Possible faulty temp sensor? 1994 VR V6 Commodore.

[Anthony .]

Hi all,
I recently changed the radiator and thermostat. Cooling system does not have any leaks, and the system was bled out correctly.
Fresh Heater tap and fresh radiator hoses and clamps were done 2 weeks prior without any problems. No coolant loss. Gauge works correctly, and moves slightly depending whether I am travelling at speed I.e. on the highway (good airflow) or if I am in 5:00pm peak hour traffic.


Does the following situation sound like the temp sensor is failing? I had this situation today.

First drive of the day is great. No overheating at all. Even after driving for over an hour in mixed road conditions.

Start the car about 5 hours later, and after about 10mins of mixed driving, the temp gauge shoots to around 3/4 (I believe it would shoot up to full if given enough time. I immediately pull over and shut the car off. I restart the car after 40 mins, and all goes back to normal. This is even in peak hour traffic on the 1 hour 40 min commute home.

Thanks in advance for the help everyone!

 

[losh1971]

They will go up to 3/4 then the fans kick in and temp should come right down to about 1/3.

 

[Anthony .]

They will go up to 3/4 then the fans kick in and temp should come right down to about 1/3.

That’s strange then. The fans on mine kick in at about the 4th indicator. When running fine without the problem above, the temp gauge will never go above the 4th indicator. This is irrespective of driving conditions, outside temp, etc. The gauge will sit on the 4th indicator until the fan kicks in.

When I say indicator, I mean the little lines on the temp gauge. I don’t know that to call them.

 

[07GTS]

if ur gauge sits about the 1/2 when driving at say 100kph to 3/4 mark when fans kick in then it sounds like u have the earlier temp sender VB-VL and not the VN -VS sender which is the same but has the lower operating temp reading on the gauge

 

[Anthony .]

if ur gauge sits about the 1/2 when driving at say 100kph to 3/4 mark when fans kick in then it sounds like u have the earlier temp sender VB-VL and not the VN -VS sender which is the same but has the lower operating temp reading on the gauge

So I must have the later one since it only sits 3 bars when at 100kmh?

 

[07GTS]

the vb-vl sender will sit about the 1/2 for operating temp and go to 3/4 when fans kick in, the vn-vs will sit bout the 1/3 (or first line) and go to about 1/2 when fans kick in, it can be hard to find the proper sender for them now days as most places just do the same for all those series, the hot reading for all is the same its just the operating temp that changes between them

 

[Anthony .]

the vb-vl sender will sit about the 1/2 for operating temp and go to 3/4 when fans kick in, the vn-vs will sit bout the 1/3 (or first line) and go to about 1/2 when fans kick in, it can be hard to find the proper sender for them now days as most places just do the same for all those series, the hot reading for all is the same its just the operating temp that changes between them

Cheers mate. Do you reckon my sensor is failing given the situation?

 

[07GTS]

they dont tend to fail much and shouldnt change like that, its more if the wrong sender is used at the start, if its reading higher can be other things causing it also, unplug the sender and turn key on see if it has 10v there using multimeter only and dont let sender wire touch earth or u can kill the gauge

 

[Anthony .]

they dont tend to fail much and shouldnt change like that, its more if the wrong sender is used at the start, if its reading higher can be other things causing it also, unplug the sender and turn key on see if it has 10v there using multimeter only and dont let sender wire touch earth or u can kill the gauge

The car seems to play up after I go to drive it after sitting for a couple hours. The car reaches 3/4 after 10 mins and then I shut it off and wait 30mins or so. Start it up again and it runs mint

 

[07GTS]

the temp gauges can read higher when there are earthing issues engine to chassis too, maby check all those are good i know some people do an earth upgrade on the VS that helps them out as factory wiring wasnt the best, there's people here that would know more on that modification then me