High temp readings

[Ron41]

I put a new [ suppose to be] revised temp sender that i got from a holden dealerin today, when i started it up the temp gauge it goes right up to the top of the gauge, I noticed the fan did not come on at all while it was going up
The old sensor used to be on the 3/4 mark then the fan would kick in, so would it be a dodgy new temp sender and a fan problem as well, or just a temp sender problem ?
thanks for any help

[delcowizzid]

the sender for the guage doesnt run the fans the fans are done by the 2 pin ecu sensor.if the single wire sensor isnt connected the guage will go right up if i remember right maybe the sensor is not making a good connection with the engine didnt wrap it in sealant tape by any chance or the wire is not making a good connection on the sensor

[aceventura]

the sender for the guage doesnt run the fans the fans are done by the 2 pin ecu sensor.if the single wire sensor isnt connected the guage will go right up if i remember right maybe the sensor is not making a good connection with the engine didnt wrap it in sealant tape by any chance or the wire is not making a good connection on the sensor

Well if he used thread tape, that would be my fault for suggesting it, however that won't be the problem. The resistance of the sender decreases with increasing temperature - i.e. if the gauge is reading too high, then there are no loose conections. I think it is more likely that the sender itself is faulty, or the sender lead is earthing onto the block somewhere.

Also, when you say "revised" temp. sensor, do you mean a longer a sender? Holden sold me a longer sender than the one that was in it, and the temperature gauge read differently to the old one. I got them to get me a shorter one and it worked the same as the old one before it buggered up. In hindsight the fact that the gauge reads differently isn't a concern, as long as it is consistent is all that matters.

[Ron41]

Thanks guys, I got some of that loctite as you suggested, there are no leaks comming out of the sender connection to the thermostat housing, I didn't think to bother measuring the senders because I thought the holden dealer would know the right part to give me, I guess i thought wrong, I think the revised sender was part no - 92063571.
All suggestions are very welcome, I am sorry that I mucked around with it now, just used to piss me off reading 3/4 on the temp gauge before the fan kicked in.

[hako]

[QUOTE=Ron41;
All suggestions are very welcome, I am sorry that I mucked around with it now, just used to piss me off reading 3/4 on the temp gauge before the fan kicked in.[/QUOTE]

Ron, the fan is not supposed to come on till approx 3/4 on the temp gauge.

[seraphic06]

Ron, the fan is not supposed to come on till approx 3/4 on the temp gauge.

I thought it was half way? Mine kicks in just below half.

[Ron41]

Ron, the fan is not supposed to come on till approx 3/4 on the temp gauge.

This is all a bit strange hako, up until about 2 years ago my temp gauge never went passed 1/2 way, the fan kicked in much earlier, then gradualy it started to creep up to the 3/4 mark before the fan kicked in, but I have seen a few posts here saying it is normal at the 3/4 mark, so buggered if i know.

The guy from the holden dealership told me there was a problem with the originol temp sender that is why holden made a revised sender in 1997.

[Ron41]

Can someone tell me how to check the low fan relay ?
I was reading in my gregories manual that to check the low fan, take off the temp sender switch off and start the car, then the fan should come on within 12 seconds, i done that and it did not come on at all, so i am guessing this could be part of my heating problem, if i turn on the air- con the fan does work then but other wise it won't.
thanks

[hako]

Reading your first post it seems that you replaced the temp gauge sender, not the coolant temp sensor which tells the ECU to turn the fan on. (as suggested by delcowizzid) If this is correct, I'd presume you are removing the electrical connector from the new sender that you installed.....which is the wrong sensor - the connector that should be removed to test the fan is the sensor that has 2 wires to it.
Good Luck.

[Ron41]

Trust me to balls it up, thanks hako i will try the test properly now.

[Ron41]

I did do it properly this time and the low fan did come on after a few seconds then the stronger one come on a few seconds later, so I guess that means the rest of it is good but the coolant sender could be suss as the fan doesn't come on at all when connected and the temp gauge went right up to very hot.

[hako]

Maybe you need to re-instal the old temp gauge sender and see how it goes. Gauge readings have no relationship to the fans coming on....it's the sensor with 2 wires that turns the fan on. Also we need to remember that our cars are getting old (we went over this before!!) and gauge readings are not going to be as accurate as they used to be. However, if the gauge reading is going to very hot when the engine is not very hot then maybe it's a bad connection at the gauge sender - the wire may be broken inside the insulation where it connects and making an intermittent connection.

[aceventura]

Do you have a multimeter?

The resistance between the centre post of the sender and the edge (or engine block) for mine read ~2.2 kOhms at ~27 degrees (from memory). I have a feeling that the temperature dependence of the sender follows that of the ECU sensor (values listed in the Gregory's manual). If you want I can take a reading from my sender next time it is at operating temperature for comparison.

[Ron41]

Yeah hako, the age can certainly make a differance for most things , I have lost the old temp guage sender, can't find the dam thing anywere so I will get another one tommorow and see how it goes, thanks again for all your help, much appreciated mate.

[Ron41]

Do you have a multimeter?

The resistance between the centre post of the sender and the edge (or engine block) for mine read ~2.2 kOhms at ~27 degrees (from memory). I have a feeling that the temperature dependence of the sender follows that of the ECU sensor (values listed in the Gregory's manual). If you want I can take a reading from my sender next time it is at operating temperature for comparison.

Yes mate, I do have a multimeter and would like to see a comparison, thanks very much for your help too, I think i had enough brain torcher for this old boy for one today will check it out again tommorow.
again thankyou.

[VS_Pete_1]

lol know what u mean
Good luck mate.

[Ron41]

Thanks mate

[Ron41]

Just found out I have coolant leaking down and dropping on the top of the sump, the reservior
needed toping up a couple weeks ago, but has stayed at the same level since, so i undone the radiator cap and it took a couple of litres of coolant to top it up again, after i done that the temp gauge it normalized again.
Next start the temp gauge went haywire again only after a few minutes, went right up to very hot then i turned the motor off just in case, so I am guess the water pump is gone or it has a leaking gasket, the pump was changed only 2 years ago.
I also have felt around the bottom radiator hose but can't feel anything wet, so what do you guys think is there anything else that it could be leaking from ?
thanks a million for your help.

[hako]

Get a small mirror and a torch and look under the waterpump to see if coolant is leaking past the weep hole....that would be my prime suspect despite being only 2 years old.

[Ron41]

Checked the leakage this morning and it was actually comming from the temp sender and running down the side of the water pump, I also rang the holden dealership and told them my problem, it turns out that they give me the wrong sensor , now the right part will be comming buy 1.00 pm today, geez, how hard is it to order the right part, unreal.
thanks to everyone that tried to help.

[NZbatman]

Hi Guys, just out of interest can people state waht mark their temperature gauges run at, I have just recently finished doing head gaskets on my VR and the gauge runs at the 3rd mark up from cold most of the time but on a hot day it has got up to the 4th mark and climbing a steep hill it goes to the 5th mark, none of which are even at half way but it is really annoying thinking that the car is overheating, especially after doing the head gaskets due to it blowing a gasket about 3 months ago. It never over heated then just noticed it was pushing coolant out after running, done a Teekay test and it had just blown so any readings from temperatur gauges would be good to determine what is in fact normal on these models. Cheers