V8S gets scary hot

[bicycleRepairMan]

Hi

I have a V8S.

The temperature gauge goes scary high! Cruising along, the needle sits almost horizontal - just below 90. But, sat in traffic (or on the drive) the needle goes way up into the red. The fan _does_ kick in, but only once the needle is almost off the top of the red. If I turn the engine off once the needle is above 90ish, it won't restart for a minute or two, probably due to a fuel vapour lock.

I've bled the radiator and the swirl pot. The radiator does get hot, so I believe the thermostat is opening correctly.

How high does your temperature gauge go? What does the temperature gauge show when the fan kicks in? (assuming you don't have an override)

I might just swap out the fan switch - Race Tech sell two replacement fan switches, one "early on", part K0094A and one "normal", part K0094B. Have you any experience with these switches?

Cheers


Ian

[glow worm]

Hot is Ok ... well on my Chim V8 ... replace the TVR mod'ed sensor and location ... Plenty have done it on Chim V8s .. it matches the dial better and gives a true reading ... mine its a true 90 in traffic but soon drops to 70-80 once moving. I'll try and find the link on an edit

A long thread but start about here :-

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by glow worm on Wednesday 10th August 19:04

[frontfloater]

The gauge may be over-reading ; it does on my S2. If you can borrow a laser-gun type thermometer, you may find that the actual temperature is not as high as the gauge is indicating. I took my car to the local specialist on a very hot day when the fan wasn't cutting in with the needle slightly above the 90 degrees line. The reading on the laser gun was only 78.

[NicBowman]

Hi, I checked my actual running temperature with a Heston Bluementhal cooking temp gauge! Not sure if my wife would have approved! Kitchen gauges, electronic, with a probe, cheap!

Just stick the probe on a pipe. Run with bonnet open till fans come on.

Good luck.

Nic

[glow worm]

Get a copy of Rover Gauge S/W and a cable and look what the ECU is getting from the sensor.
Assuming a V8S has Lucas ECU and three pin cable connector

Pretty sure your fans are operated by the otter switch in your rad.

Edited by glow worm on Thursday 11th August 10:08

[bicycleRepairMan]

• UPDATE **

I spent some time annoying the neighbours running up to temperature with Rover Gauge connected.

With the bonnet open, the temperature goes to 93C, the fan comes on, and the temperature drops to 92C, the fan turns off, the temperature goes to 93C. And this cycle continues indefinitely.

With the bonnet shut, the temperature continues to 95C, even though the fan came on at 93C.

The whole time, the rover gauge temperature matched the dashboard gauge temperature.

I'm thinking the system is only just coping, so when I'm in traffic the temperature is going even higher.

As a start, I'll try check the thermostat is a "big bore", just incase the wrong one is fitted, and maybe change it....


Ian

[glow worm]

Two fans on a Chim .... maybe consider a manual fan override switch on the dash . Strikes me the fans could stay on longer . Only trouble with this hot weather , the air being sucked in is not very cold.
Water under pressure will not boil until over 110... my tuscan was 106 today after it was parked up with no fans running.

[magpies]

glow worm said:

Two fans on a Chim .... maybe consider a manual fan override switch on the dash . Strikes me the fans could stay on longer . Only trouble with this hot weather , the air being sucked in is not very cold.
Water under pressure will not boil until over 110... my tuscan was 106 today after it was parked up with no fans running.

/\ /\ This.

Mind you, I would expect more than a 1 degree drop between fan ON/OFF - probably around 3

[Beast Master]

My V8S's gauge sit's just a hair below 90 during normal running. But if stopped in traffic the needle will rise and sits right at 90. Continued sitting it will start to edge above 90 but I have never let run it natural course to see how high that it goes. I've gotten into the habit of switching on the manual override as soon/ before I hit stopped traffic, and that stops it going above 90.

[Deeman]

I attended a classic car show this weekend which tested my nerves. V8s, but 34 c ambient air temp and car heading to the red pretty quick. So resorting to turning engine off etc. just went into bottom of red at worst, but that’s enough for me. Going to take rad out for a recore. Never been the same since a garage chucked some rad weld in it! Prior to then it was always acceptable.

[Beast Master]

Deeman said:

I attended a classic car show this weekend which tested my nerves. V8s, but 34 c ambient air temp and car heading to the red pretty quick. So resorting to turning engine off etc. just went into bottom of red at worst, but that’s enough for me. Going to take rad out for a recore. Never been the same since a garage chucked some rad weld in it! Prior to then it was always acceptable.

Yeah anything heading towards the red makes me crap myself.

[SlimJim16v]

That seems like a very small window of operation for the fan. Is it supposed to be like that?

[Colin RedGriff]

Might be worth checking over the radiator to ensure it is in tip top condition, fins are not damaged/blocked.
A flush through the radiator and engine block to clear out any muck.

[v8s4me]

If the fan comes on when the needle touches the red then that's normal. So long as the temperature then drops then all is working normally.

Re-core* your OEM rad this winter and all will be well next summer. You could also consider fitting twin fans with the second one operating from a switch on the dash. Wire this second fan on a separate circuit with a separate power supply and its own relay. You then have a back-up if the first fan fails for any reason. I did this and found I only needed one fan most of the time and only needed the second fan when stuck in traffic on hot days.

• You do not need to junk your OEM rad for an alloy one. The old copper one will work perfectly well with a new core.

[magpies]

I would also check what the gauge indicates at (close to) 100degC

I removed the sensor and temporarily extended the wire and fitted an earth to the sensor, so I could place the sensor in an electric kettle I also placed in the engine bay. Had the kettle boiling and checked the gage needle position.

[tvrgit]

Even the tiniest pinhole in a soldered joint in the radiator (or at a hose joint etc) will cause a slight loss of pressure - which in turn causes a slight rise in temperature.

Most problems are caused by some tiny fault in the system and you don't need to be spending money on alloy radiators etc to cure it - it might coincidentally be a solution but it's usually cheaper to diagnose and get the OE system working properly.