coolant leaking to ??

[crisra]

hi i new in this forum, i have a 97 grand prix gt whit 169K and i notice that is losing coolant (like 1 galon per week), I check the oil and no sings of coolant no leaking to outside the motor,the car is runig great with no smoke can you helpme.

[BNaylor]

Welcome to AF.

It is common especially for 97-98 Grand Prixs with the SII 3800 engine to suffer from internal coolant use due to a bad UIM causing by the EGR stovepipe problem or simply bad UIM and/or LIM gaskets. I've seen cases where there are no signs of smoke (white) coming out the exhaust and no driveability problems.

[abaird]

Yeah the notorious GM intake gaskets, although I have never replaced one on a 3.8(yet) the 3.1s are known for leaking. Pressure check the system first because some external leaks can be hard to see. I saw one leak at the thermastat housing the other day so don't overlook the easy things.

[crisra]

Originally Posted by crisra

hi i new in this forum, i have a 97 grand prix gt whit 169K and i notice that is losing coolant (like 1 galon per week), I check the oil and no sings of coolant no leaking to outside the motor,the car is runig great with no smoke can you helpme.

i see water in right side of motor in the cv joint...and a heavy smell of coolant under the hood(when is hot) but no visible leaks ...thanks.

[BNaylor]

By right side are you referring to the passenger or driver side? Right side is normally the passenger side. Is this water or coolant you see on the axle shaft? Chances are if you have a heavy smell of coolant then it may be an external leak. Possibilities for external leaking are the water pump leaking, heater hoses on the tensioner, radiator hose and the 90 degree plastic elbow from the lower intake manifold to the tensioner.

[crisra]

is in the passenger side I search for leaks in water pump, heater hoses on the tensioner and the 90 degree plastic elbow. And I dont see any leaks, i figured that is the LIM

[crisra]

thanks for your support...

[BNaylor]

Let us know how it turns out. Thanks.

BTW - Flip a coin it could be the UIM or LIM but since you have a 97 model I would replace LIM gaskets, UIM gasket and install an aftermarket Dorman or APN plenum (UIM).

[richtazz]

don't forget to replace that little plastic elbow too. They will split along the seam, and only leak under pressure.

[crisra]

Originally Posted by crisra

thanks for your support...

I change LIM, UIM and the 90 degree plastic elbow. And now i dont need to add more coolant. Thanks...

[rbsteve]

On a similar note, i changed my upper plenum a cpl of years ago thanks to the help of some of you AF guys. However, i never actually changed the lower intake gaskets...Now it seems i have antifreeze in my oil again, and i am regretting not spending the extra couple of hours doing the whole job.

I changed my upper plenum with a new improved design one which i am guessing is still ok. Does anyone know the part number for just the gasket set for the new upper plenum. I wouldnt want to order gaskets for the old style and find out they dont fit.

Also, is there a difference/advantage over using aluminum lower gaskets from GM over plastic aftermarket ones ??

Thanks for the help

-Steve

[richtazz]

the new metal gaskets are much more resistant to the side to side forces caused by the different expansion rates of the engines metals, so there is a big advantage. Fel-Pro hasn't come out with one yet (they still offer only the plastic/rubber oem design), so the GM dealer is the only place to get them.

[BNaylor]

Originally Posted by rbsteve

Does anyone know the part number for just the gasket set for the new upper plenum. I wouldnt want to order gaskets for the old style and find out they dont fit.

GM UIM gasket GM part # 89017554.

GM aluminum framed LIM gasket part number is 89017816 for pinned and 89017817 for unpinned.

[rbsteve]

Thanks for the info, ill be heading to the dealer to get their prices.