Another heating problem KAD 43

[A_8]

These seem quite common so I'll add a problem I've not seen on here before.

This year one of my KAD43's started running a bit hotter than it used to, it would reach 85-86c at 3000rpm and very slowly climb over 90c at WOT and move toward 100c. It did not used to do this and should stay at 90 or 82 if at 3000rpm.

I've changed the impeller -twice, installed a new water pump (for other reasons), changed thermostats, cleaned the heat exchange unit and the intercooler (they were both very clean) and I still have the exact same problem.

Another difference is when I get on the plane just as the engines have reach around 75c from start, this engine does not reach 90c and then quickly settle at 82 as it should and have done before. It just slowly increase the temp.

I have checked the exhaust leg's temp and it's not higher than the other engine, this indicates the seawater flow is good.

My conclusion is that the internal cooling systems heat distribution is ineffective or slow if you will, i.e. the heated water does not reach the thermostat housing and temp sensor quickly enough.

If so the pump is not working as it should or something is blocking the flow, the pump is new and there are no leaks, the problem was the same with the old pump. I also find it unlikely that something is blocking the flow, what could that be? Anyone know how I can confirm that the coolant is flowing freely in the fresh water system?


The other angle that keeps bugging me is if I got the wrong antifreeze-water mix (too much antifreeze) when I changed it this winter. Anyone know if this could be causing the above symptoms?

Thanks /Michael

 

[[2068]]

Just because the exhaust temp is okay doesn't necessarily mean the seawater circuit is completely clear : is there an oil cooler on the seawater pipe before the pump?
Have you checked the exhaust elbow?
Belts in good condition and tight enough?
Swapped senders / gauges ?

A gross error in mixing the antifreeze wouldn't help, as pure antifreeze doesn't conduct heat as well as the correct mix. But it would have to be a big error.

 

[A_8]

Just because the exhaust temp is okay doesn't necessarily mean the seawater circuit is completely clear : is there an oil cooler on the seawater pipe before the pump?
Have you checked the exhaust elbow?
Belts in good condition and tight enough?
Swapped senders / gauges ?

A gross error in mixing the antifreeze wouldn't help, as pure antifreeze doesn't conduct heat as well as the correct mix. But it would have to be a big error.

I was not clear enough, it was the exhaust elbow I checked and as it's were the seawater exits I am pretty confident its not the seawater system. All belts are new and tensioned correctly. Its not the sender or gauge, I've checked with an IR temp thingy. The whole seawater flow is cooler then the other engine but the engine block is warmer.

 

[[2068]]

Hmmm. Seawater system cooler on the hot engine suggests that either there is an airlock in the freshwater side, a blockage, or a dodgy circulation pump/belt. But if you've replaced the pump, belts ok, that only leaves blockage or airlock. Or something completely different like "abnormal" combustion from a faulty pump or injector or head gasket that is generating more heat than normal.

What did the IR temp thingy show when pointed at various parts of the freshwater side? Hot evenly all around?

 

[A_8]

It seems that the antifreeze mix was wrong, I drained 8 ltrs and filled up with water, took her out and all of the syptoms were gone!

I guess I learned something