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| Truck & Diesel Mechanic Forum - ASE Medium/Heavy Duty Truck Forum :: Forums :: Cummins | |||
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 Cummins engine seizing/hard starting due to a/c compressor failure |
| Author | Post |
| RAV4guy68801 |
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  Joined: Fri Sep 18 2009, 10:50AM Posts: 149 | Had a really strange one come in a couple of weeks ago that still stumps me to this day, even after researching the problem in question. Truck came in with hard starting issues. Asked the driver how long it had been occuring and he stated that particular morning before he arrived at our shop that he had trouble starting. Ran our standard electrical systems test on the truck and found nothing out of the ordinary. Cranked the engine twice with no problems and 3rd time nothing. Ran volt drop across the circuit and found proper drop across circuit. Pulled the starter & bench-tested it & found slow engagement. Put new starter in and had sme problem. Removed oil fill tube & put a 3/4 in ratchet & extension in the barring hole & attempted to turn it by hand with no success. Advised fleet that engine is possibly seized. Truck was towed out and when we heard back from the fleet they advised us that the a/c compressor was locked up which caused the hard starting problem. My boss & I discussed it at length amongst ourselves and he said that cummins are slow-cranking engines to begin with and that any extra resistance on the engine will cause the engine to seem "seized." Truck in question was a 2007 Volvo with ISX475 cummins engine. Is this true or was this just a fluke? Since then I have been removing a/c drivebelts from and ISX engine I perform an electrical systems test on just to make sure I do have a starter failure occurance and not an accessory failure instead. Any thoughts from those of you guys who work in fleet shops or in shops that do cummins engine work is greatly appreciated. Anything worth doing is worth doing well!! | ||
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| hdtrktch |
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   Posts: 301 | I can testify to the slow cranking. We have a ton of new ISX engines with 50k or less miles on them. When we had the subzero cold snap a few weeks ago, we couldn't get the engines to start for nothing. I wonder what made the compressor seize? In my experience, the compressor shaft seal usually leaks at around 300-350k. Along that thougth. I wonder if taking the belt off next time we have a cold snap will help with starting? ASE Master Truck Technician L2 Advanced Level Certified | ||
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| Master Mechanic |
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 Joined: Wed Feb 04 2009, 05:01AM Posts: 207 | There is something you all need to look at and think about when you are looking at these starting issues. It all depends on how that ISX was speced. A 42 MT starter on a 15 liter ISX is going to work harder than on a 12.7 liter S60. The 42 MT is rated up to 14.8L. A 39 MT is rated up to 15L and other gear reduction brands all have a higher liter capacity. This is why you see many fleets switching to the gear reduction model starters. You can take brand new trucks with brand new cables, batteries and starters on a hot day and the ISX with a 42 MT will pull 1,300 to 1,400 amps to turn the engine over and the s60 will pull 450 to 550 amps. So I could see how a locked up compressor, cold conditions, possible connection problems and a 42 MT starter all added up, could lead to this problem. www.TruckMechanicTips.com ASE Master Truck Mechanic L2 Advance Level | ||
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| wcdiesel |
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 Posts: 227 | I agree MM - and most manufacturers fit 42,s because they are cheaper Regards David wcdiesel | ||
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| RAV4guy68801 |
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Joined: Fri Sep 18 2009, 10:50AM Posts: 149 | Master Mechanic wrote ... There is something you all need to look at and think about when you are looking at these starting issues. It all depends on how that ISX was speced. A 42 MT starter on a 15 liter ISX is going to work harder than on a 12.7 liter S60. The 42 MT is rated up to 14.8L. A 39 MT is rated up to 15L and other gear reduction brands all have a higher liter capacity. This is why you see many fleets switching to the gear reduction model starters. You can take brand new trucks with brand new cables, batteries and starters on a hot day and the ISX with a 42 MT will pull 1,300 to 1,400 amps to turn the engine over and the s60 will pull 450 to 550 amps. So I could see how a locked up compressor, cold conditions, possible connection problems and a 42 MT starter all added up, could lead to this problem. So is it true that the warmer a Cummins engine is, the harder it cranks, as well? And as far as misapplication goes, I cna see that happening a lot lately with new trucks on the road. Anything worth doing is worth doing well!! | ||
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| BlinkerFluid |
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  Joined: Thu Jul 09 2009, 10:16PM Posts: 137 | I can testify that I had a similar issue, however, international with ISX cummins... Driver advised he needed jumpstart, hopped in the service truck and away we go... Well so I thought... Checked voltage of batteries, Low, around 11.6v, Applied Jumpstart for nearly 30 mins, voltage returned to normal, however, Cranks slow... Voltage dropped tested circuit roadside, all good readings... I was stumped... Driver elected to see if another truck at the plaza would pull start him... Poped the clutch and she started right up, however, smoke billowing out of the hood and a freshly snapped belt determined bearing failure in the alternator was the culprit.... I now always check all pulleys off from drive belt to see if anything is binding... | ||
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| Steve Goen |
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 Joined: Wed Mar 17 2010, 03:15PM Posts: 4 | We had similar with our school bus fleet with Freightliners with Mercedes engs. Took the starters off an every thing.If any thing Locks up on these engs. they won't start. Like somebody else said take the belt off if you doubt it. Steve Goen | ||
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| Wyochimneysweep |
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Joined: Tue Mar 30 2010, 05:06AM Posts: 105 | I've always said to pull belts before giving up on the engine. alot of good cars and trucks are in the jard yard cuz of a bad alternator or water pump or a/c compressor | ||
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| MasterTech_TA022 |
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Joined: Tue Oct 20 2009, 08:30PM Posts: 78 | I have seen the same issue happen with the C-15 cats not starting due to locked up a/c compressors. I agree truck fails to start or hard starts..Pull belts and double check before sending for engine work.. MasterTech_TA022  | ||
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| streetsurgeon750 |
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 Joined: Thu Sep 03 2009, 07:11AM Posts: 17 | I had a truck on our lot the other day for a jumpstart. put our jump truck on the tractor for ten min and it was still turning over slowly. i had the driver turn the engine over while i was looking at the belts and found the a/c belt not to be turning. i removed the a/c belt and had the driver started the motor with no problem. it started just fine and the a/c clutch was locked up. i found this to be true on the cummings isx with the sandon a/c compressor. | ||
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| Moderators: Master Mechanic, popskull, Muffler Bearing, irishniners, hdtrktch, wcdiesel, proffesor |
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