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Old 11-03-2009, 09:47 PM   #1 (permalink)
kevv
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CAT C7 or 3126

Do we have any Cat mechanics or parts people on the board here?

Looking to get some C7 and 3126 information.

Please send me a pm if you could help


Thanks

Kevin
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Old 11-04-2009, 04:10 AM   #2 (permalink)
BrandonWatts
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c7's have a lot of injector and heui pump problems. i have personal had 6 trucks at work i have had to replace 2 to 3 injectors in. also have had a couple i have done all 6 injectors in. we have had 2 trucks that have had heui (hydraulic electronic unit injector) pumps go bad. i have not been really happy with them. also dont have a lot of power. our cummis ism's are a much better motor hardly ever have problems with them also seem to have more power. well that is my 2 cents someone might have a different opinion.
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Old 11-06-2009, 06:21 PM   #3 (permalink)
usafracer
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For the most part they are the same engine. I think they are both JUNK!!! I agree with Brandon the HEUI injection system is crap. It is basicaly the same system that the powerstrokes use.
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Old 11-06-2009, 07:02 PM   #4 (permalink)
heymccall
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Quote:
Originally Posted by kevv View Post
Do we have any Cat mechanics or parts people on the board here?

Looking to get some C7 and 3126 information.

Please send me a pm if you could help


Thanks

Kevin
Unless the engine is hot (stolen)(and even then), why not ask away here???

What happened???
Running poor?
Hard Starting?
Oil Cooler Leaking?
Front Seal Leaking?
Looses Prime?
Wanna uprate?
Rocker Boxes Leaking?

Can't think of any other common points of problems.
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Old 11-07-2009, 04:13 AM   #5 (permalink)
BrandonWatts
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Quote:
Originally Posted by heymccall View Post
Unless the engine is hot (stolen)(and even then), why not ask away here???

What happened???
Running poor?
Hard Starting?
Oil Cooler Leaking?
Front Seal Leaking?
Looses Prime?
Wanna uprate?
Rocker Boxes Leaking?

Can't think of any other common points of problems.
have to agree with all of the above the 3126 doesnt seem to have as many problems. we have a loader with that engine an older one and it is a good engine. the c7's are just junk plan and simple maybe that is why cat isnt building over the road engines anymore after 2009. they are teaming up with navistar. the maxx 15 will be a cat bottom end which have always been strong with a navistar upper end, turbo, head, egr system.
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Old 04-02-2011, 01:43 PM   #6 (permalink)
evozarkov
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[QUOTE=BrandonWatts;3544844]c7's have a lot of injector and heui pump problems. i have personal had 6 trucks at work i have had to replace 2 to 3 injectors in. also have had a couple i have done all 6 injectors in. we have had 2 trucks that have had heui (hydraulic electronic unit injector) pumps go bad. i have not been really happy with them. also dont have a lot of power. our cummis ism's are a much better motor hardly ever have problems with them also seem to have more power. well that is my 2 cents someone might have a different opinion.[/QUOT

I have a C-7 in a C6500 GMC and seem to have a problem w/ either injector,s or HEUI pupm, as told by pulling codes from engine. How can I narrow down which of the 2 above mentioned is the problem? Thx very much for Ur input
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Old 04-10-2011, 01:37 AM   #7 (permalink)
KEVINL
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We hace a couple of fl70's at work with 3126's they are god awful gutless but remarkably reliable only water pump replacements
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Old 04-24-2011, 11:23 PM   #8 (permalink)
jeremyfrank14
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[quote=evozarkov;4249577]
Quote:
Originally Posted by BrandonWatts View Post
c7's have a lot of injector and heui pump problems. i have personal had 6 trucks at work i have had to replace 2 to 3 injectors in. also have had a couple i have done all 6 injectors in. we have had 2 trucks that have had heui (hydraulic electronic unit injector) pumps go bad. i have not been really happy with them. also dont have a lot of power. our cummis ism's are a much better motor hardly ever have problems with them also seem to have more power. well that is my 2 cents someone might have a different opinion.[/QUOT

I have a C-7 in a C6500 GMC and seem to have a problem w/ either injector,s or HEUI pupm, as told by pulling codes from engine. How can I narrow down which of the 2 above mentioned is the problem? Thx very much for Ur input
Whats the code? The C7 is notorious for putting metal into the heui rail due to a heui pump failure which will also cause an engine miss. A good way to check for this is to remove the fuel pressure regulator from the back of the cylinder head and inspect it for metal debris. Also remove one or both of the 5/8 allen head plugs from either the front or back of the cylinder head and run a magnet down it. The plugs are pretty tight and sometimes you have to use an air hammer with a flat bit and hammer on the top part of the head while applying pressure to the plug via a ratchet/socket combination. If you have 157-17 faults then you more than likely have a faulty heui pump and possibly a bad injector if the engine is missing as well. Another thing to check is an injector that is leaking excess oil, will be easy to tell which one is if you pull the valve cover and look at the injectors with the engine running.
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Old 05-14-2011, 02:14 PM   #9 (permalink)
VTpuller
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is a C9 any better ?
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Old 05-14-2011, 11:30 PM   #10 (permalink)
jeremyfrank14
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Quote:
Originally Posted by VTpuller View Post
is a C9 any better ?
For the most part they are, heui problems are not as common but do happen. Biggest problem on the C9's I've seen is fuel in oil which is injectors or seals leaking and oil pressure problems which are mostly caused by the bypass valves in the pump. Went out on 2 C9's last week, one was an overheat problem in an 800 hour C9 the other was a low oil pressure problem. Got a job monday on a C9 for high oil pressure, depends alot on what application the engine is in and how well the its maintained.
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