Overheating and non working Fans !

[Jitzz]

Hi All,

In preparation for Chatsworth, I got the Cerb MOT'd on Saturday (went through fine - thanks God!!)

During the emmissions test though, it started to overheat and I noticed that the fans didn't come on, so switched it off as soon as possible - think the temp gauge went above the 110 degrees make and lost some fluid out of the expansion tank.

I let the car cool down and then drove the short distance home - temp went up to 100 and stayed there

I've done a quick search, but can't seem to find anything conclusive....do any of you know what I need to check for i.e. relay, fuse sender unit/switch ????.....also the horn doesn't work either now !!

Don't want to compound any overheating issues so I've not used it since until I get a better understanding. It's a 4.2 1996 Cerb which hasn't been used since last year so been in the garage...shame on me I know

Thanks for any advice !!

Jitzz

[ukkid35]

Don't ignore the wiring around the fans themselves. Mine has been repaired at some time in the past, and that area is prone to corrosion if there rad has been weeping at all.

[P S K]

As above check the connections to the fans in the wiring loom under the radiator, they're prone to corroding.

Do you have the software and lead to check what the ecu temp sensor is reading, from memory the fans should come on at 92 & 94 degrees. The capillary gauge is renowned for over reading.

[C3BER]

Pull the temp sensor which you will find near the bottom off radiator passenger side. With that off the fans should come on. If they do its simply a matter changing the sensor as its shot. Cerbs are buggers when it comes to water. Your engine will be fine with the quick boil.

[C3BER]

The fans will come on higher than that.

[Jitzz]

Guys

the speedy response is very much appreciated...I'll pull the temp sensor at the bottom of the rad and see if the fans come on, as I don't have the ECU cable or software to check.

Didn't think about the connection being corroded - so will check that too...ta

Nearly, sh#t when I saw steam coming out of the engine bay....It did a little 'wee' on the workshop floor to so have topped up the fluid.

Should I also check the fuses and relays - do they play up too?

Thanks so much

Jitzz

[C3BER]

You can put to much or to little water in the cerb and it will spit it out with your own personal geyser but yours seems temp related.

Yes it could be a fuse but you will know more when you pull the temp sensor.

As for the horn...could be the ribbon has gone.

[Supateg]

Number of issues here,

The temp gauge will be reading high by min of 5+ deg so you need to get connected up to the ecu to see the real temps.
Too much water in the tank (over half) will cause it to spit out. (The expansion tank is off a car that has 5 litres of coolant the cerb has over double so needs room in tank to expand) The expansion cap can fail frequently.

Fans are controlled by the ecu so check wiring, most likley connectors tie wrapped on the chassis behind the fans.

Mine suffered this problem last year and turned out to be expansion cap and holed rad plus a failed k nut on the cylinder head water jacket.

[NeilH]

I had a similar issue following a winter lay up..

I popped the cover off at the front of the engine bay (sorry I do not know the correct name for it - but it has the washer bottle under it) Anyway, under here are where the fans plug into the loom. As someone has suggested, by unplugging them, the fans should come on. If they do, as was the case with me, some electric contact spray applied and plugged them back in. Once engine up to temp, the fans came on individually as required. Assuming they were working when you parked her up, chances are this will be the same simple fix ... Good Luck

[Cerbieherts]

Just to echo what others have said above, check the two white plugs for the fans for corrosion. I've also had a couple of cars that had sticking stats, although those both overheated quite quickly.
My Cerb has gone through 3 tank caps in 4 years!

[Tang Soo Tim]

Did you have a flickering MIL light at all ? Temp sensor was my problem on day I got my car .....



Unplug clean up and put back in, although at some point I would suggest replacing the sensor in the hard pipe !

The two connectors to fans will be the other thing to check as already suggested

Temp gauge never reads that accurate as the capillary runs throug the engine by it can heat up before getting to the gauge easily in hot conditions. Especially if running near manifolds !

Get stuck in there

[Supateg]

If you have your heart on making Chatsworth......

If you provide a picture of your car for everyone to see; i'm sure we will allow you to the front of the queue to avoid overheating

or it might just be cold and rain..

[Tang Soo Tim]

Supateg said:

If you have your heart on making Chatsworth......

If you provide a picture of your car for everyone to see; i'm sure we will allow you to the front of the queue to avoid overheating

or it might just be cold and rain..

Is the traffic going in always bad then ? Never been but hoping they get us all in quick without racking up TVR's with hot clutches and blowing steam

[Supateg]

Never been for a tvr event

Other times always been a little wait.

Anyone can enlighten us?

[C3BER]

Depends on the time you arrive. Carry water just in case as you should anyhow.

[Gazzab]

Was your expansion cap on properly? Also the caps sometimes need replacing.

[Jitzz]

Thanks guys !!

I'll check the contacts for the fans and clean, as I've got the cover off and can see them.

Also might replace the temp sensor as suggested after cleaning the contacts too - although my MIL light didn't flicker might just be a safer option in the log term.

I'll start working on this checklist tomorrow as I'm away with work at the moment and will report back...fingers crossed it's a simlple fix as all was good before the winter lay up

Big Thanks fellas, hope to see you all at Chatsworth !!!

Jitzz

[wiggycerb]

Had a similar problem with mine a few years back, turned out to be the electrical connectors to the fans themselves.

Gave them a good clean out with contact cleaner and put some fresh switch grease in and they have been fine ever since.

I also had a manual over-ride wired in, this is a great thing to do as i just flick them on when approaching traffic etc and it will sit at 75/80 all day.

Good Luck.

[ridds]

Also a dodgy ECU temperature sensor connection can not only stop your fans from coming on but also not show a MIL fault. Very poor bit of design on TVRs behalf.

I've had the issue on my car where it was getting hot, thought the fans should be on. Got in the engine bay and wiggled the temp sensor plug and the fans would sporadically come to life.

The sensor connection is definitely something I would check. Clean the terminals and use plenty of electrical compound on it to prevent corrosion.

[C3BER]

My sensor was faulty so we changed it and with it on the laptop it still boiled at 98 causing a lot of head scratching and worries on my behalf. Turned out to be another faulty sensor which fooled the laptop to thinking the temperature was ok.