98 3800 II, How long will my Intake last?

98 Le Sabre with 48K short trips of Minnesota miles. I am hoping that the UIM and LIM still have lotsa miles to go before the inevitable happens. [1]Does anyone have an example of a 3800 II that has defied tradition and escaped the dreaded stove pipe problem or lower gasket problems and lived to a ripe old age with the original manifold? [2]What is the earliest that anyone has seen problems? I get the impression that this is a ticking time bomb and I want to prevent big problems if possible - but also I don’t want to over react.

98 Le Sabre with 48K short trips of Minnesota miles. I am hoping that the UIM and LIM still have lotsa miles to go before the inevitable happens. [1]Does anyone have an example of a 3800 II that has defied tradition and escaped the dreaded stove pipe problem or lower gasket problems and lived to a ripe old age with the original manifold? [2]What is the earliest that anyone has seen problems? I get the impression that this is a ticking time bomb and I want to prevent big problems if possible - but also I don’t want to over react.

If you've changed your DexCool every 30K miles or two years like you would have the regular stuff, you may not have a problem. The seepage sometimes starts from DexCool and the early plastics in the gaskets. The plastics were changed early on after the problem surfaces. Sometimes the failure is the EGR tube through the upper intake manifold getting hot and deteriorating the plastic around it which happens to impinge on a tube carrying coolant up into the part of the upper intake manifold and to the metal throttle body to warm it up quickly for improved gas mileage. That allows seepage.

The best thing you can do is watch the coolant level when motor is cold and car is parked in the same position as usual. The coolant expands a little if there is a wide range of ambient temperatures. Mine is in a garage which is 45 and up in winter and about 80 at hottest in summer.

There are other things that can lose coolant, like water pump, or radiator seepage, rubber hoses where clamped, etc. But if definite coolant loss starts have a trustworthy garage check.

Mine started at about 65K miles on a 98 after 2 -3 years. And I had it replaced at 75K miles.

Also change the transmission fluid in the car every 36K miles or three years. don't let them flush, just drop the pan and put in a new filter and reuse the original gasket.

I have a 97 with 145,000 miles. It has the original manifold. I think for every 3800 with the problem, there are many, many more that don't have the problem.

I used to focus on the ones that where bad at my friends shop. Now I forget about them and focus on the ones that nothings wrong. I ask almost everyone that has a 3800. At store parking lots, etc... Almost everyone doesn't have the problem.

The car came from an elderly lady and it was driven fairly regularly. Mostly short trips in town but occasionally 100 miles of highway driving. I only have a sketchy maintenance history for the car's first 9 years (47K) but it had been maintained regularly by the local Buick dealer (who is now out of business). I did dig up what records are available but there are still a lot of gaps in the maintenance history. When I recently got the car, the coolant looked pretty good and I suspect that it had been changed at some time in the past. No signs of sludge in the radiator or overflow tank but do plan to drain and refill coolant in the near future. It is good to hear that some 3800 II engines have escaped these problems (LIM gasket & UIM EGR heat damage). I would guess that the primary influences on either of these two problems would be the number of hours operated at the hottest temperature and the number of cold - hot - cold cycles seen by the engine. Please feel free to add any more stories that might give us a perspective on the likelihood of me needing to replace my intake.

If you've changed your DexCool every 30K miles or two years like you would have the regular stuff, you may not have a problem.

I disagree and that is nothing but speculation. :shakehead

The UIM/LIM and EGR stovepipe problem on a SII 3800 is not the result of Dex-Cool or replacing it early. There is no need to replace Dex-Cool at the interval you stated if there are no known problems. GM recommends replacing the Dexcool, specified as a service interval, at 5 years or 150K miles, whichever comes first. Take note of the 5 years. I would not wait to 150K miles if you have a GM car that is 5 years old still with the original Dex-Cool.

However, there is nothing wrong with doing fluid maintenance at earlier intervals. That is a choice and decision of the car owner.


I get the impression that this is a ticking time bomb and I want to prevent big problems if possible - but also I don’t want to over react.

On capricious and arbitrary replacement of the UIM plenum and UIM/LIM gaskets there is no need to do that unless you have the symptoms such as poor driveability, unexplained overheating and/or coolant loss. Don't fix it unless it is broken.

I've done several GM cars '95-'98 with the SII 3800 and only one had EGR stovepipe damage which required replacement of the UIM plenum.

We have documented cases on AF where the original owners of GM cars with the SII 3800 made it to well over 300K miles before replacement of the plenum and UIM/LIM gaskets. The UIM plenum had no EGR stovepipe damage.

I disagree and that is nothing but speculation. :shakehead

The UIM/LIM and EGR stovepipe problem on a SII 3800 is not the result of Dex-Cool or replacing it early. There is no need to replace Dex-Cool at the interval you stated if there are no known problems. GM recommends replacing the Dexcool, specified as a service interval, at 5 years or 150K miles, whichever comes first. Take note of the 5 years. I would not wait to 150K miles if you have a GM car that is 5 years old still with the original Dex-Cool.

However, there is nothing wrong with doing fluid maintenance at earlier intervals. That is a choice and decision of the car owner.




On capricious and arbitrary replacement of the UIM plenum and UIM/LIM gaskets there is no need to do that unless you have the symptoms such as poor driveability, unexplained overheating and/or coolant loss. Don't fix it unless it is broken.

I've done several GM cars '95-'98 with the SII 3800 and only one had EGR stovepipe damage which required replacement of the UIM plenum.

We have documented cases on AF where the original owners of GM cars with the SII 3800 made it to well over 300K miles before replacement of the plenum and UIM/LIM gaskets. The UIM plenum had no EGR stovepipe damage.


As for recommending changing the DexCool at 24000 or two years, that is not speculation. That is the recommendation of a mechanic who does a car repair talkshow available on the internet at www.55krc.com on Saturdays 4-8 pm if you care to listen. Previous program hours are downloadable as MP3 files from home page. He's extremely knowledgeable. He and/or others have indicated the plastics in originals were affected by DexCool and were changed.

The sludging that has occured in some DexCool systems comes with age and deterioration of additives. Another test that one may feel better with is using a voltmeter and grounding one lead and putting the other into the radiator. When the electromotive force generated there is 0.4 volts, it's time to change the antifreeze because it's reacting with the metals.

My UIM has a hole in where the EGR tube deteriorated and coolant started to seep. This occurred at 65-75000 miles. I noticed coolant loss.

You're welcome to keep DexCool or any antifreeze in for 5 years if you wish. I change mine and refill with DexCool because of its good chemical properties for use with aluminum in motors.

As for recommending changing the DexCool at 24000 or two years, that is not speculation. That is the recommendation of a mechanic who does a car repair talkshow available on the internet at www.55krc.com on Saturdays 4-8 pm if you care to listen. Previous program hours are downloadable as MP3 files from home page. He's extremely knowledgeable. He and/or others have indicated the plastics in originals were affected by DexCool and were changed.

:bs:
No thanks. :rolleyes: Just because some mechanic on the Internet says so. :screwy:

We have plenty of old threads at every relevant forum on AF concerning the UIM issue that covers it without re-hashing it. All the original poster has to do is a search and be the judge.


The sludging that has occured in some DexCool systems comes with age and deterioration of additives. Another test that one may feel better with is using a voltmeter and grounding one lead and putting the other into the radiator. When the electromotive force generated there is 0.4 volts, it's time to change the antifreeze because it's reacting with the metals.

I've seen that test pass on GM cars with Dex-Cool as old as 7 years old so it does not prove anything. :rolleyes:


My UIM has a hole in where the EGR tube deteriorated and coolant started to seep. This occurred at 65-75000 miles. I noticed coolant loss.

You are just one such case but there are thousands without a similar issue. :wink:


You're welcome to keep DexCool or any antifreeze in for 5 years if you wish. I change mine and refill with DexCool because of its good chemical properties for use with aluminum in motors.

I have with no problems with Dex-Cool. Plus there are other coolants on the market so why use Dex-Cool. Just about all coolant on the market now is similar to Dex-Cool. Based on OAT - Organic Acid Technology. Prestone and Peak extended life are such examples (5 yr/150K miles). No damage to aluminum. What coolant you use is a matter of personal preference not that any one is better. :grinyes:

[QUOTE=bnaylor]:bs:
No thanks. :rolleyes: Just because some mechanic on the Internet says
[QUOTE]

I realize you're just trying to minimize his knowledge by saying he's on the internet. He's a trained mechanic from the vocational school and has had a shop in Cincinnati for decades. He's a more knowledgeable mechanic than any I've seen on the net or heard on the radio. The fact he has a 4-hour program, up from 2 then 3, that's filled with calls says a lot. I've listened to others, some streaming on the net, and they don't have the mojo. Oh, and he's not on the 'internet.' He's on a Clear Channel radio station and has been for years. The station streams the shows on the net and makes mp3s available for download. I gave the info.

But I'll change my DexCool and transmission fluids and oil at regular prudent intervals on both Buicks. I urge others to make an educated decision on their own.

Hello, I have a 98 custom and had to have my UIM replaced at 50,000 :(

The good news is that i now have 71,000 miles and the car runs like its new. :)

Hello, I have a 98 custom and had to have my UIM replaced at 50,000 :(

The good news is that i now have 71,000 miles and the car runs like its new. :)

I am guessing that the LIM is still original at 71K or did they replace both UIM & LIM?

I urge others to make an educated decision on their own.

Good point and I agree. That is why it is good for whoever posts on AF to get both sides of the story, different points of view, or opinions so he/she can make an educated decision. :biggrin:

STATISTICS would be better to make decisions upon.

Where are they?

:eek:

Statistics? If you have nothing better to do why don't you do that for us. :rolleyes:

In the mean time on the Dex-Cool issue:

GM = 3
'95-'04 GM Car Owners = 0

Click here (http://www.carcomplaints.com/news/2007/federal-judge-rejects-dexcool-lawsuit.shtml)

:popcorn:


February 24, 2007

ST. LOUIS -- The push for a national class action lawsuit against GM for problems related to their Dex-Cool coolant suffered a setback Friday, when a U.S. federal judge ruled that national class action status would be too complicated.

U.S. District Court Judge G. Patrick Murphy rejected the Dex-Cool class action by ruling that the magnitude of the class action, combined with the wide array of state laws involved, would make it impossible to cover all claims under one national class action. The decision can be appealed, but GM vehicle owners may ultimately be forced to pursue claims either in statewide class actions or as individual cases against General Motors.

The class action contends that in over 35 million GM vehicles manufactured from 1995 to 2004, GM's "Dex-Cool" coolant caused serious car problems such as plugged radiators from coolant sludge, as well as head gasket and intake gasket failure possibly resulting in engine damage. GM marketed Dex-Cool coolant as good for 150,000 miles or 5 years without needing to be flushed and replaced with new coolant.

The law firms involved are seeking national class action status to include plaintiffs from 47 U.S. states. A number of statewide class action lawsuits have been filed, although two of those have been rejected already in Michigan and California. Another class action goes to trial in Missouri in November 2007.

I started loosing coolant at 71000 miles, replaced upper plenum, and no more coolant loss

I am guessing that the LIM is still original at 71K or did they replace both UIM & LIM?

They only replaced the UIM.

182,000 miles on my 3800II. Never changed the coolant, never any problems with the manifold leaking.