Front Crankshaft Seal (Front Main Seal) Blown Out Twice in 10,000 miles

I've got a 2001 Tacoma with the 3400 v6 and 280,000 miles. The front crankshaft seal blew out around 10,000 miles ago while on a trip out of town so had to have a mechanic replace it. Now a year later it has just blown out again. What could cause this? It's not a slow leak that gets worse, both times it's coming out fast i.e. losing a quart in 15 miles. The PCV valve was replaced after the first blow out though it was not clogged as that was my first thought. It does not burn oil very fast at all compared to any other vehicle I've had with high miles. Probably not more than a quart in 10,000 miles so I don't think I'm getting major blow by pressures.

 

What brand of seal did you use?

 

I'm not sure what brand the shop used. For replacing it the two options I have available right now are National and Fel-Pro. Does anyone know what OEM is? I can't find the part on dealership websites diagrams or in searches.

 

Someone recommended checking for lateral crankshaft movement which I believe is called crank end play. I'm sure you are supposed to use a dial gauge but I don't have one and didn't even have room for a calipers so I just used a tape measure but there is visible end play and it seems to be a solid 1/16" of an inch which would be in the neighborhood of .06. I can't find specs for this motor but that sounds like almost like 10 times too much play compared with other numbers I find. I don't think I should be able to visibly slide the crank in and out right? So at this point even replacing the main bearings is probably not enough right? I'd need to replace the whole crank too I'm guessing? Or will the crank thrust washer set (1101162010) be a softer metal and wear first? Am I best off giving up and getting a re-built motor?

 

FYI for anyone who finds this in the future. On the 3.4 you cannot pull the main bearing caps with the engine in the truck. The main bearing caps are all one giant casting and it can't come off the block without taking a plate off the back of the engine that holds the rear main seal. And to get that off the engine needs to be separated from the transmission.

When I took the pan off the thrust washers were all lying in the bottom of it. I have the engine out and on an engine stand and it doesn't look good. I think the thrust washers have been out for a very long time. When they came out the crank used the block and the bearing cap as it's thrust washer. On one hand this means the surface that would push on the thrust washers is completely unmarred and the part that is marred wouldn't be touching anything any more, but the problem is that there isn't much material left to hold the thrust washer in.

The crank was definitely getting pushed or pulled forward at all times. All wear is on those surfaces and looking at the thrust washers I can see two halves are very thin. Looking at the bearing cap there is a .076 inch lip on the good side and .041 inch lip on the other so almost half of the lip to hold the thrust washer in is gone. This is true of the block as well.

I'm thinking I will put in a used engine in it then but am wondering if I need to be concerned about this forward pressure. It seems like it was most likely the torque converter doing this but I'm not sure of a good way to know for sure or to address it.

 

subbed for the outcome and possible pics.

 

I'd put in a used motor

 

this ^^^^^^^^^^^^^^^

drop in a good used low mileage motor and forget about it. that path will cost you $1k-$1.5k depending on how much work you do yourself.

if you get into an engine rebuild, be prepared to spend $4k-$5k on that and that's "If" you don't find any major issues which you seam to already be getting into.