Head cracked or not?

[PeteE30Tourer]

I posted on here some time ago about the following symtoms my 325 Touring was having:

1. Missing on at least one cylinder when running from cold for first minute or so, after which it ran fine

2. Masses of white smoke from the exhaust for the first couple of miles when starting from cold

3. Gradual loss of coolant.

4. Drop in mpg from usual 23 to 20 mpg

The general concensus was that it was either my head gasket, or more likely the head itself being cracked, although there are no signs of water in the oil or oil in the water.

However, after reading the thread here: http://www.e30zone.co.uk/modules.php?na ... pic&t=7566 with interest, I decided it was worth fitting a new temperature sender for the sake of Ԛ£10 and half an hour of my time.

The first thing i noticed when taking out the old sender is that no water escaped as i would have expected it to. I tested the old and new senders side by side in ambient, warm and boiling water and they both read about the same, so i guess there was nothing wrong with the old one - as there shouldn't have been as i only replaced it about a year ago. It was pretty clean too - no oxidisation or deposits growing at all.

None the less, I fitted the new one and bled the water system at cold then hot. I left the car overnight to cool down fully then tested it this morning. It ran smoothly, i.e on all 6 pots from the start, but there were some clouds behind me still, though not as much as before.

So, anyone got any views on this before I spend a fortune replacing me cylinder head?

[bennyp]

i have a very gradual loss of coolent too and heaps of white smoke on start up.

I have decided / concluded after much looking that the smoke is due to a stainless exhaust system, they tend to change temperature at a different rate to the standard ones which causes loads of condensation when cold, or when its been raining ( my theory anyway! )

coolent loss im still stuck on, but done an oil change very recently and no sign at all of water in the oil, so i too am stuck on this prob.

[Ritchie]

Hi guys, just because there is no coolant in the oil or vice-versa doesnt mean the head or head gasket are ok. The gasket can be gone between the combustion chamber and the cylinder water jacket this will take a very long time to leak enough water to be noticable in the sump. or the head can have a crack from the combustion chamber through into an inlet or exhaust port. Hence no coolant will find its way into the oil galleries. Hope this helps

[stappin]

Hi guys, just because there is no coolant in the oil or vice-versa doesnt mean the head or head gasket are ok. The gasket can be gone between the combustion chamber and the cylinder water jacket this will take a very long time to leak enough water to be noticable in the sump. or the head can have a crack from the combustion chamber through into an inlet or exhaust port. Hence no coolant will find its way into the oil galleries. Hope this helps

Ritchie, wouldnt you have white smoke from the exhaust?

[Ritchie]

Yeah, if its through to the water jacket you will get steam coming through the exhaust.

[Ant]

if you're looking for signs of a blowing H/gasket theres a good tip.......

pull the plugs, the one you're looking for is the clean one, any water will turn to steam and effectivly steam clean the affected cylinder and plug.

trust me dudes, I earn a living looking at these things

[PeteE30Tourer]

Thanks for the advice guys. I guess i'm just desperately looking for the faintest glimmer of hope that i dont have to spend out a fortune here!

The only thing i've noticed about the water in the expansion tank is that it looks dirty, i.e. cloudy, as opposed to being the colour of the antifreeze. There's no sign of an oily film on the surface though, so i assume this is just dirt from the engine built up over the years.

That's a great tip about the plugs Ant. I do take them out regularly to check they're ok, but i cant remember if i've done this since having this problem. Would it be best to take them out after running the car for a short time, i.e. when the steam cleaning has done it's bit, but before the normal operation of the car has "dirtied" it up again? Might try this over the weekend.