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Discussion Starter · #1 ·
a motor my father and i recently cleaned and painted seems to have a leak. it could be the rear main seal or just the back of the oil pan. we are gonna remove the oil pan and put on a new gasket even though we already did that a few months ago. if it is the rear main seal, how do you replace one on an old 289. do you have to remove the entire crank or just the rear main cap?
 

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Depends on if it is rubber or rope seal. You dont have to remove the crank in either situation. If it is original it is a rope seal. I would replace it with a rubbber one. I use a small dent puller that has a sheet metal screw on the end and screw it into the end of the rope seal and have a partner turn the crank over by hand and you gently move the weight of the slide hammer up and down until the rope is out far enough to grab it with a pair of neddle noise and pull it all the way out. Reinstall a new rubber seal so the lip is facing towards the front of the engine and slowly feed it around the the crank while turning the crank. Sometimes I will losen the rest of the main caps to help with the removal and installation. I have replaced alot of the and never had one leak. You should also clean the main cap and block and use a very little good rtv at the very edge of the main cap. This will keep oil from seeping out.


Good luck

Blue Fastback
 

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Same applies to pretty much any engine. Most people are afraid of replacing rear main seal for some reason. They are actually pretty easy.


Blue Fastback
 

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Food for Thought:
I had a slow leak from the back of my 302 for years after I did a 5-speed conversion. I figured it was the rear main or the oil pan. But when I tour the engine down for a rebuild I found that when I put the flywheel on I didn't use silicone sealant on the threads and the crankshaft on my late model 302 had bolt holes that went streight through. So the synthetic oil I was using seeped through the threads and caused a small leak. This also looks like a rear main seal or rear of oil pan leak.
 
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