Volvo Penta 4.3L Temperature Question

[ksbhjohnson]

I recently upgraded boats from one that had a 1993 OMC 3.0L motor and outdrive to a 1999 Four Winns Horizon 180LS with a Volvo Penta 4.3L motor and outdrive. I notice some differences in the way the temp gauge reads between the two boats and just want to make sure I do not have a temp issue with the new boat. On my previous boat, the temperature would rise (never overheat though) as I was going across the lake (accelerating) and would drop back down after slowing down or just sitting at idle for a bit. On the new boat, once the engine warms up it stays at about the 3/4 mark of the gauge and does not fluctuate at all regardless of the speed of the boat. Neither of the gauges provide an actual a temperature reading and just show a range between hot and cold. Is the new Volvo Ok or do I have an issue? For what its worth the impeller was replaced in 2015.

Also, I have ordered a temp gun just so I can reassure myself and check some true temps at the motor. At what points on the motor should I take readings?

Thanks in advance for the help.

 

[bruceb58]

The temp should always remain constant. Personally, I would replace the gauge with one that read in degrees.

Take readings at the thermostat housing and where the temp sender mounts to the engine.

 

[ksbhjohnson]

The temp should always remain constant. Personally, I would replace the gauge with one that read in degrees.

Take readings at the thermostat housing and where the temp sender mounts to the engine.

I wish I could swap gauges but I have the all in one integrated dash cluster. Thanks for the info

 

[rkilpa]

The impeller was replaced in 2015, but I bet previous impellers have failed and pieces of them are stuck in the thermostat housing.

When my boat was just a couple of years old, my 4.3GL ran at the 3/4 mark after I had an overheat due to a failed impeller and I paid a mechanic to have the impeller replaced. I was assured by the mechanic that he got all the pieces out. I just assumed that the motor was running warmer after the overheat episode because it never went past 3/4 and ran fine.

After another impeller failure many years later, I took apart the TS housing myself and found many more pieces lodged in the passages in addition to the current impeller pieces. Turns out the mechanic didn't get all the pieces out from the 1st failure. The little passages to the risers were practically closed off they were so blocked.

After cleaning out all the passages, the temperature gauge stayed just below the 1/2 mark like when the boat was new.

FYI... the temperature gauge should stay pretty constant once warmed up regardless of speed. If the gauge rises above the 1/2 mark when you are running on plane, you probably have blockage in exit passages of the TS housing as described above. If the gauge lowers to cold when you are running on plane, you probably have blockage in the bypass passage of the TS housing.

I would suggest removing the TS housing and do a thorough cleaning of all the passages, or just replace it with a brand new one.

I would also recommend changing the impeller yearly. In my boats current environment, I can't even go 2 years before the impeller starts to degrade. I've experienced both higher gauge readings and lower gauge readings indicating an impeller failure. It all depends on what temperature the motor is at when the impeller fails. If the motor is warm and the TS is open, the pieces will lodge in the exit passages. If the motor is cold and the TS is closed, the blockage will be in the bypass passage.

It is easier to replace the impeller than the TS housing, so I replace mine yearly now.

 

[ksbhjohnson]

Great info. Thank you.

Once I get the heat gun what temp readings should I see at TS housing and sending unit?

 

[bruceb58]

Depends on what thermostat is spec'd for your engine. Anywhere between 140 and 160