losing coolant and white smoke

[Jasikasisback]

along with the cold temperatures i get white smoke on startup for a few minutes. car runs lumpy initially but once up to temperature is fine.I had the engine pressure tested but this is after driving it (warmed up) so engine and water system show no leaks. But the leak is there when engine cold. in summer there are no problems at all. ewI have a leak at the transmission coolant unit. (the hex key circular part on the top of the cooler closest to the front of the car weeps oil) .i have to top up coolant once every couple of months.
Car does not overheat. no coolant in oil and no mayo on oilcap. some drip out of tailpipe but it has no sweet smell and is tasteless. If it sits for a few days the amount of smoke rivals that in Bond movies.A real head turner but stops after a few minutes. As I said the leak cannot be found as car pressure tested after driving it to garage .
So I was wondering if a rad sealant would be a temporary fix over the winter.

[Gti_Jamo]

Ive got a rover 400 outside that leaks water directly from the head gasket when cold but the thermal expansion after a minute or so of running stops it. If its only using a wee bit of water and there is no mixing of the oil then i wouldn't worry about it too much.

[Jasikasisback]

i was wondering if radseal would help or just cause more damage by affecting the waterpump...etc

[Gti_Jamo]

Radseal wont do much if its the head gasket. There are other, more expensive, chemical based products that may do a better, more permanent repair but they are hit or miss. I've used steel seal on a freelander gasket before and it worked but a big price difference to redseal.

http://www.drbcarspares.co.uk/catalogue/oils-additives/radiator-cooling/steel-seal-repair-for-blown-head-gaskets

[thai-wronghorse]

Radseal wont do much if its the head gasket. There are other, more expensive, chemical based products that may do a better, more permanent repair but they are hit or miss. I've used steel seal on a freelander gasket before and it worked but a big price difference to redseal.

http://www.drbcarspares.co.uk/catalogue/oils-additives/radiator-cooling/steel-seal-repair-for-blown-head-gaskets

Products like that always concern me with their long term effect on the rest of the engine components.

[Gti_Jamo]

Of course obviously the best course of action would be to strip the head off, pressure tested and skimmed but thats not always an option. In regards to steel seal the only issues ive read of is clogging up due to other contaminants in the cooling system. It worked for me anyway so i can only recommend it.

[Jasikasisback]

I have had it pressure tested and no leaks were found...of course this is on a warm engine or one that has been driven. so I sense the leak is small and only when the engine is cold...so the sealant may not even work as it only works on a warm engine???Well it didn't smoke at all today...but maybe tomorrow

[Jasikasisback]

Coolant level has dropped only slightly...still a worry for me...

[Jasikasisback]

ok i slightly overfilled it with coolant and it is holding for the moment...strange but true....makes no sense to me.