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MG Midget and Sprite Technical - More head gasket woes

Starting a new thread as the old one has buried itself in the archive. I'm not asking for help, just thought you might be amused. Being too clever by half I decided to fit a heater valve that I could operate from the cockpit. I bought one for a Mini and made an adapter plate to get it at an angle that would accept a cable and the heater hose. Within a week it leaked and dumped all the coolant. After a great struggle with the supplier they sent a replacement, and that went on a couple of weeks ago. I have hardly used it, but today it was colder so I opened it a bit. We were on the M3 and the rad fan came on. Not good news, so I stopped on the hard shoulder. Once it had cooled enough to check, I found the rad was empty. I put a pint of water in and the heater valve jetted steam. I called the RAC and 1.5 hours later the man and van turned up. He blanked off the valve and it held water, but there was obviously a head gasket leak. He reckoned that the gasket had failed and pressurised the system, causing the valve to fail. On reflection I am not so sure. Abnormally high pressure would have blown off the pressure cap (only 7psi), and there was not the slightest sign of anything coming out of that. All the coolant stains were around the heater valve. I still believe the heater valve was at fault, especially as the previous one did the same without the head gasket leaking.

I am though thinking about an engine rebuild, as I would like to ensure that the block deck is perfect. If I do that it might make sense to rebuild the original engine so that I have 'matching numbers'. The cost would not be dramatically different.

The final amusement is that on the way back in the recovery truck, I got a call from Highways England. They asked if I had been recovered yet. This was over 5 hours since the breakdown, when presumably their cameras had spotted me. So good to know someone is on the case.

Les
L B Rose

What radiator? I had a later crossflow rad fitted to my frogeye along with the expansion tank and that system can blow water out the expansion tank when the head gasket leaks causing the system to pressurise.
David Billington

Very bad luck there Les.

I know it's not amusing, and can be quite costly, as I've had 5 HGF, that I can remember, on various cars including my present midget after only 7k-miles on a reconditioned engine, and a couple of small insignificant leaks at the Midget heater tap or adapter.

A good few years back I thought about fitting the Mini valve but was told then that they leaked so I didn't bother.

Ashley Hinton makes and supplies the sink tap type heater valve and it doesn't seem to leak like others from elsewhere.

BTW I also discovered, to my surprise, that my reconditioned engine needed another and thorough coolant clean even after the first clean/flush/refill I gave it shortly after getting the car with 50 miles on the reconditioned engine.
Nigel Atkins

Dave, it's the standard rad which I have had recored twice. For most of the time I have had these cars since 1971 I have not had problems with overheating.

I could whack on another gasket and see what happens, but I remain nervous.

Les
L B Rose

Nigel,
Do you suppose that you are flushing and changing the coolant on your cars too often? Its a serious suggestion, but for rust to form it needs water and oxygen. The oxygen is depleted or boiled off in coolant so after a while it ceases to be available for further rusting inside the water jacket. Replacing it with fresh oxygen rich water simply re-envigorates the rusting process. It is a principle well accepted in sealed central heating systems with iron bolers and steel radiators. Once the initial rusting has used up all of the free oxygen then the system stabilises and inhibits further rusting. If you repeatedly drain and refill with fresh water it simply prolongs the rusting cycle.
GuyW

i think your idea of taking the engine out is the right thing to do. A knowingly decked block and flat head are the only real way that you are going to be able to get to the bottom of your issues (in my opinion)
I have in part followed your thread/s but have you replaced a radiator to ?
Apologies if you have mentioned all that you have done and that i have missed it, but a recap would help me understand your set up.
P Bentley

I have not replaced the radiator but I had it recored about 12 years ago. That didn't last long and I had it done again about 7 years ago. It has not leaked since. The engine does run slightly hotter than it used to, but short of boiling out the block in a tank again (did that for original rebuild) there is not much more flushing and cleaning I can do.

Les
L B Rose

Hi Guy,
I take your point but no I'm not and I'm not suggesting anyone else should, in fact quite the opposite, I think that one thorough cleaning and thorough system of flushes at the start should be enough to see simply drain and refills of coolant for many years in future.

I've only cleaned the heating/cooling system on my Midget twice and that was towards the start of my ownership and would have been only once had I been more thorough the first time and not thought that a reconditioned engine would already have clean waterways and forgetting about possible migration of crud and muck from other parts of the system like rad, matrix, hoses, ect..

I've also only twice thoroughly flushed the system in the 11+ years of my ownership despite the, far too, numerous times I or whoever has had to drain and refill the system.

I wanted to clean the system, put 4-LIFE in and forget about it for at least 10 years but Sod's Law, poor workmanship, poor parts and bits of poor luck all went against my plan, too regularly, so it may seem I've done a lot more cleaning than I have. Remember Guy I unlike yourself and others here loathe working on the car so look for the least amount of work required to achieve the best result - which is always the greatest ratio of trouble-free driving against work required. :D
Nigel Atkins

ETA: not that I've ever achieved that ratio - quite the opposite
Nigel Atkins

Nigel,
it was only that last paragraph in your earlier messyave, which mentioned having to clean the system twice in a short space of time that made me think. But I did also remember that you were an advocate for the 4-Life stuff which by implication would suggest infrequent draining, even if in practice that isn't achieved!!
GuyW

Les,
I was thinking that you perhaps might not have already cleaned and thoroughly flushed the whole system rad, hoses, matrix, pump, etc. and perhaps that muck/crud/grit/glup could migrate from other areas of the system to the block or indeed other areas and perhaps even been loosen and helped to be transported by the overheating.

Your engine rebuild was done x-years ago (sorry I forget), the rad 7 years ago, since those times the innards might not have remained spotlessly clean. The rest of the system could have bits that have accumulated and added together plus you've had heating issues.

With the engine out you could look at its internals and the internals of the rest of the system, some bits by just removing them and looking at them and/or others perhaps with one of these cheap wotsitscope cameras or viewing instruments. I'd do this with whichever engine you chose to install, and check the rest of the system including the rad for piece of mind.


Nigel Atkins

Ironically Guy I deliberately didn't use 4-LIFE (4-NOW in my case) initially when I got the Midget to check that the engine and heating/cooling system and components were good so that I wasn't wasting my money on long life coolant that would soon be spilling over the dirt on the chassis.

Same way I ran the car very regularly, serviced, repaired and maintained it for six months before I trusted it enough to take it to Europe (the Belgium mountains) only to have the red light come on as we pulled into the Chunnel car park at Dover, but that's another one of my classic car motoring history stories.
Nigel Atkins

I have now done the thorough clean and reverse flush process again. Hoses disconnected and checked etc. There was a tiny bit of sludge in the heater matrix but everything else was crystal clear. Not much more I can do. Maybe try a cooler stat if still running hot.

Les
L B Rose

I forget Les, but what makes you think it is running hot?
GuyW

Les,
sorry you didn't find anything much but Sod's Law as you've checked you wouldn't, on the other side at least you know for sure and Sod's Law if you hadn't there would have been something.

As regards the heater matrix, depending of what the sludge was made up of you could just loosen more by further cleaning and never come to an end of it unless you can get some sort of industrial or commercial cleaning so you could just accept it as it is or replace it with new (recored?).

Just quick thoughts -

You could also use the heater as further engine cooling(?).

The original Sprite stat was 73 degrees so perhaps if your current stat is well above that then a lower one might help, racers go without a stat.

I see you already have an oil cooler so if its working and your using a good quality oil, especially one that doesn't mind higher temperatures that side's covered.

Did the engine running hotter than it used to tie in with the rad recore(s) or perhaps engine upgrades, change in petrol.

Any news on the engine?

I remember a mate having a heated-up 1098 Spridget and running it all the time without any overheating problems so it suggest the obvious with yours, that it's either running too hot or not enough cooling or a bit of both but which and why. :(
Nigel Atkins

Re-reading your first post on this (and I confess I haven't read all of the intervening messages) it sounds to me that when the heater valve originally leaked, the loss of water caused it to overheat and damage the head gasket, if not fully blow it.

You then replaced the valve but on then using the car it was already leaking coolant because if the earlier damage, and this in turn was causing the car to overheat. i.e. the overheating is caused by loss of coolant, not the other way around, and there is therfore probably nothing wrong with the cooling system as such. No blockages, no sludging and no faulty pump.

I would do a compression test and then remove the head and inspect and replace the head gasket.lts a pretty quick and straightforward job.
GuyW

As very often happens I may well have got it wrong but from previous threads I thought the running hotter was before the Mini type valves were fitted.
Nigel Atkins

Just to clarify a few points:

1. I repaired and calibrated the gauge a while back. It showed 190F for several months when fully hot but went up to about 205 few weeks ago.

2. The system never loses water except when the valve leaked.

3. Yes it ran hotter before the valve leaked.

4. I have done a compression test and all cylinders are fine.

5. I have now fitted a genuine Rover gasket (Payen out of stock everywhere) and reverted to the original heater tap.

6. The rad recore was years ago.

The engine seems OK but I have done few miles since the last episode.

Les
L B Rose

This thread was discussed between 24/09/2018 and 06/10/2018

MG Midget and Sprite Technical index

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