Running on 3 cylinders!

[Squiggle]

Car in local garage! Wasn't only petrol pump points that need attention.

Running on 3 cylinders. Compression check [100 85 110 50] suggests head should come off for inspection.

Thanks Cam so much for you phone advice and moral support.

Garage not really familiar with sidevalve engine so I have left the workshop manual with them.

If the head is being removed, does it make sense to replace the head gasket and valves as a matter of course? Actual mileage 92000

Garage said the lead substitute I use might not be doing it's job in protecting the valves. I'll have to check which products are thought to be the best.

They also said they are wary of fitting new parts [in this case valves] in an old engine as it could affect other worn parts in an adverse way. Any ideas on this please? Sort of makes sense.

Monsoon weather and car's gonna be outside for a week while they find time to work on it. Seems they bill me for less hours this way.

[d_harris]

If the head is being removed, does it make sense to replace the head gasket and valves as a matter of course? Actual mileage 92000

As I said on the other thread, HG's dont like being squished twice - so replace that as a matter of course.

If it was an OHV engine I'd say dont bother with the valves, but not familiar with SV lump

[rayofleamington]

They also said they are wary of fitting new parts [in this case valves] in an old engine as it could affect other worn parts in an adverse way. Any ideas on this please?

as it's a side valve, the valves are in the BLOCK, not in the head.
I hope your simple engine is not going to melt their minds

I've never ever ever heard that you can't fit new valves in a worn engine. However you only need to replace a valve if it's damaged (otherwise they may just need reseating) - and until the head's off, it's all guesswork*. Valve guides and valve seats can be reworked if needed.
If the bores are badly worn, then fitting new pistons and/or rings is normally not advisable - rebores prefferable for fixing that.
Same goes for other things like not fitting new big end bearings if the crank is worn outside of limits (however we're not talking about dodgy big ends here!)

[* guesswork - could be anything including:- cracked rings, scored bore, damaged piston, damaged valve, pitted valve seat, over-worn bore and not to forget a leaky headgasket]

Before stripping - have they checked the tappet clearances?? This may be preventing the valves from closing properly.

Headgasket - yes definately need to get a new one.

ps - glad the fuel pump is sorted.

[Squiggle]

If the head is being removed, does it make sense to replace the head gasket and valves as a matter of course? Actual mileage 92000

As I said on the other thread, HG's dont like being squished twice - so replace that as a matter of course.

If it was an OHV engine I'd say dont bother with the valves, but not familiar with SV lump

Sorry Dan, I wasn't ignoring your advice!

[Squiggle]

They also said they are wary of fitting new parts [in this case valves] in an old engine as it could affect other worn parts in an adverse way. Any ideas on this please?

as it's a side valve, the valves are in the BLOCK, not in the head.
I hope your simple engine is not going to melt their minds

I've never ever ever heard that you can't fit new valves in a worn engine. However you only need to replace a valve if it's damaged (otherwise they may just need reseating) - and until the head's off, it's all guesswork*. Valve guides and valve seats can be reworked if needed.
If the bores are badly worn, then fitting new pistons and/or rings is normally not advisable - rebores prefferable for fixing that.
Same goes for other things like not fitting new big end bearings if the crank is worn outside of limits (however we're not talking about dodgy big ends here!)

[* guesswork - could be anything including:- cracked rings, scored bore, damaged piston, damaged valve, pitted valve seat, over-worn bore and not to forget a leaky headgasket]

Before stripping - have they checked the tappet clearances?? This may be preventing the valves from closing properly.

Headgasket - yes definately need to get a new one.

ps - glad the fuel pump is sorted.

Is it more labour intensive to rework valves than to replace them? [thinking of the bill!]. As regards melting their minds, I'm not happy the car is with them but feel a bit helpless. No recommended Moggy garages nearby.

Why did you put leaky head gasket last in that scary list........? ha ha

Will call them tomorrow to see if they have checked the tappet clearances.

Wonder where to get a good HG.

Many thanks and Hi to the little fella.



Thanks guys.

[jonathon]

You have a PM ma'am

[Squiggle]

You have a PM ma'am

Trying to reply kind sir but it won't go........must be the monsoon.....

[mike.perry]

What needs doing to the engine all depends on what you find when you lift the head. If the head gasket has blown and there are no signs of other problems then check that the head is still flat, clean up the combustion chambers and replace it with a good quality head gasket.
Check the condition of the valve heads for signs of burning.
Turn the engine so that all the pistons are mid way up (or down) and pour some oil down the bores and see which empties first. If the oil disappears quickly then you are in for an engine rebuild.
I would be very wary about letting anyone with no side valve experience loose on my engine. You really need the special tools valve spring compressor 18G 270 to get the valves out and it is very easy to drop a valve collet into the engine.
You also want to be sure that he can source all the necessary parts before he presents you with a bag full of bits and admits defeat.

[Squiggle]

What needs doing to the engine all depends on what you find when you lift the head. If the head gasket has blown and there are no signs of other problems then check that the head is still flat, clean up the combustion chambers and replace it with a good quality head gasket.
Check the condition of the valve heads for signs of burning.
Turn the engine so that all the pistons are mid way up (or down) and pour some oil down the bores and see which empties first. If the oil disappears quickly then you are in for an engine rebuild.
I would be very wary about letting anyone with no side valve experience loose on my engine. You really need the special tools valve spring compressor 18G 270 to get the valves out and it is very easy to drop a valve collet into the engine.
You also want to be sure that he can source all the necessary parts before he presents you with a bag full of bits and admits defeat.

Ho hum. Two hours labour @ £40 ph so far. Have just phoned to say I'll collect it tomorrow. He said he didn't think any specialised tools would be necessary.........think he was a bit offended. Ho hum again.

Thanks Mike.

[bmcecosse]

Definitely new head gasket -and yes - I would fit 4 x new exhaust valves. I had these side valve engines in my Morrois 8Es - easy enough to work on them - but also easy to drop collets as Ray has said! The compressions you quote are desperately low - ok - I know the side valve engines are not great compressors - but any less than 100 is very very poor. The running on 3 may just have been an oiled up plug - did you try new plugs ? But the compressions are poor, so worth finding out why - ask them for the new figures now they done some work on it!

[Squiggle]

Definitely new head gasket -and yes - I would fit 4 x new exhaust valves. I had these side valve engines in my Morrois 8Es - easy enough to work on them - but also easy to drop collets as Ray has said! The compressions you quote are desperately low - ok - I know the side valve engines are not great compressors - but any less than 100 is very very poor. The running on 3 may just have been an oiled up plug - did you try new plugs ? But the compressions are poor, so worth finding out why - ask them for the new figures now they done some work on it!

They did swap the plug for one of the others and they did look fouled up. Will try new ones 2mrra.

No new figures as they have only worked on what the car went in for originally ie fuel problems.

Fixed the fuel problem then car had problems starting. Once started they noticed it running badly. Did compression tests etc and came up with decision that block has to come off.

Thanks

[d_harris]

Sorry Dan, I wasn't ignoring your advice!

Never said you were. Just wanted to make sure you didn't miss it!

[bmcecosse]

Well - the low compressions are not side-by side - so the gasket has not blown between the cylinders. Well worth checking the valve gaps - and trying different plugs. And finding somewhere that knows about the side valve engine !

[alanworland]

Surely, compression will be atmospheric pressure (14.7psi) X compression ratio (standard is 6.5 to 1) which is about 95 psi, so with a bit of coke in some combustion chambers and bore/valve leaks they dont sound a million miles away (except for the 50!)

[bmcecosse]

Well - the 85 isn't brilliant either - but yes - the '50' is the worry - and would explain running on 3 cylinders effect! It's most likely to be a burned valve on that bore.

[autolycus]

Surely, compression will be atmospheric pressure (14.7psi) X compression ratio

That's for isothermal compression, that is where the compression takes place so slowly that energy is transferred from the gas being compressed to its surroundings such that the temperature stays constant. The opposite extreme is adiabatic compression (constant energy) which cannot be achieved in reality but which would be governed by p*v^gamma is constant, where gamma is around 1.4 In reality, the compression can be modelled by p*v^n, where n is somewhere between 1 and gamma, depending mainly on how quickly the gas is compressed and the temperature of the cylinder walls.

You also need to allow for the fact that the cylinder does not achieve 100% filling, which is why so much effort is devoted to improving the gas flow through air filters, carburettors, manifolds, and ports.

So the practical implications for compression tests are: it must be done at full throttle; you cannot strictly compare results from different designs of engine; and you'll get different results according to the engine temperature and speed of cranking. Then there's the question of gauge accuracy and volume of "dead" space, such as the volume of the spark plug hole if the gauge doesn't have the same reach as the plugs.

But it's useful for discovering underperforming cylinders. To discover underperforming garages, ask them if they even have a clue about checking tappets on a side-valve. A job every budding mechanic should be made to do is fitting collets to a Morris 8. It's a test of the cruelty of the instructor whether the idea of bunging up the holes in the bottom of the valve chest is suggested before or after the first collet finishes up in the sump.

Kevin

[bmcecosse]

The 'lesson' above is of course correct - in reality the lack of complete filling is pretty much balanced out by temperature transfer into the air from cylinder walls etc - so the idea of 1 bar x CR is actually quite a good guide! The biggest influence will be the cranking speed - so battery condition/starter condition/all plugs removed and throttle held open will all have an influence - and yes - should always be done on a nice hot engine to give it the best chance to shine !

[alanworland]

I thought I would try and keep it simple!!!!

[RogerRust]

I'll try and meet up with Squiggle today and do wet and dry compression tests. I'm concerned that it was running well until it went into the garage, and they only worked on the fuel pump. I'll have a good look around before she starts spending money on repairs.

Unfortunately I've no idea how to check or set the tappets on a side valve. However just a thought - I wonder if the smooth engine noise that the engine has is due to tight tappets?

Edited later;

I've just had a look at the manual doesn't look too difficult, lets wait and see what the wet compression test reveals.

[mike.perry]

Roger. Have you got any tappet spanners and double jointed wrists and elbows? You will need to strip off the carb and manifold assembly and ignore the 17 thou hot label on the tappet chest. (18 thou cold will do). You will also need a new cork side plate gasket, exhaust joint gasket and possibly a manifold gasket. Head stud torque is 42 lbs ft. If the plugs need replacing I have plenty of spares.
Just trying to help.