Morris Minor Owners Club

So there we were out on a run to Banbury and just into Banbury the engine became a bit lumpy then all of a sudden a rattling and a banging and I lost power. We were fortunately very close to a spot where we could pull over. It was very lumpy on tick over and removing the leads I found No 3 was not firing/compressing. I had to call out my recovery people.

A compression test on No 3 indicated little or no compression so we had to be taken home on a flatbed. He didn't test the other cylinders.

Am I right in thinking that no compression=big end gone or worse, rather than cylinder head gasket? I would have thought if the gasket had gone I would have some compression. If I have time and the weather is fine I'll take the head off tomorrow for a look see but it could be weeks before I can devote enough time to getting underneath and checking the bearings and conrods. Too bloomin cold for one thing.

Big ends would be a nasty knocking noise. No compression on one cylinder would indicate that a valve or seat has disintegrated, or possibly a stuck tappet. Turn the engine over on the handle with the rocker box off to check that the valves are all moving correctly. As you will have to take the head off you will be able to inspect the valves, gasket and pistons. Any problems should have left signs in one of the combustion chambers. Did the oil pressure light come on whilst the engine was running?

Didn't notice the oil pressure light to be honest, I was too busy looking for somewhere to pull over. The engine won't fire now but it turns over. I'm going to have to pray for fine weather tomorrow so I can take a look. At least I can turn the engine over with a starting handle to watch the valves. On the Midget I have to rock it back and forth in gear. If it is a valve, now would be a good excuse to send it off for rebuild and lead free conversion

I have a week's holiday booked for 2 weeks time so it may have to wait until then.

I'd put money on either a burnt valve in number 3 or a head gasket between 3 and 4 (I'd lean towards the former).

I have a week's holiday booked for 2 weeks time so it may have to wait until then.

whip the head off now, it only takes an hour, then you'll be able the pop it back on at the start (or before!) your hols and be able to cruise around in a refreshed minor!

Andrew

Oh I will get the head off tomorrow weather permitting, I meant if I need to take the bottom end apart it will have to wait.

sorry, missed the rattling and banging bit. Look at the engine. You don't have anything poking through the side of the block do you?

As Mike says, a big end is quite a big bang and rattle. I had one once which fairly quickly broke through the block, it was quite spectacular. If a little annoying .

probably a sensible precaution to do a visual check of the outside of the engine and check the valve gear's working as others have mentioned before de-heading! You have to take the rocker cover off anyway to do the head, so worthwhile check before you get too far.

Andrew

Work so far this morning - I did a compression test on all 4 cylinders first and discovered no compression at all on 3 & 4 and 155psi on 1 & 2. That seems more encouraging and I think tends to implicate the headgasket. I'll find out soon. I removed the rocker cover and checked that all the rockers move which they do. I removed all the ancilliaries and was only 9+4 nuts away from removing the head when my wife called time and we had to go shopping. I'm just enjoying a cuppa before I go back out and see what is underneath the head.

yes, sounds very head gaskety. You lucky thing!

Except the shopping...

Andrew

You may well hear a hissing noise when you crank the engine over as the pressure escapes passed the failed gasket from one cylinder to the next

Well the results are in and it was the head gasket, phew! Rather big hole between 3&4 as expected. With the head off the engine turns smoothly with no problems and all pistons fully functioning. The bores look smooth and everything else looks reasonably healthy. Here is the blown gasket:

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On closer inspection it wouldn't have been too long before it blew between 1 & 2 too! Seems my Spring project to spruce up the engine bay has been brought forward. Doesn't seem much point in putting it all back together again if I'm going to pull it all apart to dress it all up in the Spring. Might as well get on with it now.

If anyone hasn't done this before, I've created a little photo documentary of the head removal which can be found here:

http://www.woodburnguitars.co.uk/Minor/head.htm
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Not too bad really. Does look like a bit of a leak between 1 & 2. Make sure everything's really clean and that it's torqued down properly when it goes back together. Check the block between all cylinders for flatness, damage etc.

Like the photo-documentary!

Andrew

stuart_k wrote: I've created a little photo documentary of the head removal which can be found here:

Thanks for the excellent run through - just hope I never need it

Great job with the photo documentary. Why did you put the plugs back in though? Was this to create compression to free the head from the block?

Also, just a tiny correction. The bypass hose can be fitted without removing the head - you remove the water pump instead

You can also put the bypass hose on with out removing the head or the water pump. It can be a bit of a pig to do but it can be done.

like when you refit the head, torque it down, refit the valve gear etc then realise you've forgotten to put the bypass hose on.

I've never done that of course, a "friend" did once though....

It is bit of a pig, so this "friend" told me...

Andrew

eastona wrote:like when you refit the head, torque it down, refit the valve gear etc then realise you've forgotten to put the bypass hose on.

I've never done that of course, a "friend" did once though....

It is bit of a pig, so this "friend" told me...Andrew

You know this "friend" well??

might do...he's done all sorts of other daft things aswell!

Andrew

"Bit of a Pig" is an understatement! It's hard enough if you use the concertina style hose, but impossible with the thick walled one.

5 Minutes to whip the pump off, that's the way to go

David53 wrote:Great job with the photo documentary. Why did you put the plugs back in though? Was this to create compression to free the head from the block?

Yes. Although it wasn't needed. The head came straight off.

I'll correct my little "how to" with regard to the bypass hose and the water pump.