Is it my head gasket?

[Martin Cooper]

1989 Type 25 1600 Turbo Diesel. You have all been very helpful sorting out my water sensor flashing light problems and it is all now working properly. However the level indicator has been coming on when the bus climbs a steep hill. It only goes off when I bleed the rad. This morning I needed to do it again. When I had finished, I checked the water level with the engine ticking over and noticed occasional bubbles popping out of the top hose into the top up tank. Is this the dreaded failure of the head gasket or is there a calm and sensible explanation.
I know early models were notoriously difficult to bleed and the front had to be jacked up but I understood my model could be bled on the level.
Thanks
Martin

[ghost123uk]

Simple way to be sure = take to any half decent garage and for very little money (it only takes 5 minutes to do) they will do what is known as a sniff test. This involves putting the exhaust probe of their exhaust gas analyser into the top of the coolant tank and checking for the presence of any combustion gasses.

[Sagemagoo]

I've always used the method I think was attributes to Baxter of running the engine up to temperature, revvin it with the dalek cap off (coolant drops quite a bit) and topping it up before putting the cap back on and dropping the revs - has worked every time for me.

[Martin Cooper]

Thank you ghost123uk, I'll arrange for a sniff test.

[Martin Cooper]

Thank you Sagemagoo. That has been how I have bled it but gas or air seems to be creeping in when the engine gets a little hot. Normally the needle sits just on the cool side of the warning light, when the needle covers the light as I climb a steep hill the warning light starts flashing and I need to bleed the rad to get it to stop. The thing is that the engine isn't running hot and losing lots of water as it did when the head gasket failed.
Cheers
Martin

[RogerT]

Did you get this sorted? Came across your two threads when looking into my leaky coolant level sensor. I've only recently solved all my coolant leak issues (fortunately head gasket was not one of them), and the symptoms you describe are familiar. Jus thinking you may have small leaks that leak when the system pressurises, and then when the system cools and the pressure goes negative, instead of the water being drawn from the top up tank it is drawing air from the outside at the leak. I had several leaks that only became apparent in turn as each was sorted, and a knackered dalek cap, and not even a top up tank when I bought the van, such was my ignorance!!