Replacing crank or rebuild engine?
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Mountain Pass
Joined: Jan 2006
Posts: 195
Likes: 4
Replacing crank or rebuild engine?
In my 79 F150 I have a good running 351M with 110,000 miles. The rear main seal leaks badly and has been replced but soon leaks again which tells me my crank is bad.
I am going to test the compression and if it's okay I am told I can simply replace the crank and seal.
Any experience?
I am going to test the compression and if it's okay I am told I can simply replace the crank and seal.
Any experience?
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
Have you checked the oil pressure sending unit? These parts are notorious for leaking and the oil runs down the motor and looks like a rear main. It's pretty unusual for a crankshaft to go bad and simply leak at the rear main. You should be able to see something on the crank like a groove which is causing the leak if it actually is the crank. I'd also check the rear of the intake and the back of the valve covers.
Elder User
Joined: Jan 2004
Posts: 867
Likes: 0
From: Eastern Pa
Check what Bill said first before moving on. I had a leak in mine which someone had put a reman crank in just 5000 miles before. It was cracked straight across the rear journal and was starting to chew up the bearing. Glad I caust it when I did before it became a hand granade.
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