gmcmhdriver

Hi folks - -

I have a 1999 24 valve 5.9 engine in my diesel pusher motorhome. Less than 60K miles. It has a six speed Allison 3060 Transmission. I've posted here a few times a year or so ago relative to head gasket replacement and received tremendous help. The head gasket coolant leak has been history for the last year thanks to your guidance and technical expertise. Thank you all.

I now have an oil leak in the fan end (in my case, the rear) of the engine and thanks to the pusher fan, oil has sprayed all over the charge air cooler and the radiator which in-turn has attracted a ton of dirt. The dirt has clogged perhaps 40-50 percent of the cooling module. No wonder the temps were a little high when climbing grades in the Utah desert. I have removed the entire cooling module (intercooler and radiator)to fix the leak. Cooling module removal is a super PITA, like big time, but I now have complete access to the fan end of the engine. I can even sit on the trailer hitch framework when working on the engine LOL.

The oil leak seems to be coming from the area where the air compressor (suspension and brakes) bolts on to the backside of timing gear case. Lying on my back, this is where I see the drips when the engine is idling and the area (1 inch diamenter) has been washed clean. It is directly under the intake manifold and I think this is where the vacuum pump bolts on to the engine when used in the Dodge PU's. The air compressor appears to bolt to an adapter which in-turn bolts to the backside of the timing gear case. The leak seems to be located at the junction of the adapter and the rear side of the timing gear housing. The question I have is: Do most leaks occur where the air compressor (or vacuum pump) attaches to the timing gear case or do they occur more often between the gear case housing the engine block itself? Is there an o-ring or a gasket here? I'd hate like hell to have to remove the timing gears and the timing gear housing but I will if I have to since there is really no other choice. I'd hate like hell even more if I removed the timing gears and the case and discovered there was no leak between the case and the block.

I have the timing case cover removed and cleaned up and the crankshaft seal is a little stiff to be sure. Maybe this is where the leak is coming from and the oil is weeping toward the intake side of the gear case - -or am I just hoping too much for an easy fix? LOL. I'll replace it regardless. The seal is a little different than what I've been accustomed to seeing. It has the normal lip part which is oriented toward the oil but there is a somewhat harder yellow plastic-like ring that is on the atmosphere side of the seal. There is a slight groove worn into the crankshaft where this yellow ring rides on the crank. Is this groove beneath the yellow ring normal or do I need a speedy sleeve? Is there a preference as to what brand of seal works best or any designs that I should stay away from?

I have searched this site and found that some folks say it is best to install this crank seal totally dry which is totally contradictory to what I have been told to do told regarding other engines. I have always used grease when installing seals and why not do the same thing here?

My apologies for the long-winded post. Just don't want to screw this up and have to once again remove the cooling module. One PITA is quite enough. The engine has to be leak free or thanks to the pusher fan, the cooling module will be clogged up again in no time flat.

As always, thanks very much in advance for your thoughts and assistance,

Jake

00 CTD

The 5.9 in a medium duty, truck or motorhome, has the air compressor mounted to the gear housing, then the power steering pump is mounted to the back side of the compressor. There is a gasket between the gear housing & compressor. They can leak, but what usually happens is the support bolts for the compressor either break or fall out, and from all that weight hanging off the housing, it'll break/crack the gear housing. The support bracket is on the bottom of the compressor. I would check that.

On the crank seal, I would use a Cummins seal, and install it dry. There should be a seal, clear plastic install sleeve, and a metal depth/install sleeve also. Might be a thin plastic dirt guard with it too. The seal depth can be adjusted for wear on the crank, but if it's that bad, Cummins does make a seal kit with a wear sleeve.

sheriffav8r

I guess once you rule out the common puke bottle problems, I would buy about 5 cans of brake cleaner and clean the heck out of the front end of the engine and then sit there with a flashlight waiting for the leak to develop. Better to totally define the problem before yanking stuff off to try to fix random things.... Good luck.

gmcmhdriver

Thanks OO CTD and Sheriff - -

The air compressor is secure to the engine and the bottom support bracket is tight as well.

I've decided to remove oil pan and the timing gear housing and seal up everything. Might as well take the time, do it right and not worry about any leaks for a while.

Another question: How does a person remove the camshaft gear prior to removing the timing gear case? The other gears are bolted on but the camshaft gear seems to be pressed onto the camshaft. There are two bolts that are that are accessible through spaces in the camshaft sprocket that appear like they secure the camshaft into the engine - - ie, thrust plate. Or do these bolts merely secure the cam drive gear itself?

Please don't tell me that it's necessary to remove the camshaft before removing the timing gear case.

Thanks again for your help.

Jake

Hodge

I forget where i heard this, but clean the engine extremely well, let it dry, then "apply" baking powder to the engine exterior, in the regions of the oil leaks. The baking powder will show right away where a leak is, once it starts leaking again.

00 CTD

Yes, the whole cam has to come out. The gear is heated & pressed on. The 2 bolts you see hold the thrust plate on.

To pull the cam, you have to take the valve cover off, rockers & pushrods out, then insert wooden dowel sticks to hold up the cam followers, then slide the cam out. It's a little involved, but not too bad to do.

gmcmhdriver

Well, certainly not what I wanted to hear. During the head gasket replacement the rockers and pushrod were removed so perhaps the "dowel/lifter procedure wont be too bad.

After replacing the head gasket and finishing this seal-up, the engine will have had almost every gasket replaced. What could be next - the rear seal? Sure as hell hope not. These things should not have happened on an engine with less than 60,000 miles. It seems like time/age is every bit as much of a factor as is mileage.

Thanks OOCTD - your help is greatly appreciated.

Jake

gmcmhdriver

00 CTD and others too - -well it seems that you've been here and done this before so I'll ask another question. How in the hell do you get the dowels to stick in the lifters in order to get them raised up and out of the way?

I have 3/8 dowels and all they do is slide out of the lifter everytime I try to raise any of them up. These 3/8 dowels do not grip the lifter at all, but rather they just slide in and out. The top of the lifter where the pushrod (also micked out 3/8 inch) fits is only perhaps 1/4 inch deep if even that, so there's not very much lifter to get a grip onto. Regardless how hard I push the dowel against the side of the lifter, it always just slides out. I have a 1998 Dodge truck 12-valve service manual (trying to use it for my 24 valve engine) and it says to "properly install" the dowels and hold the lifters up, what ever the hell "properly install" means. What am I doing wrong here - is there a trick to wedge the dowel so it sticks in the lifter?

Or, do I need to buy 1/2 dowels and trim them down and if so, what diameter should they be trimmed to?

I'm beginning to wonder if I should leave well enough alone and just replace the crankshaft seal and the gasket that is between the air pump and the timing gear cover and call it good. I still wonder just how much of a chance the gasket between the timing gear case and the block is leaking at all. I have no idea is this is a common leak point or not.

Again, I owe you folks - - sorry for my frustration - lol..

Thanks for your assistance.


Edit:: Well, after a few hours of searching I think I have answered my own question. I guess I need 1/2 inch dowels and then cut a grove into them with a hacksaw and that's the way to hold the lifters up.

Searched for hours last evening but struck out - must have been tired I guess.

My apologies for the rant and thanks for all who have helped.

Jake

00 CTD

Sorry I didn't see this sooner. Yes. 1/2 dowels. You can either cut slots in the ends, or trim them down on a bench grinder. Trimming them down is more of a trial & error fit, but it still works. Tap them gently down into the lifter, then pull on it to see if the dowel stays in there. Then you rubber band the 2 dowels together on the same cylinder to hold them up. I put a 4-5' piece of 2" PVC pipe in the bore after the cam's out in case a lifter would happen to drop out of the dowel.

You'll have to pull the pump gear to get the case off. Need a puller to pop it off. The air compressore & pump will hang on the side of the engine when the case is pulled. There's also 2 bolts on each side of the case at the bottom that need to be pulled, you can miss them. The oil pan bolts in the front have to be pulled, they bolt into the case. If the oil pan can be dropped easily, might consider replacing the gasket since the gasket get ripped at the front when the case is pulled.

gmcmhdriver

OOCTD - -Thanks for the comeback. I've got the thing on the way back together.

The RV pusher application uses a u-shaped cast iron bracket as part of the motor mount. It is directly under the crank pulley, bolts to the block and it has to be removed prior to removing the timing gear case so I had to find a way to support the engine before I could remove the case.

The oil pan gasket was going to be replaced anyway so I dropped the pan and supported the engine with a hydraulic bottle jack, using a 2x4 flatways across the second main bearing cap. Also c-clamped a 2x4 between each frame rail and the block to prevent the engine from moving sideways. It worked out rather well.

I'm glad the pan was removed because unlike you, I did not install a piece of PVC in the cam bore and I did bump one of the dowel sticks and it was followed by a clank and then by a soft thud. A lifter had fallen out, hit the block then the cardboard under the engine. Another PITA - now what to do?

Discovered that 1/4 inch Gates fuel line "not for fuel injected engines" is a snug fit in the lifter. Took a one-inch piece of this hose, ran a thin wire down the center and then immediately up the outside of the hose and pushed it into the lifter. Now it's a very snug fit in the lifter with the wire along the outside the hose. Takes perhaps 2-3 times the force to pull it out of the lifter as does the dowels. Used the bench grinder to bevel the hose so it would guide itself into the lifter bore - some electrical tape on the bevel might have made things a little easier here. Took a second wire and from the top of the motor, threaded it down through the lifter bore, connected it to the wire with the hose & lifter assembly and fed the lifter back into its bore. Piece of cake really but it took some searching around my shop to find something that might work. I highly recommend 1/4 inch Gates "not for fuel injection" hose for this job - -LOL!

This project is finally in the home stretch. The new crank seal and the case cover are installed. Rocker arms are in place. So, the oil pan, pulleys and drive belts, cooling module and the air compressor and I'm done. Still have the cooling module to clean and UPS should deliver the air compressor gasket in a couple of days. Almost there- LOL!

Anyway, thanks a million for your assistance.

Jake

00 CTD

Sounds like it's going along OK...that's good.

Yes, motor mounts are different on a Dodge & motorhome or medium duty truck. We do the same thing with a bottle jack to support the engine like you did.

You can reach up & put the lifter in by hand, but it'll take 2 people to do that. The other one needs to push the dowel back in while you hold it, then a piece of PVC like I mentioned. That way you can tap the dowel back into the lifter, and the lifter has something to rest against. If you do that, might want to give a little tap to all the dowels .... just in case. Then leave the PVC pipe in there until the cam is ready to go in.

gmcmhdriver

00 CTD and others. Thanks for your advice and support.

The new air compressor-to-case gasket arrived today and it's not the same as the one which was taken out. The original was a steel gasket entirely covered with rubber which seems to be a good thing as it has substantial sealing area. The replacement is nothing more than a piece of sheet steel with a very small, and I mean very small, ring of rubber around the inside bore. The ring of rubber is perhaps .030 inch radially at best and and not appreciably thicker than the thickness of the steel. I do not see how this can possibly offer any sealing at all.

I've chatted with Cummins a few times during the past week and they told me previously and again today that this gasket #392 9751 was and is the correct part. Somehow I just don't think so. The steel part is not embossed and does not have a raised ring or anything else to offer as a seal and the rubber on the inside bore is too small to act as much as an oil barrier.

So, since you are familiar with the Cummins medium duty engines, do you think this is the correct gasket or do RV medium duty engines equipped with air compressors use a different gasket than do the DTD's that use a vacuum pump?

I guess it's obvious that I'm a little anxious and nervous here about having no leaks. The engine has to be almost leak free or thanks to the pusher fan, the cooling module will clog up again real quickly and I do not want to have to remove it again - one cooling module is PITA enough.

Thanks again for you help.

Jake

00 CTD

They changed the gasket from a paper one to the metal one with the rubber seal around the inside. It is specific on how the gasket goes, it'll be marked on the gasket...engine side, so look for that. I usually put a small smear of the grey silicone around the bolt hole in the gasket too.

One other thing you might do after getting everything mounted is to pull the comp support bolts one at a time, clean them & put blue loctite on them...for piece of mind while you're working there.


One other thing, if the compressor is a single cylinder, it has to be timed otherwise you could get an engine vibration. You'll have the engine on #1 compression when you put the cam in. All you have to do with the comp is look for a line on the front of the gear, it'll be about a 1/8-1/4' long kinda like this ! Line that straight up & down with the compressor, then turn it back to the left about 30* and that'll put the comp on the comp stroke. There may even be a little dimple on the left side of the front of the housing that you can line the mark up with that.

gmcmhdriver

I finally found what I think is the correct air compressor/vacuum pump gasket at the Dodge dealer. It is Mopar #4638 531 and is the rubber/teflon coated piece. It cost twelve bucks.

I chatted with the Dodge diesel mechanic and he said to clean everything and install the gasket dry - my older 12-valve service manual says to use a sealer. I went with the service manual recommendation and coated the gasket with Permatex ultra gray sealer.

The engine ran for about an hour with no oil leaks but I'll be go to hell if there is not a coolant leak from the radiator core. So, I now have to do the cooling module PITA thing once again and install a new radiator.

My $20 dollar, one day oil leak repair project turned into a three week super expensive nightmare.

I guess that's why they make beer and weekends for - to forget this stuff, for at least a little while - LOL.

Jake