Engine Problem..

[Squeezebox]

This doesn't look good. Before I launch into UXC with the spanners I'd like to put the symptoms to the panel for advice....

Basically - the engine is exhausting oily smoke from the filler cap in quantity, the starter motor has quite a covering. The car now only ticks over on 3 cylinders. This only happened on the way home last night, previously it had been running really well. I have traced No3 cylinder to be the dead one. The spark plug functions alright and there is some recognisable compression detectable at the open plug hole (though I have not yet been able to measure it). The coolant looks fine. I suspect a piston related problem - but what does anyone think or suggest?

Any help appreciated.

Mike

[MarkyB]

take the plugs out. put you thumb over number 3 and spin the engine over.
The put your thumb over number 1 and compare them that way.

Keep the HT leads well away from your hands while doing this!

[mike.perry]

Check for cracked dizzy cap, it can do strange things. Also are HT leads secure? If comp. is low check h/gasket or burnt valve.

[Squeezebox]

Thanks for this. It blew quite a bit of oil out via the filler kneck and cap, could a burnt valve cause excess pressure in the crankcase?

[mike.perry]

Crankcase ventilation is normally via the tappet chest and the breather pipe which should be attached. Are you losing oil from there?i

[Squeezebox]

Crankcase ventilation is normally via the tappet chest and the breather pipe which should be attached. Are you losing oil from there?i

Yes - it looks like it. It's almost like the tappet chest has been put under extra pressure. I'm beginning to think that it might be a ring thats gone. Like I say, it'll only tick over on three but appears to go onto four with a few revs. I'll have to have a go at limping it to my garaging space where I can work on it and have the head off, I guess. And it was running so well..........!

[MarkyB]

Higher revs give the compression less time to escape from where ever it is going.
Did you try the "rule of thumb" compression test?

Did you do anything like, see what top speed it's capable of before this happened?

[mike.perry]

Compression check, head off, gasket, valve or piston.
If you need to remove a valve remember to block all the holes in the tappet chest with kitchen roll or something or you will be stripping the engine down looking for valve collets. There is no need to remove the springs.

[Squeezebox]

...did you do anything like, see what top speed it's capable of before this happened?

Ha! It's always gone well, however I am a very mechanically sympathetic driver so don't go at it with a lead right foot ! I think something just called it a day for no reason other than, probably, age. The big problem really is that it lives in the Pennines so does have to work hard at times. In a way a 948 or 1098 would make more sense, but.....

Sadly, it was running beautifully before this happened. It will probably be next Wednesday afternoon when I get to lift the head and delve deeper. From the amount of pressurising of the crankcase my money is on a ring - but we'll see. There is definitely still some compression. I'll report back when I know something for definite. Meanwhile, it's the branch rally a Leighton Hall this weekend - we're going to have to go on my 1941 Ariel motorbike and hope nobody notices....

Mike

[mike.perry]

How many cylinders has your Ariel got?
You should not have any problem with engine parts. My engine has just had a complete rebuild.
Best of luck

[mike.perry]

Have you found the problem yet?

[Squeezebox]

Hope so. Apologies for the late reply, had to deal with another(!) crisis and the Morris had to be put on hold. Anyway - I finally got to remove the piston from the suspect bore today (with the engine still in situ) and found the top ring broken up. I'm not sure if any bits had escaped as it showered down when I withdrew the piston and rod. The second ring may also have been broken. Obviously I will be looking at the other pistons in due course.

What has got me puzzled is that the piston itself differs greatly from those depicted in the BL mechanics handbook in so far as the arrangement and configuration of rings is completely different. Can anyone advise here? Note - the lower oil ring (which does not appear on the one in the book) has been removed.

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Mike Gott

[mike.perry]

I have just had two engines stripped down, one had the pistons like your's the other had no ring down the bottom of the piston. It all depends who supplied the pistons.

[DAVIDMCCULLOUGH]

My old pistons had no bottom ring groove but the new Australian made ones had it, so chances are that the engine has been bored out in the more recent past. On mine it had broken all the top rings and the pistons themselves also started to break up.

Was the bore damaged by the broken ring? Mine needed a +30thou rebore to get rid of the wear and scoring.
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[Squeezebox]

The bore looks ok - it now sounds like I have to source a new ring set. At least it sounds like it has correct type pistons - I was wondring if it had some out of something else!

Mike

[Squeezebox]

How many cylinders has your Ariel got?
Best of luck

Only just spotted this earlier post - the Ariel has just one cylinder (thank goodness), it's a 1941 War Department model (W/NG). 350cc ohv. I also have a 1957 350cc Ariel Red Hunter single - but it's in bits in the process of a rebuild, delayed by amongst other things, the Morris breaking down.......

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Mike

[MarkyB]

Lovely bike but it doesn't appear to have any oil leaks.
Did the War Department use grease instead of oil in these?

[mike.perry]

With a side valve there is a good chance that anything breaking up in the bores will be blown straight out of the exhaust. I had a valve seat insert break up once, it tinkled for a couple of seconds and dropped onto three cylinders. The only damage was a few marks on the top of the piston.

[Squeezebox]

Lovely bike but it doesn't appear to have any oil leaks.
Did the War Department use grease instead of oil in these?

Well - the gearbox is a grease box! As far as the engine is concerned - look hard at the exhaust directly under the engine - there's a definite dribble of SAE 50 there. However (!) this has now been fixed, a joint on the oil feed to the rocker shafts had become unsoldered, so it is pretty oiltight at the moment. What with modern sealants, it should be, really.

Incidentally - as far as the Morris is concerned, I'm just on with Club Spares about the availability of suitable rings. Bryan Gostling has identified them as Heppolite pistons.

Mike

[MarkyB]

SAE 50 "

Treacle then, not grease
Reminds me of a bike I lusted after when I saw it at the MOT place.
A war dept Harley with a rifle holster and a siren that could be driven off the back wheel when the rider pulled a lever.
The saddle was something to behold too. flipping enormous! Obesity may not be a recent phenomena at all.