I have oil down the front of the flywheel inspection cover of my 1955 287 Pontiac motor. I'm pretty sure it looks like a rear main leaking but how can I be sure it's not the rear top of the oil pan? Also could it be that the pan shares a bolt with the inspection cover so if the cover is off the rear pan would be a little loose in the rear top and leak a little. It's a small drip about every 45 seconds, and I believe gets worse while running. This is what lead me to think its a rear main but I want to be sure it's not something much simpler. Anyone do I rear main in this motor and have any advice? Thanks guys.
unless its a old asbestos rear main seal ( anything newer than the late 80's is fibregl***) they leak , can't really fix them , the pan seals are ussually pretty tight on the ponchos , I have heard guys using the rubber lip style seals they offer with success , pesonally ,I haven't tried them yet as I am still reusing my old asbestos rope seals and my stash I have of them .
to replace the rope seal you have to drop the pan and the rear main bearing cap . there is a graphite impregnated replacement that BOP engineering sells thats supposed to be as good as the asbestos one . when you install the new one making sure its packed in the groove with a chunk of old crankshaft or steel rod rolled over it is imperative otherwise it will leak or worse spin in the groove also makes it easier to cut to fit perfect so it wont leak .
Be sure that the oil is actually coming from the lower rear of the engine first. When I was in the repair business, 8 out of ten 'rear main leaks were actually oil sending units, intakes, or valve cover gaskets. Clean all old oil off with brake cleaner, run the car, and recheck to [hopefully] isolate the source of the leak. ---John
Low tech tip on rear main seals. Works on nailheads and should work on the Pontiac. http://www.buickrestorer.com/re****al/re****al.html
I'm pretty sure it's not coming from the top of the engine, I checked distributor, valve covers and intake. I will triple check them tonight. The thing that gets me is there really isn't any oil on the flywheel, so it leads me to think (hope) that its the oil pan because its in front of the flywheel. Other rear main seal leaks I've seen get all over the flywheel. Then again this could be because that's usually on a car that drives... My 55 is getting there but not driveable yet... And won't be until I trace and fix this leak.
Worst part is I just had the engine out to do a freeze out plug that had been pushed out by frozen water. I inspected all the other plugs and they looked like the new ones I was putting in, even the water jacket plugs in the head still had original paint on them and were clean. I would have done the rear main but the engine ran before I pulled it for 30 minutes with only a small water leak, not even a miss. After not running since the 80's, of course took some tinkering with the carb and distributor first. Goes to show, do it right once.........
Since you have to pull the pan you might as well replace the rear main seal and get it over with. They make a tool called a "sneaky Pete" that works like a Chinese finger puzzle. You remove the upper seal and thread the tool into the groove around the crankshaft. Open the mesh end of the tool and push the main seal into it. As you pull the tool back around the crankshaft it will pull the seal around the upper groove. After the rope seal comes out the side you cut it flush with the block. Now push the bottom seal into the lower main bearing cap and bolt it in place. Clean up the pan gasket surface and replace the pan and gasket.
Turned out the corner of the the oil pan is bent so the gasket does not seal tight. Don't understand why there wouldn't be a bolt right on the corner instead in about 4 to 5 inches in on each adjacent side of the corner Posted using the Full Custom H.A.M.B. App!
This is good advise, had a small oil spot under the car that made me think pan gasket or rear seal. Motor was very fresh so leak was frustrating. Turned out it was valve cover gasket out of posittion at the top rear corner, replaced it and the "pan" leak was gone.
Il keep an eye out, but I stuck my nose pretty deep back there and around the top of the engine. I also cleaned really well and ran it a couple times to confirm my thoughts of the pan before getting the gasket. I think the leak is solved but I'm going continue to investigate it to make sure... The car is still very much a project so Il keep it in the front of my mind. I want the built to be 100% correct and even if it mean pulling the engine again this time to trace a oil leak that I "thought" I'd fixed.. Il update this thread if with any future results, but for now it's solved... Thanks for the help fellas as always you guys get a noob like me and pack in the knowledge!!! Love it!! Thanks for letting me drain some brains Posted using the Full Custom H.A.M.B. App!
Can you rig up a low presser air regulator and pressurize the engine and spray some soapy water around and look for bubbles?
Haha never said it was easy, i just took my time and cleaned over and over, double, triple, quadruple checked my theory..... And went for it. But this was over a couple of weeks and I am if read my build forum I pulled the engine so I going back in I may have bumped the pan. Also replacing the gasket took me three tries (two gaskets) and a snapped pan bolt that I had to drill and chase. It was my first oil pan gasket I did on my own and I leaned a decent amount from it. I can tell you the next time il never put an engine back in without a brand new one just to be safe. Wish I did mine while the engine was out but it never leaks oil. Draining the brains of good mechanics since '92
Wow that's great advise never thought to do it with the lubrication system, iv done it to test coils at work and radiators at home. I'm thinking this would have been really good when the engine was out as well. But hey... This here is how I love to learn, and will never forget to pressure test another oil system while an engines out. (And replace pan gasket!) I am going to try the test today but now I wish I had donei t before so I could really inspect everywhere for and leaks. (Especially back of the engine) thanks for the advice and knowledge! Draining the brains of good mechanics since '92
What pressure should I put the system to for testing? Draining the brains of good mechanics since '92
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