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CAT D6R w/C9 fluttering under load

02Dmax

Senior Member
Joined
Dec 4, 2007
Messages
687
Location
MO
Just like the title says. A customer of mine has a D6R with the C9 and the engine makes an un-godly fluttering sound under load. Doesn't seem to matter if its got a big load of dirt or just tracking across the field. It sounds a bit valvey so we pulled the head, had it checked out, found one burnt valve and thought "good, we found it". Wrong, still does the exact same thing. I've ran the overhead 3 or 4 times and its never changed or been off. Local dealer has been out half a dozen times running cut out tests, replacing sensors, updating flash files, trying anything they know. About the only thing they've changed is made the smoke go completely away (used to give out a puff of smoke slightly at initial acceleration).

Anybody else ran in to this or any Cat mechanics have any ideas? My gut tells me its the Heui pump or an injector but I can't sell 6 injectors and a pump on a gut feeling.
 

DPete

Senior Member
Joined
Feb 21, 2007
Messages
1,677
Location
Central Ca.
You mean the dealer can't figure it out? There must be a way to test the pump & injectors. Cam is OK?
 

Dickjr.

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Mar 24, 2011
Messages
1,484
Location
Kentucky
Totally in left field here but an operater I know was bad about feathering the decelerator and it sounded as if it was not really missing but just sounded weird. This makes me wonder if the decel pedal is loose or the switch is defective. Are there any codes? The machine I am referring to had a fluttering sound. It ran fine and pushed as good. Even sounds like its bumping the governer on and off. I think the pump is good or bad based on pressure , the injectors another story how many hours?
 

MrKomatsu

Senior Member
Joined
Jun 12, 2009
Messages
437
Location
Houston Tx.
Had a d6 in the shop not to long ago...same issues, found #5 pin in electrical connector
in rocker box for internal harness to have pushed itself back a bit and was not makeing
a good connection but enough to not generATE any codes or such.......just sayin good luck.
P.s. Sorry for yellin caps lock is stuck....lol:usa:drinkup
 

02Dmax

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Joined
Dec 4, 2007
Messages
687
Location
MO
6800 hrs. Dickjr. - Every 6R I've been around does exactly what you're describing when the op feathers the decel but this one sounds like that all the time, but that was my first thought too, I'll take that pedal apart and check it out just in case. I haven't actually had the cam out to inspect it but that was a suspicion of mine too. I've ran the overhead 3 times and measured rocker lift once and everything seems to be uniform, and nothing was overly loose the first time I checked to indicate a lobe knocked off or something. The wiring deal has always been on my mind but it seems almost to rhythmic to be a loose wire, but still I should check that and I will. It's had wiring issues in other areas. My brother works at am injection shop and they just bought a common rail injector test bench. As soon as they get it set up I'm taking the injectors to them if I don't have it figured out.

Thanks for the help guys, its nice to have some real world suggestions and experience. My local dealer is decent but when an unusual problem like this comes up its pretty much just blank stares and them asking me to let them know what it was when I get it figured out.
 

02Dmax

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Dec 4, 2007
Messages
687
Location
MO
also, no codes. Anybody know what the pressure is supposed to run on those Heui pumps? Fuel pressure is 60lbs.
 

DPete

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Feb 21, 2007
Messages
1,677
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Central Ca.
Please let us know when you get it. Just bought the same machine, heui is new to me, dealer tech said to watch oil samples for aluminum which is a sign the pump is failing
 

Per Eriksson

Senior Member
Joined
Oct 24, 2007
Messages
650
Location
Sweden
Not alu, Heui pumps is known to fail but then it is all steel parts that fail, leaving high readings of iron but usually you'll notice it when injectors start getting mechanical errors or it is hard to start due to low heuipressure.

Checked the return fuel for air?
Maybe running it with one injector at a time shut off completely?
 

Lee-online

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Jan 16, 2010
Messages
1,023
Location
In a van, down by the river
If you have ET, monitor the injection actuation pressure. desired and actual will be within 50psi of each other. If not its either the sensor but probably the pump.
You can remove the top of the pump and look inside, there is a coil in there that attracts any metal debris so you can see if the pump is failing. You can also remove one of the plugs in the high pressure galley of the head. If the pump failed and you find metal on the plugs it will need cleaned out along with new injectors.

I too have found loose connector and bad crimps on the harness inside the valve cover. Cat sells new plugs that plug onto the injector if you have a bad one.

Engine oil with high hours also can make it rough so if its close to its change interval that could also be it.
 

Bob/Ont

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Joined
Sep 18, 2012
Messages
1,605
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Ontario
also, no codes. Anybody know what the pressure is supposed to run on those Heui pumps? Fuel pressure is 60lbs.

02, ran into this a few months ago on a 385 hoe. May or may not apply but it had an intermittant misfire. It would not do it under increasing load or steady full load. It would misfire only when you reduced the load slightly. With the excavator it's easy to vary the load but not so easy on your dozer. What found our problem was to get it into the misfire condition and then use ET to cut out individual cyls to find the bad injector.
Later Bob
 

Service Truck

Member
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Oct 29, 2012
Messages
8
Location
Braxton co Wv
The D6R s that i have worked on the heui pumps run very high psi and cause the problem your talking about also takes out your injectors i have replace acouple pumps and injectors at the same time. i also have seen junk inbetween the magnet that pulls the injectors open. but cat ET should show up on the injector cut out
 

02Dmax

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Dec 4, 2007
Messages
687
Location
MO
Thanks guys, its coming into the shop hopefully over the weekend and we'll pull that cover off the pump and see whats in there. It's been doing it long enough that the oil has been changed multiple times so I can rule that out. Cat dealer put another injector in it and it sounded better for a couple hours, now it sounds worse than it ever has. I don't really want to find a bad pump but I hope I do so this problem can be solved and put behind us. lol
 

ben46a

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Mar 11, 2007
Messages
773
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Waverley NS/Fort Mac AB
I wonder if these have the same style injector seats as the 3126? Those would become unseated and allow compression back into the fuel supply. If you stick the return line in a bucket of fuel and it bubble during a torque stall then its a seat. Would give similar symptoms.
 

02Dmax

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Dec 4, 2007
Messages
687
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MO
That would be easy enough to check if they're the same setup. Maybe Lee-online will chime in but I think its the same setup. No longer than it would take to check I might just do it anyhow.
 

Per Eriksson

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Oct 24, 2007
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Sweden
Yes, the injector cups can leak compression if the injetor isn't seating properly, that's why I asked earlier if it's been checked for air in the return line.

The fact it got worse after an injector were replaced points to this as well.
 
Last edited:

ben46a

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Mar 11, 2007
Messages
773
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Waverley NS/Fort Mac AB
Yes, the injector cups can leak compression if the injetor isn't seating properly, that's why I asked earlier if it's been checked for air in the return line.

The fact it got worse after an injector were replaced points to this as well.

I must have missed that in your post. But I thought the same when it got worse after injector replacement.
 

jake980

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Dec 9, 2012
Messages
49
Location
Canada
hey 02... I would also check the return fuel check valve in the back of the head... see if you can pinch the return line off somewhere.. another this is to plumb a guage directly into your high pressure rail and watch it while operating, I think it should be around 800 psi *you"ll need to look up spec* this may tell you if your control valve section of the heui pump is faulty. If you do find steel like lee-online has mentioned, the best thing to do (not what most costumers like to hear though) is a "heui overhaul" which consists of changing the pump, 6 injectors and flushing the rail. costly but effective, if you dont you will more then likely find yourself chasing and changing injector after injector...
 

02Dmax

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Dec 4, 2007
Messages
687
Location
MO
I replaced that check valve at the back of the head. Ya, I already told him that if its the pump its going to also need new injectors to properly repair it and get all the contaminant out. I think of it as a small hydraulic system (which it is) and in a hydraulic system when something fails and you don't flush everything you'll be chasing problems forever.
 

02Dmax

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Dec 4, 2007
Messages
687
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MO
Well, nothing! Lol. The machine wasn't in the shop before I left for vacation and I won't be back until the 14th. Customer is supposed to clean it up and put it in the shop, pull the air cleaner can and all the easy stuff out so I can pull the lid and replace injectors if I have to. I'll update you when I get back to it. Weather got nasty before Christmas and doesn't look like they'll be working anytime soon. I've got an urgent job when I get back but planning on starting on it the 15th or 16th.
 
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