I got my 92 c4 with the LT1 on 12-20-11 and all seemed well. It had 109K miles on it but the carfax and service records showed everything done to this car all the way back to it's first oil change at 470 miles, and faithly every 3000-5000 miles since using Mobil 1. It also shows a new front crank seal at 80025 miles.

At around 110K I noticed the oil smell after parking. Opened the hood and found nothing. Next day put it on a lift and found oil on pan at the drain bolt. I changed the oil put on a new drain bolt washer, cleaned the bottom of the engine off, and went on my way. After about 100 miles no oil smell, no oil under the car. After about another 100 miles the oil smell returned and a drop oil was on the tranny pan.

I had read on the forum about the leaks at the rear of the intake
manifold. I used a l.e.d. flashlight and was able to finally see behind the manifold. I was shocked to see how oilly goo was built up there, and the wet oil on top of that. I am of the belief that the reason it takes time to appear on the bottom of the engine is the distance it travels to get there. Does this seem reasonable to you guys. I found no record of them (intake gaskets) ever being replaced, so they have gone over 100K miles.

Anyway my local Chevy dealer is going to replace the gaskets Monday.
We will see what happens then. Any input is welcome.

 

If you have the tools and any mechanical ability, do it yourself. A very easy/cheap job on an LT1.

 

I have tools, but my mechanical ability is in off road motorcycles. I have learned that my knowledge from my 63 and 69 Vettes from 30 years ago is of no use with this car.

I guess my confidence is rattled that I did not find the problem sooner.

 

Could also be from the oil pressure sender or oil pressure fuel pump enable sender to the rear of the intake.

Pull the electrical connectors from each of the two "cylinders" that screw into a fitting mounted on the rear of the block towards the driver's side of the car. If there's oil inside either of the connectors, the sender with the oil is bad.

Replacing an intake on an LT1 is a 90 minute job since the intake has no coolant flowing through it.

 

OUCH!
A dealership?

Thats gonna sting !

The LT is an EASY intake...its one piece, d/c obvious things like hoses, vac lines, label and set aside. Pull bolts and unveil the mysteries beneath the manifold..Its not bad at all. The Gen-I SBC could be challenging with more things to pull and remove. TPI was 3 piece, then a dist.

Like someone said, look closely at the oil sender to see if the T- fitting is leaking...fairly common and it'll leak a lot. You might want to revise your work order at the dealership....they will do exactly what you ask for. Change intake gaskets. That may not fix the leak...

Ask them to diagnose the leak, then talk to you before proceeding and get a written estimate...

A shop with vague work order is like giving them a blank check....scarey !

Sounds like you got a good car. Those miles are nothing. Thats broke-in. Not much more.

 

Buy a FSM and it will give you step by step instructions on the intake gasket replacement procedure along with the proper torques for the fastener. It's sort of like a cookbook. Pretty much anyone can do most any procedure with the manual.

 

You guys are giving me way to much credit. On a dirt bike I can listen to it and tell you what the problem is. I would have never taken days to figure this out. Also I will check the oil sending units as suggested. I do have very good oil pressure at all rpms and I am not seeing any loss of oil on the dipstick.

I will be more confident as time goes by I'm sure. This car is dream revisited and do not want to mess it up.

 

i started off with atv's (2 and 4 stroke) and now i've done a cam, heads, lifters, intake, etc etc

Just do it...all nuts and bolts

 

 

I bought a service manual today, and I see what you guys mean about how easy it is to replace the intake manfold gaskets. Armed with this info I got a much reduced price for the job at the dealer, and the work will have a 1 year warranty.

Also I checked the oil pressure sending units and they seem fine. Judging from the amount of oilly goo on the back of the motor at the block/manifold junction I am satisfied that this the leak, just was hard to see with out artificial light. Of course I was satisfied the the Colts were going to win the Superbowl over the the Saints.

Hopefully I am right this time. Thanks for all of the help.

 

There's a pretty good chance you're right.

 

This was one of the first "major" repairs I did to my car. With the help of the FSM and some good pointers from the forum, it was a pretty easy job.

 

just did mine last week, i took my good old time and it only took a few hours. did the job a few days ago on my 99 GMC Jimmy and it was much more of a PITA. had coolant running through it, had to remove distributor, fuel lines were a pain to get off. the lt1 was easy. good luck!

 

The gaskets were replaced yesterday, and so far so good. Drove about 80 easy miles and no oil smell or oil on the bottom of the car. Also no oil at the block/manifold junction.
It was cleaned during the installation and is still clean. Before it took about 10 miles to smell oil and find it on the bottom of the car, (The manifold/block junction was to hard see if the oil was there, plenty of goo though).

After I bought a manual I believe I could do it if it needs it again, but this time a Chevrolet dealer did it, at greatly reduced amount, after I negoiated with them. They also warranty the work, threw in a oil change (Mobil 1) and filter, as well as the VPS Cooling system flush and treatment that Chevy dealers are pushing.

We will see if this has the leak fixed, there not much left if it doesn't, except the rear main seal and they said it is fine.

 

Hope the repair proves successful. If by manual, you mean the FSM, good move. Even if you don't work on your own car, it would be a resource for your mechanic. My experience is, you're better off to seek out a well-recommended independent shop rather than a dealer, if possible.