9T3VETTE

Well, I just got done doing a water pump on my dads corvette about 2 weeks back. I was hesitant at first but everything went smoothly and she works fine. Thought everything was good until this weekend.

We took the car to a show and smelled oil burning on the way home. Pulled into a gas station and smoke was coming from the back of the motor. I assume it is intake manifold seal leaking but I am having trouble confirming if it is.

The underside of the car is soaked (with what i believe is oil) The starter, the trans, the exhaust, everything, and it is dripping quite heavily. When i look at the back of the manifold the silicone seal is wet but in my mind it doesn't seem like it would produce as much oil as it is. So is there a way to make sure it is the intake leaking? Is there something else in that area that could leak?

Also, I swear I read on here that the coolant does not need to be drained in order to do the gaskets but then I pulled out the handy FSM and the first step is to drain the coolant. Is this correct?

Thanks for the help guys!

0Paul Ruggeri

You need to drain the coolent to change the intake gasket.
It could be the oil pressure sensor or the valve covers leaking. You may have to clean it off and look closely to see where its coming from.

cumbercr

You just need to drain enough coolant so the level is below the manifold. Are you maybe leaking from the valve covers? Check the lower rear corners. Oil pools there on the heads.

JackDidley

Look under the distributor toward the drivers side. The pressure sensor and switch are there. When mine wet bad it pumped out 2 quarts of oil in about 10 miles.

John A. Marker

I think it is either the oil pressure unit...picture showing it on the back of the block....

or here is a picture off the block.... The two pin unit is the oil pressure switch which runs the fuel pump. The larger unit is the oil pressure sending unit.

With the amount of oil you are leaking it has to be one of these units. You can get these out (takes four hands) if you pull the distributor cap.

9T3VETTE

Thanks for the responses. I will check out the oil pressure unit and the valve cover gaskets before i jump into this.

I will report back with my findings.

DonMeyers

When the leak is from the switch or sending unit, does this mean they need replacing or is there an O ring or something else to be replaced? Or maybe new teflon tape on the threads?

Thanks,
Don

9T3VETTE

Did some searching and still have not found the source. It seems to be leaking above the starter but checking from the top I dont see a severe leak at all. The underside has oil running down a getting the oil filter, starter and the bottom of the trans wet.

Im gonna try cleaning it up a bit and taking it for short drive. Hopefully I find something.

c23racing

If you remove the wiper motor you can see a lot better. use a can of brake clean and blow it off until clean. Let it run in the shop first and watch, if no leak drive it, then ck it out. more then likely if does not leak at idle, it is the intake gasket. but don't forget to look at the dist. gasket.

9T3VETTE

You mean the optispark gasket?? My leak is in the back of the motor and the optispark is in the front..

or am i totally missing something here...

pr0zac

well you didn't say what year it was so he assumed it to be an l98. regardless its the back of the motor.. and it being an lt1 you should be able to see that area fairly clearly.. i would bet its the valve cover gaskets. also you wouldn't have to drain the coolant on an lt1 to change the intake gaskets

9T3VETTE

Ok, that's my bad. It's a 1993 LT1. I cleaned the area up around the oil pressure sending unit and on the rtv bead. Let it idle and no leak at all. Im gonna take it out and come back to see if it is wet.

I did torque the manifold bolts to 35ft/lbs as they were not tight at all. I think this may have solved the problem but im not sure. As far as the valve cover gaskets I dont see/feel anything leaking around them but I will go buy the correct tool to tighten them down (i dont have that big of a star key).

Also as far as draining coolant I'm curious as to why it says in the FSM to drain the coolant??

STL94LT1

There is coolant running through the lower part of the throttle body. This can be bypassed or the throttle body can be seperated from the intake, when removing the intake.

9T3VETTE

Well it seems that it is indeed the rear of the intake leaking. I cleaned it up with some brakes parts cleaner and took it for a highway drive (didnt notice anything at idle).

Came back and the whole back seal is wet. Gonna start tearing it apart this week and fix it up.

STL94, Thanks for clearing that up for me on the coolant.

Thanks for all the help!

natec

I just had a similiar oil leak and it was the oil pressure sensor behind the distibutor. Try to look real closely, it can be hard to diagnose.Take abright light and look at the engine block between the oil pressure sensor and the distibutor. My sensor looked fine from the top but I could see a wet area on the block. I replaced it and fixed the problem. I used a long thin walled 1" socket, could have been a 1-1/8". My pressure switch was about 2.5" or 3" in length.

9T3VETTE

Well everything went smooth. Had a bit of an episode when some shavings dropped in the oil valley when pulling the intake off. My suggestion to other people would be to blow the area around the intake with compressed air to prevent this.

Otherwise, "the right stuff" from permex seems to be a really good sealant and the fel pro gasket kit is the way to go with all the replacement gaskets.

94vettelover2

The right stuff is the best silicone/sealant in the world in my opinion
I hope you did alittle porting & polishing on ontake while it was off or even painted it-red of course.
I always do an oil change after test drive any time intakes(upper or lower) are taken off any vehicle due to dirt/debris falling onto valley.

tblt44

How long did it take you to replace your intake gasket?

9T3VETTE

Took me the better part of the weekend, as i went slow and made sure to mark bolts, etc. It wasnt very hard just a little time consuming.