Classic cars forum & vehicle restoration.

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh

Following in UJ's footsteps here's a problem for you to solve. I've just figured out what the problem was but it took me 2 days. Can you solve it a bit quicker?

I took my old Jag down to the Selkirk rally on Sunday which is a run of about 35 miles. The car ran fine but there was a queue to get into the field which probably involved about 20 minutes of slow or non-existent progress.
Unfortunately for the car behind me, who just happened to be a friend into the bargain, my car started to put out quite a bit of smoke from its exhausts.
This continued until I was parked up on the field. I didn't see any sign of it on the run home and I haven't been able to reproduce the problem since.

Can you figure out what the problem is or was?

Peter.

p.s. You might get a clue in some of my other recent writings to this
forum.

p.p.s. Sorry, there are no prizes to be won.
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Greeney in France · Posted: Wed Sep 24, 2008 7:39 pm Post subject:

Was it Blue or White, I can only think that oil was getting sucked from the valve seals and getting on to the spark plugs maybe because crankcase breather blocked in someway?
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We do these things not to escape life but to prevent life escaping us

SV8Predator · Posted: Wed Sep 24, 2008 9:55 pm Post subject:

We can't read the smoke signals until you either show them or describe them.

White, dense smoke? Worn master cylinder?

47Jag · Posted: Wed Sep 24, 2008 10:47 pm Post subject:

Peter,

My guess the smoke was black due to too rich a mixture.

Art Smile

47p2 · Joined: 24 Nov 2007 Posts: 2009 Location: Glasgow

I would have guessed valve stem seals leaking caused by the oil being warmer hence thinner than usual when sitting in the queue of traffic
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ROVER
One of Britain's Fine Cars

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh

Sorry for the lack of response. I've been out this evening but you are certainly asking the right questions and making suggestions that closely linked to my initial thoughts.

My valve guides are sloppy on this engine but the smoke only occurred whilst queuing to get into the rally. I now can't reproduce the smoke.

I would say the smoke was light grey or white in colour.

What do you think?

Peter.
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Scotty · Joined: 23 Nov 2007 Posts: 883

Has your car got vacuum assisted brakes?

Greeney in France · Posted: Thu Sep 25, 2008 7:23 am Post subject:

White or grey smoke Hmmm... brake servo leaking fluid in to the servo and being sucked into carb because you are resting with your foot on the brake pedal I hope for your sake its not water getting in via the cylinder head gasket being under more pressure while sitting in traffic?
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We do these things not to escape life but to prevent life escaping us

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh

No, the brakes are rod operated and have no servo assistance.

There is clue in this thread: http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?t=5669

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Penman · Joined: 23 Nov 2007 Posts: 4850 Location: Swindon, Wilts.

Hi
Dashpot oil leaking down into the venturi?

peppiB · Posted: Thu Sep 25, 2008 3:15 pm Post subject:

paint burning off your new manifold?

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh

Full marks to PeppiB!

Yes, I had replaced my broken manifolds with a pair that I bought many years ago and they had been painted with high temperature paint but not just on the outside. Clearly the inside temperature just got too much for it.

Thanks for all your sporting replies.

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

Jim Walker · Posted: Mon Oct 06, 2008 8:25 pm Post subject:

Hmmmmm..... It is well known in the Motor Trade that man-made faults are the hardest to diagnose. I am put in mind of the exWD Austin 8 which a customer brought in many years ago. It barely ran and had all kinds of overheating and mis-firing. The chap had just de-coked it so we suspected (side) valve trouble and found that for some reason the valves were reluctant to return to their seats. Eventually we removed the head and found a thick coating of red-lead paint over the block, valves AND pistons instead of a gasket. The chap never did explain why!

peter scott · Joined: 18 Dec 2007 Posts: 7211 Location: Edinburgh