Coolant Fan Problems

D2BBA · October 15, 2005, 07:20:49 PM

Hi folks,

A little Saturday night puzzler for you!,......

Got back from WGT this afternoon following Pip dynoing car for me and sorting a prob with second turbo (another top job from Pip and at very short notice I may add!!!)

Anyway, the 6 1/2 hour round trip threw up the usual problems on my \'92 Fd (no mods). The temp was great heading back (steady around mid eighties) however when on drive "cooling down" it overheated!

Seems the fan aint working and the water temp increased and p1ssed out of the poorly secured (my fault) rad cap. Waited for it to cool, topped up and confirmed fan didnt work (got to 100o, well past the 95o). Turned engne off and low and behold fan came on. Fan only seems to work when inginition is on but not engine!!!!!!

To add to this I finally split the expasion tank (probs caused by added pressure I think) so if anyone knows where I can get one quick I would apprciate!

To sort the fan what should I check? Does it sound like a fan relay problem or a dodgy earth? Any ideas folks?

Help much appreciated!
Chris D.

Steve Burnett · October 15, 2005, 07:26:09 PM

Not sure about the coolant problem, maybe faulty wiring???

My help is: AST from Pip. About Â£90-100.

D2BBA · October 16, 2005, 12:43:55 PM

Quote from: Steve BurnettNot sure about the coolant problem, maybe faulty wiring???

My help is: AST from Pip. About Â£90-100.

Hi Steve,

Would an aftermarket AST really make that much difference? Will order one whilst I\'m on with new expansion tank and sorting fan if so!

Ta
Chris

Steve Burnett · October 16, 2005, 04:52:01 PM

Chris, sorry I posted without taking my time. I thought you were saying you split the AST tank. I would suggest that you do replace your AST tank with an aftermarket one though. Its a good mod as the stock one has been known to split.

D2BBA · October 16, 2005, 05:18:49 PM

Cheers Steve,

Will look at that!

In the meantime have spend all of this afternoon attempting to work out why fans aint comming on while engine is on, but are on when engine id turned off (ignition pos 2).

Checked relays and all is fine.

Does anyone have any ideas, or is there a way to have fans on full all the time or fit an overide switch?

Cheers in adavance
Chris

D2BBA · October 17, 2005, 11:27:52 AM

Any thoughts anyone???

Dan Norton · October 17, 2005, 11:35:01 AM

Cant help you with the fans i\'m affraid chris, but on my old crx vtec, all the fan wiring corroded and instead of trying to sort it all out, i had an overide switch installed, and turned the fans on and off when i wanted....was very handy and worked a treat!
Any car electrical place will help you there.

As for AST tank, deffinatly get one from pip, they are metal, so will never split!
Heres mine.

Dan!!

D2BBA · October 17, 2005, 04:08:21 PM

Hi Dan,

Cheers for the tip on the overide!

I spoke to Pip today who is sending me a new shiney expansion tank! He also came up with a possible cause of the fan prob:

Apparently there is a sensor within the coolant system that turns the fan on. If the levels are too low (ie mine with the leaky bottle) it may not be comming on when I test.

I will fit the new tank then check, if it still aint comming on I will speak to my local auto electrican and ask them to have a quick look at fixing it and to fit the overide switch!

That and a new rad should keep me cool! Will have to remember to tighten the filler cap on better in future! Hopefully to 1ltr of water i lost out of it aint dmaged anything.

Will keep you posted
Chris

nikp · October 17, 2005, 04:19:13 PM

How do you know exactly what your temps are? Do you have an after market gauge? I have some thoughts on your situation, as I have been looking at my cooling recently, and have made some interesting observations about it.

antnicuk · October 17, 2005, 04:58:08 PM

I thought if you switched the aircon on it would overide the fans to make them come on.

nikp · October 17, 2005, 05:01:20 PM

This is also true.

Martiny · October 17, 2005, 06:02:32 PM

Its true CHris, put the aircon on, and the fan/s should run.

D2BBA · October 18, 2005, 08:12:23 AM

Hi gents,

Yep I have an aftermarket GReddy gauge which seems to be spot on.

I\'ve also found a few posts relating to the fan working with the AC on. This is true, but you may have noticed that the fan has three speeds (high medium and low). Its all managed by the fan relays. Hitting the aircon button alone will only get you a low speed fan, however what I could do with is more! I found a webasite that alows you to overide the relays and fit an overide switch!

Will hopefully get new alu expansion tank today / tomorrrow to fit and check Pips theory!

Will keep you posted
Chris

nikp · October 18, 2005, 09:29:30 AM

Well, I have detemrined that the temperature the greddy gauge shows (I have a greddy gauge too) is not necassarily the temperature of the coolant in the engine. The gauge could be showing 95, but in reality the temperature in the engine could be higher than that. In all likelihood, they\'re going to be the same, but if you\'re having collant problems then there could possibly be a temperature differential. The fans work off the temperature of the sender connected to the engine, so they may be seeing a different temperature to that of your greddy gauge.

antnicuk · October 18, 2005, 09:54:46 AM

i know of a stock FD with an apexi on it, it was showing temps of 100 plus upto 115 all day long on the commander. The stock fans dont start swithcing on until over 95 nearly 100. I wouldnt trust an aftermarket gauge for checking the exact temp as the ecu, it may well give you the correct rise and fall of the temp but the sender is in a different place.
You might find that the fans come on after you switch the engine off because the water stops moving through tha rad which makes it get hotter after you turn the engine off as the sender is almost in the engine block.