cat cooling systems 2

[mechanic6]

we have several cat gensets,3500 series and 3600 series.in the last few years we have had to replace 3 rads and 1 jacket water aftercooler core due to corrosion.
the antifreeze is as per the cat recommendation and is changed out every 2nd year(usually).

we monitor the additive levels but still have this problem.

we do not have this problem with our detroit disel or mitsubishi diesel gensets.
ideas???

 

[MikeHalloran]

Check that the genset frame is grounded locally, and not through the coolant and radiator.



Mike Halloran
Pembroke Pines, FL, USA

 

[Zapster]

Do the Cat's radiators use the same material of construction as the Detroit's?

Are the Cat's radiators subject to more vibration than the others? If so, could stress induced corrosion be an issue?

 

[catserveng]

What kind of antifreeze are you using? Should be an HD antifeeze with a diesel engine inhibitor package, low silicate and nil phosphate. How about the water you're using when you refill, does it meet the CAT spec? How often are you adding SCA (corrosion inhibitor)? What inhibitor are you using? How often do you test and how? Take a sample of coolant, let it cool and give a sniff test, if it has an ammonia smell you need to check for active biological growth and may need to add a biocide, especially on the 3600 engines.

You can check for grounding or excessive coolant conductivity by using a DMM, measure the coolant to ground with off and then running, should be less than 500mV and reading shouldn't more than double when engine is running from stopped measurement.

3500 series can be shipped with CAT branded raditors, packaged on the rails with mechanical fan drive. 3600 series radiators are usually specified for site ambient conditions usually from AmeriCool or Rocore.

Is the problem all water side corrosion?

Maybe with some answers we can be more helpful.

 

[EzGoingKev]

"we do not have this problem with our detroit disel or mitsubishi diesel gensets.
ideas???"

Yes, it is a CAT product.

When I was turning wrenches at a truck lease company the only problems we had were with the CAT engines. All the Cummins & Mack engines didn't have issues for the most part.

 

[dicer]

It can also be galvanic, from dissimilar metals that makeup components in the system. Kinda why keeping proper PH level would be important. You could be having combusion gas intrusion into the systems as well. All brands have their share of problems, I agree Cat seems to have issues.

 

[mechanic6]

thank you for your thoughtful replies.
we shall look carefully at the galvanic flow and the combustion gases in the coolant(my pet idea).

we have similar problems with our winter equipment fleet,sits most of the year,rads seem to rot(corrode) quite quickly.
one common thing is both the gensets and the winter stuff are plugged into block heaters 24/7.
could this cause the glycol to breakdown more rapidly?.
might this be a potential(no pun) source of stray current into the cooling system?.
once again thanks to all for your suggestions.

M6

p/s the cat people are of little help here,they say we must be doing something wrong but cannot suggest anything other than to change out the coolant more often(like 6 months???)sorry this is not an option.

 

[catserveng]

If the jacket water heaters are convection type, then yes, they can degrade the corrosion protection. If you pull a heating element out and see a white to tan deposit, and loose debris in the bottom of the tank, then your tank heaters are affecting your coolants corrosion protection. KIM Hotstart sells smaller jacket water heaters with small circulation pumps, actually work better than the convection units like the horizontal KIM Hotstarts or the Watlow heaters.

Jacket water heaters are rarely, at least in my experience, the cause of stray currents in cooling systems. Usually this is the result of poor grounding practises or coolant with too high conductivity. To be sure check for corrosion around the voltage connections of the heating element. If you have an accurate clamp on ammeter, go around both conductors to the JW heater and see if you have a measurable current, means you have some leakage thru the engine, hard to see unless the heater has a real problem, but have seen it.

Do you engines have a bond strap between starter negative and the block? Is usually a piece of 2/0 cable about a foot long. CAT stopped bonding engines for awhile, bad mistake, if it's missing install one. Also make sure if an alternator is installed it also has a battery neagative wire going back to the starter negative terminal. Depending on the vontage these were eliminated on several models for cost saving.

Are these gas or diesel units?

 

[patprimmer]

Cat

I just learned something new and useful. Thank you.

Regards
Pat
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[mechanic6]

gentlemen
thanks for your tips.
we will take a close look at both the block heaters and the electrical bonding on the engine block & rad.

M6