I was losing coolant (empty exp. tank after a 5 mile journey) Originally I thought this was an e/fan problem as it wasn't cutting in at idle after a journey. But after finding a small amount of coolant on the garage floor, I traced it to a split pipe coming out of Oil Filter base. Pipe replaced, problem solved.

Trying to find the source of the leak threw up a number of puzzles. According to the Haynes comicbook, the sensor for the e/fan is either in the sidetank of the radiator or fits into the top hose. On my 940 it isn't in either place. I traced it to a plastic covered brass unit, bolted to the engine block!

Neither does the Haynes comicbook cover the 2 (or 3) pressure switches fitted low in the rad. front. I found out (by shorting across) that the e/fan is two-speed, presumeably depending on cooling system pressure to increase or decrease fan speed?

My local dealer wasn't very helpful. After all, I wasn't wanting a new car, just advice on an 11yr old one! But the dealers chief-mechanic said he'd heard of my type e/fan sensor, but didn't say where.

Reading other posts on this forum has raised suspicions that my 940 may have a 240 engine fitted? Is this possible?

Look over by the over flow bottle and see if you have 2 black relays that are exactly the same.If so one is for the fan and the other is for the fuel pump.
I think the engine computer reads the temp and tell it when to turn on with your car.

Thanks Tech :)

I'll take a look at that tomorrow.

Ok let me know how you make out.

Sorry for the delay in replying, Tech, work commitments have kept me away from the forum.

I looked all round the Overflow Bottle (Expansion Tank) but there's no sign of any relays whatsoever.

Should a partial loss of coolant, say half the Overflow Bottle, result in a notable rise in coolant temp on the dashboard gauge?

I ask this because all through my particular problem, the temp gauge needle has never risen above the middle of the gauge.

Is there a simple way of testing the temp gauge, just to make sure it is reading properly?

Thanks in advance,

melter65

It usually takes more than a half of the bottle loss to make the temp rise.
There is a way to OHM out the sensor and compair it to a chart and see what the temp is but I don't have the chart with the spec's.

The relay might be on the other side under the hood.It is a black relay with a square plug on it.
The relay looks like the one in the pictures.

Attached thumbnail(s)

Thanks for the pictures of the relays, Tech. I'll look on the other side of the engine bay when I get a chance.

Good news is that because of the warm weather, combined with getting stuck in traffic, my e/fan actually cut in this afternoon! At least I know it's working now!

Having said that, the temp gauge never rose above the middle before, and it never dropped below the middle when the e/fan came in. This is why I'm worried that the dashboard gauge isn't working properly.

One more quiestion have you replaced the thermostat lately?
They sometimes break and will make the guage read funny.

Good call, Tech! I'll see about changing the 'stat this w/end.

I know the 'stat is opening (because of the sudden temp rise in the top hose) but I don't know if it's opening fully, or at the correct temp.

Let me know if itis broke once you get in there.

Haven't had chance to get the 'stat out yet (work again!)

Back to the pics of the relays, Tech. Are they back-to-back in a bracket on top of the wheel arch? If so, they are on the (British) passenger side of my engine bay.
This is the opposite side to the overflow bottle, so I may be wrong!

They might be.If they look exactly like the picture I posted then yes it will be them.

Just to bring this up to date and close this thread :)

Since my last post, I've replaced all the hose clips with new jubilee clips, replaced a couple of the smaller hoses that were fraying at the ends, replaced the thermostat (sorry Tech, I binned it, forgot to test it!) Removed, cleaned and replaced the pressure switches in the rad, completely flushed the cooling system through and replaced the expansion tank (overflow bottle) lid :blink:

Something worked! During the recent spell of hot weather the e/fan kicked in whenever I pulled up in traffic, or I was parking the car. Just as it did when I bought the car last August :grin:

Thanks to Tech, for all his ideas and suggestions :clap:

The beers are on me :beer:

Glad I could help :banana: