MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - IOW Frogeye radiator can't breathe!

Bit of a longshot here, because IOW Frogeyes use a MkI Ford Fiesta radiator with remote header tank, not the standard Sprite rad, but any ideas will be much appreciated. I had had coolant loss for quite a while last year, and noticed after a run that water was running out of the long overflow tube attached to the radiator screw cap. Thinking that perhaps the cap had lost its sprung pressure release function, I bought a new cap in the autumn. Coolant loss, quite rapid, still happened, but it stopped coming out of the overflow - rusty water stains around the header tank cap suggested it was from there. I ran the car for 15 minutes this morning. Fully warmed up, water started hissing out from the header tank cap. Nothing from the radiator cap relief tube. Very carefully, and with gloves and goggles on, I slowly released the radiator twist cap and WHOOSH - loads of steam and really hot water exploded out. Although the sprung cap is new, that could still have failed of course. But is there anything else that might block the radiator system causing such a build-up of pressure and consequent leaks? It's never "blown" while out on the road, but does lose coolant at an alarming rate.
C Whiting

With those symptoms, Chris, one simple test I would do is to run the engine with the radiator cap off, and watch carefully for bubbling in the coolant in the filler neck. It could be an early indicator of a partial head gasket failure, presurising the coolant with combustion gasses. its a simple check, takes only a few minutes and hopefully would rule out this possibility possibility of HGF
GuyW

Hmmm. That's interesting. Just tried that, although with the coolant already rather hot. Yes, there is a foamy bubbling, made worse by removing the cap. I hadn't suspected the gasket, as the engine has only done about 3,000 miles since a nut-and bolt rebuild and tuning by Bill Richards Racing. Are there any more ways to check gasket symtoms without removing the head, along with all the scary Titan 1.5 roller rockers et al? I know it's a copper gasket from the tuning specs. Thanks, Crispin
C Whiting

Crispin,
you can get litmus paper strips or send off for a Combustion-Leak-Tester-Kit-Head-Gasket-Block-Detector tester kit or see if a local garage has any.

Just one example, 1st Class post so less delay - https://www.ebay.co.uk/itm/124392170566?

Are you running on just water as a coolant or antifreeze mix as coolant?
Nigel Atkins

Just water Nigel - losing a pint of antifreeze every 30 miles would be a little costly. Many thanks for the eBay link - off to have a look now. I had assumed that because there is no sign of water in the oil that the gasket wasn't at fault, but it sounds like it may be exactly that.
C Whiting

Just water isn't such a good idea but we can go into that later if you want.

I take it your car is just fast road rather than track use?
Nigel Atkins

Do you have a compression tester?
Dave O'Neill 2

HGF and doing a compression test was the first thing that sprung to my mind too.

Malc.
Malcolm

Nigel, the just water option is as needs must - I haven't been on any long journeys since the problem started, about 10 miles maximum, but that uses about a litre if it gets warm enough. Under normal circumstances, I would of course use proper coolant. It certainly seems to be the head gasket - I will make a proper thank-you problem-solved post shortly, but in the meantime, thank you!
C Whiting

Nigel,

That's a good alternate use for a fermentation lock.
David Billington

Guy is spot on. Any gas bubbles/foaming in the overflow are very likely HG failure. Sniff test is another giveaway - does it smell of exhaust fumes? There will be no water in the oil as the pressure of the gases are greater than that of the water. Gas will just find its way from the HP side - the engine - to the LP side - the overflow.
Oggers

Just water is fine for testing or whilst still likely to need any dismantling. When I need to refill a system I always use plain water until it has been run and tested for a week or two, before then draining and topping up with a coolant mix.

Its very possible to have a leaking head gasket that just pressurises the water system, without getting oil and water mix, (at least until things start to get worse!)

The litmus, or dye test that Nigel links to is what I would suggest next, they are quite sensitive. Or if you have a compression tester, try that although a slight leak may not show up on a basic compression test - or not very clearly.

If you are on good terms with a local garage they can put a "sniffer" probe into the coolant and that will also detect combustion gasses. It would only take a few minutes so they may not even charge, though perhaps that isnt an option right now?

Sorry, Oggers just covered that
GuyW

Crispin,
I understand. For future you can buy concentrated antifreeze coolant to water down so it doesn't work out that expensive, especially when compared with the premixed stuff.

HGF, I think I've had at least 3 on my MGs which is another reason I alway use good quality engine oils and timely changes as added protection for when things go wrong.

I'd definitely recommended after sorting the HG that rather than the usual drain and refill of coolant that you do a thorough drain of the coolant and heating system and a clean and thorough drain and flushes and thorough drains to get the contaminated water and coolant out of the whole system.

If you've not had my simple notes on a thorough clean and want them, just email me.

At 3,000 miles, if you've not already done so, I'd also do an oil and filter change and go to a high quality oil with added and extended protection so that you can make full use of the expensive work you've had done without worry or holding back.

Do bear in mind what's good for racing/track cars isn't necessarily so good on road use cars.
Nigel Atkins

Actually I now see Ogger's sniff test uses a human nose, not a garage probe. Much more versatile and accessible. Assuming you have one!
GuyW

If this was a new build engine by Bill Richards Racing 3000 miles ago, did it go back in for retorquing after the initial shake down use? Or did they not suggest that?

Even now, you MIGHT get away with it if the head is retorqued, but it probably won't give you a great feeling of confidence! And your valve clearances will need resetting.

(Sorry Crispin, I called you Chris earlier. Not sure why!)
GuyW

ETA: David, I thought it looked familiar for some reason. :)

That kit says it does 25 tests so you could get your money back on it with checking for K-series owners. :) (Joke, I'm joking)

Sniffer test, block test, compression test all a good indicators if done properly with clean fresh equipment but care is need not to put over reliance in any one test to avoid 'maybe' type result, false positives and false negatives - that's not to say one test can't give the correct answer but I've known a false negative off one test only for HGF, and the other way you don't want the head off unless you have to (unless that's the type of thing that floats yer boat of coure).
Nigel Atkins

Right. Thanks very much to everyone for the advice - really helpful. I have ordered the ebay combustion/leak/ checker. And less than eight quid. I am so sure that the gasket is to blame though that I have checked which copper job Bill used, and he says it's a GEG300 from Mini Spares so I have ordered one of those, which I will need eventually anyway. Our village garage is not only open, but is very Sprite friendly - and the main man used to race Minis, so knows A-series inside out. I may ask them to give it a sniff, but I'll try the ebay checker first. Guy - yes, it certainly did go back for Bill to give it a full check and tweak after 500 miles. Pictured above. And it's on it's third oil and filter change (I've actually done over 4,000 miles). I don't race it, although it is showing just under 100bhp on the rolling road. Bill calculated that it should be over 110, but he may have been over-optimistic (although the rolling road bloke refused to take it to maximum revs).
Again, many thanks to everyone. I was concentrating on the radiator/header tank and didn't think of the gasket being the likely culprit.




C Whiting

Crispin,
I'd check with your builder about which (copper) gasket to order.

Definitely give the whole coolant/heating system a good and thorough drain/clean/flushes to help with cooling and help prevent internal corrosion.

I'd definitely be going to a high quality ('synthetic') oil at the next change and forget about it for 12 months (or 12k-miles if sooner).

Extra power is extra heat and fibreglass is an insulator so the more you have that can handle it easily the more you can get heat up by using the extra power.

This time of year is good for cooling, where you can use the car of course at the moment.
Nigel Atkins

Crispin, no criticism meant or implied of your engine builder or of you in my asking if it had been back for re-torquing I was just interested. There are differing opinions on the practice and not everyone advises it.

There is of course another, though far less likely explanation if the coolant system is being pressurised, but you would probably not want to even think about that!
GuyW

Guy

My nose is very versatile and highly accessible. Everyone I know at least has one, but yes, sniff test at garage will prove it.

100 bhp from an A-series?

Oggers

While I agree that a head gasket failure is one of the more likely sources of this problem, it is not the only possible source that needs to be investigated.

First, what is the actual running temperature of the coolant? This can be checked with a meat thermometer inserted into the coolant in the header tank. Bubbling is characteristic of a head gasket failure. It is, also, characteristic of pure water boiling. "Anti-freeze", besides lowering the freezing point of the coolant also provides rust protection for the system and flow modifiers that keep bubbles from forming and the coolant flowing smoothly within the system. Pure water lacks these things which is why one uses some form of additive (e.g. Water Wetter) to allow for better coolant flow. Poor water flow can cause bubbles, over heating and problems similar to those described. Best way to check is to refill the system, run it at idle until it reaches the highest operating temperature (with the pressure cap off) and observe the readings on the meat thermometer to see what is actually happening.

Another possible cause is some form of pressure leak within the system. This is checked by using a pump that has a gauge attached and a line having a fitting to clamp onto the radiator neck or overflow tank neck. The system is filled up with coolant, the pump attached and the system pumped up to normal operating pressure (i.e. the rating of the pressure cap in use) and allowed to stand for a few minutes while the operator observes the gauge. If the gauge does not hold pressure, there is a leak somewhere in the system. Sometimes, this may be observed visually on the radiator, expansion tank, thermostat housing, or rubber hoses. Do not forget about the heater, if one is fitted, as the inner core can leak and be hard to detect.

The radiator pressure tester should have an adaptor that fits onto the end of the hose and allows the pressure cap to be turned onto the adaptor, then pressurized to see if it will hold pressure and if it will lift properly. As an example, my 15 psi cap should hold pressure at 15 psi and release pressure when pumped up to 16 psi when, with no further pumping, the cap should start to hold again at 15 psi.

One final area that can cause some of these problems is the thermostat which may remain closed or may barely open, restricting coolant flow and allow overheating. Thermostats operate on "the rule of 20" which means that they begin to open at the rated temperature, say 180 degrees F, and are fully open (allowing full coolant flow) at twenty degrees above that or 200 deg. F.

Trouble shoot the problem in a systematic manner rather than chase possibilities, Correct problems as you find them and continue testing--there may be a combination of problems rather than a single issue.

Les
Les Bengtson

Nigel, it was Bill Richards I checked with re copper gasket - and the one on the Mini Spares site which I asked him about was track tested for them - by Bill.
Guy: Er, no I probably don't want to hear about a less likely but more frightening possibility - but what is it?
Oggers: It is balanced and bored to 1380, TDC Vol 10, CR 10.6:1, lightened con rods, race valves, Titan 1.5 roller rockers, Kent 266 cam, A-plus duplex vernier cam drive and a load of other stuff that I don't fully comprehend but am copying from the engine specification that comes with the build. I can however confirm that it is smooth as silk and goes like sh*t off a shovel. Strangely, it averages about the same MPG as the old standard 1275 lump.
The attached picture is of Bill Richards seeing how fast his A-series Mini can go.



C Whiting

Les Bengston, sorry did not see your post until after I sent my last one. Gosh. Interesting. I will try the tester I sent off for first, but it sounds like I may need to ask the garage to do a proper pressure test in the way you suggest - they should have the clamp, gauges and pump. The thermostat is opening as it should though. The heater on an Isle of Wight is from a 1980s speedboat (!) and although it would be hard to find a replacement, it does not leak. It is very clear where the liquid loss is coming from, I just need to find out why.
C Whiting

Crispin, the other, unmentionable, fault that you really don't want to hear about (leave the room NOW if you dont want to hear the results) is
..........









It could be a crack in the head or block 😱
GuyW

Definitely not the time of year to have plain water in the cooling system unless you can ensure it can't freeze, A series heads and blocks aren't 10 a penny like they used to be.

When I had a system pressurisation issue with a cross flow rad I moved the expansion take-off from the left side header to the right side by the filler bung so the gas would vent rather than the water being pushed out. I figured what the problem was in the end and cured it. I don't know the Fiesta rad layout or the IOW system so don't know if a change would be practical
David Billington

I thought about putting a post like Les did but thought if getting to a garage is awkward at the moment, which Les might not understand not being in the UK, for the sake of £8 it's a simple test that could help. It'll also show if the head or block is leaking, in fact it won't say if it's gasket, head or block which is why more tests/inspections are required.

The loss could be from other than HGF, or cracked block or head.

Lets see if the the combustion leak tester kit says yea or neigh and go from there (I've another idea unpopular that off at a tangent from my car 'experiences' so far too rarified to air fat too soon).

Nigel Atkins

David,
it's water added to coolant rather than just water but the diluting effect of more water added to less coolant won't help with antifreezing.

To me, the rusty water stains perhaps suggest the whole of the system wasn't/isn't completely clean (who's is) and/or the lack of coolant is adding to the corrosion and/or the heat and bulbing are putting more rust and other stuff into transit.

Be interesting to know the outcome as the plumbing with this car isn't the same as standard with pressure cap on rad, single (double?) outlet sandwich plate, boat matrix and all else. :)
Nigel Atkins

Aha - extensive modifications. These may well add to the list of possibilities. The first of which as Guy states is a cracked head/block - especially if the block is bored out and the head has larger valves - as the web/meat between each cylinder and valve will be reduced. Not disastrous but probably expensive. Second could just be as simple as the head not being correctly torqued. If the head is modified, torque settings may be different to the norm.

Probability is still the head gasket though...
Oggers

I initially only suggested checking in the filler cap for bubbles as ONE possibility to quickly and easily eliminate. It wasn't intended to suggest that this might be either the only problem, or to on its own being a definitive test of a HG fault.

But having confirmed at least some foaming, some further testing is needed to confirm more certainly if this is caused by combustion gasses - Nigel's litmus test kit and the well recommended ONST (Ogger's Nose Sniff Test) All worth doing before disturbing anything else in case the foaming isn't from combustion gasses.

If it is, my next step would probably be to retorque the head and see if that reduced the foaming. But only because I am tight fisted and prefer easy solutuons. A more reliable solution would certainly be to remove the head and closely inspect the gasket and surfaces to look for any evidence of leakage there, and to check bores and head for any signs if cracks, though they may not be visible without a dye test.

But that's all getting a bit ahead of things. Gas tests first, when time allows!
GuyW

Agreed Guy - Personally if the re-torquing does not work I would just pull the head, clean off all mating surfaces, and replace the head gasket regardless. Not that big a job to do, and yes, reset valve clearances.
Oggers

I would too, Oggers. But immediately on lifting the head careful visual examination of gasket, head, bores, chambers etc before doing anything else might give further clues.
GuyW

Guy

Yes for sure. I wonder if you did find any cracks or soemthing you could grind them out and fill flush with Belzona or solder - or is that a bodge too far?
Oggers

Blimey, that was quick. The reagent tester I ordered yesterday afternoon has just arrived. Although the bung supplied is too big for the header tank and too small for the angled radiator cap, I improvised and the blue reagent did indeed turn yellow after a few minutes. So it's either gasket (here's hoping), or a cracked head or block (noooo!)
By the way, I thought the engine was 1380 - looking at the spec it's actually 1330 (+60) so slightly less chance of head cracking. The new copper gasket should be here next week. Once the head is off, I'll know what the problem is and let all you all know. Many thanks again.
C Whiting

Crispin,
it was one of the first ebay listing I hit but had 1st class post and 100% Feedback on a good number of sales so I hoped it'd be a quick step forward for you.

As you had rusty coolant and been running for a while with gases and diluting the coolant mix with water I'd again recommend a thorough (hot) drain and clean/flushes to restore (or improve) the cooling/heating system.

Email me if you want the simple system I use, the more thorough the more 'fun' at this time of year.

You can get sealants to put in the system that can sometimes stop leaks but I'm not sure your engine builder or others here would be happy with such things.

Nigel Atkins

Old style radweld is ok for minor coolant leaks, but not for a pressurised head gasket fix. There are sealants sold for that purpose but I have seen the results of using them and they really clog up things like radiator and heater cores.

Out of curiosity I sectioned a BMW 325 heater core that I had to replace for a friend after he bought the car at auction only to discover it kept overheating. The cabin heater didn't work at all and when I opened it up it was completely clogged with a sort of silvery sludge. A PO had used a HG leak sealer on it!
GuyW

Hopefully it will be the gasket and not the head. Its unlikely to be a cracked block unless you are very unlucky!! They tend to be quite robust.
Bob Beaumont

Personally I'm not a big fan but if it gets you home then I am a very big fan.

I think like a lot of things times and standards can perhaps change and can improve (sometimes, excluding many classic car parts).

Then there's perhaps the matter of how well the instructions of the use of sealant have been followed and how clogged up the system and its various items already were to impede flow of coolant and sealant.

I'd thoroughly clean the system after suitable application of the sealant to remove as much free flowing excess as possible anyway. I much prefer to put in extra effort at home rather than at any roadside.
Nigel Atkins

As it costs nowt I'd go with trying as Guy suggested and torquing the head to see what (if any) difference it makes.

I know to others and particularly racing types, whipping the head off is nuffink but to me changing the HG is a royal PITA, and back, and is a big job that disturbs items that can get damaged or broken.

I find HGF, particularly if after low mileage, really annoying, two bits of metal joined with a (usually) bit of paper, how sophisticated for late 20th century technology.

Do I take it if this HG is copper then if it's failed in itself it's likely to be its sealing rings?


Nigel Atkins

Crispin, when you next talk to your engine builder can you ask him why he's recommended a copper gasket rather than the BK450 Metro Turbo gasket that is used by all the racers I know with 1380 engines including myself?
David Smith

David,
Crispin's engine building and tuning was done by Bill Richards Racing, the Mini Spares GEG300 copper gasket was track tested for them by Bill Richards.

(My previous HGF and current gasket are BK450.)



"HEAD GASKET COPPER PERFORMANCE 1275, MINISPARES OWN GEG300

Genuine Mini Spares Performance Copper/steel head gasket.

Based on the original AF460 pre 2000 design plus the old Payen Special tuning C-AHT188 with superior sealing rings.

With modern day technology and NON asbestos legal requirements this gasket is made on our own tooling with 3 expansion holes smaller than original C-AHT188 but with the superior sealing rings now required.

Suitable for all 1275 large bores the compresed volume is 3.4cc.

This gasket was originally tested in 2013 on Bil Richards 1380cc 8 port head race car for 500 laps and was in perfect condition when taken off. Since then many big names in the tuning world have adopted use of this gasket owing to the poor reliability of other gasket manufacturers who were once held in high esteem.

Introduced to the market in May 2013."

http://www.minispares.com/product/Classic/GEG300.aspx
Nigel Atkins

Yes Nigel I have already read all that. None of it answers the question - "why"?
If one also reads the comments for the BK450 on the same website there are vague allegations about thermal barriers which 'in some cases can lead to failure'. All very odd, it either does or it doesn't. I'm looking forward to seeing pics of the GEG300 when removed from Crispin's car.
David Smith

Fair enough David, I wasn't sure if you caught the rest of the thread.

I did wonder if the copper HG itself failed then would it be its sealing rings.

As discussed in another thread recent BK450 have had problems of their own with needing to leave putting the coolant in until the engine was ready to fire up otherwise the coolant could get into the gasket and cause a leak.

Nigel Atkins

In the 'olden days" I had a motorbike that was prone to HG failure to the point that I carried a couple of spares with me. They were solid copper gaskets that I would re-anneal after use ready for the next time. On a number of occasions I changed the HG at the roadside. Being a side valve engine it was a pretty quick job although it involved juggling a hot cylinder head or balancing it on the ends of spanners or twigs as I positioned it back on the barrel, to avoid burning my fingers.

A series engine requirements are pretty sophisticated by comparison!
GuyW

David

I too wondered about that. Copper gaskets are very prone to being permanently deformed. The BK is far more forgiving.

Guy

Coincidentally I have just been fettling my Ariel VB600 SV and the head gasket is indeed annealed copper. Mind these things are low compression sloggers so not exactly high performance - or medium performance come to that! Looks lovely though. I seem to recall the advice being the head gaskets are single use only. However, if you can re-anneal them then I guess you may be fine. Perhaps similar advice applies to Crispin?
Oggers

Nice bike to have, Oggers!

The beast I was referring to was a lot less sophisticated even than that. A BSA M21, with a sidecar. The HG was quite thick, perhaps 3/16" or more.

I doubt that annealing would be the way to go with Crispin's
GuyW

Apologies for the delay. Yes, the original GEG300 copper gasket had indeed developed a leak between 2 and 3, which accounts for the coolant system pressure. It is now all sorted and running as it should. It was fitted today by the Mini-racing A-series enthusiast at our village garage and I was all set to drain off and clean out the coolant system tomorrow, but he's done that as well, flushing it and running it with no coolant before final torquing down, which is something recommended in several posts on here, and he reckons it shouldn't need tweaking down again. He used Bluecol, or Bluestar, claimed to be most suitable for classic cars. I had done more miles than I thought, but 5,500 still isn't too good for a gasket designed for tweaked 1330s. Attached are pictures showing the blow top and bottom. Many thanks to everyone who commented and advised - much appreciated.






C Whiting

Hi Crispin,
thanks for reporting back.

Well, yes, er, perhaps it's the light/reflection/focus but I'd be interested in what knowledgeable people make of that gasket.

My first gasket on my midget only lasted 7,000 miles, I never saw it so no idea what type it was or how it looked when it was took out. It was replaced, so I discovered last year, by a BK450 which failed last year after 45,000 miles.

Later in warm weather this year, even though it's had a flush and run without coolant, I'd still give it a thorough full system clean including, block, matrix and rad as the garage won't have done the same level of thoroughness or you'd have a bill including those hours of labour. Or at the very least do it all at next coolant change in 18-24 months time.

Same as me by the time it's sorted you can't go out and get some payback of the hassle and expense it's given, not even to test the heater. :)
Nigel Atkins

Crispin

Good result. Sounds like you have located a very handy local garage for all things A Series and worth continued support. Pity they are not close to me, but Kent BBS members might like to know who and where they are?

You might want to update your engine builder on the gasket failure and alternative part replacement as he may appreciate the feedback for future offset bored 1275 (1330 or perhaps 1380) engines for non-race customers. Bill Richards would be high on my list of very experienced and highly respected folk for a potential engine build (for example if I wanted a 1293 short engine to old school in period spec, noting they can build much wilder and more modern specs). I do realise there are other tuners out there too and specs that are beyond BMC Special Tuning/Works Comps and Vizard.

Best wishes
Mike
M Wood

This thread was discussed between 07/01/2021 and 10/02/2021

MG Midget and Sprite Technical index

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