St 44 195 degrees

All-
We have a 2014 ST 44 w/+/- 450 hrs. About 3 years ago the STBD engine started to display 195 deg coolant. Temp would jump from 185 (normal) to 195 and stay there. Back off a few hundred RPMS, back to 185. This only happens when the seawater is +/- 80 degs.
Temp sensor, t-stat replaced and heat exchanger cleaned.
Anyone else having or had the same situation?

Have you replaced the raw water impeller?

Are they Volvo engines?

Hi,

Start the impeller check, the raw water filter line in addition to checking the coolant level (when did you change the fluid last?)

If Ok you also need to measure the IR thermometer on the actual heat of the engine, the question may be the sensor, wire connection, oxidation or meter failure. The thermostats are also not eternal, so keep a check on them as well. If there is still no reason, it may be time to clean the heat exchanger.

NBs

Welcome to the wonderful world of Volvo. On the the newer D Series engines the gages will only Display a max of 185F, and then will tell you if you hit 195F or higher; as you experienced. IE, you will never know if you are in between 185 and 195.

Correct on the 185 to 195. Volvo calls it "dampening".
Coolant changed, impellers yearly, heat exchanger cleaned, strainer gasket, seacock inspected.
IR and showed about the same as the temp gauge.

Real headache...........

Thanks for the feedback

Is 195 a problem? What's the acceptable range for that engine?

195 is inside the acceptable range
For 1 1/2 years ran at 185 @ all RPMs

I am not sure I can see a logical reason not to show the correct temperature.

You may want to pull your after cooler and have it checked at the shop. Don’t try to inspect it in place.

From a volvo tech:

"The thermostat starts to open at 180 Degrees and is fully open at 198 Degrees. The alarm will sound when the temp reaches 204.8 Degrees."

I noticed the same where in warmer waters, especially under load (i.e. tons of gear, full fuel, water, etc) I would see 196 at higher RPMs and occasionally 199 when water temps were at their peak in summer. I dont tend to run at higher RPMs except to exercise the engines for 5 minutes here and there. Backing down to normal/cruise RPMs and I saw 185 degrees again. After I was told 204.8 degrees is considered overheat I was not worried. That said, I still plan to do a barnacle buster flush and flush the coolant system and replace this year (even though its not due yet).

Attached is the Volvo bulletin for flushing the coolant system

Since I have a hot water heater and de-misters also looped into the heat exchange loop, I may have to disconnect/drain those depending on the curves in the hose.

I am only flushing because my coolant looks weird. Its possible that the old coolant type was in the system initially and then replaced with VCS. I had it tested by a lab and they said it looks fine, not contaminated, still has proper coolant properties but I am just going to remove, flush, replace as a pre-caution, if not this Spring, this Fall.

Have you check the exhaust mixer/water injector? The water has to be able to get out as much as it has to get in. Also, some folks have seen water hoses delaminating internally which will certainly affect flow.


Ken

Earlier someone said that the Volvo gauge reading jumps from 185 to 190 (or whatever jump you are seeing) and it is the way the gauges work. It seems odd, but if that’s how they work, and the higher temp is not out of range, then I suspect you have completely normal operation

Fletcher500 said:

You may want to pull your after cooler and have it checked at the shop. Don’t try to inspect it in place.

Click to expand...

About every 5 years even with no suspicion of overheat.

Sun, agree, as a bare minimum. I think every 3 years to be proactive is even better but that is another thread.

OP, I have been in your exact shoes with D Series engines and had the same issue. If you are jumping from 185 to 195 periodically at high loads, then 196 or higher may be in your future. If you have not had the After cooler pulled and bench checked, I would suggest you do. I don’t know the particulars of your situation...Just my .02 based on what you have described.

Thanks

What did you end up doing?