Cm 870 cry for help

[DDlighttruck]

(09-13-2019 )Rawze Wrote:  * Front axle leaf spring bushings both ends worn slap out. it is bad enough to make it pop real bad around corners and eat tires in wavy patterns on both sides. - This needs repairing very soon, if not right away.


* Water pump has smaller then normal pulley that requires different belt than rest of engine, keeps eating belts up. it needs replacing with the correct one that matches the rest of the engine.

Can you elaborate on these two things, please?

I have weird steer tire wear, despite replacing shocks and alignments, plus I have abnormal belt wear issues

[Waterloo]

Tire wear, if suspension is in good shape, I would high speed balance the steer tires. You are checking for balance and roundness of both tires. Could also be normal wear, take a photo of tread and post.

The abnormal belt wear could be a sign of a failing damper. How many miles on your motor? Cummins recommends repacking at 500,000 miles. I was chewing up belts and losing accessories, I replaced the damper and problems stopped. The damper is the big round disc on the end of the crankshaft, under the fan, it has a viscous fluid internally that hardens over time. When this occurs, the damper, or harmonic balancer, loses its ability to do its intended balancing act.

This is a regular wear item, unfortunately there is no way to inspect, replacement is the only option. If you do not replace, problems will persist, and you risk the damper failing completely, which entails blowing apart. You don’t want to go there.

When I replaced mine, it was $635 at my local Cummins shop. I had them install, as it was that winter that was nonstop -20, I was not replacing that in my driveway, LOL! They charged me two, maybe three hours labor. The bill was $1000 out the door, I dropped off at 1700 picked it up the following day at 0800.

If you replace, the damper must be painted so as not to void the warranty. Use the Cummins red paint, it ain't cheap, just use it, it is meant for the wear and tear of these external parts. One can will be plenty, as it goes a long way. I would also mark the timing stamps in the damper, use a sharpie and spray a clear automotive clear coat over the damper after marking the stampings. When it is time to do an overhead, you will be glad you did just that. Use multiple coats, paint over two or three days, seriously.

[DDlighttruck]

I think my motor has about 300,000 miles on it, but who knows on the age of the harmonic balancer. I seem to remember you changing yours and it was night and day difference.
Did you use an OEM balancer or an aftermarket?

[Waterloo]

OEM, I would not go aftermarket with that item. One thing to do too, is to remove the belts and check all of your pulleys. Maybe one of them has a slight wobble or bearing about to fail. Check the AC and Alternator too, lose bolts and make sure they are properly aligned with the rest of the motor. Also, that little pulley up top by the AC compressor, those seem to fail every two or three years. Gates makes a good replacement pulley for half the price of what Cummins wants. Could be that little guy ready to fail on you. Easy to replace.

[DDlighttruck]

I've checked and rechecked belts and pulleys. I've even gone as far to order in the correct alternator pulley for my engine serial number. I've also taken off the bracket where the tensioner mounts to a machine shop and had the mounting surface machined flat/square.

My belt used to walk and slowly chew itself off, then after I had the tensioner pad machined all was good for 4-5 months and the belt just grenaded driving along. I was using OEM belts, switched to Gates (which was the one that grenaded), now I'm going to switch to a Continental belt before winter.

That damper is a pricey sucker, but it's probably a lot cheaper than fixing it on the road. Was it hard to change out?

[Waterloo]

If you have done all of that, I am thinking damper. About the only thing left in my mind. I run Gates belts, no issues here, and that Gates pulley I mentioned. Damper.

[DDlighttruck]

Alright, I'll order one in. Thanks!

[Lonestar10]

Another thing a bad damper can possibly do is snap a crank so 600-700 is cheap

[ynot]

There aint nothing wrong with a vibratec damper. That's what all the "performance" shops sell, though that aint saying much lol. Its priced around the same as oem. I've used one on my last 2 trucks without issue