Volvo overheating ???

[goboats]

Have an md11c raw water cooled that is new to us. Had water in the oil , replaced a few parts and cured. But the temp gauge isn't working and engine seems to run hot so put an infra red temp gun on the cylinder head and found reading of 230f and 190 on the manifold . No smoke but seems hot or is that normal right at the head ? Also steams a little at higher speeds

[gmakhs]

Your prespective is wrong ,you can't calculate the engine temperature measuring the outside temperature of the cylinder or the manifold temperature, I have work with engines working on 450 celcious on the exhaust manifold , you will have to measure the water temperature that come out of the cooling line ,and should be from 60 to 85 degrees Celsius depends on the manufacture standards . If you have lower temperature you need to fix your thermostat since low temperature can cause damage as high temperature as well.
Fix the hearing censor of the engine and proceed from there .

[goboats]

Well right or wrong basically I was asking what the outside temp might be on the cylinder heads . Thermostat housing is very difficult to get to in my boat. And there doest seem to be enough water out the back of the boat . Appreciate you opinion though thanks . Most marine engines with raw water cooling will allow you to touch the cylinder. This one no way .

[Drew13440]

The thermostat should be fully open at 75c/168f. If you're steaming at high revs, you're too hot. I'd check for coolant blockage and/or a therm stuck partially open.

[Pete7]

Originally Posted by Drew13440

The thermostat should be fully open at 75c/168f. If you're steaming at high revs, you're too hot. I'd check for coolant blockage and/or a therm stuck partially open.

I think it should be cooler than that for a raw water cooled engine. Our slightly later 2003 has two different temperature thermostats depending if the engine is raw or freshwater cooled.

Pete

[goboats]

Thanks drew that's next on the list...impeller cover was worn so flipped it around and now cleaning exhaust elbow but looks good ...they have some kind of valve union in the water injection line ...looks corroded but water came out of the line at the elbow

[goboats]

Book says 170 to 185

[gmakhs]

Originally Posted by goboats

Well right or wrong basically I was asking what the outside temp might be on the cylinder heads . Thermostat housing is very difficult to get to in my boat. And there doest seem to be enough water out the back of the boat . Appreciate you opinion though thanks . Most marine engines with raw water cooling will allow you to touch the cylinder. This one no way .

You can't calculate the outside temperature, it varies from engine to engine and from load to load , the water temperature should be under 85 c .
If you can touch the cylinder head the engine is definitely overcooled and that's as bad as being overheated if not worse .
What do you mean thermostat housing is verry difficult?
You can try to clean the hole system by running the engine and supply her water intake from a basket with fresh water and backing soda to clean the silancier and the lines.
If you have issues with the thermostat you should solve them and I am telling you that as a licensed marine engineer (work in tankers)
If your thermostat is broken and the spare part is too expensive for you you can fit an Chinese one on your engine ,the process is as difficult as changing an impeller.
You can solve the issue other way and get your engine to "work" but will be for.little time and unsafe if you relay on it.

[Drew13440]

Originally Posted by Pete7

I think it should be cooler than that for a raw water cooled engine. Our slightly later 2003 has two different temperature thermostats depending if the engine is raw or freshwater cooled.

Pete

Interesting. OP's engine manual is online and contains the thermostat specs, though. Page 29 -

https://www.manualslib.com/manual/10...page=29#manual

[gjordan]

There is a chance that the previous owner simply removed the thermostat thinking the engine would run cooler. If the MD11 is like the smaller MD7, removing the thermostat will allow water to flow out the exhaust without circulating thru the rest of the engine. I dont remember the details, but there was a passage that could be closed off to get the water to flow thru the whole engine without the thermostat. Just something to keep in mind. _____Grant.

[gmakhs]

Originally Posted by gjordan

There is a chance that the previous owner simply removed the thermostat thinking the engine would run cooler. If the MD11 is like the smaller MD7, removing the thermostat will allow water to flow out the exhaust without circulating thru the rest of the engine. I dont remember the details, but there was a passage that could be closed off to get the water to flow thru the whole engine without the thermostat. Just something to keep in mind. _____Grant.

You are right thermostat is like a 3 way valve , putting water in cylinder and bypassing to the exchaust manifold the rest . Same on md5

[goboats]

Ya good advise thats ..what i meant was thermostats housing is very hard to reach on the boat...looks like one head is hotter than the other so might be plugged

[goboats]

Thanks drew great link

[goboats]

Thanks grant good point...will look at a bypass when I check the thermostat...there or not

[gmakhs]

Originally Posted by goboats

Ya good advise thats ..what i meant was thermostats housing is very hard to reach on the boat...looks like one head is hotter than the other so might be plugged

It can mean that one head doesn't work as well or have low compression or clogged injector.