CAT 924K and 926M EGR cooler leak

[DennisZ]

Good morning.

Our Cat 926M has started using coolant, and is getting to the point where it has difficulty starting in the morning, I assume from water on top of a piston. Our 924K had the same problem a few years ago, to the point it would crank anymore. Turned out to be the EGR cooler, whole exhaust piping, cooler and valves were full of coolant. Dealer replaced the cooler, cleaned and serviced the egr valves etc but machine was never the same as in having lack of power. They came back, thought the turbo was bad but send it to a turbo specialist and they said nothing wrong with it. They did all sorts of tests, even a forced regen (almost an hour with engine at high rpm to get exhaust temperature up) but still lacks boost pressure and thus HP.

I am afraid the 926M is going the same route. It's our main machine, with the 924K as a backup.

Is it a known problem on these engines, although engines are not the same? (924K has the C6.6 where the 926M has the C7.1).

Is there a delete kit for this sh!t?

Thanks, Dennis

 

[ahart]

Dennis-
Yes, it’s a very common failure on the Perkins engines to have a NRS cooler failure. Though different engine models, they are very similar. Main difference is one is T4i (924K) and the other is T4F (926M) The 926M has a more sophisticated regen system and is not as tolerant as the T4i system. An NRS cooler failure usually starts slow and will show up on an oil sample before you start adding large amounts of coolant. When the antifreeze burns, it creates a residue that often restricts the flow through the clean emission module as it accumulates on the face of the DOC. The main thing on a cooling system with an NRS cooler is to not have any air in the system, easiest way to achieve this is to vacuum fill the cooling system. If the dealer downloaded a status report with ET, you could request a copy for each machine and post here.

 

[DennisZ]

Thanks

Had dealer mechanic out on Thursday, confirmed "probably leaking" cooler. Wanted to take it off, take it with him for testing etc, and if necessary order new one. i told him to order a new one and when he had it to come change it. Friday morning machine started to blow a little white/blue smoke now and then, and after i shut it off to refuel my tractor, it won´t start anymore... Probably water locked on 1 cylinder now... Called dealer and asked if part was in yet, he told me "sorry, will order it :-( "
Had to get by the weekend with the old one (which sucks because it is not a high lift, the 926 is)

 

[Monkeywithawrench]

Hey Dennis,
Sorry to hear about your problems. Just curious.........how many hours on the loaders?? We have a 930M and I'm wondering if I should be watching out for this issue. No water showing up on the oil sample reports..........yet. Our machine has 9895H on it.

Thanks in advance and good luck!! Keep us posted how you make out!!

 

[DennisZ]

Hey Dennis,
Sorry to hear about your problems. Just curious.........how many hours on the loaders?? We have a 930M and I'm wondering if I should be watching out for this issue. No water showing up on the oil sample reports..........yet. Our machine has 9895H on it.

Thanks in advance and good luck!! Keep us posted how you make out!!

The 926M has 6000 hours on it. The 924K had it a few years ago, probably 7-8000 hours back then. Both had full dealer service since new, always CAT oils, filters and coolant. The 924K had 5000 hours contract on it but managed to get a another few free services for it when we closed the deal on the 926M, little over 4 years ago.

 

[Monkeywithawrench]

Thanks Dennis.......
Just my 2 cents........but if your not doing oil sampling at every service (doesn't seem like you are from your post, I could be completely wrong) then you really should start doing it. Oil sampling has saved my bacon a few times over by catching things going wrong before they became a HUGE problem.
I can't help but think if you were doing engine oil sampling, the oil samples might have caught the coolant issue before it became this big of an issue.
Then the issue would have been, where the hell is the coolant leaking!! That's always fun trying to figure that out.
Again, best of luck.........and thank you again for the hours.