Technical white smoke after head weld and skim

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Technical white smoke after head weld and skim


New member
Dec 31, 2011
hello I have just replaced the head gaskit after welding and skimming the head as it blew on no 1 cylinder. then it started white smoking after a couple of mins ,so i took the head off again and took it for pressure testing ,all ok, new gaskit and put it back on fine for about 2 mins then white smoke very frustrating ,could i have got the timing wrong?
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It could just be it's running rich after first startup, and because it's cold / damp and you're looking for it more, the white smoke seems like a worrying sign when it's perfectly normal :)

Best bet is to run it for a few days, have a look at the smoke level when it's fully warmed up, check for water in the oil (and vice versa), coolant loss / bubbles and maybe buy one of those 'sniffer test' things so you can see if there's any CO or CO2 in the coolant for ultimate peace of mind.
Petrol, as we all know only too well these days, is a hydrocarbon carbon fuel so when you burn it in an oxygen rich gas - air - one of the byproducts is H2O - water. I remember being amazed when my college instructor told me that for every gallon of petrol burned slightly more than a gallon of water comes out the exhaust pipe! Of course mostly you don't notice it because, once the engine and exhaust system is hot it comes out the end as superheated steam, which is invisible. In colder weather it will probably condense in the cold air so you see the white smoke and when the engine is first started, so the exhaust is cold, it will condense inside the exhaust and you'll often see, on cold winter mornings, the car in front of you at the lights or in a traffic hold up, dribbling liquid water from the exhaust pipe.

One of the classic signs of a blown head gasket, or anything else which might be letting water into the cylinders, is white exhaust gasses (steam) but, especially with modern cars with Catalytic converters, you'll often see white smoke or water at the end of the exhaust shortly after start up or when idling and people think there's a problem when there isn't. So mj2k's advice above, especially keeping a regular check on coolant level, might be a good way to carry on?
I had a Morini V twin air cooled so no water, if left
ticking over for a min or two water would drip out
of the silencers.
I'm concerned about the need to weld the head. Any crack suggests severe overheating, and welding the visible crack may not cure anything deeper, unless the repairer dug deep enough get to the bottom.

Is this the alloy head from a 1.1, or is the 899 head iron?

If an alloy head, the crack can go quite deep, and must be dug fully.

Cast iron does not like being welded. Generally the iron needs to be very hot before the welding, professional repair shops would cook it in an oven for hours before taking it out, welding a bit, putting it back into the oven. Repeat until fixed.

I fear the head may be scrap. In the UK, these engines are plentiful from scrapped cars. Hopefully you can source something there too.