[Marc68SS]

Hi guys,

Looking for opinions before I head off to the mechanic with my '68 Chevelle 396 ss convertible. Just pulled out of storage and had a big engine overhaul by local classic car garage, new Holley 750 carburetor , timing chain, manifolds etc etc. etc....after a long wait, finally reunited with the car on Friday, she was purring and running like a top....

Took the kids out for a bit of fun and some ice cream on Saturday, about an hour of driving at 50-60 mph the whole way, zero issues and a great day. When we got home, I noticed I had some oil spotting on the driveway, popped the hood and took a look around. Quick chat with the owner of the shop and he quickly surmised that I likely had a "bad rear main seal", which sounded like horrible news based on his tone. This was based on the observation that I could see a very slow drip of oil from the undercarriage of the car, mid body and just rear of the engine compartment. Planned to drop the car off with him on Wednesday but crushed at the estimate of "a couple of weeks before we can get to it".

A bit of poking around on my part after the fact and I came upon this pool of oil below the valve cover, driver's side. Dipstick still showing full on the oil levels, so I ran the car around the block, let idle for a while, can't see more oil escaping here, but there was certainly a good little pool there. Would love to hear some thoughts on how best to approach this, certainly not in my wheelhouse to work on engines like this.

Many thanks in advance, very much look forward to hearing back.

-Marc

 

[LeoP]

I would start with that valve cover gasket. If that didn't fix it, I'd make an appointment with your garage and only take it there on the day of the appointment. Good luck!

 

[Aml383]

The guy you talked to on the phone after discovering the oil leak is the same guy who overhauled the engine ?

 

[Humberd]

Looks like it’s leaking around the valve cover T bolt
Wipe the area down and Try snugging it down a bit see if it helps, don’t crank on to hard. Otherwise as stated above replace the valve cover gasket.

 

[blm]

Its very hard to tell where oil is coming from when it gets blown all over from driving at highway speeds. Clean up the oil with some kind of cleaner. Get yourself some florescent dye at your auto parts and run engine for a bit. Get a black light and it will illuminate the dye in the oil. Should be able to pinpont the leak.

 

[Road Roamer]

Change your valve cover gasket to these. Takes 20 minutes. Fel Pro 1635

 

[69velle]

Change your valve cover gasket to these. Takes 20 minutes. Fel Pro 1635

X2. They are expensive but well worth it. I’ve had mine on and off a whole bunch of times and no leaks. I just make sure my surfaces are oil free and dry using carb or brake cleaner on a rag.

 

[GuysMonteSS]

I would have to agree with the other guys.
The first thing to try is the new gaskets linked above.
Another possibility is that the valve cover is warped where they bolt to the heads.
And one more thing that can lead to these small pesky leaks is a faulty PCV valve.
If it is either one of these,it would be an easy fix compared to replacing the rear main seal.
Guy

 

[Bob's66396]

Hi guys,

Looking for opinions before I head off to the mechanic with my '68 Chevelle 396 ss convertible. Just pulled out of storage and had a big engine overhaul by local classic car garage, new Holley 750 carburetor , timing chain, manifolds etc etc. etc....after a long wait, finally reunited with the car on Friday, she was purring and running like a top....

Took the kids out for a bit of fun and some ice cream on Saturday, about an hour of driving at 50-60 mph the whole way, zero issues and a great day. When we got home, I noticed I had some oil spotting on the driveway, popped the hood and took a look around. Quick chat with the owner of the shop and he quickly surmised that I likely had a "bad rear main seal", which sounded like horrible news based on his tone. This was based on the observation that I could see a very slow drip of oil from the undercarriage of the car, mid body and just rear of the engine compartment. Planned to drop the car off with him on Wednesday but crushed at the estimate of "a couple of weeks before we can get to it".

A bit of poking around on my part after the fact and I came upon this pool of oil below the valve cover, driver's side. Dipstick still showing full on the oil levels, so I ran the car around the block, let idle for a while, can't see more oil escaping here, but there was certainly a good little pool there. Would love to hear some thoughts on how best to approach this, certainly not in my wheelhouse to work on engines like this.

Many thanks in advance, very much look forward to hearing back.

-Marc View attachment 711936 View attachment 711937 View attachment 711938 View attachment 711939

Looks like a simple fix with a new valve cover gasket. I would look into the condition of those valve covers, repair/replace. Is just me, or does that engine rebuild look like it was done a long time ago?

 

[LaVelle]

Huck the chrome covers, or texture the gasket surface. ( smooth chrome surface won't seal )
Make sure the covers have decent baffles.
No mountains from overtightening the fasteners.

One thing commonly overlocked and the cause of the problem, is the PCV system.
No leaks of issues putting around town, but leaks after highway/spirited driving?
The PCV might be a place to look into.

 

[frank1911]

Looks like it’s leaking around the valve cover T bolt
Wipe the area down and Try snugging it down a bit see if it helps, don’t crank on to hard. Otherwise as stated above replace the valve cover gasket.

This first . If it continues to leak, proceed with purchasing new valve cover gaskets.

IMHO if you mechanic is worth their weight, they will have you bring the car back and take care of that leak free of charge.

Btw, beautiful car you have. Remember the worst thing you can do to a classic car is letting it sit. Gaskets begin to dry up and leak. It's the car's way of getting back at us.

Sent from my SM-G930V using Tapatalk

 

[Marc68SS]

Thanks guys, really appreciate the input, good simple fix starting points to work on. cheers, keep ya posted. Marc

 

[Buzz1969]

If you just got the car back and its leaking oil ,I would'nt be buying or doing anything until the shop looks at it. If you do anything they will blame your work as the reason , over tighten ect. ect. Just my thought.

 

[Marc68SS]

Thanks guys, opted to go with a new set of valve covers to go along with gaskets etc, these older ones were tired and just warped enough to be a pain... will fix it right with something that'll outlast me!! Really nice to be part of this site, appreciate the input.

 

[GuysMonteSS]

Thanks guys, opted to go with a new set of valve covers to go along with gaskets etc, these older ones were tired and just warped enough to be a pain... will fix it right with something that'll outlast me!! Really nice to be part of this site, appreciate the input.

Please be sure to let us know what parts you use and how it works out !!
Guy