The 'E' Type Forum

Hi , I have now got my vehicle on the road in the UK , first job has been to road test for reliability in use.
All going OK for first 100 miles and then found engine suddenly getting warm.
Investigated and found one cooling fan not working and the relay burnt out.
The set up looks original so was going to get new fan motor and relay, fit , test and drive.

Any advice ? I am hoping that the factory fit is OK as it has been used in the hot sates of USA.
I did not want to start changing everything if I can do a quick fix and enjoy driving it !

Dear Tilty - as there is only one cooling fan relay (part number C31791) fitted on my October 1972 Series 3 (and I assume that's the case for all Series 3's), it would seem unlikely that the relay is at fault if one of the cooling fans is coming on when the thermoswitch (located on the hose behind the lower part of the radiator) makes the circuit. Instead of having to run the engine until it reaches the required temperature for the fans to operate , you can "by-pass" the thermoswitch by removing both terminal wires and then connecting the terminals with a wire (experiencing the wonder of crocodile clips). When the ignition is on both of the fans should work. If one of the fans fails to operate, the connections and wiring to that fan's motor needs to be checked (I'm assuming you have an electrical tester to first check continuity) before assuming that the motor has failed. If the wiring does not seem to be at fault and the motor fails to operate, the motor can be tested by connecting its wiring directly to the battery (preferably put a 30 amp fuse in that test circuit). If the motor still fails, then a replacement would seem to be the only solution.
I would also suggest replacing the relay in any event as it gets quite "cooked" in its position under the shroud.
Hope that helps but I defer to other more experienced owners to provide their solutions.
Good luck
Best regards and hope you have many miles of enjoyable driving.
Chris

Hi: For last 30 years, I have just wired the fans direct to a switch on the dash. In fact, the last flip switch is usually empty, use that if you wish, and I simply control the fans as needed. No more worries of relays , etc. Just on and off depending on conditions. Works for me. As for a dead fan motor, just open , clean, and replace brushes. Every body sells them.....only around $40.00, as opposed to $120.00 or so here in US.

John

Original owner 1973 OTS

Hi
Before you go and spend money on another fan, check out http://www.coolcatcorp.com/V12Fan/V12Fans.html
for an innovative solution using modern fan motors(VW) and a modern replacement for the otter switch. The owner Mike is on this forum and his service is second to none.

http://www.coolcatcorp.com/Merchant5/me ... e=Cooling3

I did this on my S3 and feel a lot happier with the cooling setup.

I would also replace the old tin can relay with a modern Bosch one, much more reliable.

Then finally use one of the dash switches in the manner that John suggests, as an override to the Otter switch. I turn mine on any time I stop in traffic in warm weather, before the Otter switch calls for them on, gives peace of mind.

Happy motoring
Mark

And my car is running fine with original fan motors, controlled only by fan switch mounted where otter switch used to be.

No overheating issues in our 35degC or higher South African summers - and my car has aircon...

Hi Guys ,

Firstly many thanks for all your helpful replies , it is very much appreciated.
I think the bearings had seized in the one fan motor , causing fuse to blow.
I went to SNG and purchased new motor , relay and otter switch for car.
All have now been fitted and all seems to be working correctly at present.

I will run car over summer and if all OK leave as is , if not upgrade over winter.
Also have an override switch fitted which will be on all the time at present in
the UK at moment weather is very hot 30 deg c some afternoons!

42south wrote: ↑

Thu Jun 28, 2018 11:27 pm

Hi
Before you go and spend money on another fan, check out http://www.coolcatcorp.com/V12Fan/V12Fans.html
for an innovative solution using modern fan motors(VW) and a modern replacement for the otter switch. The owner Mike is on this forum and his service is second to none.

http://www.coolcatcorp.com/Merchant5/me ... e=Cooling3

I did this on my S3 and feel a lot happier with the cooling setup.

I would also replace the old tin can relay with a modern Bosch one, much more reliable.

Then finally use one of the dash switches in the manner that John suggests, as an override to the Otter switch. I turn mine on any time I stop in traffic in warm weather, before the Otter switch calls for them on, gives peace of mind.

Happy motoring
Mark

Dear Mark,

i have just finished to rebuilt my series 3 and even if i have not driven it so much, the temperature is currently pretty high in France (32 - 35 degres C) and i get conscious when i see the temp moving up above the NORMAL range. Thi usually happen when i stop at traffic light or drive through villages at low speed and/or stop a lot. last week end i have installed a switch to activate the fans earlier and it seem that it helps a lot.
On the 22sd of June i'll attend to a special classic event through Paris and it ll be almost only satrt and stop every 10 meters and i'm getting concerned.
I'm therefore considering fitting the VW fan mentionned in the first link. I found them easily on the net(around 30 euros each).
I nevertheless need some confirmations from your experience:
1) you fitted them in lieu of the originla one without any modification?
2) You wired from the original wiring the low speed terminal for both fans?
3) You have not changed the relay?
4) do you confirm that even at low speed the level or air blown is as gogo as the orgiginal?
5) For the high speed one you have a dedicated wire with a swith with a 50 amp fuse?

Therefore the interest of this installation is really to take benefit of the extra flow activated by the switch?

Many thanks in advance
regards
Jérôme

Djerome60 wrote: ↑

Mon Jul 02, 2018 4:28 pm

i have just finished to rebuilt my series 3

Did you measure the thermostats to be sure that they close the bypass circuit when they are open?

I found the thermostats on my car stopped about 2mm short of closing the bypass ports thus allowing considerable amount of coolant to continue bypassing the radiator, even when the thermostats were open.

jagwit wrote: ↑

Mon Jul 02, 2018 5:14 pm

Djerome60 wrote: ↑

Mon Jul 02, 2018 4:28 pm

i have just finished to rebuilt my series 3

Did you measure the thermostats to be sure that they close the bypass circuit when they are open?

I found the thermostats on my car stopped about 2mm short of closing the bypass ports thus allowing considerable amount of coolant to continue bypassing the radiator, even when the thermostats were open.

Philip,

thanks. I have indeed looked at your post on this prior changing my thermostat and it seems that the original one (that i did not replaced) are closing well the bypass when fully open.

Regards
Jérôme

Hi Jerome,
Congratulations on your rebuild, nice to hear you are going to drive it regularly.
So for the fan upgrade
Yes The fans fit in the same fitting as the originals with no modifications. I did spray can mine with black paint.
For the relays I fitted two relays, one for the low speed side, replacing the original, and another one for the high speed side, that is operated by one of the dashboard switches. I will try to post a picture of the wiring otherwise PM me and I will email it to you.
I fitted the lower (250 watt) motor and did not use the 50amp fuse.
The air flow is better than the original on low speed, and very high on high speed.
I would suggest perhaps cleaning out the radiator before you go by a radiator shop, if you have time.

Get someone to check my diagram is correct as I am not an auto electrician.

Hi Mark,
I have the same VAG fans installed in my S3 and have tested the two fan speeds. I agree, there's a significant difference in the amount of air they can move. BTW, the current for each fan on low and high speed respectively is 5.8Amps and 12.2Amps, which is within the capability of the standard relay and the new aftermarket relays I have used.
I have a small suggestion to your diagram. The relays I have are a version with an 87 terminal and an 87a terminal. One of them is connected (87a) when the relay is disengaged, the other (87) when the relay engages. This can be used to switch the 12V from the low speed connection to the high speed connection, when you manually select high speed.
I'd also suggest fitting two wires from the 87 and 87a terminals into two control lamps in the car, to indicate power being fed to the either one of the selected speeds. Lets you know all is OK in the cooling department.
One last thing I have done is to install a delayed relay, which allows the fans to run for a maximum of 10 minutes, if the otter switch is closed. This helps reduce under bonnet heat when you turn off the engine.
I can post diagrams, if interested.

Cheers ........ Ole

Hi Guys
Ole, the relays I used are the 5 pin version with the extra 87 terminal, but we didn’t use it, so thanks for your input, others will benefit.
I would be interested to see how you wired up the delay relay.
Here is a pic of the 2 relays on top of the radiator. Yes, I have put in an alloy radiator, forced to really, as my old one was rotten. The alloy one was cheaper than rebuilding the old one.

42south wrote: ↑

Sat Jul 07, 2018 3:28 am

Hi Jerome,
Congratulations on your rebuild, nice to hear you are going to drive it regularly.
So for the fan upgrade
Yes The fans fit in the same fitting as the originals with no modifications. I did spray can mine with black paint.
For the relays I fitted two relays, one for the low speed side, replacing the original, and another one for the high speed side, that is operated by one of the dashboard switches. I will try to post a picture of the wiring otherwise PM me and I will email it to you.
I fitted the lower (250 watt) motor and did not use the 50amp fuse.
The air flow is better than the original on low speed, and very high on high speed.
I would suggest perhaps cleaning out the radiator before you go by a radiator shop, if you have time.

Get someone to check my diagram is correct as I am not an auto electrician.

Hi mark,

many thanks for yoru email. Your diagram is more than fine for an no electrician ;-). This is no my major as well (far to be).
I have ordered the 2 fans as well as a 50 A relay and fuse (before reding your post). If i understand well the 250 W fans do not requires this level of amp and therefore i'll order a lower capacity relay 25 or 30 A and fuse for the hi speed wiring.
The radiator is brand new and has been rebuilt with an higher capacity core.
Keep you postred.
Thanks again
Jérôme

Ole-xke1974 wrote: ↑

Sat Jul 07, 2018 12:40 pm

Hi Mark,
I have the same VAG fans installed in my S3 and have tested the two fan speeds. I agree, there's a significant difference in the amount of air they can move. BTW, the current for each fan on low and high speed respectively is 5.8Amps and 12.2Amps, which is within the capability of the standard relay and the new aftermarket relays I have used.
I have a small suggestion to your diagram. The relays I have are a version with an 87 terminal and an 87a terminal. One of them is connected (87a) when the relay is disengaged, the other (87) when the relay engages. This can be used to switch the 12V from the low speed connection to the high speed connection, when you manually select high speed.
I'd also suggest fitting two wires from the 87 and 87a terminals into two control lamps in the car, to indicate power being fed to the either one of the selected speeds. Lets you know all is OK in the cooling department.
One last thing I have done is to install a delayed relay, which allows the fans to run for a maximum of 10 minutes, if the otter switch is closed. This helps reduce under bonnet heat when you turn off the engine.
I can post diagrams, if interested.

Cheers ........ Ole

Ole,

would be really good if you have the diagram posted.
Thansk in advance
Cheers
Jérôme

Gentlemen, is it really necessary to keep quoting? You can edit down to just one sentence if you really need to quote, otherwise you are simply taking up a lot of space.

Gentlemen,
attached is the diagram of my delayed cooling relay.
I haven't made a diagram of the low/high speed switching, but will get to it in a few days.

Cheers ........ Ole

Ole-xke1974 wrote: ↑

Mon Jul 09, 2018 10:43 am

Gentlemen,
attached is the diagram of my delayed cooling relay.
I haven't made a diagram of the low/high speed switching, but will get to it in a few days.

Cheers ........ Ole

Many thanks Ole.
regards
Jérôme

Hi Jerome....when you post a reply there is no need to quote the whole of the previous post.....this has been pointed out by one of our members........it does use up valuable server space....please just use the post reply button and not the quote function...thanks...Steve

Steve,

apologies. I have NOW understood what you meant by do not reply the full quote.
Regards
Jérôme

Hi Jerome

There is no need to order another relay, the 50 amp one will be fine (actually better than using a lower rated one).

I like the delay circuit, I may use this idea on mine.



PS Why is there not a thumbs up smilie but there is a thumbs down one?

Regards