Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Viscous coupling

A lot of airflow leaks around the sides (& top) of the rad because of the body cowl shape, better to worry about that than the bit a fan restricts

I think Dave W did quite a lot of work on testing mods to neatly direct the cowl flow ?

Have a good old Kenlowe fan fitted to my 1971 4/4.

Did a 'before and after' on a rolling road prior to junking the engine driven fan and found removing the fan liberated 3 bhp

Arwyn

I have always been interested in the air flow through the radiator and whether the fan should be a puller or a blower comments. The same fan is used whether it be in blower or puller mode, the radiator cools by the air flowing through it. If air can flow through the radiator with the fan mounted behind the radiator in puller mode i.e. no blockage created, then air can flow through the radiator with the fan mounted in front in blower mode. Or at least my experience has shown that. One of the most effective solutions is to shroud the radiator to force more of the little air that goes into the radiator through it.

Aluminium replacement rads from the likes of Mulberry and SiFab (When he was in business) have an electric fan bolted virtually flat on to the back of the rad. The original cowl is done away with.
I have found mine very effective, but of course the rad is probably far more effective than the OEM unit.

The Mulfab Crossflow Rad has the fan mounts on the front (grill) side.

https://www.mulfab.co.uk/products/aluminium-4-4-radiators/

Looks to me that the standard one MFRAD01 has the fan on the grill side but the heavy duty one MFRAD51 is on the engine side.
A bit peculiar but maybe a space issue?

As far as airflow is concerned not being able to get away from the back of the rad is just as bad as not being able to get in at the front .... I doubt which side the fan's mounted makes a ha'porth of difference.

K

with the setup that came on my car, large fan in front, the temp would rise significantly, when driving at say 50mph, with the fan switched off, switch the fan on & the temp comes down, at 50 mph you shouldn't need a fan! Just goes to prove the rad was being blocked, in my opinion. Fan has now been removed & temp stays steady at idle in the garage & goes down when on the road, i know its not exactly hot at the moment but it wasn't when i got the car 3 weeks ago!

i think i will be fitting a nice 10" slim fan when i am rebuilding the car, until then the standard setup seems fine in this weather!

It maybe that the unsuitable fan is the problem ... designed for another vehicle with a bigger radiator possibly, so blocks too much of your rad ..... I have a standard rad and fitted a Davies-Craig electric fan to the front of it ((surplus off my racecar) ... just a manual switch on the dash and fitted in case of exceptional circumstances as others had reported overheating in traffic...have never had to use it in two years .... temp stays fine and stable whatever ... recently did a 1500 mile road trip via all types of roads and traffic, two-up and all camping gear and luggage for 2 weeks on board without a blip.

On here somewhere there's an interesting vid of someone who did an airflow test having tufted the bonnet and rad area ... there's a lot of air just never goes through the rad .... just bypasses it completely due to not being able to get away from the engine bay ... air needs an 'exit strategy' every bit as much as it needs an 'entry strategy'

K

Hence the design of rear bonnet catch extenders. Basically to increase where air could flow OUT of the under bonnet area. My 2002 Plus8 fan used to cut in a lot in summer. Basically the Morgan ali rad was only just capable of cooling the engine. Whilst driving the airflow was ok but it would climb quickly to the fan trigger temp in slower traffic.
I tried various fixes such as blocking air from bypassing the rad core, rear bonnet extenders. No badges in front of the grille. My last effort was testing extra scoops to direct air to the bottom area of the rad that was being shielded by it being below the airflow stream. It got hot under the bonnet! I got readings approaching 50 deg during some tests with incoming air temp to the enging hitting 35deg+ at 20 deg ambient. My Autel maxiscan enabled live running monitoring so a handy tool.
I monitored the temp gauge.
Summer......got to 80deg easily then steadied at about 85deg. No fan running
At 95deg the fan kicked in and temps returned to my car's "normal".
Winter......temp stayed at 80-85deg and rarer for the fan to kick in.
My mods did seem to help in a SMALL way by reducing the fan frequency a bit.
The car didn't overheat as the fan worked. Noisy but ok. It did overheat when the fan failed ( blown fuse) and stuck in traffic.
The bottom line was that the rad needed an increase in rad capacity as it seemed at it's limit and no spare capacity.
If I'd kept the car I would be looking at a fan manual switch plus trying a different temp switch. My aim was to reduce the fan frequency without compromising the overall temperature, i.e desensitize the system. Probably a new rad as the ultimate fix.
Years ago I had a car with a louvte that you could use to block off some rad area for winter.