Cummins 555 rear main seal replacment ? - Diesel Truck Forum -
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post #1 of 5 (permalink) Old 06-30-2016, 01:37 AM Thread Starter
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Cummins 555 rear main seal replacment ?

I have a 1970 IHC dump truck with a cummins 555 in it. The rear main seal needs to be replaced. I have removed everything behind the engine and the only thing left to remove is the flywheel housing and the rear cover. Anyone have any tips for a proper install? engine number is 20164228. Upon removing the flywheel I found the clutch and flywheel mating surface to be severely cracked in several places, my suspicion is someone resurfaced the flywheel to thin and now the assembly has to be replaced. The clutch is about 50% but would obviously replace clutch as well.
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post #2 of 5 (permalink) Old 07-02-2016, 05:43 PM Thread Starter
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I found the "proper procedure" in my cummins manual, buried under a different topic. Without any old timer tips offered, I will follow the recommended procedure to the letter. I have removed the flywheel housing and rear cover and removed the old seal. I found the crank to be grooved, so I will have to sleeve it and install and oversized seal. Cleaning everything now and preparing parts to be reassembled as I wait on parts.
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post #3 of 5 (permalink) Old 07-02-2016, 08:59 PM
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Some rear mains are difficult to do without the proper tools and it is hard to justify the cost of the tools for just one seal. Does that one have the flange that bolts to the block that the seal goes in? On those I install the seal in the flange on the bench. Then walk the assembly over the crank like an automatic transmission hub. That is unless it has an installation sleeve. If the seal can be installed shallower or deeper I do that so a standard seal can run on a new part of the crank.
Same tool rules go for wear rings. I have had limited success heating them and other methods. Better success putting a skim on silicon inside of it and start it on the crank as far as possible with light pressure. If you have a way to push on flush without damage that's OK to. Then install the flywheel with four evenly spaced bolts, as in 12 3 6 and 9, screwed in the same amount of threads. Then tighten them the same amount, about a half turn at a time, in a 12 6 3 9 pattern, intel snug. Then torque them. That pushes the ring on the correct distance past flush. Remove the flywheel and check the ring, if it is has an imperfection it's junk. Install the seal and flywheel. Put a big sheet of cardboard under it and run it at about 1500 RPM for 20 minutes to check for leaks. It is a lot easier to to do it again before the transmission is put in it.
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post #4 of 5 (permalink) Old 07-03-2016, 02:30 PM
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Great writeup tenwheeler.
Sounds like we have another TruckShop on this site ☺
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post #5 of 5 (permalink) Old 07-03-2016, 05:21 PM Thread Starter
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Thank you Ten Wheeler: Sounds like you have done a few rear main seals! The seal is in the rear cover and I can install it on the bench. I don't have a specific Cummins tool, but I do have an assortment of seal installation tools at my disposal. I would prefer running the new seal on a different spot on the crank instead of using a sleeve and over sized seal. If the wear sleeve is not within tolerances I bet getting it off without damaging the crank is a real pain. Unfortunately I cant talk to the parts man until Tuesday. I really like your advice on running the engine before installing the transmission, I will definitely do that. Thanks again.
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