Morris Minor Owners Club

Hi,

A friends morris with a 1275 engine had 3 head gasket failures one after the other. These happened always shortly after the rebuild when the engine had been driven at higher revs for the first time. It suffers from water loss out of the water cooler cover mostly if the car had been driven at more than 4000 revs for a while. The whole engine bay is sprayed with coolant afterwards. He has no temperature gauge so he can’t see if it’s overheating. There is no other water leakage visible. There is no white smoke while driving and no water in the oil pan as well as no oil in the water. But the last time after having driven the car for a while and having the engine stopped for a break it didn‘t start again. I was with him then and removed the spark plugs. I found # 4 wet from water. A compression test showed half the compression in #4 than in the other 3 cylinders. So the head gasket was gone again.
But how could the pressure in the cooling system rise so much that a significant loss of coolant results and this mainly if the car was driven at higher revs thus generating higher temperatures? The water coler is new as is the water pump and engine block and head have been cleaned and flushed by a professional engine builder recently.
My idea is: could there be a crack in the engine block that opens at higher temperatures and let water pass into #4 cylinder and also let the pressure rise in the cooling system.
I will remove the head next week and look at the head gasket. But could a treatment with Wynn‘s cylinder-block-seal be a useful trial to save the block?


Any sugestions welcome

Chris

Isn't it more likely that the gasket has failed on number 4 causing an abnormal communication between number 4 cylinder and a waterway? This would pressurise the cooling system and cause massive coolant loss.

The picture is my 1098cc but I'm assuming that a 1275 also has waterways near number 4 as well.

Has the head and block been checked for flatness? Have you taken out the studs and checked that none of the threads are "pulled up". What head gasket is being used?

You need to look very carefully at the gasket when you take off the cylinder head.

Stephen

Thanks Stephen,

Yes block and head were skimmed and the head gasket is a new Metro-turbo-gasket. The studs are new ARP-ones in perfect shape. The nuts were torqued down to 65fl lb.
I will see next week if there is a damage in the gasket towards a waterway next to #4.
We had seen the lower water level half an hour before and topped it up with some 1,5litres of water. If such an amount of water would have been burned we must have left a huge could of white smoke behind us. But that was not the case. I guess the damage to the gasket occured after we stopped the engine. Prior to the stop there were no signs of loss of power or overheating, the engine was running perfectly.
The question is why did the three other gasket failures occur after having driven some 500miles or so and always after a ride at higher revs? That was always the case.
So I think the gasket failures are a secondary problem following another serious damage. A hairline crack in the block could be it. All the syptoms fit.

Chris

If it keeps failing I’d recommend a company such as this if you can find one near by.

https://www.jandeengineering.co.uk/crackdetection.html

They offer the popular magnaflux crack detection and have the facility to do a hydraulic / pressure test on the block.
These guys are very knowledgeable and offer a comprehensive service but they are in Lancashire.

Good luck

Andrew

Aren’t cracks in the head between the valves more common than cracks in the block? Easier to dye check the head than the block as long as you have it off.

The head is completely new and fully checked. It has just covered some 500miles. And: the problems were the same with the head previously mounted.

Chris

The syptoms: a loss of coolant each time after driving at higher revs causing higher engine temperatures without any signs of burned water or water in engine oil lead me to the suspected diagnosis, a possible hairline crack in cylinder #4. That crack will open a bit at higher temperatures and let combustion pressure pass into a waterway inside the block. This rising pressure causes the loss of coolant out of the water cooler cap and spraying it around in the whole engine bay. The ingress of water into cylinder #4 will be caused secondarily by a damage to the head gasket due to further rising temperatures after the engine was switched off and there was no further circulation of coolant. So far the theory.
Anyway, the head must come off. Then I‘ll see where the gasket is damaged. But repairing the head gasket without solving the suspected problem in the block makes no sense. That’s why I asked initially if anyone has had used Wynn‘s cylinder block sealant to solve such a problem. As there are a number of those block sealants on the market any expierience is welcome.

Chris

I do not think that you have a cracked block.
A cracked head is not unusual with 1275cc engines.
If you take out the engine check that the core plugs (2) at the rear of the block are serviceable. They do rust away over time and very few people bother to examine them for serviceability. Drilling two holes in the rear engine plate opposite the core plus will indicate a core plug failure when you see coolant draining out of the bell housing.

Hi Phil,
I hope that head is ok and has no cracks.
The owner of the car is a friend of mine and had bought the head from Minispares a few months ago after he had driven my car and decided to modify his car the same way. So I guess the head was pressure tested and checked for cracks before Minispares has modified it.
My friend had the engine rebuild by the same engine mechanic that did my engine. I really do trust in his professionality and quality of work. But he has not had the block tested for cracks or porosity and recomended a trial with those block sealants as he had several good results in some pre war engines. He said: try it, if it works Ok, if not you might need a new block.
A new block would mean a most expensive solution but my friend prefers a cheaper way - if possible.

Chris

I doubt if the head was checked for cracks or pressure tested before purchase. I would go back to Mini Spares and ask then if it was checked for cracks or pressure tested before being sold to your friend and see what they say.
As regards the block being cracked and the use of sealants - if it is found to be cracked it can be stitch welded but what ever our friend does it is going to cost money. The use of sealants to me is a bodge which will come undone at the most inappropriate time.
Unfortunately I do not have a solution other than to strip and check the block with the use of penetrating dye and go from there.
Phil

Phil,
I've sent you a PM.
MikeN.

The answer from Mini Spares:

The head was pressure tested and dye tested for cracks prior to porting it.
So the head itself shall be ok.

Chris

That was then - anything could have happened to the head since it was fitted. Unless you have the head re-tested you will not know for sure.
Been there done that and got the video and the tee-shirt.