5.0 GI Engine water temperature sensor resistance

[1994almeida]

Hi
On my Volvo Penta 5.0 GI PWTR from 1999, the engine water temperature sensor resistance is, at 100? F ( 38? Celsius) 1400 ohms.
According Seloc Volvo Penta Manual 1992-03, at 100? F, the resistance of the sensor should be 403 ? 493 ohms
The temperature at the gauge is always low, at cruise speed, 3000 rpm or higher, never reaches the normal temperature 175? F (80? Celcius). The maximum temperature is about 140? F.
I suppose I have installed the water temperature sensor P/N 3850397, but for this sensor I don?t know the resistance values versus temperature (are they available ?).
According Clymer manual, for Mercruiser engines, water sensor resistance at 100?F is 1800 ohms, similar to my situation.
Should I have a defective sensor ?? or a Mercruiser sensor installed on my Volvo engine ?? or everything is normal with a low temperature gauge?. I tested the gauge and apparently is ok.
Thanks
Almeida

 

[Fun Times]

Re: 5.0 GI Engine water temperature sensor resistance

Hi there, page 1-14 has the ohms resistance readings for you from Volvo,

Boatinfo - Volvo Penta WT series Engine Electrical and Ignition Service Manual

Typically if an engine is not getting up to the correct temperature specifications the first item to be suspected is usually the thermostat. You're engine requires a 160 degree thermostat.

Boatinfo - Volvo Penta WT series Engine Components Service Manual

 

[dypcdiver]

Re: 5.0 GI Engine water temperature sensor resistance

There seems to be some confusion between temperature senders and sensors here. The part number quoted is the temp sender.

The sensor is just a switch that makes and breaks contact at 200 F. If you are getting a reading on the gauge of 140 F then perhaps the gauge is one from a Mercruiser! other wise you would not be seeing any movement on a Volvo Penta gauge at 1400 ohms.

Have you checked the bypass passages in the thermostat housing for bits of impeller, frequent cause of engine running at low temperature. Borrow or buy an IR temperature gun and check around the engine to see what temperature it is actually running at.

 

[1994almeida]

Re: 5.0 GI Engine water temperature sensor resistance

Hi Thanks
I am talking about the temperature sender installed on an 1999 5.0 GI Volvo Penta witch resistance at 100? F is 1400 ohms and according manual should be +/- 440 ohms.

The gauge is a FARIA instrument and apparently is ok.
The thermostat housing is new, and also the thermostat.
So the problem should be the defective sender ??
And is if I buy another sender P/N 3850397 and the resistance is the same, as actually I have in the old one ?

Almeida

 

[1994almeida]

Re: 5.0 GI Engine water temperature sensor resistance

Another picture with the maximum temperature that I can achieve.

 

[Fun Times]

Re: 5.0 GI Engine water temperature sensor resistance

So the problem should be the defective sender ??
And is if I buy another sender P/N 3850397 and the resistance is the same, as actually I have in the old one?

Looking at the photos above, It appears your working with the wrong sending unit. Since you're working on the temperature gauge, You should be dealing with the water temperature sender volvo part number 3852029.

The coolant temperature sensor in the photo is utilized by the ECM. The two wire sensor is for the ECT (Engine Coolant Temp) for the ECM (yellow/black stripe and a black/ orange? striped wires).

The gauge sender should be found on the intake manifold with a single tan wire going to it.

On carbureted engine models, The alarm switch would have a Tan/black stripped wire going to it.

You have 3850397 SENSOR, Coolant temperature.
You need 3852029 SENDER, Water temperature.

 

[dypcdiver]

Re: 5.0 GI Engine water temperature sensor resistance

Frankly I believe that the temperature your gauge is showing is about right. My 1999 Gi runs at 160F all day on the odd occasions that I run at WOT (5000/4900rpm) for more than 5 minutes it will creep up to 170F but no higher.
I did have a couple of vanes from the impeller stuck in the bypass passage of the thermostat housing which caused the motor to run at 130F and would not get any higher, this was causing the motor to run a little rough and the exhaust fumes smelt really unpleasant (over fuelling), she would hesitate on going to full throttle from tickover. I don't think I'd be worried with your temperature reading.

 

[1994almeida]

Re: 5.0 GI Engine water temperature sensor resistance

Hi
I was wrong, I was dealing with the ECM sensor P/N 3850397.
For the temperature gauge, I should found the water temperature sender volvo, part number 3852029.
But, as "dypcdiver" says, the temperature showing is about right, and I don?t have problem.
Thanks Almeida