Hey all!

I inherited my Grandmother'* 1996 Oldsmobile ninety-eight several years ago.

Its a great car, has roughly 82,000 miles on it and runs great. Of course I have been monitoring the coolant levels as I was always nervous of the upper intake manifold issue.

About 2 months ago i realized it was drinking Dex-cool at unusual levels. Figuring the worst I sent it in to get checked when I had the oil changed (Full Synthetic).

Shop stated that yes there was a coolant leak (still using Dex-Cool), and that the upper intake manifold need to be replaced. Also Serpentine Belt was cracked and the front Sway Bar is completely gone. They said it was completely fine to drive for now, but should get those things fixed.

My Question is how immediate of a fix is required on the upper intake manifold, im a little short on cash at the moment and would like to put it of for a few months as I have other obligations. Is there a concern that the leaking Dex-Cool can do catastrophic damage to the 3.8 Engine.

Also any suggestions on if/what parts I could purchase myself to save some money when I have them repaired (including Upper Intake Manifold, serpentine belt and Sway bar). From my readings I am concerned that the right Intake Manifold (non-plastic) must be installed otherwise it is not a permanent fix?

Thanks for any help and look forward to learning more about mine and other'* older GM vehicles!

This car should be pulled out of service immediately until it can be repaired, while you still have an engine to repair.

If the engine is currently ingesting coolant, there is an immediate risk of hydrolock, especially if it completely cuts loose. If it happens while the engine is at speed, you are looking at a very high risk for bent rods, blown rings, etc. If it happens when the car is shut off, it can fill the cylinders, prevent cranking, and leak down in to the crank case.

You will want to look for an intake with a 'sleeved' EGR passage, which is essentially a metal insert that goes in to the EGR passage, taking the brunt of the heat. Many also take this opportunity to simply block the coolant going to the UIM. It'* sole purpose is to prevent throttle body icing in adverse conditions. I have not heard of any instances where the throttle body has iced as a result of this modification, however you do it at your own risk. The advantage is that there is no coolant to ingest in the event the UIM fails again.

You should also replace the LIM gaskets at this point, as it is simply another 10-12 bolts away, and they also like to fail soon after the UIM does. The metal framed gaskets also are highly recommended to put an end to this issue.

Also, coolant elbows are another pain point. You may as well have these replaced with metal units while all of the above is being serviced, if you haven't already.

Once you get these addressed, and keep up with maintenance, you are highly likely to make it another 100k+ miles.

Serpentine belt may as well get addressed at this point, since it will have to come off any way to get everything else serviced.

You can probably get away with putting off the sway bar repair, especially after having to deal with the UIM and LIM issues.

Thanks for the response Rjolly!


I am sending you a Personal Message with a question if you don't mind.

I don't mind PM'* as long as it isn't questions about mechanical stuff, because the responses to those questions benefit the forum forever.

Send away!

Get this sleeved UIM...ATP Automotive Graywerks 106001 Engine Intake Manifold and this LIM gasket set...Felpro MS 98014 T Intake Manifold Gasket

and these....Dorman 47065HP Elbow Type Heater Hose. I purchased mine from Amazon as they seem to have the best prices....all three items for 153 bucks!

Awesome. Thank you I have ordered parts through Amazon.




I also ordered the Fel-Pro MS95812 Plenum Gasket Set, as I am under the impression they are better than the Gaskets that come with the Graywerks Upper Intake.

The gasket that came with the ATP manifold worked fine for me.....no vacuum leaks.

sounds good, Ill probably ship them back then, if they don't look much better.


Any input on staying with Dex-cool, once it is all fixed up? I have heard sticking with the Dex is fine once the UIM is fixed, while other people recommending flushing everything and changing to coolant? If I'm changing the topic too much I can make new thread or PM also.

The main concern is that Dex Cool turns acidic when it is contaminated and can eat gaskets. Minerals in tap water, or even exposure to air could be enough to cause it. Maintaining proper service intervals is a must with it.

'Mixes with any' type coolant is also a good bet.

I myself would get rid of Dex-Cool the first chance I get, but that is also because I recognize I am not perfect in regards to vehicle service schedules and prefer worry free stuff.