2.5 TD 4WD first time overheating

[haydn callow]

Do you mean this disclaimer ??

FITTING THIS ALARM WILL HELP TO PROTECT YOUR ENGINE

IT IS NOT A GUARANTEE

[mikexgough]

if you read the first post it is said the coolant alarm did not go off,just high temps were noted!! no coolant lost,this does not point to a coolant issue to me.the head gasket could be failing at this point through a variety of reasons,and in different ways.it could be leaking engine gasses into the oil side and noteing temp increases that way,this could cause the coolant temp to rise and the expansion or rap cap to weep,but under pressure the coolant will still be fighting to keep the system cool,note the slight increase noted later.when in the morning the system has cooled and the coolant level dropped(normal)you would have to top up a little(alarm activated)
sounds a little more plausable than just inventing an airlock cause that maybe was never there in the first place.

I guess that sounds right in this case, and it would be a similar action to having an airlock but not necessarily the "boil up" outcome of having an air lock....... I guess also it's folks terminology that can also cause confusion..... Some Spanners know things by slightly different terms than others.....

[bigdaddycain]

if you read the first post it is said the coolant alarm did not go off,just high temps were noted!! no coolant lost,this does not point to a coolant issue to me.the head gasket could be failing at this point through a variety of reasons,and in different ways.it could be leaking engine gasses into the oil side and noteing temp increases that way,this could cause the coolant temp to rise and the expansion or rap cap to weep,but under pressure the coolant will still be fighting to keep the system cool,note the slight increase noted later.when in the morning the system has cooled and the coolant level dropped(normal)you would have to top up a little(alarm activated)
sounds a little more plausable than just inventing an airlock cause that maybe was never there in the first place.

I did read the first post!

I suspect (though as you suggest it's difficult to actually pinpoint the cause and ways of the HG failure) Let's assume for a moment that the head gasket was at the initial stages of failure... I have witnessed in the past a HG starting to fail, yet a gas sniffer test in the expansion tank shown no hydrocarbons to be present, as it turned out the gasket hadn't failed to such a degree (at that point) for exhaust gasses to make their way into the coolant, the coolant level was normal, but an airlock had developed, the coolant had made it's way into the actual exhaust and was vapourising off steam as a consequence (hence why the gas sniffer test was carried out). There was quite a dramatic rise in coolant temps, simply because the coolant couldn't be pushed around the system via the water pump as there was a whopping great chasm of super heated air there stubbornly refusing to move. The coolant was leaking into the exhaust ports though, hence the steamy exhaust. A coolant alarm wouldn't pick up on such a scenario as i said in my previous post, the level of coolant hadn't dropped via displacement as the space in which the lost coolant WAS is now filled with air.

Where was the steam emanating from otherwise?

Leaking of exhaust gasses oil side would only show a minimal increase in temps, the reason for such a high temp would probably be a combination of things... The head not being thoroughly and evenly cooled, and restricted water flow because of the (possible) airlock. I'm not surprised the coolant level was lower the following day upon cold start up, a fair amount had vapour-ed off via the exhaust the day before!

I see minimal difference in the "height" of my coolant in the bongo be it hot or cold, mind you, i run the correct concentration of anti-freeze/water ratio in my bongo.

[mikexgough]

if you read the first post it is said the coolant alarm did not go off,just high temps were noted!! no coolant lost,this does not point to a coolant issue to me.the head gasket could be failing at this point through a variety of reasons,and in different ways.it could be leaking engine gasses into the oil side and noteing temp increases that way,this could cause the coolant temp to rise and the expansion or rap cap to weep,but under pressure the coolant will still be fighting to keep the system cool,note the slight increase noted later.when in the morning the system has cooled and the coolant level dropped(normal)you would have to top up a little(alarm activated)
sounds a little more plausable than just inventing an airlock cause that maybe was never there in the first place.

I did read the first post!

I suspect (though as you suggest it's difficult to actually pinpoint the cause and ways of the HG failure) Let's assume for a moment that the head gasket was at the initial stages of failure... I have witnessed in the past a HG starting to fail, yet a gas sniffer test in the expansion tank shown no hydrocarbons to be present, as it turned out the gasket hadn't failed to such a degree (at that point) for exhaust gasses to make their way into the coolant, the coolant level was normal, but an airlock had developed, the coolant had made it's way into the actual exhaust and was vapourising off steam as a consequence (hence why the gas sniffer test was carried out). There was quite a dramatic rise in coolant temps, simply because the coolant couldn't be pushed around the system via the water pump as there was a whopping great chasm of super heated air there stubbornly refusing to move. The coolant was leaking into the exhaust ports though, hence the steamy exhaust. A coolant alarm wouldn't pick up on such a scenario as i said in my previous post, the level of coolant hadn't dropped via displacement as the space in which the lost coolant WAS is now filled with air.

Where was the steam emanating from otherwise?

Leaking of exhaust gasses oil side would only show a minimal increase in temps, the reason for such a high temp would probably be a combination of things... The head not being thoroughly and evenly cooled, and restricted water flow because of the (possible) airlock. I'm not surprised the coolant level was lower the following day upon cold start up, a fair amount had vapour-ed off via the exhaust the day before!

I see minimal difference in the "height" of my coolant in the bongo be it hot or cold, mind you, i run the correct concentration of anti-freeze/water ratio in my bongo.

I think that is about right in this particular case Ste. which I was eluding to but in not quite a comprehensive manner as you have.....But I guess we will never know as an absolute without seeing the head/gasket etc.