2006 CAT C7 rust in coolant problem

[Sticks]

My current service truck for work is a 2006 Kenworth T300 with a CAT C7.



When I started with this company in May, during my detailed inspection of the red headed step child (everyone else hated that truck, & neglected it, and I am beginning to see why) I noticed that the coolant reservoir tank was rusted something terrible, and the radiator drain was plugged.



I was a full day draining, cleaning and flushing the coolant system until the water drained clean (like 12 drain, fill, & bring to operating temps), & replaced the tank. I added CAT recommended coolant and figured all was well. The coolant that did come out on the first drain looked like coffee with cream.



Last week the water pump went tango uniform, and upon draining the coolant out, there was the rust again. More of a brown color this time.



By the time I got done and started refilling, the bottom 3" of the buckets I used was the equivalent of muddy water after the sediment settled out.



Anybody have any idea what is causing this rust issue? First time I have ever seen this kind of problem with a coolant system. The only thing I can think of is that maybe the radiator is rusted as well and started flaking.

 

[mwilson]

You will have to go at it again.

I am camping and my only resource is this I-pad.

Cat makes a flush designed to be run for a time. If Wingate doesn't spot this and respond I will get you part number for it when I get home.

 

[Jim W]

It has been a while since I worked at Cat; but I do remember that Cat offered an additive that had to be added to coolant. My memory maybe going could not remember the part number for the additive. Check with your local Cat dealer not a aftermarket service department that works on several engine makes.

Here is something from Cat that may help on your cooling system.
For in-depth information on coolant maintenance, refer to the Cooling System
Specifications section of the latest version of SEBU6250 - Caterpillar Machine
Fluids Recommendations or SEBU6251 - Caterpillar Commercial Diesel Engine
Fluids Recommendations.

Jim W.

 

[Wingate]

I would run several gallons of 4C-4611 cooling system flush thru it. Drive the truck and work it hard enough to get it to full operating temperature for several hours. Make sure you follow the directions completely.
Does the system overfill after running for several hours? Does the coolant smell like diesel fuel?

 

[goodguys75]

I would have the radiator serviced ( cleaned out ) im sure it is plugged...

 

[Sticks]

Thanks, I'll get on SIS and read up on those.

As far as the radiator, I'll bet that it is not at full flow. The truck does not overheat, but to me does run a little hot (not sure if 200-210 is the thermostat spec). Normal puking out the overflow hose after refill, then she stays at the proper level. No fuel in the coolant that I noticed during the water pump R&R, and if there was, Diesel would should not cause a rust issue unless there is some sort of chemical reaction with the coolant, no exhaust flavor either. I'll pull a sample and send it in.

The truck has enough issues and would not hurt my feelings if the engine went tango uniform. No horsepower POS. Great flatland truck but but a hill in front of it and life sucks (lucky to hold 45mph on a 6% grade). Even coming off a stop light I get outrun by just about every other class 7 or 8 truck on the road with me. Why they put a 225hp engine in something that they know is going to be right at the GVW (33k#) all it's life is beyond me. I'd say it's the gearing, but any higher and I'd be even slower coming off a stop. Certainly looking at a chip for it. Need to put some gauges in first (EGT, Boost). If only I had access to CAT ET to see what the thing is set at, and if we can safely tweak it.

Sounds like the coolant and steering (another thread) are going to be a winter project along with the woefully inadequate exhaust brake. I am hoping running the overhead will correct some of this.

 

[Wingate]

I dont deal with truck engines, but from what I hear, the grumpiness about the lack of power is pretty normal. Many times, there are other limiting factors that cause the engine to be de-fueled, such as clutch, transmission, emissions output, etc. . You should drive a new F550 weighing in at a nice 19K lbs... its borderline unsafe!
Theres no telling what was in the cooling system before you got ahold of it, could be creek water, ethelyene/propelyene mixture... could be anything. You may have to perform the flush several times if its that bad!

 

[Sticks]

I know in the class 4-6 the power to weight ratio was generally OK, the GMC 5500 that I had did well at 21k#, not really any complaints until they went up a step size on the tires. Why anyone however would order a medium duty truck with a light duty engine is beyond me, likewise a heavy duty truck with a medium duty engine. Especially if you live in a region with mountains.

Generally it's a customer ordering to spec issue that causes the complaint. This field service truck was built by Summit Trucks in KS, and I don't believe it was a custom order, just an inventory truck. I'll have to call them and find out the history - it may well have been a flatland truck. I've talked at length with one of their sales person and the engine options are pretty large so a customer has the option to get it spec'd for their needs on custom orders.