Engine Overheating

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Engine Overheating

Postby rlgales » Fri May 21, 2021 10:23 am

My engine is overheating since I replaced the valves going to water heater in April.

In August 2019 Coastal Marine in Seattle replaced the exhaust manifold, the thermostat box, two new thermostats, new water pump and seals and hoses ($$$). its been running great at the correct temperature ever since then, until I replaced the valves.

Could it be an air pocket in the hoses? Should I open the valves to the WH or keep them closed?
And how do I bleed the cooling system? I could not find anything in the service manual.

Thanks,
Bob Gales
North Star 1995-35
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Re: Engine Overheating

Postby rlgales » Sat May 22, 2021 7:02 pm

I pulled the thermostats and checked them. They opened close to 81C and fully opened.

Bob Gales
North Star
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Re: Engine Overheating

Postby Bruce » Tue May 25, 2021 4:39 pm

The water heater should have little or no bearing on your temp. I just did the same thing you did and as far as I know burping the engine cooling system is not required.
Assuming you did not do anything with the impeller and, your are pushing water out the exhaust when the motor is running then the other culprit (s) could be your water recirc pump or possibly the belts are loose. I know this is a long shot but is it possible the T-stats are in upside down?
Finally, you might try leaving T-stat cover off and fill the cooling system via the housing.. When almost full replace the housing cover and filled via the reservoir tank.Leave the reservoir cap off while filling via the housing

Regards,
Bruce
(Chasing Time"
Hull # 84
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Re: Engine Overheating

Postby NorWyn » Wed May 26, 2021 8:38 am

Faint hope...have you checked the connection on your temperature gauge?

Our gauge read consistently high last year. A light sanding of the male sending connection at the engine followed with some anti corrosion electrical spray onto both the male and female connections resolved it.

Good luck.

Chris
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Re: Engine Overheating

Postby rlgales » Sat May 29, 2021 8:53 am

The impeller is ok and the water is coming out strong from the exhaust. When it overheats the coolant leaks out of the cap on the coolant filler tank. Our local V-P dealer told me to keep adding coolant and running the engine at low rpms, don’t get the temperature up. They said people don’t realize how much coolant the engine takes.

Thanks for the suggestions. I’m going to the boat tomorrow and I’ll think about filling from the thermostat housing.

I take pictures of most items before I take them apart, the thermostats are in correctly!

At least we can sit on our boat and drink gin&tonics!
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Re: Engine Overheating

Postby Sea Muse » Sat May 29, 2021 3:55 pm

Hi Bob: I've read about your overheating issues since the beginning. I would highly suspect you have air in the system both from your 2019 work and more from your HW heater valve replacement. Since the 2019 work and therefore covid it may be possible that you haven't used the boat enough to notice an overheating issue. What I do is go for a run with the pressure cap off and hatch open to monitor the exp tank level and return flow from the therm housing. Keep engine speed up enough to maintain a little over the 81 C thermostat setting. In this way any trapped air will circulate thru the cooling system and escape out thru your exp tank. I've had to run like this for over 1/2 hr sometimes after a coolant change. If I remember right your raw water impeller was last changed in 2019, it is due to be replaced. A temperature gun is a valuable tool, gauges can't always be trusted. Hope this helps --- don't overheat the engine too much.
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Re: Engine Overheating

Postby Sea Muse » Sat May 29, 2021 4:08 pm

Bob, I forgot to say to leave your HW heater valves open.
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Re: Engine Overheating

Postby rlgales » Mon May 31, 2021 2:47 pm

I added coolant to the tank as it was empty when I checked it yesterday. then I ran the engine for ten minutes and checked the tank after it cooled down for 30 minutes. it was still under pressure and over flowed. I think there must be a blockage in the system. When I squeeze the hose from the thermostat housing to the heat exchanger it bubbles up in the fill tank instead of continuing on thru the heat exchanger.

Make sense?

After a day or two the fill tank is low so I think it slowly flows past the obstruction.
Does this make sense? Should I clean out the heat exchanger only or is there another place that could be blocked?

Bob Gales
North Star
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Re: Engine Overheating

Postby chrisaensing » Tue Jun 22, 2021 12:40 pm

Bob, I would definitely remove the heat exchanger & clean it if necessary. Pretty easy to do on the Volvo. While you’re at it do the aftercooler & gear cooler. If they have never been serviced it may be about time. When we got our Camano the previous owner had no idea if they were ever done. I bought the seal kits and did all of them. In fact it was a good thing I did since the aftercooler drain that fed the shaft was badly corroded & needed replacement. Check out my blog that details the cooling system http://www.pauhanacamano.blogspot.com
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