S90 almost over heated...!

anbran1 · Post by **anbran1** » 21 Jun 2013, 06:49

Hello,

I have had this car for about a month or so and it has ran great. Temp gauge always midway...
Yesterday I was moving along in stop and go traffic (outside temp was around 20 C), then I noticed the oil pressure switch flickering a bit then stay on for a minute or so, then flicker again... saw that the temp gauge was approaching the red zone...!
I put the heater on full blast to dump some heat and that seemed to work and brought the temp down a bit. (It never actually got into the red zone) The oil pressure light seemed to stay off now too...
I got to where I was going and popped open the hood...I was hoping to see the rad fan going, but it was not...(The oil was full on the dipstick) (Engine was, as always, very quiet when running)
I drove it home on the highway last night...needle position midway as usual, like nothing happened...

(Still no fan going)

What happened? Why did the oil light go on? (The engine runs very smooth with no lifter noise)
Was my rad fan supposed to be on?

anbran1 · Post by **anbran1** » 21 Jun 2013, 08:27

I just checked the rad fan by taking a test light clipped onto the "+" terminal of the battery and poked into each of the green and red wires feeding the rad fan. The test light lights up, but the fan does not go on...
Bad fan motor?

Post by **rgk** » 24 Jun 2013, 12:43

Have you checked the fan fuse(s)? Where is the fan grounded, and is that connection clean?

Post by **precopster** » 24 Jun 2013, 14:57

Making a test light is a good step but it won't supply power to the fan. You need to power the fan directly off the battery in order to check it properly

Replace the fan relay situated close to the battery. These go bad and often lead to overheat problems. The fan should always come on within afew seconds of operating the A/C

anbran1 · Post by **anbran1** » 24 Jun 2013, 21:50

I removed the fan assembly and hooked it up to a battery...The ground wire to "-" and the test light (with a poker needle) from the "+" to the green wire and then the red wire on the the fan motor.
The light lit up but the motor didn't go...
(When I turn the fan by hand, it sounds (and feels) like abrasive and scratchy...

Did I do this right?!

Post by **precopster** » 25 Jun 2013, 01:41

Sounds OK to me as long as the power was going direct to the fan and as you've tested that the leads have power with the test light it looks as though the fan has failed.

Try finding a good used fan; shouldn't be too hard as they rarely (but unluckily for you) fail.

anbran1 · Post by **anbran1** » 25 Jun 2013, 05:22

Picked one up yesterday...used $50...

Thanks for your help folks!

Post by **jimmy57** » 25 Jun 2013, 11:40

The bulb filament of a test light will not provide power flow to the motor. The bulb lighting up tells you there is continuity through the motor and it is likely good. When you use a test light that requires .5 amp to light to try to provide a motor that needs 10 A on low speed wire and 15 A on high speed wire you light up the bulb and the .5 amp of the bulb is as much current as the circuit flows.

When the engine got hot two things happened: 1. the clearances got greater, especially the cylinder head to camshaft clearance. 2. the oil got thinner as oil temp goes up if engine temp goes up and it thinned out.

As for radiator fan, the relay is down by battery and battery acid can attack it and cause it to fail. A battery being replaced may have resulted in on of the leads to the relay being left off.

Post by **precopster** » 25 Jun 2013, 15:29

From the OPs description I don't think he used the test light to complete the circuit. I was hoping he was poking the leads with the sharp end to test for power
(which seems kind of pointless if you know the lead has power in it because it's connected directly to the + terminal on the battery)

Yes Jimmy is right the test lead has a load which will lower the voltage to the fan and is also of incorrect guage to carry the high current needed for the fan to operate.

The test lead will likely burn up in your hands if it's completing the circuit to a working fan.

I already mentioned the location of the fan relay in a previous post. The yellow terminals in the centre will have voltage when the a/c is running or when the coolant temp reaches more than 105deg C. You can simulate this by removing the centre plug and replacing it with grounds (1 ground for low speed and 2 grounds for high speed)

anbran1 · Post by **anbran1** » 27 Jun 2013, 13:45

Ok, I goofed...
Turns out my fan DOES work! (and so does the $50 one!) I didn't use the test light this time...just "+" wire to "+" connector and "-" to ground from a good battery... Green wire then red wire (two speeds)
I guess I have to turn my attention to the relay?! How do I check that?!