Got oil leaks?

[Timminator]

I have an 89 K-5 with 350. This thing has been at the mechanic for chronic oil leaks. They have replaced the rear main seal several times but it only seals for a few days then starts to seep again. They indicate that the rear shaft may be misaligned by as much as 1/16"... possibly due to shotty rebuild. Not sure what to do next so I thought I would reach out to the experts.

Any suggestions are appreciated.

 

[Stomis]

Improper crank shaft end play. Its not possible for the crank to be 1/16th off to the side other wise your motor would be imploding. It is more than possible that your crank is walking though which is back and forth. You're more than likely correct, shoddy rebuild.

 

[4X4HIGH]

1989 will have a 1 piece rear main seal that is pressed into an aluminum adapter plate that bolts to the rear of the block with a gasket between the block and seal adapter. There is supposed to be 2 alignment dowels, one in each lower position of the seal adapter. If those dowels are missing it is very possible that is the cause for your leak. If the dowels are there then it is an engine with wore out main bearings which is allowing the crank to "walk" around and not allow the seal to seal properly. How many miles are on this engine?

 

[Timminator]

Not sure how many miles on the engine. Odo shows 75k but is likely 175k... or more. Bought the truck a year ago. Oil pan had dents so my assumption was that the engine may have been picked up from a junk yard that may have stored it improperly. Unless the previous owner was out jumping tree stumps which is a possibility. I had the shop replace the pan/gasket and rear main seal. They did mention that there could be the possibility that the rear bearing is on its way out. The last time in they had a machinist come by to take a look and he was the one that indicated the 1/16" offset but weren't clear which direction and I didn't know enough to ask. This time, they notched where the dowels insert to adjust for the offset - now I am concerned it may have made things worse. Didn't leak for a week... then I took it out wheelin and it started again. Doesn't seem to be leaking any worse than before but still leakin'.

Before I talk to them again, I figured I better get a bit more knowledge under my belt. They have worked on it 4 times and it just seems like it isn't going to be fixed.

How extensive is replacing a rear bearing and would it be worth it or should I just run what I have until it grenades? Just tough to justify a rebuild because of a leak. However, if there is the possibility that it will get worse (leaving me stranded out in the desert) then that might change my mind.

I really appreciate the feedback.

 

[USSkoval]

You can try replacing the PCV valve. For a couple bucks it's worth a shot.

 

[Stomis]

Honestly putting a long block crate motor in it would have been cheaper than paying to have the rear main done 4 times.

 

[bradshawtech]

Quart of oil....$3.00


Drip pan for the driveway....$15.00


Rebuilt engine, r & r by a shop.... Thousands of dollars.

Easy decision for me but I am not aware of your circumstances.

 

[1BEATK5]

removal of the oil pan and inspection of the crank thrust surface, thrust bearing and the block first is what i would do. that will verify the problem.
or even easier is put a dial indicatoron the front pulley, and pry the crank fore and aft with a large prybar. measure endplay when doitng this.

 

[4X4HIGH]

There is NO WAY that the crankshaft could have 1/16" play side to side or up and down BUT it could have 1/16" endplay (it is actually called thrust) and that means there is either a problem with an automatic trans torque convertor, plugged trans cooler, kinked or otherwise blocked cooler line, or a bad engine ground. The shop that messed with the locating dowel holes did nothing but screw you even further. If you were closer I could definately help you out but unfornately being 800-1000 miles away doesn't help me help you.

 

[Timminator]

Thanks man. Just to clarify, I only paid to have the main replaced once... they have eaten parts/labor on the last three times. I was a sucker when I bought this thing but I am learning fast. I will check for the end play.

Thanks again!