Overheating

[fd4007]

Hi all,

I know there are topics on this subject already but can't find the answer so here goes: I have a '71 Spider 1608 car and the radiator fan isn't kicking in when it should even the temperature gauge gets to red. I've had the fan tested (works OK) and apparently so does the thermostat. I've just fitted a new radiator Fan Switch (77 degree one) but still no fan. I can feel a drive to Mark in Upland coming on but before I do, any ideas? How likely is it that the temp gauge is at fault? All the best.

[So Cal Mark]

does the fan ever come on? Unlikely it's the gauge. Do all of the radiator hoses get hot to the touch?

[fd4007]

Hi Mark, firstly many thanks for the steering and suspension work the other day - handles great now! The garage I took it to here said the fan does come on but just at too high a temperature but I haven't seen it working, the gauge is on maximum and still no fan, and yes the hoses are hot as is the top and bottom of the radiator. Just a bit worrying when it's on the red and still no fan...

[So Cal Mark]

glad to hear it's handling well, we averted a possible disaster with the suspension work.
I'd say the next step would be to verify the engine temp with a laser thermometer. If you jumper the fan switch so the fan runs constantly, does the temperature drop?

[fd4007]

Not sure, bit beyond me I think...Perhaps I can bring it over to you one day next week. I'll give you a call..thanks Mark.

[So Cal Mark]

does it get hot idling, or driving?

[fd4007]

Both..

[fd4007]

...But that said it's worse in traffic or idling than at speed...

[So Cal Mark]

hmmm, if it was only a fan issue it should cool at hwy speeds

[fd4007]

Yes it does cool at highway speeds...just other times it hits the red and no fan...

[Mathew26]

You mentioned that a shop told you the fan came on. Though you've never seen this happen.... Not to say they are 100% truthfull, but you really should check it. You can simply jumper across the prongs on the fan switch to see if in fact it is working. My bet would be air pockets in your coolant, but you say it does cool on the highway. So Mark is right you need to thremo your hoses, head, and radiator tanks top and bottom. I've seen the gauge be 20 degrees off from what everything truly is.

Good luck

PS a burp kit in the top heater hose might help

[Danno]

my fan is hotwired, so my knowledge on the subject is limited. I don't know where the fan's temp sensor is, but is there a chance that it's located in a spot on the radiator that could be partially blocked and therefore not reaching the temp that would turn the fan on?

[fd4007]

Thanks guys I'll check the fan as suggested...

[fd4007]

OK I've jumpered the radiator fan switch and the fan doesn't come on instead a clicking sound coming from the Motor Circuit Relay (small silver box attached to the body). Any clues gentlemen?

[So Cal Mark]

constant clicking or one click? I assume the fan connector is plugged in to the harness?