Intermittant fan problem - Thoughts?

[aaandy]

Hopefully one of you guys can help. Got a 98 Chimaera and as a rule works like a dream and the fans always kick in at 90 degrees(ish) as they should do.

But I was on the M1 yesterday in a traffic jam, about mid-day, baking sun! Normally behaves impecably in these conditions and fans always keep it to around 90 degrees. However on this occasion the temp just kept creeping up and NO FANS kicking in! Luckily was near a junction so was able to get off the M1. Stopped at the side of the road to investigate and the fans came on, but by this time I was up to about 105 degrees, a bit too late. Fortunately was able to carefully run it up and down a nearby dual carriage way running some air through it until I could get back on the motorway.

30 mins later, bit more slow traffic and fans come on at 90 degrees as normal. Bizarre but has now made me a little weary of over heating.

Any ideas what I need to look at to stop this happening again?
(Would like to add that this was the only blip on an otherwise faultless 350 miles over the weekend )

[hut49]

Could it be a poor electrical connection somewhere that when stationery and getting hot the component expands and fails to make contact but when moving the vibration creates sufficient contact? Just a guess.

[Incorrigible]

Dodgy otter switch, happenned to me last weekend. Luckily I know where all the bits are and easily hardwired the fans to stay on till I got home

Worth knowing

[aaandy]

Otter switch sounds like it may be the route of the problem. Will look into that.

Are these relatively cheap to replace, and more importantly are they easy to replace without going to a dealer? I am not the best mechanic by a very long shot, but if it is very simple then I'd be happy to give it ago and save the pennies for more optimax!

Will also look into to how to hard wire them in case it happens again. Think I saw how to do this in the bible.

>> Edited by aaandy on Monday 4th August 13:35

[m142 yum]

Whats the downside to having the Fans permantly wired to on?. I guess it could mean the engine does not rise to a sufficient temprature during cool weather, and wear and tear on the fan motor.

Are there any others?, is this the done thing?.

[M@H]

I had this problem and it was the bottom connector to the otter switch, it had just got very dry and full of belt-dust and stuff.. it would manage to work sometimes and not at others.. A good clean off and WD40 solved the problem.

Cheers
Matt

[K4TRV]

m142 yum said:

Whats the downside to having the Fans permantly wired to on?. I guess it could mean the engine does not rise to a sufficient temprature during cool weather, and wear and tear on the fan motor. Are there any others?, is this the done thing?.

Yes all of the above, plus any minor unbalance of the fans will eventually "spring" the soldered joints - a fatique type failure. This isn't helped by the rad being as large as it is and effectively being twisted by movement in fibre glass body. Permamently switched on fans are not recommended !!

[philip_cooke]

aaandy said:

Otter switch sounds like it may be the route of the problem. Are these relatively cheap to replace, and more importantly are they easy to replace without going to a dealer?

Aaandy, I recently replaced my otter switch - went to a motor factors, showed him the offending article (I had an old one - I think they are pretty much standard - same as fitted to Alfa Romeos), said I wanted one 87/92 (off/on - degrees centigrade) and he duly placed one on the counter and robbed me of about 7 quid (phew!). To remove/refit, simply remove the electrical plug, get a large socket on it, twist anticlockiwse, remove as quick as possible and put new one in place (make sure the engine is cold first!!) then tighten clockwise, replace electrical components, run up to temperature to check function. I'm sure there is a paragraph in the bible on it.

If you need more info, drop me a line.

[Incorrigible]

m142 yum said:

Whats the downside to having the Fans permantly wired to on?. I guess it could mean the engine does not rise to a sufficient temprature during cool weather, and wear and tear on the fan motor. Are there any others?, is this the done thing?.

Only use this in an emergency, definately NOT the done thing in normal running.

OTOH it's usefull to know how to do it, you never know when it'll be usefull

>> Note the end of my last post "Till I got home"

>> Edited by Incorrigible on Monday 4th August 16:17

[M@H]

Incorrigible said:

m142 yum said: Whats the downside to having the Fans permantly wired to on?. I guess it could mean the engine does not rise to a sufficient temprature during cool weather, and wear and tear on the fan motor. Are there any others?, is this the done thing?. Only use this in an emergency, definately NOT the done thing in normal running.

I carry a paperclip in my wallet for this.. you never know when you'll need it.

Matt.

[aaandy]

Thanks very much for all your responses. As always very helpful.

I will go home and have a poke around and clean up the connectors add WD40 etc, as a temporary measure. But will also get a new otter switch regardless and put an update back on here when complete.