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[overworked]

Engine missing or fluttering at idle and on decel. White bluish smoke not steady or real heavy. Kpz s/n no alarms or codes. C15. Any thoughts. Thanks

 

[Nige]

Any oil analysis results..?
Turbo bearings shot..?
Try pulling the valve covers and look for broken bolts on the rocker shaft or valve adjusters.

Those would be a couple of quick checks. After that you're major league into cylinder heads, valves, etc.

 

[overworked]

Thanks for posting Nige, about 3000 hours, really didn't think of oil analysis. Gonna do that. Its a new customer so i will see if they have done any in the past so we can check against.

 

[Per Eriksson]

Injectors

 

[Nige]

Thinking back to our C-Series experience here I would quickly pull the valve covers and check to make sure there were no broken bolts on either the rocker shafts or the valve adjusters, even if only to discount them as the root cause. Same thing for the turbo, pull the intake hose off and check for excessive end float in the cartridge, or signs that the cartridge has been rubbing against the housing.

I tend to agree with Per that it's likely an injector, but you have to start somewhere. Apart from that all the checks I've suggested cost you nothing but time.

Do you have Cat ET handy, or can you get hold of a tech that has it..?

 

[Cmark]

Check for a broken injector spring.

I've also had a C15 with your symptoms where an injector timing adjusting screw had wound itsself right out.

As Nige suggested, you need to get ET and do a cylinder cutout test.

 

[Nige]

Check for a broken injector spring.

I've also had a C15 with your symptoms where an injector timing adjusting screw had wound itsself right out.

As Nige suggested, you need to get ET and do a cylinder cutout test.

Even before going near it with ET I'd be having a look under the valve covers for anything obviously loose or broken. I must admit I hadn't thought of an injector spring. Our C-Series issues have been confined (so far) to broken rocker shaft holding down bolts, and broken and/or loose/unscrewed valve/injector adjusting screws. Must admit though that in every case the engine was rattling like a bag of bolts.

 

[overworked]

I have yet to start on this dozer, hope to this week. ,i do have cat ET. I was looking for some of your guys experience with these engines. Intermittent engine misses are allways a pain in the ass. Drive fifty plus miles and its purrin like a kitten, get home and the phones ringin. Drive back out and its fine again.

 

[Bob/Ont]

I recall a 365 that had an intermittent misfire similar to yours. You could load the engine down with the hyd's and it wouldn't miss a beat but if you let off the load it would occasionally start to miss. Using ET and the cyl cut out test a faulty injector was found. There was no mechanical problem, injector internal problem.
Later Bob

 

[Gavin84w]

All good suggestions here guys but don,t forget about the basics, fuel filters, water seperators, fuel supply tap etc. so many times everyone goes for ET and it don,t tell you a filter is plugged inside or a fuel line has a blockage etc.

Remember the basics and simple stuff!

 

[overworked]

Thanks for that Gavin, long before i got my ET i was loosing jobs to Cat , tech would show up, plug in and order sensor, next day another tech show up and install sensor, then order more, next day different tech more parts, after two sensors, six injectors and a fuel transfer pump, still low power. I finally got called back on a sunday , checked fuel pressure and changed primary fuel filter . operator dumped out filter and said he changed it, three cat techs, four trips and no one clicked on a gauge. I always try to slow down and start at step one. I am by no means perfect, just honest.

 

[Per Eriksson]

You don't need no gauge, just check the fuel pressure in ET.......the only tool needed ;-)

 

[Bob/Ont]

Thanks for that Gavin, long before i got my ET i was loosing jobs to Cat , tech would show up, plug in and order sensor, next day another tech show up and install sensor, then order more, next day different tech more parts, after two sensors, six injectors and a fuel transfer pump, still low power. I finally got called back on a sunday , checked fuel pressure and changed primary fuel filter . operator dumped out filter and said he changed it, three cat techs, four trips and no one clicked on a gauge. I always try to slow down and start at step one. I am by no means perfect, just honest.

Your problem is not likely a fuel filter due to it occurring as you take the load off the engine. Electronic controlled injectors can do that, try to get it misfiring and do a cutout test.
Later Bob

 

[theironoracle]

I don't know if the c-15 in the dozer has the hydraulic variable valve timing fixtures on them like the trucks but in the trucks they break very often, I have only personally done two but when my local tiny cat store has them in stock it means it's a serious problem, like nige said just remove valve cover and inspect ditto with the injector stems being bent or broken springs, I have seen that pop the tip off an injector and take out a piston with those pieces.....TIO

 

[Mike L]

if it does have vva housings like TIO said, look very close at them. they are prone to cracking, and also check to make sure the solenoids on top of them are tight. they have tiny screws in them and sometimes break or just come loose.

 

[overworked]

I finally got to the site today, they had it running it seems to miss after uphill push then when decell and back up it will cough. I ran it a while and got it to act up badly at about 950 rpm, sounded like a two cyl farm tractor, able to cut out cyl four and it would clear up. Will pull covers tomorrow,

 

[overworked]

Everything was in order under the covers, changed out the injector and did an overhead adjustment, couple of the exhaust were a bit tight. .026-.027. Put her back to work.

 

[Nige]

Were there any Active or Logged Diagnostic Codes recorded..? Always a good idea to check and erase any logged codes so that next time you go back if it has any codes you know they are new codes.

Also a good thing to do is download a Product Status Report before erasing any codes so that you can see what you had beforeyou erased any logged codes.

Also look for Diagnostic Events that are generally more serious and usually need dealer passwords to erase.

 

[overworked]

There was a logged code for f n r selector a hundred hours before. I wrote it down. The psr sounds to be the way to go.