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1988 FSB, 351W, Towing Package
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Discussion Starter #1
So here’s a video, a family friend mechanic looked at it (albeit took him 3 days to get back with me). I told him I think it’s a rear main seal based on the location of the drip. He called me wanting to do the valve cover gaskets, oil pan gasket, and rear main and said around 1900. I did the leaking valve cover a few weeks ago and know it’s fixed. I still have the gasket for the other valve cover so I could do it if needed. The oil pan gasket and rear main are above my capabilities with my tools and set up. He said he could do both of these around 1300! This seems real high. I’d like to just replace one of them, what is leaking here? For sure the rear main, right?

Video here:



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Has to be the rear main seal. especially if it stops when the engine is off. I would also consider the oil pan gasket and you could do the oil pump at the same time. Essentially he will have to unbolt the engine from the transmission and raise it or remove it from the engine bay. Look up all the best gaskets for it so there is no future failures.

I'm guess the first quote of $1900 was pulling the engine and resealing it with all new gaskets? Only way I would pay that; by this age we need all new fresh modern designed gaskets. 2nd quote is just unbolting the transmission and raising the engine up off the engine mounts. Engine swaps and engine resealing jobs are no easy task. Some people can do it quick I can't. But then again maybe they have lifts to use also and aren't laying on their back on the concrete.
 

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1988 FSB, 351W, Towing Package
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Discussion Starter #3
Has to be the rear main seal. especially if it stops when the engine is off. I would also consider the oil pan gasket and you could do the oil pump at the same time. Essentially he will have to unbolt the engine from the transmission and raise it or remove it from the engine bay. Look up all the best gaskets for it so there is no future failures.
Thanks! It does stop when the engine is off. I think I’ll have him do the oil pan gasket too I suppose, he said around 700 for the rear main and usually just under 600 for the oil pan. I figure with some labor overlapping it’ll be around 1000 for both of them

They’re billing around 95/hour I believe. What would the extra cost be for the oil pump would you guess?


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Is this a fairly new leak?

When you were doing the valve cover gasket work, did you hook the PCV line back up to the its vacuum source (assuming intake manifold but not familiar with your engine)? If your crankcase can't vent, it can build up enough pressure to blow through one or both of the crankshaft seals.

A simple test I learned in the diesel world is to take off the oil fill cap off and check for blowby. I would hate for you to spend the money to reseal the engine if you have an excessive crankcase pressure problem. I can't watch the video because my company doesn't allow access to Drive, but if it is a new and significant leak, I would poke around before just assuming the rear main went bad. They go bad, but they usually show signs of failing health.
 

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1988 FSB, 351W, Towing Package
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Discussion Starter #5
Is this a fairly new leak?

When you were doing the valve cover gasket work, did you hook the PCV line back up to the its vacuum source (assuming intake manifold but not familiar with your engine)? If your crankcase can't vent, it can build up enough pressure to blow through one or both of the crankshaft seals.

A simple test I learned in the diesel world is to take off the oil fill cap off and check for blowby. I would hate for you to spend the money to reseal the engine if you have an excessive crankcase pressure problem. I can't watch the video because my company doesn't allow access to Drive, but if it is a new and significant leak, I would poke around before just assuming the rear main went bad. They go bad, but they usually show signs of failing health.
The only cover I messed with was drivers side, the only PCV stuff in that cover I believe is a vent tube that goes from the filler cap area to the air box. That is reconnected, that’s all I’ve changed.

The leak didn’t get heavy after doing this, that was 3 weeks ago. It got heavy after I installed headers, which I believe is unrelated. The only other change I made was replaced cracked vacuum lines with rubber and I removed and blocked off the EGR


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1986 Eddie Bauer Bronco 5.0L AOD Full length headers, no cats annoying Flowmasters
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Holy cow, that's a massive leak!!
 

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85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Thats not a leak, that thing is pi$$in oil! Makes me think a gasket is missing, or there is a crack in the block.

Rear main can be done by dropping the trans. Oil pan has to have the engine disconnected and raised. Thats a lot of work, and why the labor is so high.

If it were me, id pull the whole engine and check it over thoroughly. Then reseal the whole thing. As i said, thats a terrible "leak". Reminds me of my transmission that had two giant breaks in the case.
 
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