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Thomasbus24
Administrator
USA
4545 Posts |
 Posted - 01/18/2018 : 08:49:08 AM
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This was too weird for me to not share. At least I think it's beyond weird. Is this more common than I know?
Tuesday afternoon, C7 dies on route. Driver said taking off from a stop it was sluggish (even for it) and after about 100 yerds the engine light and alarm go on, engine dies, won't restart.
We switch the kiddos onto a spare and start the usual checks. Hoping for gelled fuel or ice even though we treat the crap out of it. Put on new filters, find no ice or anything. Crank crank crank, it wants to run, it tries, it might sort of start, then die. Crap.
Tow truck brings it home and shoves it inside, we go home to defrost our toes.
Wednesday it didn't magically fix itself, so we go to look for the issue. We have fuel up to the the lift pump, but not out of the pump. Ok let's take that cover off and see if the pump gears turn with the engine because right now it's about $260 to fix. You can turn them with your finger, like the HPOP snapped the shaft in half. Crap...make that $1300.
Take HPOP loose and the gear is just freewheeling, thinking "Yep, it snapped". Get out of the bus with it...the nut had backed off. The nut that holds the gear to the shaft.
SO...12 years and 180,000 miles and it just now does that? It was hanging by it's last thread, would like to see what it would have done if it fell into the geartrain there.
Tightened nut, reassembled, fired right up.
Did I mention no fault codes? |
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RonF
Top Member
867 Posts |
Posted - 01/18/2018 : 08:59:02 AM
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hehehe,
I've had this happen more the once. The first time it took forever to figure out what it was. I did everything you did. |
US Army retired CMBT |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/18/2018 : 09:18:10 AM
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| No kidding? What do you mean by "More than once"? Is it bad enough to take the time to retorque the other 5 engines that have never been apart? |
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RonF
Top Member
867 Posts |
Posted - 01/18/2018 : 09:56:08 AM
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| Oh yeah, your mileage and time are about the same as mine was. |
US Army retired CMBT |
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RonF
Top Member
867 Posts |
Posted - 01/18/2018 : 10:15:50 AM
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quote:
Originally posted by Thomasbus24
No kidding? What do you mean by "More than once"? Is it bad enough to take the time to retorque the other 5 engines that have never been apart?
I've got 6 of them, 3 flat nose, 3 conventional. All three conventions have came loose. I torqued the other three just for good measures.
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US Army retired CMBT |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/18/2018 : 10:51:56 AM
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| I have a couple C7s of this vintage. Can you explain the nut better? Never been into one. |
Bryan |
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RonF
Top Member
867 Posts |
Posted - 01/18/2018 : 10:54:47 AM
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quote:
Originally posted by bwest
I have a couple C7s of this vintage. Can you explain the nut better? Never been into one.
ON the top left of the front gear cover is a threaded plug, about 5 " in diameter. Behind that is the nut that holds the gear on the HUEI pump. They come loose over time and when they do the fuel pump and HPOP stops turning. Engine stops running. |
US Army retired CMBT |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/18/2018 : 10:54:58 AM
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| Maybe a part number so I can look it up for reference? |
Bryan |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/18/2018 : 11:50:58 AM
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I don't think I have a removable plate or cover or anything on mine. There is one down at the compressor but not up high as I recell. All in FE buses so I can't really see to check.
The Cummins have a plug like that at the injector pump. |
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Thomasbus24
Administrator
USA
4545 Posts |
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RonF
Top Member
867 Posts |
Posted - 01/18/2018 : 12:30:43 PM
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Never mind, I have the cover confused with a cummins. It's been about 4 years since the last one fell off but all I had to do was remover the pump and tighten it back up.
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US Army retired CMBT |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/19/2018 : 04:26:32 AM
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| DOH! Wish there was a series with an access point. Do you happen to have a spec on tightening the nut? We don't have a CAT book (yet). |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/19/2018 : 05:19:58 AM
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| I've got a 3126 book that shows a bolt in that position. Says torque is 110 N-m +/- 14 (81 +/- 10 lb ft) |
Bryan |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/19/2018 : 06:03:32 AM
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| Bolt holding the gear to the HPOP shaft you mean? I do recall the pumps being different on those engines VS the C7. |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/19/2018 : 06:05:12 AM
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| Yes, both instead of nut. That's all I know. Logic would say if they are the same diameter that the torque would be the same. However, I don't have a way to get the size of either one. |
Bryan |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/19/2018 : 06:27:46 AM
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| I really need to get a book for these boat anchors. Maybe I'll scope out ebay this weekend. |
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earl1412
Senior Member
101 Posts |
Posted - 01/22/2018 : 2:53:39 PM
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If I'm looking at the right part, my C7 on highway book for YPG1-UP & KAL1-UP engines states the "Unit Injector Hydraulic Pump" nut for pump gear uses the following procedure:
1. Torque the nut to 50 +/- 5Nm (37+/- 4 lb ft)
2. turn the nut for an additional 35.5 +/- 2.0 degrees
3. Ensure that the toruque of the nut is 80 +/- 4 Nm (59 +/- 3 lb ft)
(A) The dowel extends past the front face of the pump housing to the following distance... 5.0 +/- 0.5mm (0.20 +/- 0.02 inch) |
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Thomasbus24
Administrator
USA
4545 Posts |
Posted - 01/23/2018 : 02:37:28 AM
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| Thanks! That's probably right. I have a couple of the KAL series, and even more that are WAX series...both have the same pump. |
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bwest
Administrator
United States
3820 Posts |
Posted - 01/23/2018 : 05:37:37 AM
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quote:
Originally posted by earl1412
If I'm looking at the right part, my C7 on highway book for YPG1-UP & KAL1-UP engines states the "Unit Injector Hydraulic Pump" nut for pump gear uses the following procedure:
1. Torque the nut to 50 +/- 5Nm (37+/- 4 lb ft)
2. turn the nut for an additional 35.5 +/- 2.0 degrees
3. Ensure that the toruque of the nut is 80 +/- 4 Nm (59 +/- 3 lb ft)
(A) The dowel extends past the front face of the pump housing to the following distance... 5.0 +/- 0.5mm (0.20 +/- 0.02 inch)
 That sounds like Cat specs! lol, wonder why they just don't say "torque to X" instead of "turn 42.35978 degrees"? lol |
Bryan |
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C7 quit..."well that's a good one!" moment
