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Universal 5432 / M-40 Running Cold???

Kerry Kukucha

Member II
Hello All & Greetings from the Great White North!

Well here is a twist! Contrary to the usual complaints of a 5432 running too hot, the latest oil analysis I had done back in Sept. indicated that we had an increased soot level & that the engine could be "[FONT=Arial-Narrow+1]AFFECTED BY A/F RATIO, INTAKE RESTRAINT, LOW ENG.TEMP, HIGHER LOADS, OIL DUTY". [/FONT]
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[FONT=Arial-Narrow+1]I am assuming that engine temp is the culprit, insofar as the engine has only been running at 160F, ever since we had the heat exchanger boiled out last summer (brought the previous temp down from 190+ & solved an overheating problem). Am I correct in assuming optimal temp should be around 185F? In reviewing many other posts, the conventional wisdom seems to be that a hotter engine is a happy engine? [/FONT]

[FONT=Arial-Narrow+1]During a 3 week trip in August, where we put on over 100 engine hours (typically at 2200 rpm = 80% of top end) including a 13 hour run with all tanks & the boat fully loaded, as well as running against some challenging tides (running at 2500 rpm), the temp. gage never went beyond 165F! [/FONT]

[FONT=Arial-Narrow+1]I've ordered up a new thermostat in hope that it may increase the running temp, but have been told that the standard Universal thermostat is set at 160F? Does anyone know if there are any after market thermostats available at higher temp settings? Curious side note, the existing thermostat (stamped 160F) has a pair of holes drilled on it's perimeter housing base - mechanic said this might be changing coolant flow & impacting temp?[/FONT]

On the other indicated problem sources per the oil analysis, I'm not sure what an "A/F RAtio" is?

As for "Intake Restraint", my mechanic did provide me with a new air filter (new non-Universal filter foam that replaced the oily original filter foam within the filter housing). I wonder if the KN Air Filter upgrade that Rob Thomas did might have a positive impact?

I would greatly appreciate any & all thoughts, comments & suggestions!

I'd also like to thank everyone here for their great insight & wisdom shared over the past year & extend to all, best wishes for a Happy & Prosperous New Year!

cheers,
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hodo

Member III
Hi Kerry, diesels like heat. The temp should be around 180-185, while running at cruise speed of about 2000 rpm. There is probably one hole drilled in the flange to allow air to bleed out. There should be a bleeder valve near the thermostat housing to help you bleed air out of the system. Make sure the temp is accurate by using a laser type gun to test and compare to the guage reading. you should be able to get an aftermarket thermostat and gasket from NAPA , but don't buy their cheap one. I have installed the K/N filter and I am pleased with the operation. The A/F is air/fuel ratio. If the air is restricted by the filter, that could be a cause, but I think the temp issue is a good path to follow. Good luck, Happy New Year!
Harold
 

Gary Peterson

Marine Guy
The only way the A/F ratio in a Non-Turbocharged engine could be changed would be by an injector that has a plugged or blown tip or an intake that was plugged in some way. If the intake was plugged then the internal cylinder temperatures would be greater. One would see either low power and vibration or increased soot level in the exhaust.

"Well here is a twist! Contrary to the usual complaints of a 5432 running too hot, the latest oil analysis I had done back in Sept. indicated that we had an increased soot level & that the engine could be "[FONT=Arial-Narrow+1]AFFECTED BY A/F RATIO, INTAKE RESTRAINT, LOW ENG.TEMP, HIGHER LOADS, OIL DUTY". "[/FONT]


The oil analysis company used a generic answer that would cover all different types of diesels. Turbo'd and non-turbo'd.
A sailboat with a displacement hull, (cubic prop load curve), has a very low power requirement at slow speed so the engine would appear to be running colder than designed.
Do you have a water heater tank installed in the cooling circuit? That by-passes engine water past the thermostat housing resulting in cooler running also.
Yes, running under high load at 165 is too cool and the engine is probably running way too cool at idle and lower engine RPMs.

You have a "cool" engine:cool: ( Couldn't resist that!!)
 

u079721

Contributing Partner
Me too!

Well I found your comments fascinating, since I was rarely able to get the 5432 Universal on my E38-200 to run above 160°F. I checked the thermostat in a pan of hot water as folks suggested, and even bought a replacement, but still it wanted to run at 160°. Only when pushing the engine at 2450 rpm for many hours on end could I get the temp to rise, and then only to about 180°. After awhile I quit worrying about it, but I never did solve the issue. I did tend to get quite a bit of soot on the transom which I assumed was exacerbated by the engine running so cool.
 

rwthomas1

Sustaining Partner
A good while back I remember either reading or someone telling me that salt water cooled engines are deliberately run at cooler temps due to salt precipitating out and plugging up the heat exchanger at higher temps? Is that an old wife's tale?

There could be a few reasons why for high soot levels:
-poor injector operation
-restricted intake system
-overloading due to incorrect prop

How much soot is too much soot? Did they give you a % figure? FWIW, once I re-plumbed the water heater through the bypass hose and installed the new HX the engine never gets above 165*F. I get a fair bit of soot on the transom too. Never had oil analysis done on mine, just the terrestrial stuff. Now you got me thinking.... RT ;)
 

Tom Metzger

Sustaining Partner
It's true, but...

I remember either reading or someone telling me that salt water cooled engines are deliberately run at cooler temps
It's true, but only for raw water cooled engines. With fresh water cooling there is no salt in the engine and the heat exchanger doesn't have hot spots that would cause problems.
 

Gary Peterson

Marine Guy
A 160 thermostat starts to open ~ 150 and is fully open ~ 170 F. Now I will throw another twist into the equation :p !! The temperature one sees on the temperature gage can be different depending where on the engine the sending unit is placed. Engine internal temperatures are different in different parts of the engine.
All said-I would rather have an engine run too cool than run too hot.

Too much soot in the oil can also be caused by excessive ring blow-by. Different oils can also skew the results.
When one sends in an oil sample to be analyized, a sample of new oil should also be sent for a base line. In my previous life we would send in 3 or more samples from the same engine oil drain to the company we used for oil analysis and many times we would get different results. I would worry more about metals and acids in the analysis.
 
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