Update on one engine 10 degrees hotter

"Ok so went down and went thro

"Ok so went down and went through everything again and here is what found.

-Backflushed oil coolers - I think but hard to tell, that the cooler on the hotter engine is flowing less water, but not by much, did get some zinc pieces out.

-Removed end caps from heat exchanger and found some scale/shell and the remainder of the old zinc inside. Cleaned that and was able to see the tubes looked clean.

- Tightened belt on pump

Took boat out for short 20 min run and stayed cooler, basically stayed below 170 until got above 3400rpm then went just above 170. I did notice it was still 5-10 degrees hotter than other engine but better than was. I did confirm all these temps with the temp gun and still about 5-10 more across various parts of motor and exhaust.

So in doing this also noticed that the coolant portion of the heat exchanger was about 15 degrees hotter than other motor and so were all parts where coolant ran through from what could tell. SO what might cause this? Coolant system flushed and changed one year ago. Does this sound like a flow problem or something else? Where should I start? Should I try changingn the thermostat?

Thaanks for all the responses and input.

RM"

"I'd bet on the oil cooler

"I'd bet on the oil cooler have a few tubes blocked, still.

If you search the Crusader postings for OIL & COOLER, you'll come across a few threads. One will have Al's disassembled and 'boiled out' pctures done very similar to how Diver Dave described it recently. There are a few other posts describing a muriatic (sp?) rinse technique to 'boil out' the zinc remnents.

I've found it does take too many of the water holes to be obstructed to reduce flow of the cooling water. I suspect it is even worse due to the potential for aerating the heat transfer area.

The backflushing works if you keep up the maintenance and don't leave too much of the pencil inside. Beyond that, you need to disassemble them, do the acid rinse, take them off to have a radiator shop clean them or replace them."

"Any chance you have your hot-

"Any chance you have your hot-water tank looped into the "hotter" engine? I have had more than one mechanic tell me that it seems to have an affect. (I do have it plumbed and do have a 10-degree difference as well.)I have new heat exchangers, oil coolers etc. etc. which eliminates them as suspect...so must be something to it."

You need to muratic acid the u

You need to muratic acid the u-cooler.and flush dothis twice.

"Hi RM,
Check your ignition

"Hi RM,
Check your ignition timing at idle and at 3500 rpm or what ever rpm Crusader recommends. Retarded ignition timing will cause the motor to run hot . Both motors should be identical.

Good Luck
Jon Allen"