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I’m wondering why my truck has a spark coming off the bottom of the crank pulley. Every time it sparks the voltage inside the truck drops. I’ve heard it could be a harmonic balancer? Maybe a bad crank sensor? I’ve checked all the wiring and can’t find any shorts. The truck also has a bad crank seal so pretty oily around the pulley.
 

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Your damper (no such thing as a harmonic balancer on a 12 valve) is shot and creating static electricity. Inspection criteria is in the factory service manual. Genos sells stock replacements. '94-'98. 5.9L Dodge Cummins OEM Harmonic Damper The best price I've found for front cover crankshaft seals is Rock Auto. Don't forget the KDP and gear cover bolts while you are in there.
 

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Its not the damper... Its the old or cheap serpentine belt generating static electricity. Replace it with a good one, preferably a Gates Greenback. Geno's Garage has them too if you're shopping online.
 

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Inspection criteria is in the factory service manual.
Is it? I can't find it in the 96 manual, though "Inspect damper" is in the service rotation every X miles... And I swore I've seen it before, but it might have been on here.

Its not the damper... Its the old or cheap serpentine belt generating static electricity. Replace it with a good one, preferably a Gates Greenback. Geno's Garage has them too if you're shopping online.
I'm actually quite curious which of these two it is, as in either case you might have rubber-to-metal scrubbing creating static. I strongly suspect GAmes is correct and it's the damper though, as with a belt I'd expect some squealing if it was slipping enough to create static. Maybe not with the oil leak? With that said, a new Gates HD greenie belt (K080810HD) is only like $25 and a whole lot easier to replace (and you ought to anyway if you don't know how many miles are on yours), and your local O'Reilly's might even have one on hand. With THAT said... you ought to get in there and fix your crank seal, a new damper isn't terribly expensive, and at this age, it's going to need replaced soon anyway, might as well replace it while it's off. Two points on that:

A> I don't know how much mileage is on your truck but unless it's very low, just assume you're going to need the 3802820 part with the wear sleeve, instead of just a plain replacement seal. It is a slightly larger crank seal with a sleeve that slides onto the crankshaft (The seal wears a groove into the shaft after a while, and they begin to leak). You won't hurt anything by using the sleeve even if you don't have to, but if you do need it, the stock-sized seal will leak. No reason to do the job twice, just use the sleeved one. Google the p/n, you'll find the gen-u-wine Cummins kit for around $140, and aftermarkets for like $20. Up to you there. I've had luck with the aftermarkets. Others use Cummins parts only. YMMV.
B> If you buy a damper from Rockauto, it's listed under 'Harmonic Balancer', even though GAmes is quite correct (It's one of the grouchy old Texan's pet peeves :D ) that it is, in fact, not a balancer.
 

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Again, not to be the contrary one...but front crank seals rarely go bad. Instead there's more common reasons for 12 valve engines to be oily, like leaking valve covers that runs oil down the front cover. Or front cover gaskets. The engine fan blows things around too which can make it hard to tell whats actually leaking. Before replacing parts I'd suggest getting in there with some degreaser and seeing if you can better pinpoint where the leak is coming from.

As for static from the belt, its not uncommon but I'm sure no one is looking for discharge coming from their crank pulley. If you're questioning this possibility then simply put something on the belt surface which will lessen the friction and prevent electron generation in the grooves, and see if it continues. Like WD40 or some belt spray. I'm not suggesting that the belt isnt old and needs replacing but just proving a point which is much cheaper than installing parts that you cant return.
 

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I have to eat crow on this. I can't find the criteria in my fsm either, although I can mentally picture the illustration and some of the text. So, a little google and here you have it. Vibration Damper (Rubber) Inspection
A little more info. The index scribes are very difficult to see. IIRC they are on the side that faces the engine. The spark from the protrusion of the rubber insulator has been documented two or three times on this forum. Not once have I ever heard of a serp belt causing static electricity and a spark.

I buy the front cover kits that Felpro makes from Auto Zone. About $35 for seal and gasket. If there is a groove in the crankshaft snout just position the seal a little farther in or out so that it rides on a new surface. Or do like I did, install two seals. So far my double seal has remained leak free for almost 300k miles, a record for no front seal leaks. As a comparison, I killed the kdp at 104k and replaced the seal because the front cover was off, not because it leaked. At 288k the replacement (genuine Cummins) had to be replaced, so only 174k on it. I didn't dig into my records any farther. The seal leaking is a common occurrence IMO. It was only on the last two seal repairs that I used Felpro, all others were genuine Cummins. I even bought the overpriced kits with the sleeves at least two times.
 

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$27 Gater Greenback belt (which do wear out regularly)...or a $230 damper (which are uncommon to fail). Gee...which one would I try first. :unsure:

Crips...people, lets not encourage ones pride over that of giving responsible advice.
 

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It isn't pride, it is experience. The damper is easy to inspect for free!!! It only takes getting under it with a good light and a shop towel while someone bars the engine over. And they do fail more often than you think. Have you looked at yours lately?
 

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Lets be clear... Your first suggestion was to "replace" the damper.

And yes, I've looked at mine from time to time. Damper failure rates compared to a worn serpentine belt is not even a worthy argument either...

At this point I dont even care and you obviously do. "Experienced" or not...dont give bogus advice.
 

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I guess you didn't read "Inspection criteria is in the factory service manual" or the follow up post with a link. Obviously serp belts wear out faster than dampers do. I replace mine every 100,000 miles. Get over yourself, the advice is sound.
 

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Or do like I did, install two seals. So far my double seal has remained leak free for almost 300k miles, a record for no front seal leaks.
When I replaced my gearcase last spring, this was my initial plan. I was unable to get two seals into the cover, just not enough room. Completely pressed together, both were hanging out the front/back too much for my comfort. If the front seal was pressed flush with the cover, the rear seal would not stay in at all. I'm not sure if perhaps I have an aftermarket cover, though. The PO had RTV'd the heck out of the KDP-cracked gearcase, and it was clear that they at least had the cover off when they did so. It would not terribly surprise me that a KDP incident might damage the thin cover enough to warrant replacement. Anyway, that's just my experience on the double-seal thing. I ended up going with one of the sleeved kits.
 

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When I replaced my gearcase last spring, this was my initial plan. I was unable to get two seals into the cover, just not enough room. Completely pressed together, both were hanging out the front/back too much for my comfort.
They have no room to spare, for sure. Maybe Dart340w2 has completed his and will give an up date.
 

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Discussion Starter #14
180,000km on the truck it has a brand new high quality belt. I just took it of to do the alt and water pump I cleaned up all the oil from the pulleys and the only place I can see oil coming from is the crank shaft. The truck usually sat over winter but has been driven in winter and up here in northern Saskatchewan we see some very harsh winters so seals on anything are known to fail early and often. As far as the damper goes if it was starting to fail would I feel some sort of vibration in the truck?
 

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As far as the damper goes if it was starting to fail would I feel some sort of vibration in the truck?
Not necessarily. They deteriorate so slowly that you don't feel the difference. However, if it is bad and you replace it you will feel the difference immediately. That is especially true if you have a manual transmission. Shifting gets noticeably easier and gear box noise goes away. It is a 10 minute inspection, maybe less if the rubber is as bad as mine was.
 

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They have no room to spare, for sure. Maybe Dart340w2 has completed his and will give an up date.
GAmes suggested two seals to me in another post. Great advice! The two seals fit perfectly. The one in the front (towards the radiator) sits flush, then the second one got pressed in from the rear until it got tight. No leaks! I also emailed 9297oldram when mine was leaking for the second time, and he suggested two seals as well.
903253
 

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903254

Here’s the second picture that shows the front of the first seal.
 

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Looking at those pics I'm certain I have an aftermarket cover now. The stamping for the seal slopes in more gradually than that in the rear -- that second seal would be hanging on nothing. Not to mention that mine has a smooth surface, not textured like that. Well, that explains why I wasn't able to make the double-seal thing work.
 
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