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MG Midget and Sprite Technical - Frogeye radiator material and painting

I keep looking at the Frogeye radiator, not yet fitted, and wonder how much to renovate it - next job after carbs! I think it is the original rad so what is it made from? I mean the header tank, sides and bottom parts. Currently, it has faded black paint and greyish looking metal but not much rust, maybe a bit of rust on what look to be spot welds on the sides. Do I paint it black (not the centre part of course)? Presumably, matt black is the ideal colour for radiating heat.
Bill Bretherton

And picture:


Bill Bretherton

Bill
Tank is Brass: some just polish.
Frame is steel.
Core is copper.
Alan Anstead

Thanks Alan. The header tank will need some elbow grease!
Bill Bretherton

Is there an old school radiator repair place near you? I would back flush it and use it, if it leaks then get them to repair it by fitting a new core and keeping top and bottom tanks. You could ask them to pressure test beforehand?

Cheers
Mike

M Wood

At the temperature the radiator is at conduction to the passing air will be the predominant heat transfer mode, very little radiation.
David Billington

Mike, I don't know, will investigate.

David, thanks, colour of little effect then.
Bill Bretherton

It may be sensible to get it pressure tested first. Save wasted time on all the cleaning and painting. If it does need repair then then the restorers will paint it all for you anyway!
Bob Beaumont

If you take it to an old-school radiator repair shop, if they do any work on it (eg replacing the core) they might well spray it all black when they've finished (that's what happened when I had the radiator recored for my Kmidget).
Jonathan Severn

Bill,
I took mine to Arrow radiators, based in Avonmouth. This was about 16 years ago and no problem up to now.

I believe they have other locations and yes, they did paint it following a re-coring.
Philip Sellen

Bob, Jonathan, Philip, thanks.

I may try Arrow radiators in Avonmouth but I'd wondered about pressure testing it myself with an old bike innertube valve and surrounding rubber clamped onto one outlet with the other hose connection blanked off and pressurise with a bike pump see if it holds pressure. Will this work or should I have it done by a specialist?
Bill Bretherton

Bill, I don't know if you would get enough pressure with the bike tube thing to test it properly. Would 30psi be enough?

But if trying that, then cut a tube and connect the two cut ends, one to each of the rad pipe connections. No need then to seal the cut tube or the other outlet!

You might have to work out how to stop the radiator cap from releasing at 7 or 15 lbs, depending on which one you are using.
GuyW

Bill,
isn't that more or less what the pro-testers are, if the rad is out of the car you'll need to bung all the holes and submerge in water to look for bubbles, or via an accurate gauge and look for pressure drop.

If your neighbours have a swimming pool or pond then that'd help, might want a stirrup or foot pump if going to 30 to save time and sweat. I'd check 30 might be a lot, do the professionals usually go to double spec, can't remember.


Nigel Atkins

Bill

Here's the rig that I set up to test my radiator. I would have used a simple valve section of discarded cycle tyre inner tube but they'd all gone in a recent clear out.

I cobbled this together with a few inches of pond hose, plumbing fittings and araldite plus a few jubilee clips. I sealed the hose bosses with rubber gloves and poly bags.

I just increased the pressure gradually until the rad cap began to release pressure. Not wanting to remove the fan so the radiator could be immersed in water I simply dribbled diluted washing up liquid over all the suspect spots. That method has proved very successful for finding air and gas leaks in the past.

It turned out my very minor leak had been down to a poor top hose connection and proved that the hole that I thought was in the header/core joint just wasn't there.

Colin



C Mee

Bill,

I've used Arrow (on the recommendation of my old school local garage) not for a rad but to clean out my boat diesel tank that had a bad case of the dreaded fuel bug.

Friendly and did a good job.
richard b

Guy, Nigel
I assumed normal operating pressure would be enough i.e. 7lbs for my rad I think. I have a "track" style bike pump (like a stirrup pump) so 7lbs is easy. May try it. Thanks for the connection suggestion Guy - why didn't I think of that! Unfortunately, the swimming pool is drained for the winter Nigel ;-)

Colin, that looks good. I assume if left at a set pressure for a couple of hours, you'd know if there was a leak.

Bill Bretherton

Bill

I would suggest 1 1/2 times working pressure just to give a bit of 'head room', again shame about the lockdown or we could have carried out a hydraulic test - steam engine boiler test !

For a tank just part fill a dustbin or wheelie bin - just as I used to run small outboard engines !
richard b

I am lucky to have a radiator repair facility just a couple of miles from where I live, (aaron radiators)

They pressure test to 20 psi to ensure any tiny leaks are exposed.
Bob Beaumont

Richard, Bob, thanks.

I've now tried it with an innertube and my track pump and a leak was immediately evident in the core. It's arisen from some frontal damage, it appears. I'll contact Arrow in Avonmouth on Monday.
Bill Bretherton

ETA: I'm too late it appears, but keep the idea of involving the family for another time.

Bill,
does no one around your way have an indoor pool, c'mon thinking cap on.

I know you lads like to do the work by yourselves but often the family want to help, let them, make their day.

I didn't want to suggest this before in case you have a plastic bath but here goes - so as not to waste water, whilst the better half has a bath use this water with them in the bath to get the water level higher by displacement, you'll probably still need to do half of the rad and then turn for other half but at least you have a second pair of hands to help.

No don't thank me, it's just my practical mind that can sort these things.
Nigel Atkins

Nigel
The image you conjur up is almost disturbing! You'd have to handle a rad carefully in the bath to avoid sharp edges.....

But, although there are two baths in the house we rarely use them - it's showers for us, in fact I've just had one. Is that middle class?

Don't have pools here though, we swim in the sea or that "wild water" thing. Well, not me, too damn cold!

Bill Bretherton

Bill,
there shouldn't be sharp edges to a bath.

Yes, showers, very middle class, and two baths!?! you must live in a commune, good luck to you and your tribe.
Nigel Atkins

Nigel
Couldn't resist it! When the extension was built it worked out that the new ensuite size allowed for a bath as well as a shower. So we could test two radiators at once!
Bill Bretherton

Bill,
and parts cleaning! Put your address on the Services section of the site, I've got some wheels that need a proper clean.
Nigel Atkins

Radiator now with Arrow radiators (Avonmouth). One of the nut "cages" was broken off and missing so I made one and welded it on - do people still use those, with square nuts? I got a radiator fixing kit from Moss which only has standard hexagon nuts, although they hold in the cages. Access much easier on Frogeye.
Bill Bretherton

The cages broke off on mine so I just use hex nuts. Access is not a problem with a Frogeye as you say. My local rad restorer said he could not get square imperial nuts easily so reverted to Hex.
Bob Beaumont

Thanks Bob.
Bill Bretherton

Imperial cage nuts: https://www.mgbits.com/contents/en-uk/d228.html

https://www.bresco.com/acatalog/Cage-Nuts--including--J--Type--p1.html

If you are happy with Metric: https://www.namrick.co.uk/acatalog/Miscellaneous_Nuts__Metric___Imperial_.html

Cheers
Mike
M Wood

Thanks Mike.
Bill Bretherton

Is there any reason why one couldn't or shouldn't add an expansion tank to a vertical flow radiator. Connect using the original overflow pipe and obviously changing the radiator cap for a plain, non pressure one, and using the pressure cap on the expansion tank.
GuyW

Just reviving this thread briefly, I have the re-cored radiator ready to fit in the next week or two so just test fitted it. The bottom hose take off will not clear the steering rack without tipping the top of the radiator back quite a bit and I started to flatten the fins on the (plastic) fan so I'll have to remove the fan. The fan is not that close to the radiator btw. Is this normal and will I get the fan bolts back in?
The radiator is the original Frogeye one I think, no shroud.
Bill Bretherton

Bill,
It may be a challenge to get the fan bolts back in an tightened up with the Rad in place as the radiator shroud gets in the way. I took a small amount off the bottom take off to give a bit more clearance. An 1/8" inch did it
Bob Beaumont

I know my rad was tricky to fit. I fitted the bottom end of the main hose to the rad first. I'm not sure I could get it on and the clip tightened on properly if the rad went in first without the hose.
GuyW

There's no shroud Bob, I think the very early ones lacked shrouds. But reducing the bottom hose "take off" a little should do it. Reassuring though that you and Guy seem to have found it fiddly. I do wonder how my rad was fitted originally. It seems to be one thing after another with this car!
Bill Bretherton

Hmmm Bill

Unusual to find a vertical flow rad without a shroud

I understand the radiator was fitted with the shroud early on in frogeye history as the early cars experienced overheating. Like you I have a 1275 but it does have a shrouded radiator and a 6 blade fan. Its generally ok but only just!
Bob Beaumont

Bill, if your bottom hose take off is fouling on the underside of the rack, maybe your radiator isn't slotting down far enough. I had this problem, which in my case also resulted in the radiator cap being mighty close to the underside of the closed bonnet.

On mine, the shroud side panel on the drivers side was contacting the top of the steering rack clamp. I sliced off about 3/8" which lowered the rad enough to give clearance there and for the bottom hose connection to pass under the rack.

I know your rad doesn't have a shroud, but maybe something else is catching down there? I think the next bit to catch would be the part that the drain tap fits to, contacting the cross member, but that would be much harder to correct.
GuyW

Bob, definitely no shroud. In Moss catalogue they refer to earlier rad without shroud - mine is a '58 car. I wasn't aware of the shroud/ no shroud dfference and it's re-cored now so I'll try it.

Guy, the bottom take off catches the TOP of the rack so probably needs reducing slightly, as Bob did. It is also close to the driver's side clamp like yours.




Bill Bretherton

Is the early rad shorter?

I'm sure my bottom hose went under the rack, like Guy's does, from what he said.
Dave O'Neill 2

Dave, I mean that when trying to drop the rad in vertically, the bottom hose outlet (take off?) will not pass the rack - it needs reducing a bit.
Bill Bretherton

I fitted the hose to the bottom outlet first, with its clip tightened, and then fed the hose under the rack and through the gap. Slid the rad down the stanchions with the top angled back as far as it would go whilst pulling the hose through. Although the 4 blade fan was fitted the angle was limited by the shroud before the fan anyway, so the fan wouldn't have been a problem. With a bit of wiggling it fitted in place ok.

If your rad has been re-cored, did they alter or replace the bottom connector? Is the pipe beaded to help retain the hose. I cannot tell from the photo.I would avoid cutting the beaded part off if at all possible as it holds the hose on against the pressure in a hot system.

GuyW

I can't tell if the bottom outlet has been altered. Yes, it is beaded. If I hold top of rad towards engine the outlet will just clear the rack but the fins are starting to contact the fan (no shroud)and bend easily, as you will know. There's quite a gap between rad and fan and it could be I could remove the fan and get the bolts in with rad in place - will try when I get time. As I say, there's no shroud in the way, this is an old rad. I only want to fit it once so will proceed carefully. But before that I want to sort out the alternator adjuster which needs a bit of fettling.

I had a mk3 Sprite in the 70's and I don't remember rad fitting being this tight. It had a forward tilting fibre-glass front so no slam panel issue. I remember once driving to work, removing rad, taking it to local rad shop to be fixed, re-fitting it, filling up and driving home.
Bill Bretherton

Do you have a spacer on your fan?
GuyW

Yes.
Bill Bretherton

That may be one way around it - to remove the spacer, although without a shroud it may reduce the efficiency.
If you do remove the spacer, remember to use shorter bolts or they will foul on the water pump.
GuyW

Another thought, do you have the spacer between the nearside rack mounting and the cross member. Its there so the rack aligns better with the steering column. It would also improve clearance for the bottom take off.
Bob Beaumont

Guy, I think the spacer prevents the fan blades catching the timing cover breather on my engine.
Bill Bretherton

Ah, yes. Forgot it's a 1275!
GuyW

I'm afraid I can't quite picture the interference in my mind's eye, but would it help to slacken the steering rack clamp bolts? Would that allow the rack to move just enough to provide clearance?
Jonathan Severn

I remember having fun fitting my vertical flow radiator in my MkII Sprite. Not sure whether I fitted the bottom hose (without tightening the clamp) first before slotting the rad all the way down while waggling and squashing and rotating the bottom hose (remember trying this, not sure if there was the clearance to do this, if not it would have been the wooden wedge, washing up liquid and swearing for fitting the bottom hose with the rad in place). Keep the beading on the bottom rad hose fitting!

Good luck
Mike

M Wood

Maybe not relevent for your issue ? but on my crossflow rad, the bottom hose is a nightmare.

However I found that changing it to a silicon version made it so much easier to fit as its much more flexible and easy to twist into position.

R.
richard b

Jonathan, when trying to drop rad in vertically, the bottom outlet catches the rack. Yes, slackening the clamp may well help.

Mike, yes I intend to keep the beading.

Richard, I have silicon hoses.
Bill Bretherton

I've now got the rad to fit. The problem was the stanchions which were angled backwards (towards the engine) more than I realized. I "persuaded" them to move forward such that the rad almost drops straight in now. However, the 1275 plastic fan is very close to the upper tank but clears. Note that this vertical flow rad is a very early one without a shroud (unless it was removed). I'm surprised how much the upper tank projects towards the fan meaning the fan is quite a way from the core. I'm wondering how good the cooling will be - may need to make a shroud.
Bill Bretherton

Put your radiator cap on and check your bonnet clearance Bill. It's awkward, but you can get a view, or a photo of the clearance through the headlight pods. Moving the top of the rad forwards will reduce the clearance because of the curving forward slope of the bonnet
GuyW

Guy, yes I'll try it. I'm hoping the bonnet clears as I can't really have top of rad any closer to the fan.
Bill Bretherton

Wasn't meaning to worry you Bill, and it will probably be OK but thought it better to check now than run into problems later!
GuyW

I ended up spacing the rad back as the bonnet touched the top of the header tank. I made up some aluminuim spacers which set the rad back about 10mm at the top and 5mm at the bottom. I don't have the spacer behind the fan (6 blade plastic) but to clear the oil seperator have packed out the fan with a plain washer. It all clears but only just!
Bob Beaumont

Mine has 8mm thick packers at the top to tilt it a little, to aid that bonnet clearance.

Being a 1098, mine has a 4 blade metal fan with no clearance issues there.
GuyW

Bob, I'd thought about reducing the fan spacer thickness so will try that. I think my stanchions are welded to the chassis members a bit too far back as, when test fitting the right angle brackets from stanchions to inner wings, they are a bit forward of the stanchions. I'm sure I'll get there - bit of a juggling act!
Bill Bretherton

I had to adjust the right angle brackets too. They were slightly too short and did not quite meet the rad. I ended up welding another 15mm on and drilling a new hole. Odd as the inner wings were unchanged as were the rad stanchions???. I also had to shorten the bonnet lock brackets to get the locking mechanism to work correctly. Again the front chassis rails were unchanged and correctly curve slightly upwards. The shut lines on the scuttle and A post are however very good.
Bob Beaumont

I cannot remember what the conclusion was now but when welding the stanchions on mine I took lots of measurements for the positioning, but also puzzled over whether they were to be true vertical, or perpendicular to the chassis rails, meaning a 3.5 degree tilt backwards.
GuyW

I've just read through the Radiator Stanchions thread from 31st Dec 2009 and the conclusion is that the rad rails should be vertical (from the ground). Mine were definitely leaning backwards which would explain my "adjstment". Of course I should have done this before now but you really need engine and fan in to see where everything sits. There are dimensions given from top corner of footwell to top front edge of stanchion and mine are close to there so I should be ok. Front is off car at the moment so not sure when I'll check clearance to rad. Some Christmas/ family stuff to do!
Bill Bretherton

That's it Bill. I didn't want to spend time getting lost in the archives. But I know I measured mine from the top inner corner of the footwells. 23 1/2" I think was the spacing. Or maybe 5/8, I don't quite remember.
GuyW

Well the radiator is in and just clears the fan. The lower nuts were very difficult even with full frontal access (unlike Sprite mk2/3/4). You can't get your hand to rear of fixing holes so I ended up using my Maplin telescopic magnet to offer the bolt to the rear of the holes i.e. I put the nuts on the front (lower only). The bottom hose fitting wasn't too bad as it is silicone. However, the hose was fouling on the LH brake pipe clip so I removed it - not ideal as the pipe is not held as firmly but it will do for now. Of course, this is only apparent when you've struggled to get the rad in and access to brake pipe is now limited. It does feel like nothing has fitted properly on this rebuild first time round although that's not entirely true!
Bill Bretherton

I quite agree Bill. At one stage I wondered if I had a non standard radiator as it seemed too tall. As it is now fitted the bottom outlet pipe is sitting firmly on top of the chassis cross member and yet there is only just enough clearance to the bonnet at the top! I'm hoping the pipe doesn't wear from rubbing on the chassis.

The radiator is much deeper than a cross flow one.
GuyW

This thread was discussed between 12/11/2020 and 11/01/2021

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.