Overheating issues

[phillpot]

Sandgrounder said:

I know I will have to take the bonnet off to even see the fan

Not if you can jack the front up and put it on axle stands or ramps

[GreenV8S]

LawrieS said:

Good point, well made.

(I really like the Sure-Seal range of connectors that Farnell sell.)

[wild rover]

For safety I would solder in a piggy back in line fuse and use that.Seems that the contacts in the original fuse box have lost their tension.

[Sandgrounder]

Good afternoon S fans, I wanted to give an update on my findings, but as usual this spawns more questions, Sorry!
It seems the issue is most likely the quality of contact in the fuse, and the relay. I took some pictures of the relay but it has taken an eternity to transfer them from phone to laptop, so lets see if I can now get them on here:






The Part Number is 070504, but I can't find anything on the internet, if anyone has a good link for relays please? However the holder for the relay and the fuse is also melted so that is a bit more challenging to rectify. I can cut the wires behind the fuse out and solder in an inline fuse, but not sure whether you can buy relays with the holder/base?

Any tips appreciated.

Despite the melted state of fuse and relay holder, they still work (or at least they have done today on a 2 hour test drive), but I know this is something that needs to be sorted as it will probably fail again when I am stranded miles from home, ie, tomorrow in North Wales. See my next post on Roads to try!!

[magpies]

You could try Car Builder Solutions

[Ceejay73]

Standard 5 pin 30 amp automotive relay, should get one at any decent motor factors or failing that Halfords.

Edit to add, yes you can buy new sockets for them, very commonly used when adding auxiliary lighting to vehicles.

HTH,
Carl.

Edited by Ceejay73 on Sunday 24th July 15:25

[oldgeebee]

I've used Vehicle Wiring Products before and they have a good range of relays and holders/terminals here http://www.vehicle-wiring-products.eu/section.php/...
Watch out for 4 blade/5 blade options and the A or B pin layout. The 4 blade is the on/off type and the 5 blade is the changeover type.

GB

[Sandgrounder]

Thanks gents, some good options there. Clearly NOT as difficult to find as I made out!!
Much appreciated.

[Buzzlt]

Sell them in Maplin as well for £3.49 off the shelf usually...

[Sandgrounder]

Thanks Buzzlt

[Sandgrounder]

Afternoon all, rather than start a new thread, I did a bit of digging and found this one I started 2 years ago.
At the end of summer last year, I did some electrical work, so the cooling fan power is separate from the fusebox. Got an new inline fuse and new relay and holder, so hopefully any bad connections will not cause the melting plastic I have had.
Not had a hot day since doing this, but took the car for a fairly long run today to get the cobwebs off.
Temperature was fine, so when I got home, I decided to leave engine running to see if the cooling fan was working.
Cooling fan came on, and temperature on gauge fixed in the middle, however I waited for the fan to go off, but it just stays on!
Today is cool so if it is staying on today, not looking forward to a hot day (when they eventually come).
So, what are lilkely causes of fan staying on?

Thanks.

[pequod]

Otter switch?

https://tvr-parts.com/tvr-parts/part-details/tvr-0...

Did the temperature gauge rise above the horizontal before the rad fan kicked in, and then drop back to 'normal'?

[v8s4me]

The otter switch is a simple on/off switch made in such a was as to remain 'on' if the the coolant temperature stays above the point at which the switch is designed to come on, That temperature is usually stamped on the side or the bottom of the switch. See what is says and then check the coolant temperature with something like THIS. If the temperature of the otter switch boss is less than its operating temperature it's not switching off properly. So either ignore it or get a new one. The important thing is that is switches on.

[GreenV8S]

The otter switch has some hysteresis built in, and the rest of the cooling system has a lot of thermal inertia, so it might take several minutes to pull the temperature down far enough to switch the fan off.

If you think the fans may be stuck on, pull a wire off the otter switch; if the fans keep running, the fan relay must be stuck and will need to be replaced. If the fan stops, it shows the otter switch is in the hot/closed position. It might be that the engine genuinely is hot enough to need the fan. However, if it still turns the fan on when the engine is cold, the otter switch has failed and needs replacing.

[Kitchski]

Sandgrounder said:

Afternoon all, rather than start a new thread, I did a bit of digging and found this one I started 2 years ago.
At the end of summer last year, I did some electrical work, so the cooling fan power is separate from the fusebox. Got an new inline fuse and new relay and holder, so hopefully any bad connections will not cause the melting plastic I have had.
Not had a hot day since doing this, but took the car for a fairly long run today to get the cobwebs off.
Temperature was fine, so when I got home, I decided to leave engine running to see if the cooling fan was working.
Cooling fan came on, and temperature on gauge fixed in the middle, however I waited for the fan to go off, but it just stays on!
Today is cool so if it is staying on today, not looking forward to a hot day (when they eventually come).
So, what are lilkely causes of fan staying on?

Thanks.

If the fan is staying on constantly, either with or without ignition, then that's a wiring fault (or the switch). Totally separate.

If it's staying on (as opposed to cutting in and out) then it suggests the cooling system is marginal. That could be a blockage in the radiator; A partially seized thermostat; Water pump not shifting enough volume of coolant around; Dodgy cooling fan; Dicky fan switch.....could be all sorts.

Thing is these old lumps are all iron (assuming you've got the V6 like me), and it takes a fair amount to suck the heat back out of them. It's possible to get an 'early switch on' fan switch (92/87deg C, versus 95/92, if I remember correctly) so it might just be a case of getting it to cut in slightly earlier, and stop it going 'over the edge' so to speak. These cars don't have an oil cooler, after all, and once the oil is hot it's a bugger to cool it down again. All that heat has to go somewhere.

Or, if you put an early one in, you might end up with exactly the same issue, just earlier on

[Sandgrounder]

Thanks for the replies.
Its the fact that the switch cut in as expected, and maintained the correct temp (on the gauge anyway) that suggests otter is working. But as the weather was certainly far from warm, and fan stayed on, I am thinking cooling system may not be up to par!

Had a new water pump a few thousand miles ago, so I think I can rule that out. I may try some rad flush to see if anything nasty in the system.
If that doesn't work, possibly change the otter (only a tenner), take rad and fan out for an inspection, etc..

The joys!

[v8s4me]

Taking the rad out is fairly easy so if you're going to drain the system anyway you might as well take it out and give it a good flush with the garden hose. While you've got the hose out you can stick it into the various coolant hoses and flush the block and heater out as well. Do it in the street or you will stain your drive a nice rust colour

[GreenV8S]

Sandgrounder said:

I am thinking cooling system may not be up to par!

That's a distinct possibility - corrosion and dirt on the radiator (inside and out) could mean it's simply no longer working efficiently.