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Can you read the smoke signals?
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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Wed Sep 24, 2008 9:06 am    Post subject: Can you read the smoke signals? Reply with quote

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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Greeney in France



Joined: 06 Mar 2008
Posts: 1173
Location: Limousin area of France

PostPosted: Wed Sep 24, 2008 7:39 pm    Post subject: Reply with quote

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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SV8Predator



Joined: 24 Aug 2008
Posts: 137
Location: Further up the creek

PostPosted: Wed Sep 24, 2008 9:55 pm    Post subject: Reply with quote

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

White, dense smoke? Worn master cylinder?
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Wed Sep 24, 2008 10:47 pm    Post subject: Reply with quote

Peter,

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

Art Smile
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47p2



Joined: 24 Nov 2007
Posts: 2009
Location: Glasgow

PostPosted: Wed Sep 24, 2008 10:57 pm    Post subject: Reply with quote

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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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Thu Sep 25, 2008 12:31 am    Post subject: Reply with quote

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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Scotty



Joined: 23 Nov 2007
Posts: 883

PostPosted: Thu Sep 25, 2008 6:17 am    Post subject: Reply with quote

Has your car got vacuum assisted brakes?
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Greeney in France



Joined: 06 Mar 2008
Posts: 1173
Location: Limousin area of France

PostPosted: Thu Sep 25, 2008 7:23 am    Post subject: Reply with quote

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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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Thu Sep 25, 2008 8:42 am    Post subject: Reply with quote

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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Penman



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

PostPosted: Thu Sep 25, 2008 1:32 pm    Post subject: Reply with quote

Hi
Dashpot oil leaking down into the venturi?
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peppiB



Joined: 30 Jun 2008
Posts: 686
Location: Newcastle upon Tyne

PostPosted: Thu Sep 25, 2008 3:15 pm    Post subject: Reply with quote

paint burning off your new manifold?
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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Thu Sep 25, 2008 4:04 pm    Post subject: Reply with quote

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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Jim Walker



Joined: 01 Oct 2008
Posts: 124
Location: Chesterfield, Derbys.

PostPosted: Mon Oct 06, 2008 8:25 pm    Post subject: Reply with quote

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!
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peter scott



Joined: 18 Dec 2007
Posts: 7211
Location: Edinburgh

PostPosted: Mon Oct 06, 2008 9:18 pm    Post subject: Reply with quote

Jim Walker wrote:
found a thick coating of red-lead paint over the block, valves AND pistons instead of a gasket.


Not red Hermetite??? Whatever, I hope Glenn Crawford doesn't read this.Wink

Peter
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