Intake Plenum Replacement Question

[Greg5150]

I am going to replace the Plenum on my 1997 Park Ave as a preventative measure. The car has 60K on it. As I read thru old posts I see some people replace just the Plenum and some also remove the lower intake and replace the gaskets. Question - is it necessary to replace the lower gaskets as well or is just changing the planum enough to solve this problem. Thanks

[BNaylor]

Oh yeah we have plenty of threads at various "H" and "W" body forums covering the issue if the UIM and LIM.

Since you have a '97 with SII 3800 you should carefully consider inspecting the EGR stovepipe area. Whether you get the Dorman or APN UIM kits they will have replacement EGR stovepipes with the smaller diameter and all gaskets. The stovepipe should be replaced when you replace the plenum. If you plan on keeping your car and since you mentioned preventive maintenance I would do the LIM gaskets but use the new aluminum framed gasket set. It is not necessary to replace the LIM gaskets but I have seen 95 - 98 LIM gaskets and 99 and up that do not look pretty. The choice is yours. The PDF file I provided and the thread at Buick Tips & Maintenance covers basic replacement. However, there are always questions that arise over the UIM/LIM bolts, torque values, removal of old threadlocker, use of new threadlocker (blue) and whether RTV silicone sealant should be used when the LIM gaskets are replaced so don't be afraid to seek further advice.

Another overlooked PM item is the fuel injector o-rings.

[Greg5150]

Bob, am I correct when I read that the lower intake bolt should be tightened to 11 lb ft?

[BNaylor]

Hi Greg,

Yes that is correct. Also, around 2004 GM raised the torque specs for the UIM bolts from 89 in-lbs to 11 ft-lbs (132 in-lbs). On the UIM what figure to use raises a question mark. Since the Dorman and APN UIMs are reinforced and thicker plastic I would say the 11 ft-lbs is safe to use since it is only a few ft-lbs difference but you never know.

[gregk001]

Hi Bob
I am trying to find the latest 98 LeSabre 3800 II UIM torque spec from GM but am somewhat confused. I will be installing new GM UIM (89017272) & LIM (24508923) with the GM gaskets (89017816). If possible I will use the original bolts.

Here are the UIM torque specs that I have found so far:
1 - ALLDATA says 10 N·m (89 lb in)
2 - The GM Factory Service Manual (dated 1999) says 15 N.m (11 lb ft)
3 - APN says: First step tighten to 22 inch pounds. Final step, tighten to 89 inch pounds.
4 - You have mentioned that “around 2004 GM raised the torque specs for the UIMbolts from 89 in-lbs to 11 ft-lbs (132 in-lbs)”.
Do you have a TSB number or link that would clear up my confusion?

Originally Posted by bnaylor

Hi Greg,

Yes that is correct. Also, around 2004 GM raised the torque specs for the UIM bolts from 89 in-lbs to 11 ft-lbs (132 in-lbs). On the UIM what figure to use raises a question mark. Since the Dorman and APN UIMs are reinforced and thicker plastic I would say the 11 ft-lbs is safe to use since it is only a few ft-lbs difference but you never know.

[BNaylor]

Originally Posted by gregk001

Hi Bob
I am trying to find the latest 98 LeSabre 3800 II UIM torque spec from GM but am somewhat confused. I will be installing new GM UIM (89017272) & LIM (24508923) with the GM gaskets (89017816). If possible I will use the original bolts.

Here are the UIM torque specs that I have found so far:
1 - ALLDATA says 10 N·m (89 lb in)
2 - The GM Factory Service Manual (dated 1999) says 15 N.m (11 lb ft)
3 - APN says: First step tighten to 22 inch pounds. Final step, tighten to 89 inch pounds.
4 - You have mentioned that “around 2004 GM a raised the torque specs for the UIMbolts from 89 in-lbs to 11 ft-lbs (132 in-lbs)”.
Do you have a TSB number or link that would clear up my confusion?

I sent you a PM message with a link. Sorry since the thread is over 3 months old I'll have to close it. Good luck!