Leaking Rear Main Seal Replaced 5 Times within 20K Miles

Bought (2015 Tacoma, DOUBLE CAB, 4X4, V6,6MT, Tow Package) with ~109k miles in 2022 from Honda as trade-in. I had it inspected at Toyota. Toyota identified what they believed to be Rear Main Seal leak. Honda replaced Rear Main Seal and Oil Pan Gasket prior to purchase. Within a few days I noticed oil along underside of transmission. Honda replace rear main seal again in addition to the retainer that it sits in and the valve gasket covers. At this point I looked up my VIN on Toyota and saw the previous owner (under CPO Warranty) has the Rear Main Seal and Oil Pan gasket replaced twice at around 85k-95k miles. Honda investigated further and identified a head gasket leak on both sides that was dripping oil. I ultimately had to sue Honda as they did not want to pay to repair the head gaskets. I used the money from the lawsuit to have the engine completely remanufactured. This also included a new rear main seal as well as any other components that the shop demanded to warranty their work. Shortly after taking it back it I noticed leaking. The engine was pressure tested and passed (excluding the head gaskets leaking). The transmission was dropped and they noticed the rear main seal was not seated all the way in. They performed some sort of pressure test (to see if that caused it to un-seat: Passed) pushed it back into place and I drove it around. Shortly after I noticed leaking along the bottom of the transmission between the rear main seal and crank shaft.

The repair shop is hesitant to install another seal. They are in communication with the shop that remanufactured the engine to get their insights on the matter.

 

A few things sound both odd and a bit fishy here.

Regardless, you are rightfully unhappy, fish or no.

Solve that by trading it in.

 

I would be scared to touch your vehicle too with what it sounds like. Replacing a rear main seal is not a "quick" job and isnt cheap, doing this as many times as you have and going from shop to shop to shop there are so many hands that have touched this that accountability is being lost along the way. Then you leaving the shop and turning around suing them isnt going to make things easier the next go around. 109k miles and the rear seal is leaking isnt a big deal, my yoda has 118k and the rear seals been leaking since 72k. I monitor and make sure it isnt getting worse....

yours leaving puddles on the ground or enough for you to see leaking/dripping oil is a more extreme case. With at this point the motor being pulled out multiple times and multiple replacements, just get out of the vehicle. Two seals replaced at 90k, another 20k miles later and head gasket problems.... previous owner had some fun and got out before dumping more repair money into it.

 

Have you looked at the upper oil pan ? these trucks have an upper and lower and the upper is notorious for leaking toward the front. When the upper leaks the oil runs down and blows back all over everything, when it happened to me I was convinced my rear main had blown because all of the oil was all the way back there ...might be worth a check.

 

I’d be concerned that someone scored the mating surface on the crankshaft if it continues to leak from the RMS specifically.

 

Great truck on paper.... may want to trade it in. Or, bring it to a Taco guru. This girl has been passed around quite a bit, lots of hands in there, who knows what kind of puckery has gone on.

 

A continues oil leak at the rear main could be from a crankshaft out of round, the bore out of round or off center, or even thrust bearing issues.
It's really, really, really, hard to find a good engine builder these days. Even harder to find a general technician that knows what to look for in instances like this.
Even if they do, it's time consuming and tedious work. All of which cost money. Money they want/need paid, and money you don't want to spend.

The easiest way out would be to buy a newer "used" engine, and swap it in with fresh chains and gaskets..

Or buy a short block straight from Toyota.

 

This is where it was found to be leaking the last time the transmission was down. It was pushed back in and I drove for ~3k before I noticed it was wet. I never saw dops on the driveway just oil along bottom of transmission. As of today it was cleaned up and run stationary for a while (some driving) without any new drips. I am guessing it very slow.

 

Hard to tell.
Is it coming out below the crank or below the seal?

Hard to believe the tech that did it a 2nd time, didn't use a little RTV around the seal.
Just a skim coat in hopes that it would help. Is that that the correct way to do it. Absolutely not. But pulling transmissions is not fun.
A skim coat of RTV is better than "luck" alone.

To know for sure. You need to pull the rear cover and use a dial gauge on the crank. Then measure the hole in the cover. It needs to be in spec and true (round).
I don't think it's a seal issue. Too many new ones have been put in and at different times. So the seal likely didn't come from the same batch.

I hate to say it, But this is going to take work. More than sockets and wrenches are going to need to be involved.

 

Um... that might work on the outer part of the seal to the block, but ... it's pretty obvious there is oil above that.
No way to "skim coat" the inner portion.
Its been my experience that following the manufactures assembly instructions delivers the best results.
Now that said, there is something unusual going on here.

 

Obviously you can not coat the inner lip. It rides on the turning crank.
And I can't see oil above it. I see red circles.

Either way, RTV isn't the fix. It's just interesting that after having 5 -FIVE- RMS replaced, something else hasn't been tried.
Insanity = Repeating the same thing over and over, and expecting different results.
I can't believe anyone would actually beat the RMS back IN, after it was already leaking and had worked itself out, and call it good.
Who does that? I'd pay for a new seal out of my own (Tech) pocket, before I did some jank stuff like that.

 

This ^. Who heck pushes back in a seal that has unseated itself, worn unevenly because it was no longer seated correctly and calls it good. Hell they pulled the tranny and chose not take an extra 5 minutes to put in a new seal.

 

Something I didn't see mentioned here is was the PCV system checked for blockages and proper operation?
Excessive crankcase pressure from an improperly operating crankcase ventilation system or excessive blowby will cause persistent oil leaks as well.

 

Ziptie a balloon or rubber glove over the oil fill neck and run the engine. Look to see if pressure or vacuum builds up

 

Honestly,trade it in and buy a different brand,Toyota is not the brand for you.