Radiator fan not kicking in - overheating.

[serth]

Afternoon all,

I'll start by mentioning that i have a Fiesta Mk5 ZS with a 1.7 MHA early Puma 1.7 lump and box in it. Everything has been running fine apart from a couple of small teething problems, so I took the car out to Ford Fair last weekend with a load of mates. She was all very well behaved on the motorway and the backroads, much to my delight, but when i started queueing to get into Ford Fair, she started overheating, and the fan wasn't coming on. I had to turn the interior fans on blasting hot air to get her to cool down.

Now i know there are different wiring setups for the early and later pumas, and also for the AC and non AC cars but myself and several other people I've been speaking to have all experienced exactly the same problem (at the same location, queueing for Ford Fair), they too have puma engines in their Fiestas.

My fiesta originally had aircon, but i removed this as it was getting in the way of the engine conversion. However, I kept the pump as i bought an AUX belt for an AC eqquiped car to fit onto the Puma engine, and this is attached to the puma engine with the pipes disconnected but the belt connected.

As part of the conversion, i stripped out the old engine loom and put my new TAPE ECU and puma loom into the engine bay. This loom has plugs for aircon, so i can only assume the puma engine came with aircon fitted too (despite there being no pump on the engine when it arrived). I have two grey block type plugs plugged into the back of the fan (facing the engine) and nothing else.

Is there something I'm missing? Fuses and relays all seem to be present, every thing else works fine apart from this fan.

It's been suggested that i put 12v accross the fan to see if it's a dead fan but i don't know how to do this.

Any ideas would be greatly appreciated.

 

[ElDude at Allison Automotive]

overheating issue is 'usually' a knackered heater control valve as when faulty it spoils the flow of the whole system..

it's certainly the weakest link

Finis 1714716 currently £57.16 retail

don't buy any cheap ones off ebay..you've been warned.. :wink:

 

[serth]

Cheers for the reply, I had a new HCV a good year and a half ago, was a bosch one fitted by the RAC (before I had a tool kit...!), so I don't think it could be this. I get cold air through the interior fans which further points away from the HCV problem, surely because the engine only overheats in traffic on a hot day, and not when being driven enthusiastically, this shows that the problem is fan related and not HCV too, as the fan is designed to kick extra cold air at the rad when it isn't getting as much as it needs (i.e. in hot traffic)?

 

[CherryVimto]

When you start overheating, does the rad fan come on at all?

It should have two speeds.. Low and high.
It should come on on low speed initially, then if it doesn't cool down enough the fan will then switch to high speed.

The low speed can be checked by turning on the A/C, but obviously can't do that in your case.

If the low speed circuit fails, the system should default to high speed instead.

So, first I would check the fan relays. There are two, one for each speed but can't tell you off hand which ones they are in the engine bay fuse box.

On the earlier Pumas, there were two coolant temp sensors. One did the dash gauge and the other fed the temp to the ECU.
I don't know how many temp sensors the later Pumas have.
These may be another thing to check, test or replace.

 

[ElDude at Allison Automotive]

my money is still on it being HCV...if a Ford one wasn't fitted then you can bet that's the problem, whether it says bosch or not... the coolant sensor isn't expensive if you want to try that...

is the coolant diluted with too much water maybe..?? is it 50/50 with fresh stuff in there?

 

[serth]

Cheers El Dude for the reply, I'll take a look at diagnosing any problems on that soon.

The coolant is brand new pink stuff from ECP ready diluted. Had none escaping, but engine does seem to get up to temperature rather quickly, yet still steadily. Needle will be in the middle after just a mile of normal driving.

Any one know where i can locate the 2nd temperature sensor and the coolant sensor? I've been told there should be one on top of the radiator fan? Am i right in thinking the one beneath the coilpack is the engine coolant temperature sensor?

I've undone both plugs (one by one) on the back of the fan, unclipped the coolant sensor under the coilpack, put air con on and turned it off, and all combinations of above, then started the car up, but the fan still won't spin up.

I'm also getting the DTC codes as follows (on dash readout):
1) 9359 - B1359 - Ignition Run/Acc circuit failure
2) 0115 - P0115 - ECT sensor circuit failure

Admittedly I only checked for these after doing all of the above, so i probably need to reset the ECU to see if they are cleared, but I believe the first one is to do with no aircon and the 2nd one is to do with me unplugging the sensor.

 

[serth]

Also, Cherryvimto, thanks. I will look up the relay locations and see whether i can swap them over with some other items i have. Are they easy to remove from the fusebox?

 

[CherryVimto]

Yes, easy. Remove the lid from the fuse box and just yank them out.

My knowledge isn't as superior as other members on here, but I personally doubt the HVC is the cause, but I will certainly stand corrected if I'm wrong.
The reason I say this is my old '98 Puma I used to have had exactly the same problem.

The rad fan refused to work when the coolant started to get too hot. With the A/C on, the fan would run at full speed, so I knew the low speed circuit had a fault. So, I replaced the low speed fan relay and the fan resistor. After that the A/C would run the fan on low speed.
I then knew the rad fan definitely worked and on both speeds.
It had a new Ford HCV, new coolant sensors, new radiator fan resistor and new fan relays, but I still couldn't solve the problem.
In the end I just put the A/C on to get the fan to run to keep it from overheating.
I suspected it was either a problem with the ECU or a wiring fault.

 

[serth]

Cheers for the reply. Had a play with the engine earlier and I think I may be onto a winner.

Checked all of the fuses (including the big 60a one) and relays in the box and they were all present and looked fine. So i unplugged both of the sensors on the back of the fan and switched them over. I then unplugged the coolant temp sensor under the coilpack and the fan fired into life on a high speed.

When I did the conversion and wired the fan back in, i followed the plugs on the loom, and the way that the loom was bent, to help me plug the wires into the various sockets. However, in this instance, it could appear that i have wired it up wrong.

Am i right in thinking that, if the coolant temp sensor is unplugged and the fan then runs, that there is nothing to wory about and the system is now working as it should?
Surely if the plugs were plugged in wrongly then the fan should have still kicked in but at the lower speed? Could this signify that one of the relays/plugs is knackered.

I also checked the HCV over... hot pipes going to and from, hot pipe coming out of top left of rad, took cap off expansion tank and drove for a mile, then parked in the drive and revved it, but it never started bubbling or even feeling hot, however the dash temperature guage was sat in the middle the whole time.

I disconnected the ECU for a good 50 mins, and then reconnected, with a view to clear DTC codes. After a 5 mile drive, i checked the engine temp on the dash readout (87c i believe) and then checked for the DTC codes but they were all there. Can these all be cleared only by an OBD2 reader/scanner?

Thanks

 

[CherryVimto]

Unplugging the coolant temp sensor should force the fan on to high speed.

 

[serth]

Ah ok, but surely now that the fan is working at high speed, I know that the fan and the relays/plugs and even wiring are fine, would it be reasonable to extrapolate that the fan is now working fine?

 

[CherryVimto]

I would have thought so, but that's the situation I had with my old Puma.
The A/C would turn the fan on low speed....
Unplugging the coolant temp sensor would turn the fan on high speed....

But it still refused to work!

 

[ElDude at Allison Automotive]

Yes, easy. Remove the lid from the fuse box and just yank them out.

My knowledge isn't as superior as other members on here, but I personally doubt the HVC is the cause, but I will certainly stand corrected if I'm wrong.
The reason I say this is my old '98 Puma I used to have had exactly the same problem.

The rad fan refused to work when the coolant started to get too hot. With the A/C on, the fan would run at full speed, so I knew the low speed circuit had a fault. So, I replaced the low speed fan relay and the fan resistor. After that the A/C would run the fan on low speed.
I then knew the rad fan definitely worked and on both speeds.
It had a new Ford HCV, new coolant sensors, new radiator fan resistor and new fan relays, but I still couldn't solve the problem.
In the end I just put the A/C on to get the fan to run to keep it from overheating.
I suspected it was either a problem with the ECU or a wiring fault.

crikey, sounds frustrating.. :evil: :lol:

so you never got to the bottom of the issue then?.. :?