New Impeller and Engine Temp

I recently had a new impeller put into my Volvo I/O sterndrive. Before I had it replaced, the temp gauge would hover around 1/2 way (around 220 degrees i think). With the new impeller, the needle barely moves above 120 degrees even after it has been running awhile. I am wondering if the thermostat is gone or if the gauge is not reading correctly. What should the optimal temp be and is there some other way to check it?

Re: New Impeller and Engine Temp

I am not sure what the year and model and configuration of your engine is so I am hesitant to put out a temperature out here on the screen, however... If the thermostat is a 140 degree one then that may be more like 140 degrees, the gauge could just read low like that..

I would think that yours would need a 160 thermostat though, again, just my thinikng. If indeed your engine calls out for a 160 then I would be concerned about the low reading.

Since you are concerned about it I would r&r the thermostat with a new kit from Volvo and start fresh with that known value. It is $18-$20 usually. Sounds high but comes with the proper temp thermo made out of the right stuff and has all gaskets or o-rings it takes, in fact it has more as it covers a broad range of thermostat housing models.

I would like to ask if the gauge moves around any or if it is constant there once it hits the 120 mark.

I did not like the way my temp gauge in the dash was working so I put an after market electrical water temp gauge in under the dash. My thermostat is a 160 and the new temp gauge goes slowly to right at 160 and stays there (ahhhh!). The dash gauge would move up and down along with the tach and the oil pressure gauge, all at the same time so I know there is an electrical issue. The dash gauges seem to be close to correct when they are at the "low" cycle so I do not worry about the oil pressure or tach too much, but the temp reading was very important to me so I did what I did.

Re: New Impeller and Engine Temp

I have a 1995 5.0 L V8 HU series engine and drive if that helps. My guess is I would need a 160 degree with that. The needle on the gauge starts low and moves up a little when its running. I know the gauge worked before the impeller replacement. The gauge is what first told me I had an issue.

Re: New Impeller and Engine Temp

I am not a boat mechanic but,I would think a boat engine with fresh water cooling could not run at a temperature above 212f,the boiling point of water at atmosphere..the water would have to be pressurized to go above 212f and,again I am no boat mechanic but I dont think an open cooling system would have very much pressure...hopefully someone with more knowledge will clarify...good luck