I gotta change out my rear main and a exhaust valve seal on the number 1 cyl on my cummins. I was just wondering if anyone's got any tips a suggestions for me on how to do it and what to be careful about so i dont mess something up. Also what kind of a spring compressor do i need to get the valve spring off so i can get to the valve seal. Thanks for any help .

 

The main tip for the rear main is to make sure the crank is completely clean and free any burs these will mess up the new teflon seal. As for the valve seal you should be able to get an overhead valve spring compressor from a local parts store, the trick is getting a fitting to go in the injector hole so you can hook up an air hose to hold the valve up.

 

Just what mnwild said. Also on the rear main leave the oil seal house on the engine. they are hard to reseal with the oil pan on, and if you do have to remove the housing take a razer blade and work the oil pan gasket off the housing. Valve seals can be replaced if the piston is at the top of the cylinder. be 100% it's at the top or your pulling the head. remove injector to be sure its up.

 

We used one of these to pull the seal when we did the rear main on my buddys '93, IIRC ~$18 from Advance in the body repair stuff

 

Fully compress the spring, before you break the retainer loose push down, if you get resistance before the spring makes contact with the head then you're TDC, much easier than pulling the injector. Rear main seal sits in the transmission adapter plate, no need to remove the oil pan. Two self tappers and a slide hammer works to pull the seal. The new seal will come with a plastic sleeve and metal ring to seat the seal properly. Should cost you around 70-80 bucks. That's what I paid directly from cummins.


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ya to get it to TDC i was thinking of rotating the engine until the pin engages to make it top dead center. im pretty sure the number one cylinder is all the way up at that point which is the one that i have to change out. im really nervous about doin the rear main since ive never seen it done before. since i already have the engine out of the truck would it make my life easier to just take the adapter plate off? will i know right away what the oil seal housing looks like so i know to leave it on it? also anyone know of a sticky or something that has some pictures of what things will look like and such. thanks for all the help.

 

I'd leave the plate on, take the plate off and that means you have another point for leakage. Since the seal is installed in the adapter plate there has to be another gasket between the plate and block. Given the fact ive never removed the rear plate... I couldn't say for sure but logically I'm correct. take number 1 and number 6 valve covers off. Rotate the engine clockwise, watch your valves. First rocker arm; intake. Second rocker arm; exhaust. Cylinder number 1: intake rocker goes down-piston moving down on intake stroke. Intake valve comes up, approaching BDC. On the compression stroke you Should get about 180* of rotation where the rocker arms sit still, this is where you need to watch cylinder #6. at the point number 1 is moving up on it's compression stroke number 6 (it's paired cylinder) is moving upward on it's exhaust stroke. Exhaust rocker will be down, as you approach TDC exhaust stroke on #6 the exhaust valve will be closing, the last few degrees of rotation the valves on 6 will go in "overlap" the intake valve will open slightly while the exhaust valve is shutting. Soon as you see the intake rocker move stop engine rotation. #6 is in overlap and #1 will be TDC compression stroke. After that you'll be safe to break the valve free and it'll only drop afew millimeters until it makes contact with the piston. Follow me or did I lose you? You can always verify with the pin.


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The rear main Doesn't not sit in the transmission adapter plate. you remove the adapter plate and there is a rear main oil seal housing that the seal is in. had to replace mine already when the flexplate broke and damaged the trans adapter plate and oil seal housing

 

Well it's been awhile since I did mine, didn't pay much attention. My mistake then. Mine was actually spinning with the crank, leaked like a 5 gallon bucket full of holes .


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You said the engine is out? It should be a breeze. The crank journal might have a groove in it from the old seal. If so, cummins sells a kit that puts a sleeve on the journal and an oversized seal. You might want to consider putting 60# valve springs in while eng is out, at least the exh. valves for exh. brake, they're pretty cheap, I just bought 6 valve springs for $55. The rear main is nothin to be afraid of.