGR passage area, but I don't know how likely that is. I'm thinking if the cooling system holds pressure for a good long time and if you keep an eye on the coolant level in the recovery tank and the radiator, it should probably be ok for awhile.

In reading about this situation, opinions vary a bit. I think that's because the cars themselves are a bit variable.

On my Dad's 1998 and on my car, we saw clear signs of coolant usage for some time before the situation went critical. I think I figured out that when my coolant recovery tank dropped 1/2 inch, that was usage of about 10 ounces.

YMMV.

Best of luck,

Larry S.
10*B

 

[10bears]

Originally Posted By: Benzadmiral
Larry,

I've copied the essentials of your post and some of the earlier ones into a text file, and will print it out and bring it to Kevin on Thursday. To be clear, then: If the pressure test shows no leakage, then the project is not yet urgent, right? Or should he open the engine up to inspect anyway?

And when I have this done, it would be a good idea to do a couple of short OCIs to get rid of possible contamination?


Paul,

I think Buttermore recommended in one of his articles doing accelerated OCI's as follows. I used dino oil for that.

Change oil/filter at 10 minutes. (I did mine at 20 minutes)

Change again at 100 miles. (I did mine at 200 miles)

Change again at 1000 miles. (I got tired of waiting to switch to Pennz Platinum 5w30 and did it at 600 miles)

Again, I vacuumed out the pan on the first 3 because I found that the coolant would almost certainly be lying in the bottom of the oil pan... where that last 1/2 quart lingers.

Larry

 

[Benzadmiral]

Originally Posted By: sciphi
Benz, if it's already leaking, get it done, and do some short change intervals. If the pressure test is fine, then consider it a long-term project, to do when you get the chance and money.

I did a fairly short interval when I did mine. They were not leaking, but were close.

http://www.bobistheoilguy.com/forums/ubb...235#Post1647235

The above link shows what my lower intake gaskets looked like when I changed them. The coolant ports were close to breaking through. Note the mileage, too.


Thanks for the pic! Actually I do have the chance and the money (well, sort of . . .), so I'd like to get it over with. The car is a keeper for sure.