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Rear main seal replacement cost?


Reaper1354

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So my 97 ranger 4.0 is leaking at the rear main seal. I was told that this was due to play in the crankshaft which is also causing a knock. Now I know my mechanic said it was a knock but I don't haveany symptoms of a knock, i.e. Economy loss, power loss, metal shaving in oil, etc. so I'm thinking that maybe it's just a valve tap? It does become more difficult to hear it when the engine is up to temp. Regardless, how much would I be looking at to replace the rear main seal, and would it be worth it to replace on the off chance I do have a knock? I appreciate any help, trying to keep the ranger alive!


Edit: I have driven the ranger for atleast 5k miles after being told, if not more and symptoms don't appear and knocking noise doesn't get worse either, unless I'm a quart low on oil.
 
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Well, I would get crank end play actually checked with a dial indicator. There is a spec for what is allowed, and if the thrust bearing is worn it can allow crank end play to be excessive. That could let the rear main seal leak. It can also all happen without much in the way of other noticeable symptoms.

A worn out thrust bearing will eventually spin, and then you WILL have a bad knock for as long as the engine bothers to keep running. If the thrust bearing is worn enough to allow excessive end play a rebuilt or replace is in order, not just a new rear main seal.
 

RonD

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Yes, if you have a leaking rear main seal it needs to be dealt with, and you can check crank end play after flywheel/flexplate is removed to expose the rear main seal, then decide what you want to do.
Main seals do just fail(4.0l is prone to it), but worn thrust bearing will often first show up as a leaking main seal

The main seal itself is not an expensive part, $6, the labor to get to it is the expensive part.
And just as a heads up, the factory finish on the crank where seal rides can be the issue for main seal leaking, 4.0l rebuilder's often use a "sleeve kit" on these, you install a sleeve over the crank surface and then slightly larger seal that comes with the sleeve, about $25

To replace thrust bearing pretty much requires pulling the engine so rebuilding at this time would probably be best.
 
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KnockKnock

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To estimate repair cost, you can use AutoMD to ballpark it, but their estimates don't always include shop supplies and/or disposal fees that shops usually tack on there.
 

Reaper1354

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Thanks I appreciate all the help guys. Never alone would I go ahead and think of the thrust bearing.
 

cp2295

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Found a rebuild kit on Ebay for $300, comes with victor reinz gaskets, clevite bearings, and Hastings rings.... Just saying if the engine needs a rebuild!

Mine needs one too soon :(

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firenexx

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If you have to replace the rear main seal and you're having a shop do it, it can be about $900-1100 if you have 4WD. I did get a few lower quotes from backyard-mechanic types, but I ended up doing it myself even though it was 20 degrees outside. (They have to take out the driveshaft, transfer case, transmission, and the whole exhaust up to where it bolts to the manifold.)

If you have 2WD it'll be a little less but still around the same amount of labor as a clutch job.
 


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