Javelin overheating

[conrod]

Just finished Javelin restoration and the engine (not rebuilt) on tick over goes up to nearly 100 degrees
New radiator from the club - well topped up with water
Engine ticks over ok - I stop it before it boils
My first thoughts are -
Airlock - removed radiator cap when cooled down to get rid of any air (heat value open)
Faulty gauge - Not tried yet
Does anyone have any other ideas please ?

[nigel jarrett]

Try Faulty thermostat or water pump

[conrod]

That is a very good call
Water pump was rebuilt but I had not thought of the thermostat

[David Morris]

Hi Conrod,

First thoughts are to remove the thermostat entirely. Jowett's called the Javelin cooling system Thermo-syphon with pump assistance, which suggests they suspected the water pump was pretty useless. It was the first they had used on their vehicles. You could check the gauge with a cup of boiling hot tea?

Second idea is to find a new use for one of those infra red temperature gauge devices that are being used in every school to measure forehead temperatures and in lots of bars and restaurants in this Covid age. You might even have one already? That would show if you have any water circulation problems.

Thirdly, you could see if the header tank gets boiling hot and also if the radiator is hot or cool at the bottom of the core? If it's cool, it suggest there is a blockage somewhere.

Finally, did the club supply you with a radiator having a three row core or the better five row core? Have a look in the header tank to check, although it will be difficult to see into the tank without a mirror? I solved my overheating Javelin by having five row core fitted by my local radiator company. The five row cores are still available in the right size to fit the Javelin radiator frames.

Hope this helps?

Stay safe,

David

[Keith Clements]

I do not like to remind our Vice Chairman of this but I had a similar problem with her SC engine. Amy had made the head inlet gasket and forgotten to cut the hole in the middle.

[Mike Allfrey]

Could also be a build up of silt in the cylinder heads over a long period of time.

There is a JCL Service Bulletin that shows a milling machine cutter used to open up the coolant gallery at the cylinder head core plug openings.

Removing the thermostat does not usually solve over heating concerns.

Any blockages at the coolant inlets at the crankcase?

Regards,

Mike A.

[Keith Clements]

I put a quarter inch drill down these four places. Getting the angle correct may need a bit of thought. It is also easier if the core plugs are out and then you can clean out all the rest of the crap. I have seen these holes totally blocked.

headcleanout.jpg