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MG Midget and Sprite Technical - First 10 min engine run for 12 years

Hi Guys,
First engine run over 10 mins in garage today for 12 years. All hoses OK. Do you think this is long enough to test the cooling system to running temp?
The temp and engine in general seems to have settled down at about 6 mins. The top hose is hot implying that the thermostat has opened - the top hose was cool until suddenly at one point it became hot. It then stayed hot to the end of the test. I would think this is normal behaviour but all observations welcome.
I know this is a bit of a ?? but Temp Gauge reads half way between 1/2 and 3/4 hot after the 10 mins. Is this somewhere about normal for most cars?
Dave Squire - Notts

Top hose being cool then hot suggests thermostat is working OK.

Going by my temp gauge, after 10 minutes, with the bonnet open my 1500 would not have reached the 1/2 on the gauge, in fact it would still be in the 1/4 area.
But these gauges vary a lot and I have quite a new radiator and it does tend to run cool, until stuck in traffic with the bonnet shut.

I think you need to run it longer with the bonnet shut to see if it gets even hotter.

I presume you flushed it through and put in fresh water/antifreeze and made sure there were no air pockets or bubbles before giving it a run?
JB Anderson

Hi JB. Run again since your posting for over 25 mins. Seems to settle at same reading with bonnet open. Thanks for heads up re shut bonnet, (battery etc. not in place so bonnet wn't shut / daren't shut it yet) didn't think it would make mutch difference but thats based on my more recent experience rather than the long lost Moggy and Marina experiences. (long time ago to 1983 when I had my last 70s car).

All advice much appreciated and will carry out all suggestions re flush etc. (Its running with very little change from last service 12 years ago while in its previous resting place - failed its MOT - and stayed there). Thanks.

Dave Squire - Notts

Your gauge does seem high for just 10 minutes running.

My 'B' hasn't run for 12 years and I'm planning to replace hoses just in case.

I also took the rad and heater matrix to West Mercia Radiators in Wednesbury last week. They cleaned and tested both, said rad had been slightly blocked and even painted the rad, all for £20. Great peace of mind.
Dave O'Neill2

What I'd suggest -

before starting check and prepare to change *hoses, (thermostat), heater valve/tap, fan belt and filler pressure cap

*as recent new rubber cooling hoses tend to be poor quality you may also want to change your existing rubber hoses set to silicone with rounded-edge clips - http://www.classicsiliconehoses.com/

Cleaning procedure:
a) clean the whole system with something like Bars Flush Cooling System Cleaner

b) drain the whole system - engine block, heater matrix and radiator

c) get the radiator and heater matrix out of the car to give them a good shake at the same time as flushing and back flushing
• flush clean water through each of the three until water runs out thoroughly clean
• reverse flush each of the three until water runs out thoroughly clean
• final flush through each of the three until water runs out thoroughly clean

d) gently brush clean both sides of the radiator fins

e) gently brush clean the heater matrix and renew the seals and foam around the heater matrix and heater box case

f) refill with the correct coolant mixture

g) follow the refill instructions from the Driver's Handbook to avoid getting air locks or hotspots that could cause overheating of the engine

Also bear in mind oil is the secondary coolant so a thorough oil and filter change will also help with possibly using a preflushing oil too if engine has just been sitting gunking up
Nigel Atkins

typo, should be
>>before starting check and prepare to change, if required . . .<<

also should have put -
use a piece of thick wire to clear out the crud that collects at the engine block drain hole whilst draining old coolant and when flushing out
Nigel Atkins

Nigel's advice is great as a means of determining that the system is fault free and as it should be. Good if you are the risk-averse type of owner.

But of course there may not be a problem in the first place in which case it could be a pleasant, though wasted, weekend's work.

Difficult to assess whether there is a problem unless you can run the car on the road. It sounds as if your car is managing to maintain a reasonably steady temperature if it will run for 25 mins without the added airflow through the rad that you would normally benefit from with a moving car. The fact that the gauge is reading high could be explained by either a wrongly positioned gauge needle, or you may have a higher temperature thermostat fitted. The latter would simply mean that the car runs at a higher temperature than most and is commonly used for winter motoring.
Guy W

Guy,
The car actually did 10 mins, 20 mins rest, 15 mins, 20 mins rest and then 25 mins. On the second and last run the exhaust gas was clear and there was a slight leak of oil / vapour from the rocker cover gasket (not surprising as rocker cover removed when freeing up engine and not got replacement gasket yet). I think that is good and encouraging for its first real test. It was serviced by brother in law when it went into store.

I hadn't thought of different thermostats operating different restrictions of flow and therefore affecting engine operating temps. Any further pointers to info regarding this would be much appreciated or if you have suggestions re different thermostats or strategies I would much appreciate them. I hope to run this car as my other day car - the lower use one - so am looking for all practical advice to get on the road asap. (I remember sitting in a waterless 1300 Marina in the 80's in a traffic queue just outside Bakewell - too hot and popped hose). Someone said something in a thread about drilling holes in their thermostat a few months ago. My main strategy would have been to take out the thermostat in the warm months and put it back in the winter. However if there are different thermostats I would like to possibly ammend that strategy.

Should have 4 wheels with tyres that stay up in the next couple of days and then it can come off the axel stands, (ready for the real rusty wreck to go on them), so hoping to be on the road in the next couple of months or sooner, then plan is its going to be my other day car.
Dave Squire - Notts

Guy,
Just found out it was you that posted the holes bit and the toasty toes comment. (ha haaa).
Toasty toes and demisted windscreen is a definate requirement in the winter (I have a works style hard top that will be pressed into service for the winter).
So now I am up to speed with the reading, presumably thermostats are a third party part and the housings are made by the engine manufactureres for particular sizes / types. I assume the ratings vary and thats the difficult bit together with where to source them.
Dave Squire - Notts

Dave,
I use an 82 degree thermostat in summer and an 89 degree one (I think) in winter. Both are standard sizes and fit the thermostat housing without modification.

Its not that different thermostats provide different restrictions. They both open up by the same amount to give full flow. But the higher temperature one will stay closed until the engine reaches the higher temperature and this would be reflected in a correspondingly higher gauge reading.
Guy W

Great heads up Guy, I understand.

Good idea about blead nipples and shut off taps for cooling system as well by the way.

Thanks very much, Dave
Dave Squire - Notts

the engine not been used for 12 years, fair enough the brother-in-law serviced it (what extent of service(?) before it went into store but did he also clean out the engine block, the radiator and the heater matrix

to keep warm in the winter you will need the matrix to be clear and well sealed in the heater box

I've got a 82 thermostat and even in the winter your feet can get too hot from the heater matrix and windscreen kept easily clear, many times in the winter I will run with the roof down

even if you drink many mugs of teas and have a weak bladder not helped by all that running water all the work and even adding in new water pump and electric cooling fan only amounts to one day's work and I'm a slow worker

unless you have X-ray eyes I can't see how you can know if the cooling and heater systems are working at their best - if you done as I've put and you don't get any crud out of the engine block and the matrix and radiator flush clean very quickly then I'll take all the stick anyone can throw at me and sort out something for your wasted time

prevention is better than cure and cooling is very important to engines especially 1500s if they so desprately need oil coolers
Nigel Atkins

Hi Nigel,

You are correct. Under normal 'spare car' circumstances, where I can take lots of time now, (I don't work without pressure by the way), I would ideally do what you say now.

However the MOT is a 150 yards away and I want to get it there asap while I have the weather to do the things you are suggesting on a rolling program after the MOT. (and any MOT fail things that may need doing). Tyres being fixed today so I can get it out of garage. Present missus car goes back at end of October and thats the real deadline so will have flushed, serviced etc. by then. Then I either get an old van for renovation (Morris 1000 would be nice or old T4) or move onto the 'wreck' I have under a tarpaulin (otherwise known as midget 2 the final frontier - You think Malcolms is bad!?*/*&* I can't face photographing this one for the vehicle profile yet ha haaa - ).

Cheers, Dave
Dave Squire - Notts

"I use an 82 degree thermostat in summer and an 89 degree one (I think) in winter. Both are standard sizes and fit the thermostat housing without modification."

What might be a useful(crazy) mod, is to branch the top hose into a y section, and install a tap, so that you have a different stat in each branch. One for winter and one for summer. lol.

I just stick to the same stat all year round, as I can't be bothered to swap. The car doesn't boil over, and my internal heater tap allows me to keep my toes cool in the summer.
Lawrence Slater

Hi Dave,
a rolling program (or as I term it staged) is what I suggest for going through a 36k-mile service check up (the DH as always is your friend here) and it would include coolant change

of course Sod's Law the things you put back are the things that catch but that's life

brakes (always number one), tyres, steering, suspension, lights and windows are the important things the engine only needs to pass the MoT for now

remember to grease up the front suspension before the MoT to reduce the tester's comments of play

I hope the tyres aren't old and hard regardless of tread left even if they pass the MoT old tyres do you no favours for enjoying the car let alone breaking, road holding and ride comfort

good luck with the MoT but remember it's just means the car has reached a minimum standard at one point in time to one person's opinion not that it's good or anywhere near its potential but regular driving and servicing, maintenance and repair will get it there

good luck
Nigel Atkins

This thread was discussed between 05/08/2012 and 07/08/2012

MG Midget and Sprite Technical index

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