Fan Cooling Relay

[mikebh8]

Hi, I can't find another topic with this subject but if it is, please, apologise.

I am trying to find the relay/es from the cooling systems's fan.

All I could find was:

-behind the left or right headlight

-behind the front bumper in front of the radiator

-on the left or right side of the car, under the air filter or under the battery.

I couldn't find it/them ( I understand that some models have 2 or even 3) in none of the above locations.

Could someone tell me if there is other places where it could be?

Thank you.

[gordy]

Does this help, its for 2.5crd either side of 2003.....You don't give details of your car.

Edited June 25, 2016 by gordy

[mikebh8]

Hi goody.

I thought the details would come up as I opened a discussion under mk4 model.

Diesel, manual, 2.5 crd.

Online, the numbers showed on the cases of those relays give details relating to gearbox.

I checked them anyway but they seem to be ok.

I will replace them see if that fixes the problem.

Thanks for your reply.

[gordy]

I take it the fans are not working. Check temp switch by bridging over the plug contacts and if fans run its the switch.

[mikebh8]

Hi, the relay in the middle, from the ones you showed,by bridging the supply, fan started.

So, you think is the switch?

Any ideas where to look first?

Thank you for your help.

[gordy]

You will need to tell us why you think fans are faulty. Is your car overheating or what. The easy answer would be to take out the coolant temp switch and put it in a container of water slowly being heated and take a note of the temperature when the switch switches over, that's if it does. There's probably a graph somewhere to change that temp into pressurised temp. Think I would just have a replacement handy to save the hassle.

Just read your info again where are you bridging over at the temp switch plug or the relay.

Edited June 28, 2016 by gordy

[mikebh8]

Hi, the fans do not turn on, water overheating when idle or over speeding, when air con is on non of the fans comes on.

I bridged the connections at the middle relay and the fan at the right( facing the car) turned on. Power supply present at all three relays, 10.2v at the 85/86 ends and 14v ( with the engine on) at 30/87.

My little understanding about water cooling system on cars let me assume is not the thermostat because the gauge on the dash functions ok. Am I wrong?

I will try the switch tomorrow, again thanks for your help.

[andyb2000]

Hi Mike,

 

A few quick answers that should help you here. You're right, the thermostat isn't really relevant here, it only allows a small amount of water to pass when it's cold and as it warms up it allows more water to flow. They generally (99%) fail fully open so they cause the opposite problem, car runs below 1/4 on temp gauge almost constantly.

 

The fact the fans don't come on when the air con is switched on makes me think more of electrical issue, so easy one first. Take the middle relay you identified as the fan relay out and clean the contacts, put it back in and hold your breath! (I can confirm from my 2.8CRD when air con switched on, fans come on straight way, so an easy test)

Chances are that won't work, so now you need to check if the relay has gone bad.

These relays are standard 87A which has pin out of:

85 and 86 coil (so 12v power to them when relay is triggered)

87 normally open

87a normally closed

30 common to 87 and 87a

 

So, when you tested did you bridge pins 30 and 87? So that could mean the relay contacts or the coil are shot. Easy test, swap the relay for another one (I always use the horn relay as a test one to 'borrow' from the main fuse box) and see if that solves the problem. That way you know if you're looking at a simple relay fault or something else further as gordy mentions on testing the temp sensor.

[mikebh8]

Hello Andy.

I tested all three relays with a 12v battery and a polarity tester, they are fine. Cleaned the pins, went further and cleaned the female pins from the wiring.

When it stops raining ( if it does) I'll check the temp sensor.

Thanks for your help.

[mikebh8]

Update,

I removed the temp sensor and by testing it under the kitchen's tap water with an ohm meter I had the following values:

On cold- 2.25kohms

On hot- 0.83kohms and after a while started to increase.

I did that with another temp sensor from an old head that I have (same model,long story) and it gave me the same cold value but on hot dropped to 0.68khoms stable.

The other thing is, when removing the temp sensor's plug the fans (both this time) start to function on what seemed to be full speed. Connecting it back on, the fans stop.

Any suggestions would be useful.

[gordy]

I'm interested in your words overheats at idle. Is this a water pump issue where engine as said is overheating but coolant is not reaching radiator. Or thermostat stuck shut if that's possible. So are the hoses at the radiator hot when it overheats.

[andyb2000]

Hi Mike,

 

Some good diagnostics there, apologies I saw you'd tested the relays fully previously, I'd missed that.

 

So, the main electrics are correct, when you pull the sensor it should go onto full, it's a safety mechanism, so that's good, means the rest of it (BCM, wiring, relays, etc) are all good. So yes it sounds like the temperature sensor itself. Although the resistance isn't as big a difference as I'd expect, those subtle differences may be enough.

Why not put the old sensor in and test to see if any difference?

 

(Also, good point gordy. What exactly is the issue other than you're not seeing the fans kick in)

[mikebh8]

Hi again, the symptoms were:

Water low level after a while, overheating on idle ( the temp gauge on the dash going above middle when usually stay slightly bellow that, when driving with more then 60 the temp goes up and when reaching 80-90 mph goes closest to the red point.

Now, from stupidity, I have more problems.

To let the fans working, I disconnected the temp sensor plug and after driving 30 miles a big knock on the engine started and became louder and louder. I stopped the car, checked the water ( missing about 300ml) the pipe near the rad was very hard with a lot of pressure in it. On the oil cap there is vapors coming out with smell of burned( more like hot clean) oil.

Surprisingly when trying to restart the engine, it seemed like a flat battery even though the battery is new and normally works fine. My question is, the engine overheated and I broke a piston, it does not sounds like a rocker or a valve ( not that I am a professional mechanic but that's what I think)? any more help would be very useful, and thanks everyone so far.

[andyb2000]

Hi Mike,

 

That doesn't sound good news unfortunately, probably not what you want to hear but I believe I did similar to my last GV but in my case I ended up with a crack in the block due to a faulty 'repair' to the oil cooler and water systems. So in my case all oil was lost, overheat and cracked block.

 

I'm puzzled what happened though. You forced the fans to stay on by having the temp sensor unplugged, so in theory coolant should have been flowing and with enough air going through the radiator to keep at a reasonable temperature. Makes me think back to your original issue, something else is not right, perhaps the water pump isn't doing it's job properly? (I wonder, was the water flow better/worse depending on speed of engine?)

 

However from what you describe, yes it sounds more like piston if the starter is struggling to even turn over the engine as the usual (gasket, etc) wouldn't cause that as far as I know. But this bit like yourself, not sure on the actual mechanics here.

 

Sounds to me like a book into garage job as next step unfortunately :-(

 

I hope you get progressed Mike and please do post back on how you get on.

Edited July 4, 2016 by andyb2000

[mikebh8]

Hey again.

Today I start striping the engine out, I'll probably get another one but I have to see what is wrong with it.

Andy, the water pump is new (2000miles)

I rebuild the engine after the timing belt snapped and I drove the car few miles including a trip to Germany.

I am wondering: what if the temp sensor by disconnecting it would shut down some other bits that cause the engine to overheat... I'll keep the subject up to date.

[andyb2000]

Hi Mike,

 

Not a fun job to be doing but you sound like the guy to get it sorted! Hope it goes to plan.

 

The temperature sensor isn't anything more advanced than that, although it might do a 'little' trickery in the ECU, it's not going to do a whole load with the engine, etc, so it has to be something in the cooling system that failed on you, since you're stripping the engine I'd dig that water pump out and check it hasn't had premature failure or some other blockage in the system perhaps? (Gummed up radiator). All kinda basic things, but then the coolant system on these (and still most others) are pretty basic so an overheated engine only has a few things that could have caused it.

 

Good luck, and yes please do keep us updated.

[mikebh8]

Hello, while I was taking it out the new engine arrived, so far I can only say that all the water was in the oil... I'm guessing the head gasket was the fault. I replaced the head and... I will put more details after dismantling the engine ( didn't have the time).

 

 

The other problem is, and if I have to open a new topic please let me know:

After replacing the engine, won't start. It does have compression and while trying starting it with easy start it does sound nice and it runs but on high revs.

I had some help from a "mechanic" but his attitude made me take the car home and trying myself with calm and more professionalism. I mean he wanted to take out the injectors with a crowbar( likely I had the kit and did it myself), he then aligned the clutch with a screwdriver... anyway what i would like to find out is, why it wont stay on idle?

Does anyone know where the fuel filter is on this model, I tried everywhere but with no luck.

Nevertheless, if anyone did an engine swap and had the same problem, please let me know how it was solved.

Thank you very much and as usual, I will post more in the future with details and/or when the issues are solved.

Edited October 8, 2016 by mikebh8

[ryden]

Hi Mike,

 

On a 2003 2.5crd the Fuel Filter/ water separator is located underneath the rear of the car next to the fuel tank and rear axle.

 

Ive added some info on its removal and an exploded image. Hope this helps in some way.

 

Edited October 8, 2016 by ryden

[JCD]

Dear All,

I'm trying to solve a similar issue as Mike, I have a 2.8L CRD Grand Voyager. The car may overhead very ramdomly mainly after driving a few hours ( Long distance) while climbing a road or being stuck in a jam.
I have tested a few thing after reading this post:

Both Fans will switch on yet on a very slow speed. ( I was thinking of plugging it in direct as a temporary measure)
Fans does not switch if the AC is on ( It does happen but not immediatly as Andy Mentionned)

I will test the fan relay this afternoon yet I would like to know where is the temp sensor to bridge it.

 

Thanks for your help :-)

[Spigot696]

Hi, this sounds like my issue exactly.

 

Did you ever find out what the issue was/is?

 

Thanks in advance.

 

 

Dear All,

I'm trying to solve a similar issue as Mike, I have a 2.8L CRD Grand Voyager. The car may overhead very ramdomly mainly after driving a few hours ( Long distance) while climbing a road or being stuck in a jam.
I have tested a few thing after reading this post:

Both Fans will switch on yet on a very slow speed. ( I was thinking of plugging it in direct as a temporary measure)
Fans does not switch if the AC is on ( It does happen but not immediatly as Andy Mentionned)

I will test the fan relay this afternoon yet I would like to know where is the temp sensor to bridge it.

 

Thanks for your help :-)