98 w/81k miles

[ing4016]

After reading many postings about the plenum
failures on Series II 3800s, should I replace or
repair mine now or can I wait a while longer?
If I should replace it now, whose plenum is the
best?
Thanks,
Rod

[maxwedge]

Well, maybe yours won't be a problem? To stay ahead you could get a complete replacement kit from Napa/Dorman, it is updated in the problem area.

[HotZ28]

You must be one of the few wise men left, who believe in “preventative maintenance”; otherwise you would not be asking this question.

If you only use the car for short commutes (5 miles or less), you may buy some time, with keeping a close eye on the coolant level in the reservoir. The first indication of an UIM failure is coolant loss!

Now, if you use the car for longer trips through remote areas, go ahead and replace it soon, before you are sitting along the side of a long stretch of highway, scratching your head and wondering;

how much does a new engine cost?

[ing4016]

I found out the date on the plenum
is 9/25/02. That means it is at least
4 years newer than I thought.
I think the replacement was made
at a Buick dealership. Would they
have this information in their system
and would they share it with me if
they do? I would like to know how
many years/miles this plenum has
on it.

[maxwedge]

What you propose is an exercise in futility, pull off the throttle body you may be able see the start of egr/coolant passage deterioration, otherwise you are going to loose sleep because there is always a doubt, or pull the plenum and look, then the question of potential problems will really be answered.

[BNaylor]

Originally Posted by ing4016

I found out the date on the plenum is 9/25/02. That means it is at least 4 years newer than I thought. I think the replacement was made at a Buick dealership. Would they have this information in their system and would they share it with me if they do? I would like to know how many years/miles this plenum has on it.

If you know which Buick dealership did the work then it wouldn't hurt to ask. They may have a record in their computer system based on your VIN number. If the record is found it will have a mileage annotation.

Personally I would not worry about it unless you are experiencing driveability problems or coolant loss. It it ain't broke then don't fix it. Also, consider yourself fortunate since the previous owner(s) had the dealership replace the UIM plenum with the revised one based on your observation.

Based on the applicable GM TSB # 01-06-01-007A dated 07/18/2001 (Engine Coolant Consumption or Coolant Leak - Inspect for Material Degradation/Replace Intake Manifolds) it called for replacement of the UIM and the Lower Intake Manifold (LIM) to include gaskets. Therefore, there is a high probability the LIM was replaced too by the dealership since your LeSabre has the circa 97-98 SII 3800 Vin "K". If degradation of the UIM was found the TSB called for mandatory replacement of the LIM due to the new EGR stovepipe design.

Part numbers back then:

LIM part number - 24508923
UIM part number - 17113136

[ing4016]

BNaylor,
The number on the UIM is 17109477.
Does this fall in the range of better or
newer plenums? I didn't see the number
on the LIM. Where is it?
The little dial of 4 numbers closest to
the throttle body is the year isn't it?
A co-worker just replaced the plenum
on his 95 Regal. The 12 number dial
on the left end actually said 95 on each
side of the arrow. But the 4 number dial
on the right said 3. Which is the year?

Thanks
Rod

[BNaylor]

Originally Posted by ing4016

BNaylor,
The number on the UIM is 17109477. Does this fall in the range of better or newer plenums? I didn't see the number on the LIM. Where is it? The little dial of 4 numbers closest to the throttle body is the year isn't it? A co-worker just replaced the plenum on his 95 Regal. The 12 number dial on the left end actually said 95 on each side of the arrow. But the 4 number dial on the right said 3. Which is the year?

Thanks
Rod

I really don't know that much about the stampings or how to decipher them, although I have seen them. I looked at a '99 model which has the first revision addressing the EGR stovepipe problem and the dial stampings read or pointed to 4 on both dials. Also, they may not reveal whether the UIM is the updated one. The number you provided is old and doesn't cross reference to any of the newer numbers or the one stated in the GM TSB. The number I provided is still valid, however, it turns out there was another UIM revision around May 2004. According to my GM sources the UIM changed again. The new GM part number is 89017272, which is the latest improved design and includes the UIM and T/body gaskets, and the T/body mount studs. The catch is they all look they same from the outside but once removed you can tell if it was revised. The EGR stovepipe is smaller and so are the coolant passages to accomodate the redesign. It will retrofit to all SII 3800 engines going back to 1995.

Based on my research there are two UIM revisions by GM in which the one above is the latest. Hope the info helps. Good luck.

[HotZ28]

This is how the code stamps work on the factory UIM.
Facing the front of the car, on the right side of the intake (TB side), you will find a date stamp with an arrow pointing to the Year, the UIM was manufactured.



In the center of the intake, you will find a stamp for the Day of the Month, the UIM was manufactured.


On the left hand side of the intake (belt drive side), you will see the stamp for the Month, the UIM was manufactured.

[BNaylor]

Originally Posted by ing4016

BNaylor,
The number on the UIM is 17109477. Does this fall in the range of better or newer plenums? I didn't see the number on the LIM. Where is it? The little dial of 4 numbers closest to the throttle body is the year isn't it? A co-worker just replaced the plenum on his 95 Regal. The 12 number dial on the left end actually said 95 on each side of the arrow. But the 4 number dial on the right said 3. Which is the year?

Thanks
Rod

Now this is getting interesting but confusing.

Re-addressing this post above today I checked out a 1997 LeSabre with SII 3800 which has the original UIM plenum installed. Supposedly never been replaced?? The left dial indicated the so called month of manufacture, the middle dial the day and the third so called year by the throttle body had the numbers 0, 1, 2, 3. The arrow pointed to the 3. So, I can't for the life of me figure out the year of manufacture unless the UIM was replaced but the owner (original) claims it wasn't. This is really getting confusing.

Also, another annectodal observation. For some funny reason all the SII 3800 cars I inspected ('97/'05 LeSabre (2), '97 Grand Prix, and '99 Regal), the UIM showed a date of manufacture of the UIM plenum that coincided with the month and year of actual manufacture of the car at the factory. What are the odds of this coincidence.

For example my wife's '99 Regal LS shows 4 for month, 7 for day and 99 for year on the UIM. The date of manufacture in Oshawa, Canada according to the label on the driver's side door shows 04/99. GM must have some pretty good manufacturing technology and logistics like Super JIT (Just in Time). Funny to see the UIM date coincide with the date of car manufacture. It is mind boggling.

opcorn:

[ing4016]

I'm glad to see I was reading the date dials
correctly according to HotZ28. My friends
95 Regal with 95 in the middle of the left
dial is what confused me.
I have found that the Buick dealer, who dealt
with this car, sold out over a year ago. Could
Buick dealers in general have the service
records (through the VIN)for all Buicks that
have been serviced at a dealership?
In the meantime I want to thank you guys
for the interesting help you have provided.

Merry Christmas
Rod

[BNaylor]

I'm still confused.

Is the date located on the dials the actual manufacturing date of the UIM itself or what? The question I have is why does the date coincide with the month and year the car was manufactured or so called built date which is when an engine is fitted into a car on the production floor at the factory/plant?

I thought I was seeing things when I saw the coincidence. This is a reply from one of our AF Advisors that owns a '99 Grand Prix GT with SII 3800 located in South Dakota. Original UIM. Notice the UIM date closely tracks the car manufacturing date.

My UIM is 6,16,99
Car is 06/99

Anyways, for anyone that wants the most current UIM offered by GM here is the part number for the kit, 89017272 and gasket, 89017554. This is the revised gasket introduced in spring of 2004 because '99 and up SII 3800s were supposedly still experiencing problems with coolant loss even with a revised UIM.

However, due to cost and the better specs I'd take the Dorman's version of the UIM versus GMs. Dorman UIM kits come complete with everything needed for around $120.00.


Pics '99 Regal LS SII 3800, Original UIM


Left (Month) & Middle (Day) Dials - 4, 7



Right Dial (Year) 99


Driver's Side Door ID Label