Need some help with an oil leak.

[mm73]

I had an oil leak coming from behind the harmonic balancer so I took everything apart and replaced the front main seal. I just today put everything back together and the leak is still there. It doesnt leak at idle or even throttled up a little bit, but once you throttle it up to 2100 rpm or higher you can get under the front of the engine and watch it trickle out from behind the harmonic balancer. Any ideas on what else it could be besides the front main seal?

 

[Keith_J]

Worn sealing surface. Let me check the TM to see if there is a wiper that can be replaced.

Doesn't look like it. I bet there is a groove or two on the crank which won't let the seal seat properly, leading to a leak at higher RPM.

It is a forged crank which could be repaired but that is major overhaul. Can be done without pulling the engine although pulling the crank and clutch would be required. It could be repaired with nickel silver brazing, then finish machined. This makes for a tougher area of the crank and lessens heat effects from weld repair since the crank does not need to be heated above the transition point, preserving heat treat.

The cam gear is behind the seal, the oil is coming from the gear and "jumping over" the deflector, make sure that is in there. Also check the breather tube, any clog there will increase crankcase pressure, forcing oil out.

 

[rnrracing]

mm73

I am having the same problem. Where did you get the front seal? and do you have a part number? did you replace the oil pan gasket also and if so where can I get those parts. I am starting to suspect that I might have a fuel leak into the crank case. I don't have any idea where to start looking besides just rebuilding the injection pump. I am going to go to napa today to see about a kit that tests for fuel in the oil. any help anyone would have would be great. Thanks guys

 

[JDToumanian]

For the worn shaft sealing surface, I'm surprised nobody recommended using a Speedi-Sleeve to cover up the grooved area.... It would likely be a nice permanent repair and much better than tearing the engine apart!

Speedi-Sleeve shaft repair kits

As for leaking fuel into the oil, there's really only a few components that can do that when they fail.... Defective flame heater system, the Fuel Density Compensator on the injection pump, and several o-rings on and around the hydraulic head of the injection pump. Searches will produce many valuable threads on these topics and their fixes.

Having the oil tested is a good idea, but I think even in tip-top shape these engines are going to show some fuel in the oil, so I'd just do oil changes regularly.... I change mine every 2,000 miles or 1.5 years regardless of mileage. I wouldn't tear into the pump or worry about fixing leaks until you notice the engine "making" oil.

Jon

 

[JasonS]

Worn sealing surface. Let me check the TM to see if there is a wiper that can be replaced.

Doesn't look like it. I bet there is a groove or two on the crank which won't let the seal seat properly, leading to a leak at higher RPM.

It is a forged crank which could be repaired but that is major overhaul. Can be done without pulling the engine although pulling the crank and clutch would be required. It could be repaired with nickel silver brazing, then finish machined. This makes for a tougher area of the crank and lessens heat effects from weld repair since the crank does not need to be heated above the transition point, preserving heat treat.

The cam gear is behind the seal, the oil is coming from the gear and "jumping over" the deflector, make sure that is in there. Also check the breather tube, any clog there will increase crankcase pressure, forcing oil out.

The front oil seal rides on the balancer, not the crankshaft.

 

[JDToumanian]

The front oil seal rides on the balancer, not the crankshaft.

Wow, I didn't know that. Hopefully I'll never get (have) to confirm that for myself! Although for this oil leak the fix becomes simple.... Balancer grooved? Replace balancer.

 

[Jimma]

Well, if there is oil there at lest you know things are well lubricated and wont rust or stick.

 

[stumps]

Did you remember to use sealer on the balancer's bolt threads?

Basically, any bolt that passes into the crankcase side of the oil seal needs sealant.

-Chuck

 

[jwright]

I think there is a key way that needs to be sealed. I say you got a bad seal. I just did mine this summer and I got mine from Memphis for $25

 

[JasonS]

Wow, I didn't know that. Hopefully I'll never get (have) to confirm that for myself! Although for this oil leak the fix becomes simple.... Balancer grooved? Replace balancer.

I had a defective balancer causing a slight shake. It is not a big deal. A standard balancer puller just barely fits.

I don't believe that thread sealant is necessary on the balancer bolt as it fits into a blind hole in the crank. The more likely path is through the keyway.

 

[Wildchild467]

jason,

what was your shake like? My engine has a resonance that seems to fade in and out...more when its colder. there was a thread on here talking about it and nobody knows what it is. they describedit was "oscelating". wish i knew what it was because its almost anoying. another theroy to the oscelating was the compressor was not spinning the same speed as the engine because the vibe fades in and fades out.

 

[Kohburn]

that's the sign of two vibrations at slightly different frequencies - at one phase in their cycles they are almost opposed canceling eachother out and at the other end they are adding to eachother doubling the effect.

 

[stumps]

I had a defective balancer causing a slight shake. It is not a big deal. A standard balancer puller just barely fits.

I don't believe that thread sealant is necessary on the balancer bolt as it fits into a blind hole in the crank. The more likely path is through the keyway.

The path is from the crankshaft bearing, down the shaft into the hole where the shaft, and keyway fit into the balancer, and out the bolt hole. It needs to be sealed, or it will leak.

This is a very common place for a leak on almost all engines.

-Chuck

 

[m-35tom]

i don't see where it is said what the oil level is when it leaks. that is VERY important as fuel in the oil will leak like mad when beyond a certain level. JDT, one of the most overlooked fuel leaks is the booster pump. it can literally put gallons of fuel in the oil in a very short time.

tom

 

[JasonS]

jason,

what was your shake like? My engine has a resonance that seems to fade in and out...more when its colder. there was a thread on here talking about it and nobody knows what it is. they describedit was "oscelating". wish i knew what it was because its almost anoying. another theroy to the oscelating was the compressor was not spinning the same speed as the engine because the vibe fades in and fades out.

It was a constant minor shake. I may have not noticed it if I hadn't another to compare with. It should be quite smooth.