Club 80-90 Forums

how can i tell if i've blown the head gasket,on startup i get a mixture of black ,blue and white smoke which clears when warmed up,mpg has got worse too,i can lose cars behind at night with the smoke when accelerating ,she was never quick with a bungalow attached,..what checks can i do without being ripped off at a garage

Head gaskets can blow in different ways. I took mine to an expert who used a sniffer (to detect exhaust gas in the coolant), the sniffer fluid didn't change colour so he said the gasket had to be ok.......but still mine would throw all the water out after 15 miles on the motorway - the main giveaway was a continuous stream of small bubbles whenever I took the cap off plastic reservoir with the pressure cap with a little pipe coming off the side. Mine gives thick black smoke under high load at fairly high revs because the turbo waste gate has jammed shut and the blow off valve on the inlet manifold is dumping the air - could yours be doing the same?

on startup today lots of mixed colour smoke for about five minutes and was very lumpy till it started to warm up a bit, then it cleared,whilst warming up opened the blue cap slightly and water spilled out under pressure,so tightened it up quickly,once warmed up fully checked the boost pressure with a spare guage it was .35 bar,the blow off valve was fine and only black smoke was seen when reved enough to hear the turbo wine

right sometimes even with all the equipment you have in garages it can still be very difficult to diagnose correctly so at home you are up against it.
firstly. if it smokes badly first thing in the morning it could be water passing in to the combustion chamber overnight due to there being excessive pressure in the cooling system and a breach of the gasket.
this can sometimes be improved on by releasing any pressure the night before so less or preferably no water goes in over night. this will hopefully have an effect on the start up smoke which you can assess and form an opinion on.

Is it losing water? On mine if I took the blue cap off before starting it (if in good order, the tank should be absolutely full), then started the engine, when revving it a bit, the water level drops a little and rises back up as it reduces back to tickover, which is normal, however I had a slow but continuous stream of small bubbles; which is wrong. For a fully bled, normally operating cooling circuit there should be no bubbles at all. On mine after 15 miles on the motorway at 60mph, it would suddenly rapidly increase in temp and throw out a lot of water. Once I replaced the head gasket, it was fine. Your symptoms sound different to mine.....mine was blowing from a cylinder into the water jacket - maybe yours could be leaking from one cylinder to the next. If it's a big leak, a compression test would find it. Is it running smoothly on all cylinders? Grey smoke sounds more like it's burning oil. I've not got much knowledge on diesels and only my one short experience of the VW camper diesel.

my limited experience with diesels is that smoke colour is indicative of what is happening in the engine.
black smoke is excess but burnt fuel, old or worn engines would do this under load and acceleration.
blue smoke is oil being burnt - rings, valve guides maybe.
white smoke - steam is white but white smoke smells strongly of diesel and is unburnt fuel. can be injectors need to be reconditioned and/or injector pump worn. I had this with a Nissan SD22 diesel, had to get the pump rebuilt.
the above doesn't say what the cause is but this may give you a clue.
good luck, hope its not too serious or expensive!

cheers guys i will try it again today,but first i'll check the water level ,the smoke level yesterday was just a but much though