Overheating woes....still.

Overheating woes....still.

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jonzo

Original Poster:

163 posts

262 months

Wednesday 3rd September 2003
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Okay, getting dis-illusioned now. Had the head gaskets replaced, heads checked out and new thermostat fitted. Ran the car a while, checked the fan worked etc, all seemed fine for about a week. This weekend got stuck in traffic and noticed the water getting too hot along with a sound like a kettle whistling from under the bonnet, luckily was just getting to my home when this occured, so switched off for cool down. Checked the swirl tank and found about a litre of coolant missing even though it was showing full just a day or so earlier.(No signs of any leaks).
Started the car next day from cold, turned the heater on full and topped up the coolant level at the swirl tank and left to run for about 10 minutes.
Two things i noticed, firstly the fan never came on in that time (checked fuses all seem okay and fan had worked on earlier run) and secondly, the hose that goes from the swirl tank to the radiator stayed cold.
Hot air did come from the heater vents okay.
Also my temperature gauge has stopped working since new thermostat added.
Any ideas guys on any possible solutions/symptoms ?
Car is S2.

Jonzo

Original Poster:

163 posts

262 months

Thursday 4th September 2003
quotequote all
Thanks for the tips guys.

Few answers:-
1) the pressure cap IS on the swirl tank (always has been) but i think i will get a new cap to make sure its working okay.
2)Hot air IS coming from the heater.
3) Didn't know about the bleed valve on rad, will give that a try.
4) I know the fan has been working throughout the week but not sure if it came on during the day it started overheating again..i dont remember that distinctive 'whir' when sitting in traffic. Being that the fan fuses are okay, could this be an intermittent relay problem (do they do that?) causing the fan to come on some day, not on others? or a dodgy earth?
Questions:-
1) How do i 'short' the otter switch? I take it the otter switch is the one attached to the top pipe to rad?
2) Can the sender unit? for the temp gauge (the bit that goes in the block) be faulty or would it have to be the wiring/fuse to it?
Thanks again, i really want to sort this out as theres not too much left of summer !

jonzo

Original Poster:

163 posts

262 months

Thursday 4th September 2003
quotequote all
Had a brand new thermostat fitted, so be surprised if it was faulty?...though theres always the chance!
Will try and short the otter switch as well to check the fan is working when needed.

Jonzo

Original Poster:

163 posts

262 months

Sunday 7th September 2003
quotequote all
Okay, fixed my temp gauge, the wire had got cut somehow between two small resistors near the sender unit. Anyone know what these resistors do?..at present i have used ordinary cable and the gauge seems to be working fine.
Changed the pressure cap for a new 15lb one.
The overheating problem still seems to exist and i am now wondering whether its the thermostatic 'otter' switch as the fan does work but seems to come in too late ie it waits till the car gets hot then comes on rather than stabilising it at 90 degrees. The fluid level is remaining constant and seems to be circulating properly now.
Does anyone know the part number for the otter switch and/or what car it comes off of? My local car parts place had no match for it.Also, are these swtiches likely/able to fail or am i chasing shadows? it just seems to point to that with the fan coming on too late.

Jonzo

Original Poster:

163 posts

262 months

Monday 8th September 2003
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david beer said:
. Deemon Tweeks sell them as well.


As well as who?...and a rough price?

Jonzo

Original Poster:

163 posts

262 months

Monday 8th September 2003
quotequote all
RZR...yep the cold pipe from swirl was the problem at first as i think there may have been an air pocket but all pipes are getting hot now, just that the fan is kicking in too late. Anyone else fitted these variable temp switches ?

Jonzo

Original Poster:

163 posts

262 months

Tuesday 9th September 2003
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Thanks Gilesy, so if i buy a new sender does it come with all the relevant resistors etc in place, so that i just have to connect the relevant wiring? The two resistors that were 'in-line' in the wire were sage green with a red, yellow and white stripe around them, if that means anything to anyone??...it could explain why the gauge is reading say 10 degrees higher than 90?

Jonzo

Original Poster:

163 posts

262 months

Thursday 11th September 2003
quotequote all
Gilesy, yes it is the standard TVR gauge (with the logo in middle) and being that the wire with resistors seemed to be in 3 parts i would say soemone has tampered with the sender at some point! So back to original query, should i just go and get a new sender and will that come with relevant wiring/resistors ?
thanks.

Jonzo

Original Poster:

163 posts

262 months

Friday 12th September 2003
quotequote all
Gilesy & Rozza, well yeah the gauge is working but on occasion, seems erratic in that it seems to rise and fall quite dramatically and it didn't do that before said wire with resistors was broken. So ?....
Would an auto-electrician be able to pinpoint any probs at the sender end ?