Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

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Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

April 24, 2020, 12:28:24 pm

The lower tensioner for the serpentine belt that runs the hydraulic pump on my 1997 C8.3 Cummins (late 1997 engine, early 1998 coach) was bouncing and squealing. To be truthful, it had been bouncing for some time and I had not done any research, but the squealing pushed me into action. Here is a useful video from Gates on idler tensioner wear:

Gates Green Heavy Duty Tensioners

I removed it to check the bearings, they were a little noisy, felt rough and presumed to be dry. I could have tried greasing them, but after watching the video I decided to replace it because the spring probably was no longer doing its job. Cummins Quickserve indicated the idler on my engine was no longer stocked, part No. 3922900. After much consideration I focused my search on Gates and found a PDF from the Gates catalog for cross references. Here is that link:

Alliance Parts Catalog for Gates

Multiple searches indicated a Gates 38504 was the after market replacement for my Cummins 3922900. Found it at Rock Auto for a fraction of other sources. It came in a box with a Gates label and indicating "Made in Canada." Installed and the bouncing stopped and the squealing is now reduced considerably and lies somewhere else. I'm going to make inspection of the tensioner part of my annual PM. The supplied bolt was too short. Original bolt head and nut were 3/8" SAE, grade 8 with lock nut.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #1 – April 24, 2020, 12:44:21 pm

One of the keys to having "quiet" ribbed serpentine belts is to make sure all the wheels are running parallel to each other. If one tensioner wheel (or pulley) is slightly misaligned, it will cause belt noise and accelerated belt wear.

Pierce has written some excellent tutorial posts on "How to align the pulleys". A quick search of the Forum archives will find them.

Here's one example:

Pullies not quite aligned

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #2 – April 24, 2020, 01:46:52 pm

Smart to replace the tensioner. If it's just dry but spins easily, you can lube the bearings but any rough spots and noise indicate a damaged race or bearing. The bearings can be pressed out but if it's reasonable, why not replace it like you did?

Our AC clutch bearing was also making noise so you might check that. Since we don't use the dash AC, I just pulled the belt. A second alternator is going in place of the compressor. On a Detroit, good to pull the compressor mounting plate and install the block heater where it's supposed to go. You need a plate with a open spot for the cord to come out to the side if you put the compressor back on.

Pierce

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #3 – April 24, 2020, 08:16:59 pm

I had the hydraulic pump tensioner and pump belt replaced about a month ago just to do preventive maintenance and now the tensioner is jumping Would this be a defected tensional the old one wasn't jumping I also replace the alternator belt and tensioner also this tensioner does not jump I did keep the old parts as a back up it doesn't seem to be making any noise do you think I should replace it again this was replaced in Florida and I'm all the way back in Canada I was thinking that maybe the problem is in the pump I also had the hydraulic filters service this was done because the power steering box was replace

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #4 – April 24, 2020, 08:31:06 pm

Start by checking the pulleys for RUN-OUT (egg-shapped) with the engine at idle. Yes CAREFULLY.

A tensioner can only accommodate so much run-out.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #5 – April 24, 2020, 08:33:22 pm

RockAuto is closing out Gates tensioners for about $28.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #6 – April 24, 2020, 09:00:44 pm

Ideally, a dial indicator on a magnetic base would be the best way to check. But not just any dial indicator, just this type Universal Flexible Magnetic Metal Base Holder Stand Dial Test Indicator Tool...
You then rotate the engine with a breaker bar. This is the sure way to avoid injury. Hard to go wrong for about $24 delivered.

The other way would be to use chalk held so it touches the high spot on the pulley as the engine runs. Naturally, any mistake could cause a serious injury or worse.

On a 6V-92TA, the crank pulley is one piece so there will not be any runout unless somehow damaged when the engine was installed.

The pump pulley is not likely to have any runout unless damaged and that should be apparent by looking. You could also turn it by hand with the belt off to check.

Pierce

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #7 – April 24, 2020, 09:20:23 pm

That's a steal price. I just paid $125 for two of these on ebay. You should replace both of the tensioners at the same time

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #8 – April 24, 2020, 09:27:01 pm

I paid $233.52. From Cummings #8532678 and 226.89 part #8533477 for other one

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #9 – April 24, 2020, 09:32:06 pm

Rockauto is out of OEM brand. I looked and I bought two, cummins oem shipped from ebay for $140 a few months ago

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #10 – April 24, 2020, 09:46:03 pm

He's got cummins on the bill but it wasn't at a cummins repair shop I was there for a steering box and ask to replace for pre-maintenance service. I guess I should of shop around and do it myself but when you're on the road and not at home that's life and now it's jumping mayBe I try putting the old one back on to see if it works ok and keep this one for a back up but you can't drive around with all the old parts for back up l.o.l

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #11 – April 24, 2020, 10:08:17 pm

Gates 38504 for $79.99 delivered. Gates Heavy Duty DriveAlign Belt Tensioner, p/n 38504 | eBay

$50 plus shipping now at RockAuto.

Pierce

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #12 – April 24, 2020, 10:15:12 pm

How many of them are needed? 1999 8.3

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #13 – April 24, 2020, 10:34:34 pm

Be sure you get a Cummins approved one. There is some real junk for sale cheap. Dayton makes the main stream ones

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #14 – April 25, 2020, 12:14:15 am

Should have bought more when I got mine. They had several. $39.85 including freight one week ago including freight.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #15 – April 25, 2020, 01:09:11 am

I got one of the last if not the last one.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #16 – April 25, 2020, 02:45:09 am

I just ordered 2 from Rock. Hopefully they ship and I can use them on my year 8.3.

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #17 – April 25, 2020, 09:30:33 am

On the slight squeal that you still have Patrick, be sure all the groves on the pulleys are clean and have no rust or crud in them.. That's a possible free fix worth checking before buying anything else..

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #18 – April 25, 2020, 10:11:42 am

Quote from: dans96u295ft – April 24, 2020, 10:34:34 pm

Be sure you get a Cummins approved one. There is some real junk for sale cheap. Dayton makes the main stream ones

Anything Gates makes is a premium product. Not only their tensioners but also the highly regarded Green Stripe Fleet belts.

Pierce

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #19 – April 25, 2020, 10:14:45 am

A question!

What other products have been found on Rockauto that work on our RV's??

If you sign up for there news letter. Notices about clearance items will also be sent. Some items are deeply discounted.
Mark

Re: Tensioner Replacement 1997 C8.3 Cummins hydraulic pump belt

Reply #20 – April 25, 2020, 10:53:26 am

Quote from: Texhub – April 25, 2020, 10:14:45 am

A question!

What other products have been found on Rockauto that work on our RV's??

If you sign up for there news letter. Notices about clearance items will also be sent. Some items are deeply discounted.
Mark

Belts, hoses and some A/C parts are what I have bought.

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