Intermittent Fault - Engine "missing" and cut out

[almcl]

This is a long shot, but there's a rubber bush that the throttle spindle locates in at the firewall end of the linkages.

It can cause unreliable idle speeds when inevitably it breaks down.

What's yours like?

Only it might get missed on a carb refurb because it is some distance away from the exciting bits.

If you have a parts catalogue, it's C34388 - and is also shown on the Jaguar Classic parts web site although not in precisely your application.

[piman]

Hello David,

another possibility, although it should not occur after a carburettor rebuild (twice?), is that one or both of the jets are not centred. To check this requires access to the carburettor intakes and lifting the piston up and releasing it, it should drop smoothly and stop with an audible click. Should that not be the case, the jet is centred by screwing the adjustment nut fully up then slacken the jet clamping nut and hold the piston down and tighten the jet clamping nut. Screw the mixture adjusting nut down by two full turns and re check. You will now have to re-check the mixture but it shouldn't be far off the two full turns down.

Alec

[david340]

Al

Thanks for that - this is an interesting point as the linkage at the point you describe is free to wobble all over the place so I suspect that this bush is in need of changing as a matter of course - do they just slip into place ?

Alec

Will take off the air cleaner and carry out the check you have described. Thanks for the pointers here - im sure this is a steady process of elimination.

I also noted that the carb to manifold bolts were all a bit loose and it was possible to nip them all up.

The car lacks gaskets between the air cleaner and carb bodies and carbs to manifold - instead there is a black sealing compound - im tempted to clean this all off and replace with the proper gaskets.

Inlet to head bolts seem secure , I was albe to nip up the two nearest the bulkhead a little. I cant see the state of the inlet manifold gasket - all this will have been off last year when the previous owner had a "top end rebuild" carried out.

I am also suspicious of the AED unit - it has the manual choke conversion but of coures relies on the remainder of the unit being servicable. I have found a short hose situated under the AED that vents into fresh air and also a redundant hose dangling down the inner witng that connects to a smaller diameter rubber tube that runs accross the bulkhead and passed through the bulkhead on the passenger side - puzzling !!!

[piman]

Hello David,

the lack of gaskets should be addressed I feel, it doesn't reflect well on the standard of work carried out? I know that silicone RTV is often claimed 'to be used in place of a gasket' but it's not as though these gaskets are expensive and using them is preferable in my view.

Alec

[david340]

Cheers Alec

I agree on your point re the quality of work - using sealer instead of the proper gasket suggests "bodge" levels of workmanship and certainly doesn't suggest a lot of thought or care went into the work !

All the suggestions are adding up to some very good maintainance points even if theyre not connected to the problems , will keep working through it all..........

[almcl]

the linkage is free to wobble all over the place so I suspect that this bush is in need of changing as a matter of course - do they just slip into place ?

The bush does, but getting the spindle out involves releasing one of those fly-off-into-the-outer-reaches-of-the-garage circlips (if you are as cack-handed as me)

[dg4cars]

[quote="Clive Rothwell"]hmmm
Your car seems to have several issues going on here that various other members have identified for you. You have not appeared to have owned the car for all that long and so may still discover something basic.
My series 3 3.4 car also ran (runs) on carbs. I went to hell on earth to solve identical sounding issues: raised tickover, desperately poor warming up needing 5 minuted to get it off the drive. I looked at everything including different grades of oil in the dash pots. A second hand pair of carbs proved to be little better. Eventually, I gave up and bought a new pair of SU HIF 44 carbs with the manual choke in the bottom of the carb body. Instant solution to all running problems! What am I saying: simply keep checking and eliminating but be prepared for a BIG bill on a pair of new carbs! Good luck.
Clive[/quote

]
Hi Clive,
I have experienced pretty much all of the aforementioned symptoms ( engine misfiring , revs too high , revs drop on roundabouts etc )with my 2.8 Daimler Sovereign.
To be fair my garage have spent an inordinate amount of their time and effort, may I add , above and beyond the call of duty, trying to resolve the issue following many of the trials recommended previously and up to and rebuilding the existing carbs with a recommendation that the long term solution may be to install new carbs.
Following a return today of the aforementioned gremlins, subsequent breakdown and RAC call out ,my conclusion is to bite the bullet get 2 new carbs and hopefully this will resolve the issue for good.
I would be grateful if you could advise please how or where you acquired the new carbs.
From the internet I can only find kits or possible rebuilt units. Any idea of price would be helpful too.
Many thanks
Derek

[piman]

Hello Derek,

S.U. carburettors should not need to be replaced. Wear points are the throttle spindles, jets and newer spring loaded needles over a very long service. The other possible problem is worn pistons and damper chambers if they have been cleaned with abrasive cleaners rather than solvent cleaner. An overhaul kit should solve any problems in the vast majority of cases
Worn throttle spindle\bushes really only adversely affect slow speed running but should have little effect once the throttles are open. They are a deceptively simple but effective carburettor even for performance use.

Spares, full overhauls and complete carburettors may be obtained from Burlen Fuel Services:- http://www.burlen.co.uk/

Alec

[dg4cars]

Hello Derek,

S.U. carburettors should not need to be replaced. Wear points are the throttle spindles, jets and newer spring loaded needles over a very long service. The other possible problem is worn pistons and damper chambers if they have been cleaned with abrasive cleaners rather than solvent cleaner. An overhaul kit should solve any problems in the vast majority of cases
Worn throttle spindle\bushes really only adversely affect slow speed running but should have little effect once the throttles are open. They are a deceptively simple but effective carburettor even for performance use.

Spares, full overhauls and complete carburettors may be obtained from Burlen Fuel Services:- http://www.burlen.co.uk/

Alec

Dear Alec,
Thank you very much for this information.
Best Regards,
Derek

[CliveRothwell]

Hello Alec

Try Gower and Lee
http://www.gowerlee.dircon.co.uk/

Probably the BEST thing to do is to actually speak to them. Not only do they offer advice, they do rebuilds for a living and can possibly offer an alternative as they did for my car that shared your car's symptoms. You could spend many more hours fiddling with the carbs that you have but if some clown has "cleaned" them with an abrasive or they have covered some 200,000 miles then you will be wasting your time. I prefer to drive my car rather than tinker - I learnt that the hard way with this car! Good luck - tell us how you get on.

Cheers

Clive

[piman]

Hello Clive,

I don't have any problems myself, however, I do prefer to do my own fettling as I know where I am. As indicated above I generally feel that many commercial establishments don't like to do more than adjustments and if that doesn't work, then throw a new assembly at it?

Alec

[dg4cars]

Hi All,

My car was back in garage today following breakdown on Sunday. Garage have discovered water below the HT leads and the newly replaced spark plugs are very black.
Any ideas ????

Derek

[piman]

Hello Derek,

what do you mean about water under the H.T. leads, do you mean in the plug wells? And the plugs being black, is this a dry sooty black or wet oily black and are they all the same? The former indicates a rich mixture, hopefully that is all it is. Rich mixture can be simply carburettor adjustment, clogged air cleaner, flooding etc.

Alec

[dg4cars]

Hi Alec,

Yes water is in the plug wells (couldn't think of that term when I was originally posting ). The spark plugs are black dry sooty so will check out that problem.

Many thanks for your help so far.


Derek

[almcl]

Is the water plain water or coolant?

If the former, rain might be getting in there somehow.

If it's coolant then it could be a leak and finding the source is the next job. Has the coolant level dropped in the engine by a measureable amount?