6 CTA 8.3 Liner Pitting

[halftrack]

Here is a question(s) for ya!

To Bruce, Chris, Army Ed, Bjorn and to whomever else can shed light. I am currently having my spare 6 CTA 8.3 rebuilt to be put in the M936A2 I got from Bruce. I originally thought that the either the head gasket was blown or the oil cooler was bad because I found anti-freeze in the oil filter. Well, after a little engine take-down I found that both the oil cooler and head gasket did not look damage or compromised. So I figured just bring the motor to the pros.

After I found a reputable competent machine shop to rebuild it, they called and told / showed me the problem. He said the motor itself had extremely low hours on it and looked like a new motor. However, the oil in water problem was due to liner pitting (looks like worm holes) and because the liners are “wet liners” the holes allowed coolant to seep into the crankcase.

Well, after talking to Bruce and doing a little research, I found out this damage was created by cavitations caused by high frequency vibration from when the motor is running (not going to get into great detail on the specifics). I know we have similar problems in flow control valves in pipes so it was not totally new to me. After further investigation, I found that this is easily preventable just by using certain anti-freezes or having a filter setup up that treats the coolant in which I noticed on most newer diesel trucks.

My questions are as follows:

Why does the military not have a filter setup for the coolant on the 939’s (I thought about adding one on my M936A2 before this even happened)?
If I where to add one, what lines do I need to tap into to ensure proper filtration (heater lines maybe)?
Any recommend particular brand of filter and or anti-freeze (fleet guard, etc…)?

Of course I attached a crappy picture along with some background info.

I would appreciate if anyone can enlighten me on the subject?

 

[WillWagner]

We don't see that on the C series or M11 serirs too often. Usually only when the system has had plain water in it...mostly construction and fire pump applications. Early C's, like in the 900 series trucks and the early automotive engines, didn't have the dorrosion inhibitors on them. IIRC, the "88 product had them from the factory. You can get by w/o one if you use a good diesel coolant with SCA's pre charged in it and test the coolant at your oil change intervals. If you wanna install one...remember, the "filter" doesn't get changed at services, only when the system needs it, so you STILL gotta check the concentration...any pressure port like the plugs in the head or the exhaust side of the block for supply and one of the plugs on the w/p volute boss located on the front exhaust side of the block, where thet little "hump" is behind where the w/p mounts.

 

[jwaller]

whomever first used the engine prob didn't use the HD coolant required for that motor.

 

[steelsoldiers]

Dang, that really stinks, Jason! Sorry! I haven't seen that type of cavitation mentioned with our series of engines before, so it probably was from plain water or crappy coolant.

I am looking into the Evans NPG+ for my civi truck and my M925A2. It is great stuff. It is waterless and has a boiling point of 375*. You can run a low- or no-pressure cooling system since you don't have to worry about boiling over. You can run the engine hotter which means better fuel economy too. There are many other demonstrated benefits including no rusting, no cavitation, no SCA's and it is a lifetime coolant. Check it out: NPG+ » Engine Cooling Systems I think it's around $119 for a case of 4 gallons so it ain't cheap, but you only need to do it once. Just a thought.

 

[nk14zp]

Not enough SCA's.

 

[halftrack]

Not enough SCA's.

I am going to assume your typical Prestone antifreeze does not have SCA's right?

 

[zout]

correct there are no additives in this to stop liner pitting (static electrical bombardment)
You would use a test strip - similar to testing poo's - but it is to test for dca.

Piston liners are almost all protected by a coating. WHen the non treated engine starts getting bombarded with the static in the water - eventually it finds a weak area - could be 1 liner or all 6 - or 8 given the displacement.
Once it finds the pin size weak area the static attacks it worse bombarding a hole right through the liner - and they are thick liners.

Test strips are one way - coolant filters are now equipped to slowly release dca into the coolant keeping it at the proper level - I THINK 1.9 if I recall right - if not someone is sure to tell me I am wrong shortly.

You can purchase the additive at Napa- truck dealership parts counters - but be sure to run the coolant for a while and retest to get the proper level of protection.
ALSO - some coolants come with dca but you have to ask.

 

[BKubu]

Check on the back of the antifreeze to see if it is approved for use in Cummins, Cat, Detroit, etc. engines. If it is, you can be fairly sure that it is the right stuff.

 

[steelsoldiers]

Here's a good article on cavitation. It is referring to the Powerstroke engine, but most of the information crosses over to our Cummins engines. http://www.genosgarage.com/installation_instructions/GGTutorial-FD-FleetguardTestStrips.pdf

This is a good article from Cummins on coolant and SCA's: http://www.cumminsfiltration.com/pdfs/product_lit/americas_brochures/LT15108.pdf

Geno's Garage sells the DCA4 and the test strips.

 

[halftrack]

I think I can safely assume now when I see what looks to be a perfectly good looking motor in a "can" pulled out of the truck in the Army that the reason is liner pitting/holes. I bet this is killing a majority of the Army's 6 CTA motors out there. It's a shame because it seems very preventable.

 

[hemichallenger]

This can also be caused because the block does not have a good frame ground.