Newbie Needs Help, Overheating Universal M-18

[rexzy]

Hi,

Short history: Bought the boat last year and didn't realize the engine overheating at the time. First trip engine overheating over 200, took it back to marina, mechanic changes thermostat.

Try #2, results in same type of overheating. Bring the boat back, the mechanic (with us not present) realized that the boat has hot water heater and over flow tank, adds coolant, says boat ready to go. We take it to our 8 hour trip to our harbor and it is overheating at anything about 1500 rpm, but we make it and use the boat for about 2 months.

winterize ( no oil change)

This year we changed impeller with two broken tooth blocking the passage way, thinking it will fix a problem and it didn't
After our 8 hour trip to harbor we couldn't go more then 1800 rpm.

Today (after searching internet) we bleeder the coolant system as much as we can, it started to run smoother in idle. We put her in gear, and 2 min later she is at 195(max range) the oil lamp goes on and off and on and off, we bring boat back, and look at the oil dip stick level and its at very low. We put it back again and it says it has double the oil level. Several tries later, as engine cools down it indicates that oil is double the level it should be.

Could too much oil be the problem? Did we destroy the engine, oil pump? We plan to change the oil tomorrow and try this again, but I wonder if marina upon selling us the boat didn't properly get her ready for spring and didn't drain any extra oil they put in her? And could the extra oil cause overheating?

[fzjw5n]

I'm having the exact same issues with my Universal M18. It's in a 1985 O'day 31 and has well over 1,000 hours (hour meter wasn't working when I purchased the boat). I have installed a new water heater and I'm wondering if the air pocket hasn't worked its way out & is causing the heating issue. It is quickly heating up where before it would slowly heat up when running engine at higher RPMs. Over the winter I pulled the heat exchanger & removed considerable debris from the water pump impeller. Figured that would have solved the problem but it is now worst. I have removed the thermostat and still have heating problems. Will remove the internal water pump cover to inspect that next. Any ideas?

[Jetexas]

Have you inspected the tubes in the heat exchanger to make sure they're not clogged?

I don't think too much oil is your problem, but why not drain all your fluids and start again with the correct quantities?

Is your oil looking milky? If so you could have a leak in the head gasket letting antifreeze get into your oil.

[forsailbyowner]

I saw a similiar problem solved by removing an impeller that was blocking a water passage. Barring anything simple like a loose engine belt, plugged strainer or the like I would go for a complete cooling system service. Remove and disassemble the raw water pump checking the cover plate for wear, impeller , cam . Rod out or have boiled the heat exchanger, backflush the system. I usually replace all the hose clamps at this service interval and closely examine the hoses for any cracking or checking or replace all the rubber if it looks suspect at all. Read the engine manual to find the bleed points while filling. Fill with antifreeze and pressure test. Advance auto has free loaner tools and a pressure test kit can be had there. This service should be done at regular scheduled intervals anyway. Check to make sure theres non collapsable hose between the raw water pump and strainer.

[Vasco]

As for double the oil you may have a leak from the lift pump and diesel might be getting into the crankcase. I would check the mixing elbow as far as the overheating goes. It might be clogged.

[forsailbyowner]

Hmm. I wonder if the mixing elbow on my boat is a better design or something. I hear of them plugging all the time but in 7 yrs there doesnt seem to be any buildup in mine. just had it apart to replace pipe stub last week. What kind of buildup normally occurs there? scale, sludge?

[Vasco]

Originally Posted by forsailbyowner

Hmm. I wonder if the mixing elbow on my boat is a better design or something. I hear of them plugging all the time but in 7 yrs there doesnt seem to be any buildup in mine. just had it apart to replace pipe stub last week. What kind of buildup normally occurs there? scale, sludge?

Carbon buildup I think, I saw a 3GM30 where the elbow was nearly solid inside. Looked like a slightly porous bone.

[rexzy]

Update:
I think the oil was cooked from over heating, changing the oil and backflushing the raw system has helped. There was leafes and some plastic objects that came out of the heat exchanger.

So now I am able to run at about 180-185 degrees temperature, but I still think that is way to high for lake Michigan waters in early June, I only run for an hour, I am sure the temperature will climb with longer running engine. Using the infrared thermometer I was trying to read temperature at heat exchanger, the coolant comes in at 180 but comes out around 150-160 and i assume it should be much cooler than that. I think taking the heat exchanger and cleaning it is my next step.

I also have a filter for raw water, that I keep forgetting to clean, that might help a bit too. I will update again after the weekend.

[rexzy]

Originally Posted by fzjw5n

I'm having the exact same issues with my Universal M18. It's in a 1985 O'day 31 and has well over 1,000 hours (hour meter wasn't working when I purchased the boat). I have installed a new water heater and I'm wondering if the air pocket hasn't worked its way out & is causing the heating issue. It is quickly heating up where before it would slowly heat up when running engine at higher RPMs. Over the winter I pulled the heat exchanger & removed considerable debris from the water pump impeller. Figured that would have solved the problem but it is now worst. I have removed the thermostat and still have heating problems. Will remove the internal water pump cover to inspect that next. Any ideas?

You say before it would slow heat up? What temperature would it heat up to?

[GordMay]

Greetings and welcome aboard the CF, rexzy and fzjw5n.

[Dano72]

I just went through a similar troubleshooting process. When I removed my heat exchanger I found it to be clogged with the remains of several zinc pencils. They break, looks like they are eaten away so the previous owner would just replace them. This would leave the other end of the zincs sitting in there cogging up the tubes. It's all clean now, no more overheating issues.