Over heating

[DBarber]

Hi any advice on ulster A7 1931, overheats when idling, how full should system be, presumably need to allow for expansion, also is there A water pump . Cheers

[Hedd_Jones]

Itll find its own level. Somewhere about 1/4 inch above the core isnt unusual. Sometimes a smidge more. Itll spit the excess out of the overflow

[Chris KC]

The water level should normally be about 3/4" - 1" above the top of the radiator core (anything higher than that will find its own way out anyway).

Sports cars often have slightly reduced water capacity, especially if the rad has been re-cored. That said, mine runs alright with 5 1/2 pints capacity (certainly doesn't boil at tickover).

No there shouldn't be a water pump (not on a conventional A7 anyway). It's a thermosiphon system.

Use water (or water + corrosion inhibitor), not anti-freeze.

Is this a newly re-built engine? They can get pretty hot when first running in.

I would check to be sure the ignition timing is approximately correct.

Quite likely you may have some scale/ rust/ obstruction in you water passages. The 'easy' way to deal with this is a de-scale kit from Halfords. The downside is that a lot of the debris it creates will remain in your engine, and may make matters worse. The hard way is of course to strip down and clean out part by part. Or perhaps both in combination.

You can check for a radiator blockage by spraying a mist of water over it when hot, patches which stay wet indicate possible obstruction. Or simply feel for temperature differences with your hand.

In my experience the worst spot for blockages is the side water manifold, why not try removing that? It might be clear or it might be blocked solid.

[DBarber]

Great thanks a lot will give it another go.

[Greig Smith]

An old trick is to insert the toe of a ladies stocking into the upper radiator hose (although if she lets you remove her stockings she might not be such a lady...)

Drain the radiator, remove the hose at the head, poke about 6" of stocking up the inside of the hose with the handle of a screwdriver, fold the open end around the hose, refit the hose and trap the flappy bit of the open end under the lower hose clamp. Don't be tempted to stick the stocking in at the upper end of the top hose, it then goes into the header tank and snags on the fins and you have to tear it apart to get it out the tank... guess how I know this. You want it to be sitting neatly inside the upper rad hose as it's easy to pull out with all the muck trapped inside.

It acts as a microfine filter and traps all of the muck floating around the system, especially if you've been rooting around inside there or added a dollop of descale stuff - keep an eye on the radiator, if there's a lot of muck, you can block the system quite quickly. I usually do test runs with a gallon of water in the car. It's worked just fine for all our old cars from the 7's to '30 Triumph Super 7, Model A Ford, all the Alfa's & even the Nissan Silvia Coupe. We have a tropical climate so effective cooling in sunny summer temps is vital

Aye
Greig

[Reckless Rat]

If you look into the radiator from the filler hole you should be able to see a semi circular cut out in the filler neck. Ideally fill the radiator to the bottom of that, or it will just spit it out through the cap or the overflow.

However, assuming your car has a fan (some specials don't) then the capacity of the the thermosyphon system is usually large enough to cope and prevent overheating. In your case, either there is some restriction in the radiator (a back flush might help) but a more common problem is that of the galleries in the head & engine block have become blocked with rust and crud. To clear them will need a cylinder head removal as well as the side water branch. Be particularly careful though if you have to remove it because the corrosion can cause studs to shear off. Once removed you can poke, prise or blow the muck out. It will make a considerable difference to cooling.

Good luck.

[DBarber]

Thanks, very helpful

[Tony Press]

I assume you have checked the water pump.

[Robert Leigh]

I recently had my Ulsteroid Special homemade radiator repaired; a lot of the soldered seams on the fabricated header tank had started to leak. My repairer obviously cleaned it all out properly because it is running at a considerably lower temperature than it was, so I have two good results. Because running temperature had increased previously I had considered using a pressure hose into the cylinder head connection to see if anything was washed out from the block by this means, so although I did not have to do this I offer it as a suggestion. Thermosyphon circulation has not got enough oomph to shift the muck.
Robert Leigh

[DBarber]

Guys, where is the overflow located, ours seems to be a totally sealed system, no overflow or relief valve built into the rad cap?