Temperature query

Hi, all, had a ride to the show today in Astley Park in Chorley, on the way home the temp gauge went right up to the top of the green section before settling back down. I replaced the rad and hoses before the gearbox was repaired and filled the coolent as per spec, could it be an airlock? Checked level once it had cooled down, about an inch or so from filler cap. Haven't seen it do that before.

Mick

Had a couple of thermostats giving that problem before, Is the de gassing pipe from inlet manifold to rad still free and flowing?
Clive.

Hi, Clive, you've mentioned that previously, and to my shame I ignored it, sorry. I'll check it next time I start it, what's the issue if it isn't flowing? I changed the thermostat also.

Mick

Those symptoms are usually when you have air trapped somewhere in the system or the coolant is too low i.e. there is little or no hot water in contact with the stat. The stat should have a "jiggle pin" or a small hole which should be located at 12 o'clock to purge any air and let the water contact it from behind.

Many of the cheapo stats don't have a jiggle pin only a small cut out.
Drill a 1/8 hole instead.
Up until recently I've had a couple of sticking stats on minis that had only been in for a short while.
Clive.

I seem to recall seeing something on the stat, I picked it up from Wadhams when I got the rad. Am I right in thinking if there is air in the system it will purge itself? Certainly not losing any water from anywhere.

Mick

If everything is working as it should I normally run engine at approx 1500 revs at time of filling and once top hose is hot (thermostat opens ) top up to 1 inch of filler neck, sometimes you can see the water flowing across rad once stat is open.
Make sure heater is blowing hot as well showing all is flowing correctly.
Once cold recheck level.
Clive.

clive P62 said:

If everything is working as it should I normally run engine at approx 1500 revs at time of filling and once top hose is hot (thermostat opens ) top up to 1 inch of filler neck, sometimes you can see the water flowing across rad once stat is open.
Make sure heater is blowing hot as well showing all is flowing correctly.
Once cold recheck level.
Clive.

Click to expand...

Thats a Top Tip Clive -

A properly operating cooling system will leave the radiator water level about an inch to 2 inchs below the neck level of the radiator when cold, totally normal.

Graeme

machman767 said:

Hi, Clive, you've mentioned that previously, and to my shame I ignored it, sorry. I'll check it next time I start it, what's the issue if it isn't flowing? I changed the thermostat also.

Mick

Click to expand...

If the pipe is blocked off, then the highest point in the manifold which is the carb tower can gather stray air bubbles and cause a hot spot and the associated misery. Normally, the little spigot that the hose fits onto is clogged up with crud and in bad cases, it goes all the way into the carb tower.
Clearing it is done by digging it out, a small drill bit in a vise grip should do the job, and if it extends all the way into the tower, then a nail and a buggering stick followed by a bigger buggering stick if that doesn't work is the way to go. Alternatively, you can remove the manifold and pop the Welch Plugs out the tower and clear it out that way.
Check that you can get replacement plugs, though, as they are not the same size as the block ones.

On my car, if the water level is a bit down I can see the inflow of water from the pipe from the manifold tower.

The little bleed hole on the thermostat must be at 12 o'clock position to allow air to trickle through the highest point.

Chnecked the stat yesterday and found I'd put it in wrong, with the hole at about five o'clock. Moved it to 12 o'clock and took daughter to Preston station this lunchtime in v.hot weather, temp needle never went beyond the middle of the numbers so job done, cheers, all.

Mick

Simple as that!!!