Mysterious loss of coolant

[RobinLegin]

let me explain. I have just had an engine rebuild and my local guy is aware of the problem.
But after 20 miles or so and after stopping with the engine cold, I notice that the coolant in the expansion bottle has gone down. I ‘ll try and attach the photographs.
There is no coolant leak on the garage floor.
There is no evidence of coolant in the V
The car starts on the button and runs really smoothly.
My local guy checked the inlet manifolds were properly done up.
what should I be looking for please?
thanksNigel
PS
have replaced the pressurised radiator cap on the expansion tank

[RobinLegin]

Photographs attached. Before and after

[singapore stag]

How many times have you checked and topped up the coolant?
If you have just topped up a little a couple of times then there could have been an airlock which subsquently went and the coolant took its place.
Sukh.

[Lingen]

Robin. If the problem persists, it is almost certain that one, (or both) the inlet manifold gaskets is not sealing. Checking that they were correctly tightened is unlikely to cure a leak. They have to be fitted with particular care to get them to seal, as I know all too well!
Mike.

[RobinLegin]

Topped up coolant twice.
I’ll try and fit another run out with this dry spell. If the problem persists, i’ll Take it back to my local Stag specialist to sort as I can’t run it in knowing there’s a risk of loss of coolant.
i even went round the engine tightening all the jubilee clips and looked for damp carpeting in the front footwell. All perfectly dry.

[tonyh]

Looks like your not using the original expansion bottle ??

[Mark Serj]

You could ask the builder to describe how he went about making the joint off in terms of:

1. Gauging the fit dry before installation, i.e. did he do a dry run using packers for gaskets on one side bolted up, then measure the gaps at the other side? (to ensure minimal build stresses)
2. What make of gaskets did he fit? (did they have the coolant escape channel as per the Payen type?)
3. Did he use any sealant such as Wellseal etc?
4. Did the bolts take the torque value as per the manual (were they heli-coiled (or similar) before the installation?)

Hope that helps

Regards

Mark

[RobinLegin]

Looks like your not using the original expansion bottle ??

It came with car 3 years ago. At least I can visually check the level before every trip.

[RobinLegin]

You could ask the builder to describe how he went about making the joint off in terms of:

1. Gauging the fit dry before installation, i.e. did he do a dry run using packers for gaskets on one side bolted up, then measure the gaps at the other side? (to ensure minimal build stresses)
2. What make of gaskets did he fit? (did they have the coolant escape channel as per the Payen type?)
3. Did he use any sealant such as Wellseal etc?
4. Did the bolts take the torque value as per the manual (were they heli-coiled (or similar) before the installation?)

Hope that helps

Regards

Mark

Thanks. I will ask though Pete has been specialising in Stags for more years than anyone can remember. All he does is Stags!
I’ve just been out for 20 mile run and will look at the coolant level first thing - if it has fallen below the mark, it will have to go back to Pete.

[RobinLegin]

Checked the level this morning and all A1 perfect. Prior to yesterday’s run, I undid the bronze nut on the top of the radiator, filled the coolant to the very top, and resealed the nut. I also replaced the radiator cap that sits on the expansion bottlewith a new one.
it would seem that the old radiator cap may not have been working properly. Also the top of the radiator had air in it possibly allowing the coolant to boil.
will monitor coolant level prior to each journey as always anyway.
thanks everybody
Nigel

[Mark Serj]

Sounds positive Robin - keep us up to date!
Regards

[RobinLegin]

Very pleased to report that the culprit must have been the radiator cap fitted to the top of the expansion bottle. Drove the car some 60 miles yesterday trusting the new radiator cap and this morning the coolant is exactly where it should be. Phew! And all thanks to people sharing their suggestions on the forum.
I should add the old one looked absolutely fine.
Thanks all