Oh where oh where is my oil leak?

[69MyWay]

Alright, I was ready to yank the oil pan tonight and tackle a bad rear main seal. Then......

I started looking. I have oil dripping off the right front suspension compents, and along the right side of the block. Front main is bone dry, timing cover is dry, the back of the front balancer is dry, and the general front of the block is dry.

It is wet starting just below the fuel pump block off plate.

The starter was soaked in oil, but appeared to be the old green tinted 20/50 oil I had in it when the dipstick tube hole blew and I lost several quarts out on the highway.

The drain plug gasket was a little hoakey, and a couple of pan bolts were not all that tight on the passenger side above the starter.

I removed the starter and looked around. The Lakewood bellhousing makes it difficult to see much. THE BACK OF THE OIL PAN IS DRY. The lower part of the rear seal area is dry, and the counter weight on the crank is clean and dry.

I don't think it is a rear main seal. Could it be the oil passage plugs that are positioned around the cam? I can't remember if I tighted those or not, or if the machine shop put them in, or if I did. I really can't remember. However, I would think a leak up there would drip down the block and down the back of the oil pan.

Finally, I am getting micro fine oil splatter on the tail of the car after running at speed on the highway. This indicates to me I have a real problem. Then when I park the car, a few minutes later I get a handful of drips all around.

What do you guys think? Oh, the valve covers, intake, and distributor are dry as a bone in all directions. Plus, I used the high dollar felpro rubber gaskets on the oil pan and valve covers.


My clock is ticking fast on being ready for Sharkfest. I have to tackle this, paint the gas lid door, and some final dress up, then we are done.

 

[Ken]

...then we are done.

Sure you are. :L

_ken

 

[rpounds]

Chris,

You say that you have oil around the fuel pump block off plate. I'm not as familiar with the big block, but on the small block, there is a 3/8-16 threaded hole that runs through from the front of the block to the passage where the fuel pump actuator rod resides. If there is no fuel pump, therefore no actuator rod, oil is free to weep out of this hole. Even with the actuator rod in place, it is good practice to insert a short 3/8-16 bolt into this hole. Is there any chance that the oil could be coming from there? Just an idea . . .

Ron

 

[gary b.]

Have you checked the oil sending unit ? I've had those go bad before on my other cars......... just maybe.
Good luck, hope tou find it soon! gary.

 

[69MyWay]

Oil sending unit is good and dry, and on the driver side of the block.

I cleaned and fooled around with it last night and this morning. Drove it to work, then brought it home over the lunch hour. It was still leaking and streaking the back body panel.

Back underneath it. I jacked it up level and opened the trans drain plug. It ran several ounces of fluid out. Hmmm, how did it get over full?

I then noticed that my stupid fancy dipstick appears to have a light stream of oil coming down from where it pressure fits into the pan.

I sleeved that and doulbe clamped it. It don't look pretty, but who is going to be looking there anyway?

I cranked it up and let her run for five or ten minutes at an idle, and I reved it once in a while. So far, it is dry.

So, I will track it back to work on Wednesday and see what happens.

 

[69MyWay]

I am beyond baffled.

Drove it to and from work yesterday, just left a quarter size drip on the floor.

Drove it down to see TZracer last night (about 15 miles each way), got home, and she it toast down there. The starter is soaked, the right floor pan is splattered with oil, and it is all up and down in the edge of the gasket on the right side of the block between the oil pan and block.

It is almost as if the pan gasket has a weak spot in it, and the slinging of oil at speed is pushing it through out out on to the starter etc,.

The driver side of the block is dry! All around the oil filter, and the pan going from front to back and over the center is dry. The lower part of the rear lip of the pan that goes around the rear main cap is dry. It picks up drips and wet spots from the passenger rear oil pan bolt around to the starter.

Am I loosing my mind? I guess I need to take the pan off. The top of the block is dry. No sign of valve cover, intake, or distributor leak. We have ample crank case breathing.

Have you ever heard of a rear main that leaks on only one side of the engine?

 

[69MyWay]

I have really lost sleep over this!


Anyway, I am now convincing myself that one of the oil galley plugs on the back of the block around the camshaft is loose and leaking. I am thinking it is one on the passenger side of the block. It must be leaking down the rear passenger side of the block and making nice little puddle between the rear main cap area and bellhousing plate. It must then seep over and drip off of the starter.

So......


As soon as I can, I will yank ye old transmission, bellhousing, clutch, flywheel, yadda, yadda, yadda.

I will be so ad if I get all that open and find no signs of a leak around these plugs.

I am under 30 days now and counting that the 69 has to be full functional for sharkfest. I have lit my candle at both ends, and now in the middle!

 

[69vettester]

Are you sure you have the right pan gasket installed..did the 454 do a pan size change like GM did with the small block in 74-75??Perhaps the rear neck area of the Pan is not sealing with the neoprene one piece? My 2centavos is make sure the pan gasket is correct, and change the rear mainseal while your at it. Im thinking that rear mainseal leaks can be deceiving? the flywheel and clutch assembly can really sling a little leak of oil all over??
Good luck
Tom

 

[69MyWay]

Well, I did buy a high dollar Mildon extra capacity pan. Very high quality stuff. I will snap some pictures underneath.

I have what is called a Mark IV big block. As far as I know all Mark IV blocks have the same oil pan mounting.

I will check into it though.


Thanks for the idea.

 

[69vettester]

Sure,
I just cant imagine that you'd leave those plugs out or loose..
But stuff happens specially with the myriad of things you tackled to get your 69 where it is today..

Tom

 

[barrier5]

Have you checked the plug directly under the fuel pump blockoff plate? I doubt if its the oil galley plugs as oil there is under preasure and you'd get a steady stream coming out all the time. Are you sure you have plenty of crankcase venting,it sounds as if it only leaks when the motor builds up preasure.Luck
P.S. You need an old Harley,then you would'nt even pay attention to oil leaks

 

[Scott81]

69,

Go to the local GM dealer and get a bottle of the oil leak detector stuff, can't remember the name I'm having a brain cramp. It's $5 or so, put it in run the car a while and put a UV light on it. Leaking oil all the way to BG won't be a good thing after all the work you've done on that car.

 

[RalleyRed]

Chris,

I've got to ask, and I know it sounds too simple but you said you had oil at the bottom of the fuel pump block off plate.

Are you sure that gasket isn't damaged, it would be very upsetting to check such an easy thing last only to find that that's where it was coming from.

I hope it's something as easy and cheap to fix for you.

Rick

 

[69MyWay]

These are all great ideas, and suggestions.

I thought about using the black light technique. However, since I am working with an otherwise clean block, I am not sure it will tell me much.

Right now I can see the results of the leak, I just can't see where it is coming from because it is coming from somewhere out of sight (ie, up in the bellhousing, back of block).

I did check the plug directly below the fuel pump mount, and it was a little LOOSE! That is what really got me thinking that the oil galley plug could be the same on the back of the block.

I just can't remember what I did or did not do back there. I always check those, but maybe I got a phone call, or something came up and I stopped in the middle of checking them.


The leak does not get into full bloom until she has been running at higher RPM. That is why I don't have a leak problem with it just idling around in the yard.

This engine runs more pressure than I am comfortable with anyway, and since I have the ancient muncie trans and 3.55 gears, she is running 2,500 to 3,000 RPM down the highway pushing 60-65 psi on 10W 40 oil. So, there is quite a bit of pressure there during that time.

I am running dual open breathers. They seem to have a good ventalation going on. I would think if I was having a vent problem, I would see the front and rear seal for sure pushing oil out, and or the front and rear of the intake, etc.

So, it begins tonight. I will go ahead and drop the trans, flywheel, etc. At least I can get a good view of things, and clean up some of the mess this little situation has created.

 

[topless82vette]

chris

I had a leak kinda like this on my T/A turned out to be the rubber gasket that seals the intake to the block, it was also a high rpm leak, all I did was smear some silicone inthis area and the leak dissapeared ... it was bad enough to soak the bottom of my car I never had oil on flex plate or torque converter but top and side of trans was always wet, I dont know if big blocks use this same seal as the small blocks do but its a thought

 

[69MyWay]

I am more confused now than ever.

I am sure enough to bet the farm that the intake, valve covers, distributor, fuel pump plate, front seal, and other "obvious" seals are not leaking.

Here is a pic from underneath. Note the drips of oil on the starter bolts and battery cable. This is the problem. When the oil gathers like this, going down the road the wind pushes it up the right floor pan and it gets on the back of the car.

 

[69MyWay]

In this pic you can see the quartermaster clutch assembly still in place.

 

[69MyWay]

This is the trans side of the front cover for the lakewood bell housing. You won't find this set up on a stock trans bell housing.

Notice, no signs of oil slinging.

 

[69MyWay]

Well Dangit....The back of the block above the rear main, and around the oil plugs around the cam is bone dry.

The camera did not really pick up the oil drips, but in this pic, you are seeing it. Believe me, above this spot the block is dry! It is wet all along the bottom rear edge on the passenger side, and I noted I have more drips on the right front suspension.

Is this weird or what?

 

[69MyWay]

In this pic here, you can see all along the passenger side of the pan. The camera did not really pick it up, but it is wet! I realize that the crank slings oil in this direction while the engine is running.

Do you think the fancy pan gasket is bad?


I think I will go ahead and pull the pan in the morning, and the rear main cap. I will even consider putting in a new rear main seal since I have it this far apart.

Thoughts please?