I have recently acquired a 1991 imported v-special which has a number of problems, the most urgent of which is it appears to be overheating.I have changed coolant, thermostat, radiator cap & fan switch.
Symptoms are:
(1) temp guage rapidly rises to 7/8 position i.e ‘hot’ but not on the end-stop
(2) aircon fan works normally
(3) cooling fan never comes on - fuse ok - can be forced on by shorting pins on fan relay - this brings indicated temp down somewhat but still 3/4 position
with cooling fan on the temp doesn’t get below inticated 3/4 on the guage
The cooling fan is the one on the left side of the car, the A/C fan is on the drivers side, and this will come on to assist the cooling if temp gets very hot. Or can be forced on by switching on the A/C (with the cabin fan on 1 or higher).
I’ve had the cooling fan fail - motor bearings ~ make sure you’ve got the right fan in mind.
Could be a radiator blockage - have you flushed/back flushed it?, and what came out?
Thanks for your reply. yep, the A/C fan is the 1 on the drivers side & as far as I can see that all works normally. The passenger side fan does run but only if you short out the fan relay. When should the passenger side fan (cooling fan) start whe idling at a standstill? I haven’t flushed the rad - not sure how to
Goofs right it sounds like a common case of rad blockage,but have you checked the fan switch also???or the fan relay on the left hand side looking into your engine bay next to your headlight,try swapping them around first one is for the a/c the other is the cooling fan,hit this before and found the relay had give up,got a s/hand one from andrew at autolinkuk.co.uk.
If the temp doesn’t come down to normal [and i presume that it used to?] when you short the diag pins, then the fault isn’t with the fan in total. The switch that controls the cooling fan is mounted on top of the thermostat housing. This switches the fan when the water temp reaches a pre determined level, yours may well be stuffed, or a loose connection…they all need checking. I reckon the basic overheating problem is most likely the rad, given all the other stuff you have changed
The fan thermoswitch is mounted at the front of the engine, screwed into the top of the thermostat housing. If you remove the connector and short it to earth this should trip the cooling fan relay. The switch itself should normally show continuity at temperatures above 97 Celsius.
Thanks all of you, that gives me a bit more to go on. I didn’t try earthing the connector - just changed the fan thermoswitch - d’oh - £25 needlessly spent, looks like.
I looked at the fusebox by the driver’s side h/light & the cooling fan relay didn’t look like anything else - so don’t think I can swap it - but can certainly try testing it, if its knackered its an easy thing to change.
The radiator - I gather one is supposed to look for cool spots. How does one get to the lower radiator hose? Its hidden away down there.
Right, I have just bought a new rad (£70 from Autolink) & a 2nd hand fan relay for £10.
(1) the cooling fan now starts, so it was the relay
(2) have not fitted the new rad, will need to remove the undertray which is bodged horribly with tie wraps and goodness knows what, its cracked to smithereens & will probably fall apart in my hands when I remove it }:-E - so have thought ahead & also aquired a 2nd hand undertray in much better condition from the same source. Will try to sort this lot out tomorrow & will let you all know if it fixes the high temp issue or not.
Looks like you have found the problems. It would be interesting to change the fan relay first to see what temp the car runs at before you change the radiator. That said a new rad does seem to cure most peoples overheating issues (me included). They do seem to be rather critical on flow and any contamination in the cooling system if it has not been changed regularly is likely to restrict the flow.
You nicked the Rad. from Autolink that I would have got today! Ha Ha Ha! I have just rung them and they sold the last one … !!
I’m doing everything I can to unblock mine … would have popped into MX5Parts today - but they are shut Saturdays! I’m sure they used to open on a Saturday?
Aaaargh! Sorry about nicking your rad BigPete, they did say it woz the last one
OK I have removed the undertray (& sheared off one of the studz
Now I can see TWO radiators, the engine cooler that looks somewhat like the new one AND another aluminium one bolted to the front of it that is leaking what looks to me like aircon refirgerant :-))
Have changed the rad, but the wretched thing is still overheating. The top hose gets hot, but now that the undertray is off, I can feel that the bottom hose stays cold. I bought a pup didn’t I? looks like the pump.
Any other thoughts? Clearly I can’t drive the f*&$ing thing with no coolant circulating.
When the engine is hot, and the Thermostat open, squeeze the top hose tightly shut … you should ‘feel’ the water, or by looking inside the cap you should see a gush of water when you release the hose.
I’ll give you £35 for that radiator you beat me to!
nothing moving in the hoses… goodness knows what the PO was doing driving the car like that. cant believe I paid real money to buy such a wreck looks like the engine is toast then
have damaged one of the heater matrix hoses whilst attemoting to remove it in order to get an idea of fluid flow. Anyway I can now see that the flow of escaping coolant through the split heater hose is a mere trickle, even when the engine is running. Hot air does come out of the cabin vents (or did until I damaged the hose trying to remove it.
Could this be anything other than a completely knackered pump?
AND another aluminium one bolted to the front of it that is leaking what looks to me like aircon refirgerant :-))