I finally had a nice day this weekend to take my vette out for a spin.
I've spent the winter replacing seals, trying to keep the oil IN the engine.

I haven't done a thorough inpection, but when I got back from my drive, I noticed a drop of oil on the bell housing and another drop on the oil pan. Looks like my new rear main seal was a waste of time, the the OnePiece oil pan gaskets seems to be working nicely I also wonder if the oil might be comming from the dipstick tube... I noticed some oil around the top of the tube and around the bottom where it meets the pan. Anyone ever here of that happening?

It looks as though I the new valve covers and gaskets worked out, but I did notice oil around the oil fill cap... I will get a better cap, but I'm wondering if the PCV I installed it good enough. Maybe too much pressure is building in there?

Aside from the oil... I have to say that I am very happy with the way the car ran... All the suspension work and new bushings really gave the car a nice tight feel. The Poly motor mounts make the car feel like it's as solid as a brick. Everything sounded great (execpt the extra vibration from the poly motor mounts gave birth to new vibration sounds in the cab). The brakes are just as they should be. Alignment seems to be right on. I don't appear to be leaking any other fluids anymore.... And compared to how much oil was leaking before, this is nothing. But it still bugs the hell out of me.

PS - I only drove about 20 miles.

 

This rant did contain some questions

Anyone with any suggestions?

 

I want a nickle for every time the oil pan gasket or rear main seal gets blamed for a leak that was coming from somewhere else.

Here is what I would do. Clean the block with degreaser so it has no oily wet areas. Cover the gasket and seal areas with baby powder and fire up the engine. The actual source of the leak will be made visible by the stain in the powder. The problem could easily be from the rear main but it could also easily be from the oil pressure sender connection or rear of the intake manifold or even valve cover gaskets. The oil gets blown around by the air and finds its way down to the pan and bellhousing regardless of where it started and the lower seals get the blame. This is cheap and effective. Give it a try.

-Mark.

 

Check the back of the motor to see if it is leaking from the backside of the intake manifold or the oil pressure sender. Wipe off the dipstick tube and try it again, see if it gets fresh oil on it, if so pull the tube, clean and silicone it back in the hole. The rear seal might seat, are you sure you didn't dammage it on the install and you got it in correctly? It might only go in one way. Did you use any kind of sealer on the ends?
Pull the PCV out and plug it and see if you get much pressure coming from the hole. Is the valve cover on the other side vented?

 

Had this same problem. If the front of the transmission underpan and the back of the oil pan are dry, the seal is probably ok.

 

Doubt that it's your rear main oil seal, unless it was installed improperly.

Installed the one piece FelPro on the oil pan for my 73-350 rebuild. Wound up dropping the pan twice to put RTV on the top and bottom of the front of the gasket.

Leaks from the back of the valve covers sometimes look like oil pan leaks.

 

Two good ways to check for oil leaks.

First, you can go to an auto parts store and purchase a leak checking kit. It has colored dye, light source, and glasses. Helps to pin point exactly where the leak is coming from.

Something else that works is the talcum powder trick. If you can find a dye penetrant kit (for locating cracks in aluminum) they have a developer that has a fast drying powder in it. You can locate leaks with this as well.

HTHs

Bob

 

Here is the leak kit that I was telling you about. I hijacked it off another thread. Thought the kit was pretty neat.

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Update...

First of all... maybe I've been living in the dark ages...but I didn't know about the UV dye kit...this is really great! First used the yellow dye in the transmission and red in the engine oil..(since I'm still dealing with a slight leak around the oil pan and I wanted to eliminate any possibility of engine oil being the issue on the trans). Took the Vette for a 10 mile cruise and put it on the lift...UV light on and WOW! within a few minutes it was clear that the two oil leaks "are not related". Red was clear around the oil pan gasket rear area and a clear red line coming down the front of the flywheel inspection plate..goes nowhere from there..just drips. Will deal with this one after I take care of the Transmission. (fingers crossed that it isn't a rear main seal).

Next used the light on the transmission tail... yellow clear in the areas that above pictures show...however, now I can see that there is no trail from above or toward the front of the transmission. Due to the cross member, I can't really tell if I'm dealing with some leak just above it so I'm doing one final test in the morning. I took a shop rag and zip tied it about 1/4 inch in front of the rear trans seal. Since the leak is so consistent...I'm going to take a very short cruise in the morning and confirm which side of the rag is getting wet...this will seal the deal of it either coming from the rear seal or another just around there. My gut tells me that it is coming from the rear seal and blowing back up and around to the ebrake wheel and neutral switch harness. Will find out in the morning.

For those interested... here is a link to the UV leak system... Wish I would have picked one of these up a long time ago... so many hours would have been saved trying to find hidden or slow leaks. Instructions say it can be used in any of the oil based fluids on a vehicle...have special fluids for AC and Radiator.

www.tracerline.com/lampsandkits_tp-1121.html



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Give this a try and see how it works.

Bob

 

I have some oil drops on my bellhousing. It is coming from the manual transmission. It leakds down somewhere from where the front of the trans mates to the bellhousing...If it is a manual, it could be gear oil.

 

Make sure you have good vacuum to the pcv valve. I had a 71 chevelle that leaked oil every where until I found the weak vacuum.

 

Zora Lives, All Hail.

 

Ok so here is where I'm at.

I guess I will check the back of the Intake to see if there is any leaking... I'll tighten down if nessesary. I haven't checked there yet.

I know that the Manully tranny is not leaking from the front... so it can't be that.

The One Piece Oil Pan gasket is not leaking. When I installed it I used RTV in the corner spots as directed... I love this one-piece, so much easier and more reliable.

The Oil Pressure sending unit is not leaky.

The rear seal I installed was installed very carfully and perfectly. It is in the correct direction and was particularly careful to use the tool to not shave the bead. I did use RTV on the ends as per the direction. I used some grease while installing, ran the engine at operational temp for a good 30 min 1 day after the install... there were no leaks at that time.

As for the PCV... I do have the breather on the pass side valve cover... and the PCV valve is on the drivers side. The valve connects to the correct spot on the base if the carb. When I take the PCV vave off and plug the hole with my finger, I do feel pressure building up.
Do I need a larger PCV valve and larger diameter tube??? I did a crude test on the breather... blew air in and sucked air out, it was easy, so it doesnt seem to be clogged on that end. Since I am connecting the tube from the valve to the correct port on the carb base, I don't see why vaccum would be an issue.

I don't think the valve covers are leaking... I just got some nice new straight covers and got those gaskets that supposidly expand in contact with hot oil. I used RTV as directed. I think I'm ok here.

I'm going to remove the dipstick tube to clean it and seal it back into the pan... This might be the source and solution. But has anyone heard of oil comming out of the top of the Dip stick tube???

I'm going to look for a better oil fill cap... I know some oil is leaking from there... while I'm at the store I'm going to get some of that dye that you all are talking about.

Very helpful suugestions so far! Thanks!

 

Spray on foot powder works good too......

 

its not leaking oil, its marking its territory.

-alex

 

Using talcum powder, etc. works well. Is your distributor housing gasket at the intake good? Good luck.

 

Ok well here is where I stand.

I found that the Oil leaks were from the top and bottom of my Oil Dipstick tube. I put the Sealer around the bottom where the tube and the pan connect, and that seems to have got it. I put a piece of rubber on the top so that when the dipstick is in, there is a seal. So I've seemed to have solved this leak.

The rear seal is not leaking hooray

I replaced the leaky oil fill cap with second breather cap. So now the drivers side has the PCV valve setup as normal, and the the pass side has two breathers... one in the normal spot and another in the Oil Fill. IS THE 2 BREATHERS OK?? If I need to I'll talk about my PCV issues in another thread.

I Drove around for about 45 minutes on I-95... driving around 90mph for a good 5 min straight... Got home and inspected for leaks.
As far as I can tell there are no more oil leaks. I did find Power Steering fluid splashed around because I over filled the PS resivor.