Conference terri::cars_uk

When my mother-in-law's R4 showed similar symptoms, it turned out to be a
warped block - could that be the problem?

The R4 engine has a dry liner system i.e. the pistons run up and down
inside tubes which are not a part of the block. If you take the head off
you need to make sure that the tubes don't move, so you mustn't move the
pistons up and down.

The differences in compression you mention aren't too bad really, and
certainly wouldn't cause the problem you mentioned.

Why did they suspect the cam-shaft ??? If the lobes are worn, maybe it
isn't lifting the valves enough to let in enough fuel/air mixture.

	The camshaft lobes aren't worn because the followers hardly show a
	mark on them.  Two people have just told me that it's probably due
	to the piston rings, so I'll have to check this further.  Can the
	piston rings be changed without removing the engine on an R4?

	I also learned that I didn't check the compression carefully enough.
	I checked it by taking one plug out at a time, then running the engine
	on three cylinders while holding the gauge over the open plughole.

	Regards,  Geoff.

It's always best to test compression will all the plugs out. In that way
if the head gasket has gone, you'll see it better.

Just because the followers aren't worn, doesn't meant that the cam-shaft
can't be.

	My son and I finally managed to get the motor back together again.
	We did a full cylinder-head job on it, so compression is now very
	good.  There's a new water-pump and the carburettor's all clean,
	new plugs, belts and filters.

	We still have the problem of loss of power.  The engine revs up
	to a certain speed, then just stays there, not really misfiring,
	but not running smoothly either.  The car displays little power
	on the road and climbing even light slopes causes it to slow down.

	We've timed the distribution carefully and double checked
	everything.  Healthy sparks on all plugs except one.

	Things we suspect, but need some verification:

		Plug leads
		Distributor cap or rotor arm
		Mechanical timing advance (the cam is a bit loose)
		Contact breaker (although they're really clean)
		Capacitor
	
	My impression is that it is timing, but my worry is that it's
	something more serious.

	Any help would be appreciated.

	Regards,  Geoff.

    .5�	Things we suspect, but need some verification:
    .5�
    .5�		Plug leads
    .5�		Distributor cap or rotor arm
    .5�===>		Mechanical timing advance (the cam is a bit loose)
    .5�		Contact breaker (although they're really clean)
    .5�		Capacitor
    I would strongly suspect the timing advance.
    
    Check the carb for any possible air leak.

    I once had this a long long time ago on my dad's old Wolsely 15/60.
    Tried everything, before eventually finding it was the COIL!!!
    
    Richard

	The plugs are still very oily and sooty, even though the gasket and
	head job was done.  I'm back to suspecting the rings again.

	I'll check the coil though.  Regards,  Geoff.

 Sounds like the mixture is too rich. Suppose the air filter isn't
 blocked is it, or the carb is just naff ...

>		Plug leads
>		Distributor cap or rotor arm
>		Mechanical timing advance (the cam is a bit loose)
>		Contact breaker (although they're really clean)
>		Capacitor
    
    
    	I think you'll just have to work throught the list - it looks about
    the right things to check.  Personally I'd check the timing first (worn
    cam drive ? Static timing and with a strobe - does it just have
    bob-weights or a vacuum advance as well ?).  Then maybe the coil and/or
    capacitor as well.
    
    
    .Stevie.

After one month, I'm still no nearer fixing this.  Patrick Chevaux's advice
about timing is what I'm betting it is, but this means taking the engine out
as the R4's timing cover is inaccessible.  Blow-back from the carburettor also
reinforces this.  I'm still trying to eliminate obvious things.  Therefore one
last question before the engine comes out:

	How do you check a coil?

All plugs produce a spark, which I would call fairly healthy, but still I
want to check it, just in case.

The timing is single chain driven - can chains slip a sprocket tooth easily?
I can't imagine the camshaft is twisted, but then the poor thing does have:
oil-pump, distributor, push-rods, alternator, water-pump and fan to drive.

Regards,  Geoff

    (who-thought-he-got-a-smart-little-bargain-but-is-now-fearing-the-worst).

	We finally managed to get the timing cover off by loosening the
	engine mounting bolts then jacking the engine up about 5� to lift
	it clear of the chassis.

	Space was still restricted and with the aid of a mirror and torch
	we checked the sprocket alignment and it WAS OUT by a couple of
	teeth.  By pushing the tensioner over, we were able to remove the
	chain altogether by slipping it over the sprockets.

	After aligning correctly, the engine works okay now!  Hooray!!

	Now for some questions, because if the chain slipped once, then it
	may slip again... and in my lifetime, or even dinnertime:

	- Should a new chain be able to be mounted by just slipping it
	  over the sprockets, or isn't this the usual way?

	- I think the sprocket tooth jump was caused by the water-pump
	  seizing.  Can I reasonably expect this to not happen again
	  if a new pump has been fitted.

	- Would changing the tensioner help?

	Thanks for all your help up to now.

	Regards,  Geoff.

The normal way to fit the chain is to remove one of the gear wheels.

If the chain can be removed without doing this, I would suspect that
either it has stretched or the teeth on the gear wheels are worn down.

A new chain and gear wheels shouldn't cost too much.

	Thanks for all the good info guys.  I bought a new chain and found
	quite a difference in the length (about 10mm).  I had to fabricate
	a special extractor to get the sprocket off in the limited space
	but I finally managed to extract it, put on the new chain and push
	it back on with the aid of a furniture clamp.  Runs a treat now!

	It was fun, but I wouldn't want to do it again.

	Regards,  Geoff.

	PS: Anyone wanna buy a R4L??  {8o]}