Massive Oil Leak Mystery: Rear of Motor

[Sarrus25]

Hey All,

1986 1st-gen 22RE 4Runner, 5-speed Manual Transmission w/4WD Transfer Case

My truck leaks a ton of oil. I started a new job / living in a new place, so I have honestly not spent enough time thinking about it to draw proper conclusions. Now that I have thought about it, I still cannot figure out what's wrong.

The story that leads up to where I'm at now is detailed below:

BM = Brake and Muffler mechanic (current guy)
FM = Friend Mechanic (previous guy)

• Bought the truck from a buddy. He said it leaked a few drops of oil after driving it. Did not verify with my own eyes.
• Buddy took the truck to a "friend mechanic" (Let's call him "FM")to have oil leak resolved. "Friend mechanic" said it was the rear main oil seal. "Friend mechanic" replaced the oil seal.
• I picked up the truck from my buddy and drove it from Morrison, IL to Kansas City, MO, my new place of residence. It leaked about a quart of oil per hour.
• I took the truck to a Brake and Muffler (Let's call them "BM") shop to have the oil leak resolved.
• BM Mechanic said he thought it was the oil pan gasket. I let him replace it for $500 (stupid of me).
• Drove truck to Chicago / Michigan for the holidays. Still leaked 1qt/hr, so I added in 20w50 non-synthetic so that it would leak less on my roadtrip (70mph most the way)
• Took truck back to BM mechanic. They ran oil dye, but didn't spend enough time to fully analyze where it was coming out of from the motor.
• BM mechanic dismounted transmission, replaced rear main seal. BM said that the FM guy had: busted off bolts in the sway bar, busted off a bolt in the flywheel, screwed up a dowel pin on the rear main seal retaining plate (Said dowel was installed sideways). FM fixed busted bolts.
• BM re-assembled truck, said it still leaks about the same amount of oil.
• BM installed a new rear main seal on the motor, corrected dowel pin.
• BM said it still leaks the same amount of oil. (seal was apparently not seated all the way in)
• BM installed a speedi / redi sleeve on the rear end of the crank (back of motor), new rear main seal kit, valve cover gasket / half moons (not needed, but hey why not, it was cheap on RockAuto).
• BM replaced the PCV valve on top of valve cover gasket, adjusted idle.
• BM said truck now leaks a quart of oil per 60 miles (.25qt/hr).
• BM added "Rislone" (resoline? reselyn?resolone?) oil treatment, suggested by transmission mechanic "as an abrasive / polish to help the seal / sleeve wear in together and stop the leak".
• BM quoted $900 for all work after the $500 oil pan gasket; have not paid yet
• Here we are now...

CURRENT STATUS

New Parts

• PCV Valve
• Valve Cover Gasket
• Valve Cover Half Moons
• Oil Pan Gasket (it's a sealant, not gasket)
• Rear Main Oil Seal
• Rear Main Plate Gaskets
  
• Re-machined flywheel (courtesy mechanic)
• New Clutch (courtesy mechanic)
• Bled Clutch (courtesy mechanic)
• New sway bar bushings (courtesy mechanic)

Leak Rate

• .25qt/hr 10w40(?) or 10w30(?)

Facts

• LEAK ONLY OCCURS UNDER A LOAD, most notably on the highway at 70mph. Will not leak if idling for several hours (thanks, mechanic...)
• Clutch has been dry the entire time (supposedly)
• No clutch slippage at any time
• Motor shifts fine
• No loss of power
• No coolant in oil
• No smell of coolant while driving / at any time
• Front of motor has recently been replaced (timing chain, oil pump, etc.)
• Front of motor has oil buildup around gasket edges, but is not the source of the leak from what I can tell.
• Head gasket has oil buildup around the edges, however does not appear to be the source of the leak
• No oil on firewall / hood
• No oil leak if motor is pressurized via compressed air pumped down the oil dipstick tube

The motor has leaked oil from the rear of the motor, somewhere, and collects in / around the transmission bell housing. Passenger side of the transmission is always the most soaked.

I can share some pics of the truck / rear of motor without the tranny attached, but I don't think they really reveal anything I haven't already gone over.

What should I do at this point? I have been super stressed out about this, as it's my only vehicle (too cold for motorcycle) and I am still recuperating financially from my move south. I also feel like the mechanic is making guesses, and is possibly going to make matters worse . He's a great guy good intentions, but I think he has some more to learn about older motors

 

[Bad_Vision]

Sounds like the half moon in the back is not sealing. I did this once when I did a head gasket it needs to seat just so to not leak and it's we're the oil pump shoots at so it happens at full rev.
Hope it helps man. If that's not it you may have a cracked block or head that's shooting oil out under pressure.

 

[Sarrus25]

Sounds like the half moon in the back is not sealing. I did this once when I did a head gasket it needs to seat just so to not leak and it's we're the oil pump shoots at so it happens at full rev.
Hope it helps man. If that's not it you may have a cracked block or head that's shooting oil out under pressure.

Bad_Vision, I felt the half-moon when I got the truck, felt dry. After replacement, half-moon was still dry.

If it was a cracked head / block, would there be any other symptoms? How would I go about detection?

Here are some options I thought about:

OPTIONS

• Sell the truck
• Let 'em keep "trying stuff"
• Take to Toyota dealer $$$
• Trade back for S10 and take a major labor $ loss $$$
• Save for new motor (+ labor) $$$
• Live with it

 

[Bad_Vision]

None of those options are good. Get some uv dye and pressure wash the engine really good and clean then use the dye and rev it up till you see the oil dripping. Don't drive it as it will blow the oil every wet and make detecting the source hard. Use a Ultra violet flashlight to illuminate the dye then you will see the source of your headache.

 

[flyinhawaiian01]

Pics would definitely help, but here's one I had that confused the living shit outta me for a long, LONG(!!!!!) time!

The oil pressure sending unit on mine was leaking around the crimped housing, but only under load. It literally squirt oil right along the oilpan's edge where it mates to the block, and with driving, it would push that oil all the way back to the transmission, but it was such a small squirt that it wouldn't get all over everything, just on the pan and ride along that seam to the rear of the engine, where the wind would then pick it up and fling it everywhere! Craziest thing I ever saw and I dropped the pan TWICE to re-seal it with no luck!

I literally thought I was going crazy!

Try ziptying a shop rag around the sending unit, take it for a drive at high rpm, then pull it off and see if its got a wet spot on the rag. This really shouldn't cost you anything except a dirty rag and a ziptie!

If that's not it, then its de-greasing time so you can add dye and search for it that way. You should see it leaking after that with a good 2500rpm steady rev, hold it there for 30 seconds or so (might throw a check engine light, just ignore it for now), shut it down and search with the uv light. If nothing, try it again. If still nothing, take it for a drive, keep rpms up above 3500rpm. Don't go too far though, you wanna see the first signs of leaking.

 

[ellis36]

Sounds like pressure build-up in the lower engine.

Pull the PCV valve out of the valve cover and check, with the engine running, if there is vacuum present at the PCV valve. Drive it with the PCV valve out of the valve cover and see if the leak is still there.

ellis

 

[KidVermicious]

What should I do at this point?

You should ditch FM and BM, they both suck. There's no excuse for not knowing exactly what's causing an oil leak before trying to fix it, they're both lazy and incompetent and should be ashamed for trying to charge for their services.

Clean up the truck - it's a dirty filthy messy job, but you have to do it. Clean it all up, the entire motor, transmission top and bottom, engine bay, everything. Then use a UV additive to the oil and find your leak. It could be a lot of things causing it, but if you keep trying (or paying others to try) to fix it before knowing what it is you're going to keep wasting money and time.

 

[The Count]

You should ditch FM and BM, they both suck. There's no excuse for not knowing exactly what's causing an oil leak before trying to fix it, they're both lazy and incompetent and should be ashamed for trying to charge for their services.

Clean up the truck - it's a dirty filthy messy job, but you have to do it. Clean it all up, the entire motor, transmission top and bottom, engine bay, everything. Then use a UV additive to the oil and find your leak. It could be a lot of things causing it, but if you keep trying (or paying others to try) to fix it before knowing what it is you're going to keep wasting money and time.

I agree with this.

As a mechanic, I am not a fan of finding/fixing oil leaks on older vehicles (even my own). There are often multiple sources of leaks, even though only one may be bad enough to cause a drip. The other smaller leaks can lead to miss-diagnosing the cause of a drip. It's always best to clean the hell out of the engine from top to bottom and start from scratch.

If a customer chooses to gamble on fixing a "possible cause" of the leak, knowing its a gamble, that's on them. But if a mechanic tells you that paying him to do a repair will fix the oil leak and it doesn't, he is in the wrong. That's why on older stuff where it can't be 100% certain that I can fix an oil leak by doing one repair! I'll give the customer a option to do a gamble or take the vehicle elsewhere for another opinion. I would not like to end up in the situation the brake and muffler guy is in now.

 

[89FourRunner]

How do you know FM did not botch the rear main seal installation?

If you are losing oil from between the block and tranny bell housing, I still tend to think its the rear main.

Rev the truck up and lay under there and see if it sprays/mists oil from where the clutch slave links up.

Rear main seals are not all created equal, and the $50 spent for the OEM Toyota one is worth it over a $6 aftermarket one. They also need to be pressed in correctly.

Just because the clutch does not slip does not mean it isn't the rear main seal.

Good Luck.

 

[Sarrus25]

Well, after a long and strenuous ordeal with the mechanic and Toyota dealership, I ended up getting the truck back and it wasn't leaking tons of oil anymore.

I don't have a definitive reason as to why. The head gasket was replaced, rislone oil / shit treatment was run through the motor, and some stp (more shit) oil treatment was run through the motor as well.

It still leaks a couple drops per drive near rear main seal area. I'm happy with this.