Squealing Rear Main Crank Seal

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WildernessRimFab

WildernessRimFab

10 Year
Joined
Dec 2, 2014
Threads
11
Messages
315
Location
Missoula, Montana
72 fj40 with stock drivetrain. I replaced some parts a few months ago including clutch kit, rear main crank seal, and oil pan gasket. Everything went back together smoothly, nothing leaks, and everything works as it should.

After the engine gets up to operating temp for a few minutes, I get a squeal from the rear main seal area that sounds identical to v-belt squeal. I am positive it is the rear main seal area, as the noise persists if the v belt is removed. I also verified that the noise was the rear main seal by removing the bellhousing bottom cover and listening around the area with a piece of raditator hose held up next to my ear. The squeal does not change pitch with clutch operation, 2wd, 4wd, different gears, acceleration, deceleration, oil cap removed, PCV valve removed, or any other variable.

A few weeks ago I went offroading and a long hillclimb seemed to cure the noise for a couple days. It comes back now, but only after driving the truck for about 20 minutes. The truck has been through 2 tanks of gas since the new parts were installed. I thought that the seal would be fully broken and oil-wetted by this point but it hasnt happened yet.

This squeal is present at low rpms , is very loud and very annoying. It likely is there at higher rpms as well but it gets drowned out by all of the other engine noise. I'd like to fix it and also verify that I dont have a more serious problem. The rear main that I installed was a double lipped toyota OEM seal. I lightly oiled the sealing lips but now I am thinking i should have greased the area between the sealing lips.

My plan is as follows:
1. Run the truck in the driveway with the front axle jacked up to see if I can get more oil to flow back against the rear main seal. If that doesnt work, then
2. Remove oil pan and rear main crank bearing cap, try and inject some grease between the sealing lips. If that doesnt work, then
3. Remove the tranny and transfer case and reinstall seal with lots of grease.


Has anyone ever had this problem? Solved this problem?
Maybe it will just go away but I dont feel that lucky.
 
IMHO, number 1 is a non-starter, if the seal isn't lubed by now jacking up the front end is not a solution.

Have you removed the bell housing cover and looked up inside? Is the sound more pronounced with it off?

If the sound is definitely coming from the rear main area, did you set the seal properly. It think removing the trans, t-case, clutch and flywheel is your best bet. The rear main seal is not a good place to have a major failure.
 
reddingcruiser said:
if the seal isn't lubed by now jacking up the front end is not a solution.
Click to expand...

I'd have thought that as well, but the noise WENT AWAY after I crawled up this hillclimb for a few minutes and it was gone for 3 or 4 days.
Im wondering if the seal will be lubed up if I allow the truck to cool down while the front end is jacked up.

reddingcruiser said:
did you set the seal properly
Click to expand...

I dropped the rear main bearing cap and lubricated the inner lips of the seal with a little motor oil. Not enough motor oil judging by the problem I am having. The seal went into place with no drama and the crankshaft sealing surface was in good condition.

Obviously dropping the tranny is a best solution, but it is also the most time consuming solution.
 
I had this exact same problem a couple of years ago after installing a new oem rear main seal and drove me absolutely crazy trying to find where the squeal was coming from ....I removed the bell housing cover as reddingcruiser
Suggested and I sprayed some white lithium grease in between the flywheel and rear main seal as a desperate
Option before I tore it apart but be careful not to spray to much as it will sling the lubricant all over and wipe off excess
Drippings the clutch and flywheel surface mates on the opposite side anyways. My squeal has never returned ever since.
 
Thanks allan man -
I looked at the option of spraying some lube in there, but the distance between the flywheel and the bearing cap is probably about 1 millimeter? Not even wide enough for the plastic straw on the end of a can of spray lube.

Maybe I could spray some in the vicinity and hope that it hits the right place but was hoping to avoid that with a brand new clutch.
 
I tried and sprayed as high as I can to get it to hit the 12 o'clock position then any dripping I would wipe off...I kept the inspection cover off and each time I get a chance I would wipe off....again you don't need to spray a lot and the clutch/flywheel engagement is on the other side.
 
71FFJ40 said:
I would lean more towards the noise coming from the pilot bearing not so much from the rear main seal.
Click to expand...

The pilot bearing is new and went in with the clutch kit. It was is pressed into the crankshaft against a shoulder so it always ends up going in straight. Also, the pilot bearing only spins when the clutch is engaged and you are changing gears. With the clutch disengaged, the crankshaft, flywheel, clutch, pressure plate, and transmission input shaft are all spinning at the same speed. This squeal doesn't change at all whether you have the clutch in or not.

Do I have a fundamental misunderstanding of how pilot bearings function?
 
How's ur valve cover breather? I had a customers 40 make a squeeling noise that mimicked a belt noise, but it was from the clutch cover,

A pinched non oem valve cover breather hose was the cause, you could remove the PCV valve from the side cover and the noise would stop. With the valve cover breather pinched air was being drawn in from the rear main.

Would never have believed it if I hadn't seen it with my own eyes,
 
The squeal persists with the PCV valve removed and a crankcase vented to the atmosphere. I also test ran the engine without the oil filler cap with the same result.

My PCV valve is plumbed into the bottom of the air filter box on the weber 38/38.
 
Pcv valve should be plumbed to manifold vac, and valve cover to filtered fresh air. Care to snap a Pic? Just out of curiosity, noise present with the oil cap off disproves my theory.

WildernessRimFab said:
The squeal persists with the PCV valve removed and a crankcase vented to the atmosphere. I also test ran the engine without the oil filler cap with the same result.

My PCV valve is plumbed into the bottom of the air filter box on the weber 38/38.
Click to expand...
 
Well, I tried to lubricate the seal externally and the squeal persisted. I removed the trans/transfercase/clutch/flywheel and was able to grease the rear main seal in place without removing the seal, the oil pan, or the crank bearing cap. I greased the seal by carefully peeling back the outer lip with a small flat screwdriver and injected grease between the seal lips using a small dualco style grease gun. I injected grease into thr seal around the entire perimeter and the noise is gone. I ran the truck up to operating temp with only the flywheel installed to verify that the noise was gone before I reinstalled the clutch/trans/transfercase.

Lesson learned, grease the dual lip seals prior to install.
A wipe of motor oil was not enough in my case.
 
WildernessRimFab said:
Well, I tried to lubricate the seal externally and the squeal persisted. I removed the trans/transfercase/clutch/flywheel and was able to grease the rear main seal in place without removing the seal, the oil pan, or the crank bearing cap. I greased the seal by carefully peeling back the outer lip with a small flat screwdriver and injected grease between the seal lips using a small dualco style grease gun. I injected grease into thr seal around the entire perimeter and the noise is gone. I ran the truck up to operating temp with only the flywheel installed to verify that the noise was gone before I reinstalled the clutch/trans/transfercase.

Lesson learned, grease the dual lip seals prior to install.
A wipe of motor oil was not enough in my case.
Click to expand...

Wilderness, Stupid question from me, Rear main seal is installed between the flywheel and rear main bearing cap correct? I just rebuilt my motor and have a leak in the clutch cover. It has been over 6 months from assembly and don't recall if I installed it (what a dutz!).

Thanks

Boaf
 
Interesting thread. On one of my first test runs after rebuilding, I got up to speed (60-65) on the highway and heard this terrible squeal that sounded like it was coming from the tranny. Slowed down and it went away, and has never returned. I always thought it was a dry tranny bearing, but maybe it was the rear seal.
 
Yes, it's a good leak. I will take the Exhaust, Trans, Bell housing and flywheel out when I get back home. I am fairly certain that I did not put it in. What a FUBAR. Thanks
 
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