Installing Temp Guage

[ragrim]

Hi,

Lately i have been having temp issues with my VR V6, tried all sorts of things but im starting to think my car isnt actually over heating.

Id like to install an after market temp gauge but im wondering where is the best place to have the sensor for the most accurate reading? would an adapter in the top radiator hose be accurate enough to tell me what the temp of the water is?

Another question, is it possible to piggy back an electrical temp gauge off the temp sendors in the engine?

[cander24]

Is this going to be a temporary thing just to check the accuracy or a permanant addition? If you're suspicious the temp reading you're getting on the cluster is not right i'd be first replacing the basics like the thermostat and a new coolant temp sender. About $12 from Holden from memory.
Also possible that the gauge in the cluster itself is faulty so you could also try replacing this with another one.
Anywhere in the top radiator hose or in the inlet manifold close to the thermostat will give the most accurate readings.
As for piggy-backing off the factory sender in the manifold, yes this would be possible, BUT you would first need to know the exact resistance levels of both the factory sender and the sender supplied with the new electric gauge. Any discrepancy between the two and you'll be back where you started with inaccurate readings. I've fitted an electric coolant temp gauge to my vs v6 which uses a sender very similar to the factory one. For this I cut a new thread into the manifold just below the thermostat and alongside the standard one (I still run the cluster temp gauge).

[slepar]

go the top radiator hose mate thats what ive done on every car ive put gauges on, if you do have a faulty sensor pigy backing off it will just give the same faulty reading

[Andrew426]

Try sitting the sender in a pot of hot water. Use a multimeter with temp. probe, or an infared thermometer to monitor the actual water temp. Slowly heat the water with an oxy/acetelene torch (or something similar) and see if the reading on the cars temp guage correlates to the actual water temperature.

I have done this in the past to troubleshoot temp senders, guages wiring looms, and also to set thresholds for overheat lights.

[ragrim]

thanks for the replies,

the reason i want to do this is because since ive had my VR ive had constant overheating issues. i have tried the following

Replaced thermostat 3 times, 2 were not opening at all
Replaced radiator with new one
flushed system 3 times, refilled with proper coolant
pressure tested system
new radiator cap
compression test on all cylindars to check for head gasket
bled system 3 differant ways
filled system 3 differant ways

regardless of what i do my temps seem to hit 3/4 to full all the time, without thermostat my temp gauge doesnt move, ive check for blocks in system and all is good.

When car is apparently over heating my top and bottom hoses are hot, so i have circulation, water isnt boiling, not losing any coolant, but my engine doesnt smell hot, doesnt feel hot.

thermo fan works fine. so my last guess is dodgy sender, i justr need to get an accurate reading of what temp the coolant actually is.

[Ron41]

I had the exact same problem, tried everything including a new temp sender so i finished up taken mine to an auto electrician, they hooked up a scan tool and we let it run on idle for 1 & 1/2 hours and the temp did not get any hotter than 105, but the temp guage was one mark off the Hot mark.

They said it has to be the temp guage itself and wanted to put a new temp guage in for $170 without fitting cost, so I went to the wreckers and got another one, installed it and it read nearly exactly the same as my old one, just slightly less.

I spoke to a radiator place and the guy said this is very common in these models, this was also backed up by every gmh dealership I phoned enquiring about about it., some VS models read normal and others read high [ providing there is nothing causing a problem] , they all said don't worry about it.

It was to close to Hot for me so I finished up taking the temp guage out and just slightly bend back one of the metal tags inside it, now it sits on half way in city traffic without air/con on, about 1/4 on a hwy, on really hot days goes up to 3/4 before the fan kicks in and brings it down to half way, this does me, stuff paying $170 for a new guage.