D6 intermittent erratic water temperature readings

[Shano]

So for a while now our Volvo water temperature reading will very occasionally jump around from showing 180 to 160 then 2 seconds later then 155 then 173 etc. Most of the time after the engine gets to operating temperature it just sits there at 185. It has always shown erratic readings less than 185 - if it was showing reading higher I would be more worried. When it has been doing this erratic reading situation I will go to neutral and then reset by shutting of the engine, pressing the engine switch and turning off the engine main battery switch — which sometimes works sometimes not, other times I just watch it and it eventually goes to 185 and stays there. Anybody else have this happening lately and what was the issue? I’m guessing that the sensor is faulty, or the sensor connection is loose perhaps. Anybody know this sensor is located?

 

[TA_73]

Our 2015 CW with the D6-435 jumps around a little bit when it is below operating temperature but not as much as yours. Once it hits operating temperature it rarely moves. I put it down to the thermostat opening and closing as it warms up but I could be wrong. Has never really concerned me much.

 

[Sojourner]

Our D6-435 is doing the same thing, bouncing around below operating temperature much faster that one would think possible if it were the thermostat. Did you ever resolve the problem?

 

[dbsea]

Mine is doing the same. I think it’s a faulty sensor but I’m not sure exactly where it is or how to replace the part ?

 

[dbsea]

Circling back on this, I found the problem. The coolant temperature sensor was faulty, and this is a known failure part over time. It was $400CAD for the part up here in pender Harbour but I appreciate the peace of mind knowing it is fixed. Volvo Part number 1624368 for reference.

 

[JonR]

I have a 28ft cutwater and am having the same issue. My temp would go anywhere from 28 degrees F to it's normal 185 degrees. I recently purchased the new sensor and know where it is located on the engine. However, there is a mounting plate for wiring connectors in front that makes it difficult to get to. The main engine computer mounting is also in the way. Has anyone here replaced one and, if so, did you unbolt either of these items? Responses are appreciated!

Jon R
'Good Time Tour' 2014 Cutwater C-28
Edmonds, WA

 

[JonR]

I have a 28ft cutwater and am having the same issue. My temp would go anywhere from 28 degrees F to it's normal 185 degrees. I recently purchased the new sensor and know where it is located on the engine. However, there is a mounting plate for wiring connectors in front that makes it difficult to get to. The main engine computer mounting is also in the way. Has anyone here replaced one and, if so, did you unbolt either of these items? Responses are appreciated!

Jon R
'Good Time Tour' 2014 Cutwater C-28
Edmonds, WA

 

[JonR]

I have a 28ft cutwater and am having the same issue. My temp would go anywhere from 28 degrees F to it's normal 185 degrees. I recently purchased the new sensor and know where it is located on the engine. However, there is a mounting plate for wiring connectors in front that makes it difficult to get to. The main engine computer mounting is also in the way. Has anyone here replaced one and, if so, did you unbolt either of these items? Responses are appreciated!

Jon R
'Good Time Tour' 2014 Cutwater C-28
Edmonds, WA

Replaced my sensor today and all is well. Unbolted to bracket and computer for ease of access and had no issues.