over heating issue

[wooly350i]

Me thinks there may be a problem with relay or wire to it cos it seems to stick intermittently thus stopping fan coming on at around 92'c,by then its too late and she starts to bubble up.Now bearing in mind its a new engine and we gotta run it in we're a bit hessitant about bbwf next week.Going for mot tomorrow and probably rolling road again to check settings but will look at putting in a fan over ride switch.Why the f--- does it need a relay anyway,im no auto electrical brain but my thinking is to take the power from ignition live via a 40 amp fuse to otter switch then switched live to fan,where did the relay come in???
Anyway we fixed our door mirror with a new motor and glass and we got the rear fog light to work without input from the front fogs so it stays on without flashing the bloke behind whilst flashing the bird in front.So will she be going to BBWF?, dunno yet!!

[ferlin]

Have you tried cleaning up the otter switch tags and connetors before you think about fitting a switch? Just put a link wire between the two wires off the switch to test the circuit/ fans.

[wooly350i]

Pulled em off and linked together,still no power to fan.Then later on working again,now buggered again we think so wire from battery to fan in the morning for mot trip! Tools galore and lots of water in the boot just in case of road side shinnanigins.

[Number 7]

Is it possible that there is a air in the cooling system from the engine re-build? They can be tricky to fill / bleed?

7.

[adam quantrill]

If the fan has a part of the winding or commutator that is a poor/open circuit then if it's in that position when the power applies, it won't move, try nudging it by hand but watch your fingers!

[wooly350i]

Ok so yesterday we took the old girl down to the MOT place,stopped on route cos the alarm started shouting at us but that was cos we disconnected its fuse and the back up battery must have powered it up after a while,so that sorted we try to restart and nuffink.Scratched heads for a minute then bingo the small wire had worked off the starter solenoid right next to hot exhaust so gingerly put that back on and we're in business again for MOT. PASSED with flying colours but running very lean(0.62% co),up to 3.5% allowed so back to small town rolling road guy and he dabbled on the puter to raise co% and richen her up.Also connected lambda sensor on one bank to ecu to help it work out fuelling,may have to fit lambda on other bank cos ecu has wiring for it and its only getting half the story so to speak.Fan started behaving itself again but car definately dont like heat and driving in slow traffic.
Yesterday evening after farting around with clutch all afternoon we took her for a run and generally ran great,fan had no need to switch on as she kept below 92'c all the way until we got home,when the missus bked us both for going out when we should have been in the bath!! Anyway apart from that and the clutch car is fairly good for BBWF,see my topic on clutch.John

[honestjohntoo]

wooly350i said:

Why the f--- does it need a relay anyway,im no auto electrical brain but my thinking is to take the power from ignition live via a 40 amp fuse to otter switch then switched live to fan,where did the relay come in???

Please dont! Unless you fancy toasting your ignition switch. All high current applications usually go thro' a relay of sorts. Your correct course of action is

A. Check the connections, en-route to the relay and

B. Likewise from the fan 12 volt pickup point to the relay and owards to the fans, including the local earth connections.

C. Open ALL the connectors, clean them up with WD40/Switch cleaner and lube with Petroleum Jelly before reclosing them.

D. Likewise with the earth connections, scrape away any corrosion, lube and remake.

E. If the relay is actually sticking then replace it but you may find it can be prised open and the contacts inspected and redressed with a fine emery board, if there has been burning/arcing. Short term solution, but very effective in a crisis.

Why relays? Think SOS! "Save Our Switches".

[wooly350i]

Thanks for your input guys,explanation by honestjohntoo is helpful,Having been out there best part of afternoon i took a 27.5amp cable straight from the battery into a 20amp fuse and on to a 20amp switch with neon then back out to the fan so its not via the ignition, seems ok at the mo just have to remember to turn it off!!

[jmorgan]

Personality I would try to use the least abrasive material I could with contacts. It depends on the state of them.

I had a dicky connector on the rear of the fuse board and when the fun seized it cause the connector to heat and melted the fuse body. So replaced the fuse and as cooling is important I installed a suitable circuit breaker at a suitable location so I could get to it easily. You can get fuse sized ones but I do not think they are meaty enough at the higher amperages.



Don't forget, engine expensive very quickly, new relays cheap in comparison.