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MG MGA - Radiator Shroud

Having just fitted a radiator shroud, from Moss, I have an additional noise. Is this expected from changed airflow or perhaps something catching?

Paul
P M Dean

Yes the fan does get noisier with the shroud. I guess with the fan now being in a short duct it is blowing a lot more air through as the tips of the fan will be working much harder with reduced vortex type tip losses. If there is something touching - worry..!
Pete
P N Tipping

I have a "B" fan with the shroud, and, if anything, it got quieter....Maybe the stock fan makes more noise....
Edward
Edward Wesson 60MGA

Pete,
The fan is sucking, or it should be. You can check this with some smoke, or look at the fan blade to ensure it is mounted the correct way round on the water pump pulley.
Peter.
P. Tilbury

Can I correct you here Peter. If you put the engine fan on back to front it will still blow the right way but less efficiently. Understanding aerodynamics it can only go one way,,,
Pete
P N Tipping

Try a 7 blade MGB fan since it is asymmetrical.
Symmetrical fans set up a vortex of air that is like the whirlpool of water when you pull the plug in a bathtub. This causes more fan noise and is not as efficient at cooling as an asymmetrical fan which moves the vortex over the rad cooling from a constantly changing spot.
Top read more go to:

http://www.tigersunited.com/techtips/JCrawleyRest/rt-JCrawleyRest9.asp

Jc
John Crawley

Jc
That pretty well confirms my experience with the shroud and MGB fan.
Edward
Edward Wesson 60MGA

I took the fan shroud off my MGA as I do not drive the car in parades and didn't find that it made any difference at hi-way speeds.
David Werblow

Me too - it didn't solve my overheating. Mine came out as I couldn't find a way to adjust or replace the fan belt with it in situ. (Just get that bilge blower fitted for slow hot traffic)
A few weeks ago I fitted the richer 'RO' SU needles in place of the original 6's. I thought this might cool things down a bit. So far the incessant run-on has virtually disappeared, the water temp is appearing to stay down at the stat's level and strangely it even feels and sounds more powerful. Meanwhile I'll have to wait for our one and only hot day of summer, when I can report back on any motorway cooling improvement.
Pete
P N Tipping

Pete,

Do you have the two 4 in. air tubes in place on either side of the radiator and the thick felt pad attached to the bonnet over the radiator? If not, do it; they mare a big difference.
David Werblow

David - Yes I have tried everything. As normal the RH duct goes to the heater and the LH one is now fitted with a 3" bilge blower (see relevant old thread) which works, both ducts have the flexible tube to the grille. I have the bonnet seal you refer to, I have straightened up the grille louvers, hot tanked and restored the engine, replaced incorrect (USA fitted) distributor with correct MGA type, replaced the radiator, (always filled with distilled water and A/F every other year) tried all the thermostats, the timing is spot on, the distributor's vacuum system is perfect too with a new pipe and I'm still managing to run on 99 octane fuel with 0% ethanol. Got any better ideas to keep it cool?
Pete
P N Tipping

When you replaced the radiator, did you buy an aluminum or copper core?.....
Aluminum cores are not nearly as efficient as copper cores, and require more cores for the same cooling....
This has to do with the heat coefficient of the two metals.....
Did you replace or rebuild the water pump?
Finally, are you sure your cap is the correct depth and pressure for the new radiator?
Just my thoughts.
Edward
Edward Wesson 60MGA

Hi Edward - Radiator is copper. Originally made in China, but this leaked after a year so was rebuilt with a new 'MGA' core and cooled similarly. This is the one thing I know it isn't thick enough at 1-11/16". When its had its day I'll get the correct 2" thick type from Bob West here one day.
Have gone through a few caps. One dropped into the fan (and broke it) on tick-over while topping up - we don't talk about this! One just fell apart. Naturally they were all the correct reach 7psi type and temperature has been up to 100psi on the Oil Gauge - so I think they are fine. They don't make it run any cooler of course.
The water pump really replaced a perfectly good one and made no difference as the blades were identical.
I'll stay with the MGA fan - it just looks and is right. Forgot to mention I reluctantly fitted a Kenlowe electric fan which keeps the water temperature under control, a new heat shield and the bilge blower keeps the carbies cool and stops vapourisation problems in stop-go traffic on hot days.
Having done everything I know, now with the richer needles I'm pretty happy but you wonder, can there be anything else?
Pete
P N Tipping

This thread was discussed between 03/03/2014 and 15/03/2014

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