Engine/Transmission (1994 - 1998) Oil leak driving me CRAZY

[JeppinHackSaw]

the other day I put a quart of oil in the truck that I don't normally use, didn't want to but it was all that I had in the garage and was in a hurry.



The truck has leaked a little bit of oil since the day that I got it, which also pisses me off.



Anyways, I ran about 35-40 miles down the freeway (65-75mph)



Well, I stopped and was in a resturaunt for our club meeting and I came out and there was a puddle about 8 inches in diameter of oil under the truck. The tailgate was covered, oil was dripping off the rear axle and the whole underside of the truck is now rust-proof.



What the heck did I do?



I got home, changed the oil, and pressure washed/degreased the motor/underbody/axle. This is REALLY starting to bum me out.



I pulled the inspection cover, dry (which is a plus I spose) meaning that I dont have a rear main leak. I thought maybe I damage something internally causing massive quanities of blow-boy, as it looks like some oil MAY be coming from the vent tube.



Part of me doesn't think its the vent tube as the passanger side of the motor also is leaking oil. It runs down and drips off the bottom of the trans inspection cover.



I looked with a mirror and it doesn't appear to be leaking down the side of the head or the back of the head indicating that the vavle covers are not sealin, but part of me still thinks that it could be the culprit as it's the 3rd set I have put on it in 2 months.



The other part of me thinks that replacing the valve cover gaskets was chasing a different problem.



The motor is covered in oil, (front cover is leaking as well, plan on fixing that this weekend when I tab the KDP) I can NOT tell where this is coming from. Leaks down both sides of the motor... I'm ready to pull out my hair...



PLEASE anyone. . advice is greatly appreciated. The leak in the front doesnt bother me nearly as much as the leak in the back as that would only leave a drop every few days, the leak in the back is leaving a puddle now... .



Theres no water in the oil or oil in the water.



Anyways, I'll stop now.

 

[blacksheepdiesel]

Have you checked torque on the oil pan bolts? Also, the oil line that runs from the P7100 to the block has been known to cause massive oil slicks. As the air from the fan picks it up and distributes it, or it makes a puddle when sitting. Have you checked for leaks at the vacuum pump?

Godspeed,
Trent

 

[SMorneau]

I hope you are not too late



You can buy a UV leak detection kit at northern tool for about $50 it will help you find the source(e) and it's far cheaper than new hair:-laf

 

[Joe G.]

Your KDP may have got you.

 

[bdcraig]

I have the same problem. I put a new front seal in a tabbed my KDP. Test drove the truck around on country roads and no leak. Then I got it out on the interstate for about ten miles and checked it after that. A nice big puddle was forming and oil was everwhere. It was dark and I got to looking with a flash light and found nice clean fresh oil running down the side of the block just below the inj pump. It is right around the oil line to the pump. The line is not leaking but my best guess is that it is the side cover gasket leaking. My theory is that the vent tube is stopped up and has caused pressure to build up and blow out the gsk. I've had it happen on a tractor before. Bad thing is the pump must come off to fix it.



Brian

 

[JoeBioDiesel]

I think you should degrease the engine, remove the coolant fan(optional) and run the engine while looking for a leak. I take the fan off to make it easier to look around. No wind blowing in your face while you check the front fo the engine. If you can't see it pick up a UV leak kit like SMorneau suggested.

Joe

 

[tolmsted]

I see you have a 12 valve however mine is 24 valve and the seal behind my front gear case failed last week after I had replaced the crank seal. I could see that the section of the red gasket was not in view in the area just to the left of the KDP location on the exterior of the gear case. I had to remove the entire front end of the truck and front of the engine, including pulling the cam out today. I have $38. 00 of seals and a new gasket from Cummins this afternoon and will be putting it back together tomorrow. I had oil all over the front also. JoeBioDiesel is right about power washing. I suggest you power wash and blow dry the engine and then idle the truck and check the engine for the leak before driving. Thats the way I was able to find my leak.
Good luck. Tom

 

[JeppinHackSaw]

Well.. I found it

Well, Unfortunatly I found my oil leak...



I power washed/degreased the engine today... to try to track down my leak. . figure I would extend my breather tube as well to rule out that possbility.



Well, Let the truck sit and run for about an hour with NO leaks. . so im like what the hell, took it for a drive on the roads around here about 40-45 mph... no leaks still



Figure I'd jump on the freeway and buzz it up a little higher. .



much to my dissatisfaction, Pulled in the driveway and there's oil running off the rear axle, coming out of the blow by tube.



We aren't talking little bits of oil either. . enough to COAT the rear axle and form a puddle as soon as I stopped.



Well, go back and look at the motor. . bone dry... ok. . what the hell #@$%! #@$%! #@$%! #@$%! #@$%! :{ :{ :{

 

[JoeBioDiesel]

Just to be sure, you're talking about the crankcase vent tube, right? and not the vent on the differential. If you're only getting oil out ofthe vent tube when going down the highway, then you most likely have an engine problem. Excessive blowby comes from combustion gasses that make it past the piston rings. Check for a couple of things:

1) Make sure you don't have a vacuum line off or a large leak. The vacuum pump vents into the crankcase. A large leak adds extra air to the PCV gasses.

2) Check to see if you had a failure of the air filter or air filter housing. If there is dirt on the clean side of the air intake you probably dusted the motor, and it would be time for a new one.

3) Try a compression test. While good compression doesn't mean the oil rings are OK, low compression would be a sure sign there's trouble in the bottom end.

4) The last possibility I can think of, but have never seen it on a Cummins, is if the valve guides are badly worn, boost gasses can push up the guides and add to PCV gasses. I've seen this on older VWs and it would really make them puke out the vent.



Pray for a vacuum leak.



Joe

 

[JeppinHackSaw]

Well, I talked to RBratby (that guy must just LOVE my 100 questions)

He told me the same issue about vaccuum leaks. .

Then It clicked that the cruise quit working the other day. Noticed it the day after the first major blow out of oil. . never woulda thunk it.

anyways, kinda late but I might make my way outside to check the lines...


Anyone have a diagram that would show all the vacucuum lines?

 

[CumminsPower98]

The turbo is another part that can cause crank case pressure if it has a bad seal and might be worth considering since it only happens at higher speeds. Lets hope it's just a vacuum leak though.

 

[JeppinHackSaw]

The turbo is another part that can cause crank case pressure if it has a bad seal and might be worth considering since it only happens at higher speeds. Lets hope it's just a vacuum leak though.

Well the vaccuum leak makes sense, especially that the cruise quit working around the same time that the blow out developed. .



lookin for a wirirng diagram, went outside to check and it's 23 degrees out, so that can wait till tommorow.

 

[GOlsen]

I'm also having a similar problem. Not quite enough to coat my rear axle, but leaves a good size puddle and coats the bottom of the pan. Also have cruise control that doesn't work. When I was going to try to fix it, I took the driver's side battery out, and tried taking the tray out to get to the cruise control, and can't get it out. I also have no idea where to look for this vacuum line.

 

[JeppinHackSaw]

I'm also having a similar problem. Not quite enough to coat my rear axle, but leaves a good size puddle and coats the bottom of the pan. Also have cruise control that doesn't work. When I was going to try to fix it, I took the driver's side battery out, and tried taking the tray out to get to the cruise control, and can't get it out. I also have no idea where to look for this vacuum line.

Mine runs from the battery tray, to the cowl, across behind the valve covers down the other side to the vaccuum pump



I found my main supply line coming from my vaccuum pump just hangin out there when I finally got to lookin this morning, ran the heck out of it on the freeway, problem solved!

 

[GOlsen]

I'll have to check that out in the morning... thanks

 

[arthr31]

Mine runs from the battery tray, to the cowl, across behind the valve covers down the other side to the vaccuum pump



I found my main supply line coming from my vaccuum pump just hangin out there when I finally got to lookin this morning, ran the heck out of it on the freeway, problem solved!

problem might not be solved. watch the vacuum pump closely, near the PS pump, it might have a seal leak, which is pretty common. There are seal kits available so don't be too concerned. If the PS pump goes, that's a pure replacement...



but, as you wrote, it's oka now, so keep an eye on it... good luck

 

[JeppinHackSaw]

problem might not be solved. watch the vacuum pump closely, near the PS pump, it might have a seal leak, which is pretty common. There are seal kits available so don't be too concerned. If the PS pump goes, that's a pure replacement...



but, as you wrote, it's oka now, so keep an eye on it... good luck

No, I think that its okay. The main supply line coming off the pump was just hanging there. I dont think there was a seal leak, bein that the line was complety off there and causing a major leak.

Problem solved, now that it is running good I need to have the transmission gone through as I can sleip the living daylights out of the convertor.