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#1 cooling fan

Posted: Thu Jun 25, 2026 8:22 am
by Stevemorris
Hi chaps,

I have moved on to the next part of re-commisioning now, cooling system/fan.

The plan has always been to get the car to a position where it can be driven safely, then drive it for a while to see how it is overall, and then hopefully be able to do the little bits etc when the winter arrives...

I now have good engine compression, stopped various fuel leaks, set carbs up, and am moving on to the cooling system. The front brakes are sticking, but this may be due to disc corrosion where the cars been sat..

The Cooling System.

My car has had a 'different' fan motor fitted (not quite sure what it is from?) which is held onto the mounting platform using a large jubilee clip. Now this sounds like a terrible bodge, but it is very secure, and has worked it would seem for quite a long time. Long term plan is to maybe fit a modified fan system (Kenlowe or Cool Cat?) but initially I want to get the one that's fitted working so I can run the car to temperature etc..

My car has had a manual switch for this fan fitted in the dash, along with a warning light, just below the choke lever. The wiring was appalling so I will re do that of course.

The thing I find a bit strange is that my car has no relay for the fan motor? I have searched fan motor/relay and there are quite a few topics on the subject, plus looking at the workshop manual I downloaded in the 4.2 supplement there is no mention of a relay, and in the 3.8 manual under Fan Motor Relay it mentions 'early cars only'?

I know how it all works, and how it should work, but not knowing what motor is fitted to my car I can't really decide whether a relay is needed or not. The fan motor fitted has been on the car for a long time, and I did hear it working, plus the car has been used for a number of years like it is, presumably without issue, so I have to 'assume' that the fan motor fitted is sufficient for the job??

Anyway, I really need a couple of questions answered if I could,

1. Am I correct in thinking the Series 1 4.2 with a standard fan set up (mines a 1965) DID NOT HAVE/NEED a fan relay?

2. What is the best option for upgrading the fan motor system?

3. I do love original stuff, would anyone suggest putting an 'Otter' switch back in and running a standard set up??

Also, if anyone has fitted a manual switch/warning light (with or without relay) would you mind posting the schematic/diagram used?

Many thanks all,

Steve.

#2 Re: cooling fan

Posted: Thu Jun 25, 2026 8:55 am
by mgcjag
Hi Steve....lots of fan options info on the forum..start with the similar topics posted below.....single fan S1 no relay...is one required...your choice....Steve

#3 Re: cooling fan

Posted: Thu Jun 25, 2026 9:07 am
by MSM
Hi Steve

It would be helpful to have a photo of the fan / motor installation. Someone may recognise the parts.

It certainly will do no harm having a relay controlling the motor.

And as the other Steve has said look at similar topics.

Mike

#4 Re: cooling fan

Posted: Thu Jun 25, 2026 4:36 pm
by Allrand
The S1 3.8 has a fan relay, as does my '64 3.8, and also shown in the service manual.

#5 Re: cooling fan

Posted: Thu Jun 25, 2026 4:41 pm
by mgcjag
Hi..yes l was refering to the posters car a 4.2...Steve

#6 Re: cooling fan

Posted: Fri Jun 26, 2026 8:39 am
by Stevemorris
Hi all,

The attached picture is not for the faint of heart... I know it looks awful, but it works, and has been working for the past goodness knows how long so it will stay on, for now at least...

I tested the standard circuit this morning by removing the wire from the Otter switch and earthing it with the ignition on and the manual override switch disconnected, it works fine. This suggests one of two things, either the manual override switch was fitted as a precautionary measure, or the Otter switch has failed. I will run the car up to temperature and see if it cuts in, and if not I will test the Otter switch. If the system works OK, (as many have said on this forum they have a standard system and it works fine?), and I do like standard stuff, I may well just leave as is for now, i.e. re-fit the manual override switch as a 'just in case'.

The long term plan is to renew the picture frame as it looks like it has had some 'rough treatment' over the years, and a new one isn't that expensive. When I do this, I will look to maybe modifying/changing the fan motor.

I have been looking at CoolCat/Kenlowe systems, and have to say I do like the look of the standard motor, plus they are still available and a sensible price too. Only slight mod I may do is replace the 2 blade fan with a multi blade one. Has anyone done this? Is it even possible??

Thanks,

Steve.
Image

#7 Re: cooling fan

Posted: Fri Jun 26, 2026 8:43 am
by mgcjag
Hi Steve....is your fan blowing or sucking.......Steve

#8 Re: cooling fan

Posted: Fri Jun 26, 2026 9:48 am
by Stevemorris
Hi Steve, Definitely sucking. i.e. pulling air through the radiator. It is doing what it needs to do, albeit a bit unsightly mate!!

Thanks, Steve.

#9 Re: cooling fan

Posted: Fri Jun 26, 2026 10:29 am
by MSM
Steve M

That looks like it might be a very early Kenlowe fan before they started using pancake motors.

I would not bother with the single blade ‘Flymo’ fan, I would save up for the Cool Cat multi blade version.

Mike

#10 Re: cooling fan

Posted: Fri Jun 26, 2026 10:32 am
by Stevemorris
Thanks Mike, It pains me to say it as I do love originality, but I think you are correct!

Thanks all. Steve.

#11 Re: cooling fan

Posted: Fri Jun 26, 2026 10:35 am
by MSM
The world has become a warmer place since 1961 and traffic density has increased!

Mike

#12 Re: cooling fan

Posted: Fri Jun 26, 2026 10:38 am
by Iansparky
I have the fossway performance fan and their otter switch, very pleased with it, looks good and keeps the car cool, it does need a relay though
Ian

#13 Re: cooling fan

Posted: Fri Jun 26, 2026 11:36 am
by Stevemorris
Thanks Ian, I'll take a look...

#14 Re: cooling fan

Posted: Fri Jun 26, 2026 1:15 pm
by bitsobrits
That crusty fan is no doubt an improvement over the original item, but its small diameter blades relative to the fan shroud is leaving airflow on the table. Best performance will come from a multi blade fan with a diameter slightly smaller than the shroud, i.e. Cool Cat. My otherwise stock S1 4.2 car never overheats even in >100f heat with it's Cool Cat fan.

#15 Re: cooling fan

Posted: Fri Jun 26, 2026 7:06 pm
by RICHOT
I have an ‘old’ 2 speed Kenlowe on my 4.2 and decided to convert to a manual switch.
This is because many years ago, on a scorching hot day, I was caught in very slow moving stop/start traffic on the M25 and as we were waiting many minutes before moving another few car lengths, I decided to switch the engine off.
But, when I turned the ignition on again, the Kenlowe started automatically (as the engine was hot) and there was only just enough power left in the battery to turn the engine over twice - luckily she started on the button. (The Kenlowe is quite a power consumer)
I then vowed that I would convert it to manual on/off and have never had a problem since even in 36*c plus weather in Spain.
Best of luck with whatever you decide to do.
Cheers, Richard

#16 Re: cooling fan

Posted: Fri Jun 26, 2026 7:57 pm
by MarekH
Firstly, think about the wisdom of fitting a fan that consumes more current than you can easily supply with your current alternator/battery combination when the car is most stressed, heat-wise. Then look at https://forums.jag-lovers.com/t/solving ... ple/377151

kind regards
Marek