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 Cummins 6.7 Water pumps + Tensioners
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unclefish
Senior Member

69 Posts

Posted - 02/07/2019 :  04:28:26 AM  Show Profile  Reply with Quote
We have 2009 to 2019 6.7L .Bluebirds
Are we the only ones having Tensioner and Water Pump failures.
If I can remember right even the 5.9 had water pump issues.
We use the factory antifreeze in these also.[maybe the problem]
You can actual look down at tension and tell when the belt is riding close to half of the pulley you better replace it. Reach up and grab the pulley on water pump and see how much play is it. Had them go between 30k to 90k.
we have tried gates tensioners and Dayco and factory [which is probably 1 of these brands anyways]
water pumps we get the Gates seems to last alittle longer than the factory.
Also it seems like our Flatnose FE go more frequent than the conventional

1Dieselman
Active Member

19 Posts

Posted - 02/07/2019 :  06:26:36 AM  Show Profile  Visit 1Dieselman's Homepage  Reply with Quote
We seldom have water pump or tensioner problems. Most of ours have well over 200k miles on them. I only use oem water pumps and gates (from Napa) tensioners when replacements are needed. I also only use Napa HD belts (green) for both v-belt and serpentine. They run much smoother and last longer. I don't have any 2019 buses yet (coming soon), so will see if that changes. I was just looking at one of our 2009 buses with 306k miles on it and amazingly it still has the original water pump on it
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Thomasbus24
Administrator

USA
4388 Posts

Posted - 02/07/2019 :  06:45:21 AM  Show Profile  Reply with Quote
I'm not where I can look for the exact feature code, but we have had units that for whatever reason were ordered with a feature code for an engine configured for AC. We do not have air conditioning, so no parts for it were installed.

Blue Bird and Cummins both had the incorrect belts listed, and used for production. It was just a tiny bit too small and would destroy pumps and tensioners. Once we identified which of our buses had this weird configuration, and started using the correct belts, no more issues.
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unclefish
Senior Member

69 Posts

Posted - 02/07/2019 :  07:01:04 AM  Show Profile  Reply with Quote
we also only use the the gates greens stripes or napa greenstripes which are the same..if you don't mind me asking what state are you in and what are using for antifreeze. I am in the northeast. I have sent more buses back to cummins to have tensioners put on cause when they break they wipe out the electric fan clutch or if lucky just the harness. The pin snaps off on tensioner and all hell breaks loose with the belt wipon around. Water pumps we end up doing here cause it will cost me more 2 send 2 drivers 40 minutes each way then a return trip to pickup and 1 to 2 day loss on using the bus.
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busrench
Active Member

29 Posts

Posted - 02/07/2019 :  07:10:52 AM  Show Profile  Visit busrench's Homepage  Reply with Quote
Out of seven Internationals with the 6.7, I've had to replace three tensioners. Twice on one bus, all with under 40,000 miles. The water pumps so far have been fine, knock on wood.
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unclefish
Senior Member

69 Posts

Posted - 02/07/2019 :  07:27:19 AM  Show Profile  Reply with Quote
Thomasbus24 we do not have AC either. We did have a problem with a certain year when they changed where the belt ran on the idler pulley. But it was due to a to large of a belt and kept snapping the pin of tensioner and blowing the belt off. especially when the electric fan clutch kicked in. It could be very possible that the belts we are using could be to small but isn't that the tensioners job to keep a constant pressure on it. Thanks Mike
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1Dieselman
Active Member

19 Posts

Posted - 02/07/2019 :  08:41:08 AM  Show Profile  Visit 1Dieselman's Homepage  Reply with Quote
I'm in Northern Arizona. It gets cold here but not like you see. We only use Fleetcharge coolant. We do have ac on some of the buses from 2011-12 and all the buses after that. When I came here a little over 6 years ago their coolant and a couple of other maintenance programs where for the the lack of a better word, crap. Shortly after that everything was changed over to the Fleetcharge and the green HD belts.
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buster133
Advanced Member

USA
495 Posts

Posted - 02/07/2019 :  4:55:32 PM  Show Profile  Reply with Quote
Not sure if it means anything, but lately when ordering OEM Cummins water pumps they seem to almost always be on backorder. Since 2011 I've only had two belt tensioners seize up, the rest I've either replaced proactively with the replacement of a bad water pump or with a new belt to address belt noise complaints from the drivers. ISB water pumps are a walk in the park compared to the setup on the MBE926!

[URL=http://s7.photobucket.com/user/buster133/media/6f2e0703-1970-4ac9-bb1f-b6b9d7c12297_zps1741e113.jpg.html][/URL]
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bestguessrepairs
Active Member

24 Posts

Posted - 02/08/2019 :  12:48:46 PM  Show Profile  Visit bestguessrepairs's Homepage  Reply with Quote
Your not alone.
Check with Cummins Insite or call Cummins some of your buses may be under a TSB or a Campaign for the fan belt tensioner.I have had 3 qualify. All 3 times they came on sight and replaced.
Overall I have proably done 6 other buses for either water pump bearing failure or tensioner failure. Once tore down I replace tensioner, pump,and belt regardless.

Also Thomasbus24 is correct on some buses having to small of a belt installed. When I call BB dealer they have to double check and make sure they send correct belt. If memory serves me correct its on BB buses 2009ish-2013ish.
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Tb4020
Senior Member

United States
82 Posts

Posted - 02/08/2019 :  4:08:39 PM  Show Profile  Reply with Quote
I always chocked it up to the electric fan clutch, the sharp kick in at high rpm's. I noticed on our birds even with cats in them they ate belts and tensioners way more than any of the cat or Cummins that had the plain old viscous drive clutches. I run semi trucks that use the on-off air operated fan clutchs but, they all have double vbelts. The vbelts seem to last for ever even with constant fan cycling, although wind through the front probably helps as a bus would be making constant stop/starts.
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eddo
Advanced Member

USA
254 Posts

Posted - 02/11/2019 :  12:28:29 PM  Show Profile  Reply with Quote
3 2016 IH with the 6.7L- all 3 have needed new tensioners pretty early.
2 2017 IH with 6.7L- 1 needed tensioner pretty early
2 2018, and 2 2019- none needed. yet.

no issues with any water pumps, though.

Edited by - eddo on 02/11/2019 12:28:53 PM
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BigPapa
Senior Member

177 Posts

Posted - 02/11/2019 :  1:44:16 PM  Show Profile  Visit BigPapa's Homepage  Reply with Quote
Out of our 421 buses with the Cummins 6.7, we've billed:

2017 - 44 Tensioners (21 - 3973820, 23 - 5270678)
2018 - 39 Tensioners (12 - 3973820, 27 - 5270678)

This is on '09-'18 model Thomas and IC's. Most every one of them has the stop broken off. I don't have a report of how many were warrantied, but I'd say it's easily at least that many. We have replaced water pumps, too, but nothing like the number of tensioners.

-Scott

Edited by - BigPapa on 02/11/2019 1:47:59 PM
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aaronwilmoth80911
Top Member

510 Posts

Posted - 02/14/2019 :  07:21:43 AM  Show Profile  Visit aaronwilmoth80911's Homepage  Reply with Quote
Has anyone had issues with the Green Stripe belts wearing a funny line/groove on the belt? We have had many do this and the only reason the belt was changed was due to age. Only happens on our Cummins
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krmvcs
Advanced Member

346 Posts

Posted - 02/14/2019 :  11:13:23 AM  Show Profile  Reply with Quote
I had that happen. Cause was due to a design change to the vibration damper. Sister buses with the same engine and didnt think about looking up the belt by the part number. Upon closer inspection the belt rubbed on itself near the tensioner because the vibration dampers were different.

-Ken-
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unclefish
Senior Member

69 Posts

Posted - 02/21/2019 :  02:12:04 AM  Show Profile  Reply with Quote
just set a record .. 2012 BB FE 6.7 cummins 131,326 came in yesterday original waterpump and tensioner, tensioner failed. original Blue antifreeze in it also come to find out that it was 1 of our slowest drivers. I think he was the only one that ever got called in on the hotline about driving to slow. This is a highway bus pickup at 1 school bring to another school. so not a stop and go bus.
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Poolguy7250
Active Member

USA
11 Posts

Posted - 03/02/2019 :  6:39:43 PM  Show Profile  Reply with Quote
We get 45 to 60k out of water pump.Cummins has come out with a new water pump last month. Tensioner bearings fail regularly also. I replace the bearings at pump replacement.
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Poolguy7250
Active Member

USA
11 Posts

Posted - 03/02/2019 :  6:43:37 PM  Show Profile  Reply with Quote
Our 2018 busses have a different belt and pulley configuration. It puts more belt on the water pump pulley.
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Thomasbus24
Administrator

USA
4388 Posts

Posted - 03/28/2019 :  04:15:54 AM  Show Profile  Reply with Quote
I found out that Cummins is currently working on a plan to have a service campaign to change belt routing on 6.7 engines in the IC buses.

I'm not able to say if there will be one for Blue Bird or Thomas, or if this was specific to the IC configuration, but everyone should keep an eye on the situation.

I'll post updates as I get the info.
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