Iain T

Just to revive the post I put some foam around the boot lid in an attempt to get a better seal. I thought the exhaust fumes could circulate around the rear and enter into the boot and cabin. It seems to have worked as after a trip out and 2 hour drive yesterday the wife said I didn't ponk! Iain

Or to get TDC you can use a piston stop (less than £10) that screws in the plug hole and rotate the crank forwards and backwards. Use a graduated disc fixed to the pulley and half way between is TDC. This method reduces any slight rotation variations trying the find TDC with a dial gauge. Advantage is it's simple to use! Iain

Better to use a car than have a show piece where you're frightened to see the light of day! Only my Vitesse and a Spitfire at Brands plus a TR2 racing. Then there's this trio of historically important race cars, a Lister, Connaught and Frazer Nash. Yes I did dribble.....

A hot 30 minute traffic jam at Blackwall tunnel coming home from Brands and with the electric fan on manual the water temp was 75-85C. I was 110C! Kevin as long as you have water exiting to the overflow bottle and then being drawn back I wouldn't worry. If the temperature gauge stays around normal even better! Iain

We'll this celebratory beer could pressurise the system. A very nice tipple and only 3.4% alcohol.

Thanks for your help Johny, at least I found a leak and know more about the workings of the rad cap! This is all essential information to bore the wife with....... Iain

More googling and I think my system is working sort of correctly as I pressurised the system via the vacuum release valve as evident when I opened the cap. The fact that it didn't hold pressure could be down to the top seal? Iain

Firstly my apologies Kevin for hijacking your post. Test result in. Using my foot pump I attached it to the overflow pipe. Gave it a few pumps and noticed a few drips out of the top hose to rad joint and hence no pressure. Tightened the clamp! Tried again and got up to 10psi but it reduced to zero in less than 30 seconds. Unplugged pump and no pressure in the overflow hose. I then carefully undid the rad cap (note the system is cold) and air and fluid gurgled down the overflow hose. Is it the top cap seal that is leaking? What seems to happening is I've pressurised the coolant system from the wrong side. I'm unsure how that could happen if the bottom seal is working correctly. There was definitely pressure when I release the cap so the bottom seal was doing something. Next test is to see if any fluid rises in the overflow when the engine is hot. Just read Johnny's post, there's a vacuum release valve? Hmm, I'm not twiddling anymore today as I'm driving to Brands tomorrow for a historic race meet and I don't want to prod the Gods! Any thoughts? Iain

I agree I don't want to over pressurise the system. It's old like me! Iain

I think 1" would be too deep. It's the Bastuck rad that's at fault. Iain

But this doesn't check the first lower seal?

Been there several decades ago!

Thanks Ian my neck is deeper and the cap very similar to yours. Perhaps the simplest way to rectify would be an additional rubber washer placed on the rad neck seal face. I'm not sure a say 1mm steel ring would seal. More testing tomorrow! Iain

Ian, it's as my photos in previous post which measures the depths not diameters. This will determine if there is a bottom seal. Iain

Ian, can you measure neck to seal and cap? Ta Iain

Snap! Well almost

Kevin, there are big dimensional differences in repro manufacturing. The i/d of my rad neck is 41mm and the o/d of my cap bottom seal is 38mm. So there is a 1.5mm all round clearance. From the bottom of the neck outlet tube to the bottom seal is 6.5mm and the thickness of the cap seal and metal pressing is also 6.5mm but with clearance around the periphery water should still escape. I'll run the engine up to temp tomorrow and do the same check on my bottle. One (dangerous) way to check if the system is pressurised is to very carefully release the cap when hot. 🥵 Iain

Somefink wrong 'ere! The depth on my rad neck is more than from seal to seal on the cap! Therefore the bottom seal stands no chance of pressurising the system? Iain

I'm following this thread with interest as my expansion bottle doesn't seem to fill with any water when the engine is hot. I have a Bastuck rad and new cap. Anyone ever measure the depth from the top of the neck to the bottom seal surface? Iain

Kevin said he installed new hoses but worth a try. Kevin as to heat the engine naturally gets hotter when turned of as the heat cannot be quickly dissipated by circulating water and air.

Yes it does which is a real pain! Iain

It gets easier after the third or fourth time 😂 Don't forget the hardened washers and correct grade of nuts. Iain

We all learn by our honest mistakes. At least it seems as though the problem has been identified 🤞 Iain

Kevin's profile says mk3 so it should be the higher torque setting. This could undoubtedly be the cause. Iain

Just a thought, did you have spacers under the rocker shaft pedestals? If you did have you put them back on? Iain