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boxofbits

Yellow valves

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Hi All

 

Having removed the cyl head of the TR4a today Im surprised to see number 2 exhaust valve looking like a daffodil! In a way Im not surprised as Id previously noted the ceramic insulator of the spark plug was also yellow..

 

The reason for removing the head was water seeping down the pushrod tubes on number 4 which must be a hairline crack in the casting somewhere as the gasket/ block look good.

 

It may have been running lean at some point but wonder if the yellowness is something to do with modern fuel?

 

Kevin

post-12159-0-26596000-1528556268_thumb.jpeg

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.? Head gasket leaking water into No2 pot

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Hi Iain

 

Agree it has to be water, as the rear valves nice coffee brown so can't be fuel. Oddly enough the visible cylinder head leak was at the back. The gasket also looked okay in BOTH areas...I didn't think these heads were that prone to cracks..?

 

 

Kevin

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Kevin, if you do find a crack all is not lost. I strongly recommend Fraser Brown engineering of Nigg, Ross-shire, tel 01862 851600 www.fraserbrowneng.co.uk This company did a super job on my 4A head. Usual disclaimer, no connection other than as a very satisfied customer.

 

Tim

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Hi Tim

 

Thanks for the info.. Out of interest whereabouts did your own cylinder head crack. I dont think mine has cracked due to lack of coolant as new liners were fitted and the block de-gunked especially at the back where they sludge. I didnt think these heads were noted for cracking?

 

Ive also noticed the outlet for the top hose has corroded quite badly and prone to leak between head and alloy housing..Has anyone had the head cast welded and re-machined in this area?

 

With new castings being in the region of £1850, which I hope are as good as OEM, repairing is worth consideration !

 

Regards

 

Kevin

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In my case Kevin the crack was down the throat of #4 inlet valve. You may be able to see on the attached.

On my head all the valve seats were inserted but without the correct interference fit and were peened in place! This one dropped out when the car was parked and lassoed the valve. The car only ran on 3 cylinders for a short while and no damage was done, just a slight kiss on the piston crown. The specialist who refinished the head after the weld repair said that he could spring most of the inserts out easily with a screwdriver so I was living on borrowed time.

 

Tim

 

 

 

post-9073-0-19626900-1528732995_thumb.jpg

 

post-9073-0-35256800-1528733028_thumb.jpg

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Surprised it didn't wreck the engine and I can see where the insert made a hefty indent in the head..bit of an engineering fail that!

 

At least it was a visible crack in a repairable area, though in my case it may be difficult if not impossible to see it..

 

Kevin

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