I have a 1700 (Kent) Cross Flow engine fitted to a Caterham. I have recently rebuilt this; decoking the head, lapping the valves and fitting new valve stem seals and fitting a new head gasket. I have not touched the bottom end.
On starting it up for the first time, it ran hot and plumes of white smoke came from the exhaust. I stopped the engine and believed I had blown the head gasket. I fitted a new one and restarted and everything appeared to be okay until white smoke billowed from the exhaust again. Compression is down to about 70 psi per cylinder.
Can anyone list the possible causes of this?
Many Thanks
Chris
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Chris
is it steam? You can tell as this quickly disperses.
if it is and the gasket is Ok, you may have a cracked head.
regards
john
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Would a cracked head affect a drop in pressure in all 4 cylinders John? Surely not? Any more thoughts?
Simon
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Simon
Yes - the usual post in haste without reading the note!
I was more interested in confirming if this was steam or oil smoke. The options are - as has been suggested - that the compression tester is at fault, or the bottom end is shot. However, only 70 lb/sq in suggests that it must be so bad that oil burning would have been obvious.
Other thought - if the head is modified, has it been cut away so as to reduce the nip on the gasket near a waterway or waterways, or indeed, has the correct gasket been supplied? Does this modified engine need a bespoke gasket? Seen this problem on A series which use similar looking gaskets for different capacity engines - and I was once given the wrong one!
Regards
john
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Chris,
There is something very wrong with these compression readings.
I think you need a cooling system tester that applies pressure via the rad cap. You can then watch the gauge and actually hear any pressure loss....and hopefully the source of the fault.
David
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Chris, I read in an engineering manual that it can be inadvisable to attend to the top of an engine without thoroughly checking rings and bores,cranks etc. The increased efficiency of the valves(their increased gastightness) will exacerbate any defects in the lower half of the engine. This can therefore be a self defeating project Also avoid guesswork. I know from experience that this wastes both time and money and increases the frustration ratio! Don't take my word for this, but it sounds like this could be the cause. Cheers, Mike
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Odd one this, can't help technically, but if it had been a Citroen, Peugeot, FIAT, VW etc, the server would be resounding to the cries of "cr*p French/Italian/VW cars" by all the partisan types out there.
What is it about Ford that makes everyone search for the technical answer?
BTW, I applaud the technical guys' efforts.
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I would go with the "top end good - bottom end as loose as a Devonport Dumpling" theory.
If it's steam it will condense onto a sheet of thin ally plate - oily smoke won't.
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I've a vague recollection of hearing that brake fluid causes dense white smoke if it gets into cylinders. I think this was to do with a leak in a brake servo; it was long ago and the details have been forgotten. Check the fluid reservoir. That wouldn't explain the low compression, so I think it's more likely to be coolant.
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Yes, you're right - I posted a note on this some time ago.
Regards
john
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the compression would be that low if the engine is worn and also COLD. You could try taking the compressions with the engine at normal running temeperature and, if still low, squirt a little engine oil into the spark plug holes. This will temporarily improve the seal around the piston rings, if the compressions are then higher it proves bore/piston/ring wear. Alternatively, a good engine tuner will attach a compressed air line to each spark plug hole in turn, with the piston at top dead centre. The air will leak from either the carb (inlet valve fault), the exhaust pipe (exhaust valve leak), the oil filler or dipstick holes (piston/bore wear) or finally, into the radiator (cracked head, water jacket fault, gasket failure).
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Chris,
were those guys in Epsom any help with the brake caliper bolt or were they a total waste of space? Like to know as I can put it on our subcontractor database @ work.
Cheers,
Stuart
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Bravo gentlemen, a most comprehensive & helpful batch of answers which will give Chris plenty to bite on, I am sure he will update us.Incidentally, the bolt
was still available(old stock on the dealer network!) & they claim to have a high degree of success in locating old parts.
Regards
Simon
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Stuart
In the end, I actally managed to get an original Ford part from a remote Ford dealer up North, so didn't have to go the bespoke route.
Thanks for your help, but I cannot report on them
Cheers
Chris
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