Overheating!

[Bidz]

So, Charlie doesn't like motorways.

According to the temp gauge we've been running at over 120!
We've boiled loads of water off, so we're stopping often to refill the radiator... After cooling off a bit.

When I checked the oil this morning it was only just above the min mark. Should I fill it up??

Currently in Stoke, about sixty miles from our destination.

I'm fairly sure we don't have a leak.

Any thoughts?

[bmcecosse]

Well OF COURSE you need to fill it up to the top mark - but it's nothing to do with the overheating.... Assuming you have checked the fan belt.....and inspected the hated 'bypass' hose........ If it's boiling off water then probably the head gasket has gone and you need to consider if it's wise to continue........ Fill up and run the engine with the cap off - are there constant bubbles streaming up through the water? If yes then game over. If no - you could take a chance and continue home slowly NOT on the M/way - stopping every few miles to check water level. And of course - run the heater all the time..... But frankly - unless only maybe 10 miles or so from home - probably best to phone the Recovery included with your Classic Insurance.

[simmitc]

How do you know that you don't have a leak? The only way to check for sure is to pressurize the system (but don't overdo it). This will show a small leaks that you might have missed. All hoses and the heater control valve are suspect, but then, so is the radiator Is the thermostat working correctly - try removing it as an emergency measure and see it it makes any difference.

Other thoughts: is performance OK - binding brakes and poorly tuned engine can cause problems, particularly on motorways. Check that the water pump is OK - not leaking and not with a worn bearing. The head gasket is certainly a possibility - check as above, but also a quick compression test.

[Bidz]

We made it.

Stuck to nice a roads all the way home and it hardly lost any water - just required about an inch or so every fifteen miles at about fourth mph. I'm home now...

No performance issues., I don't think.

My heater is not connected. The pipe coming off the engine with the valve has a bung in it, the valve is not connected and the return pipe has nowhere to go - the radiator goes into and out of the engine, at the front. Heater return pipe doesn't exist.

Granddad, former Minor owner, says to try removing the thermostat, so should I try that. Can someone explain how it functions?

[bmcecosse]

You can take it out as a TEMPORARY measure - but you must not run the engine for any length of time without a good working thermostat. I've never heard of one sticking shut....but there is always a first time .... It should be tight closed when cold - and opens as the engine heats up allowing water to circulate round the radiator. You can test it by heating it up in a pan of water on the stove. If found stuck shut - then certainly the engine would overheat - BUT - the radiator would be cold (or little more than warm) to touch..... Be sure to have a gasket in stock before removing it - and take care not to snap the studs....(or the housing) ..... Release Oil will be handy !

[Bidz]

Okay. I have access to a hose Sunday so might try a good flush?

Ray what do you think about the lack of heater, shouldn't affect it right?

[bmcecosse]

No - it doesn't NEED a heater to keep cool - but it's a handy way to lose a bit of extra heat when necessary......and it keeps your toes warm.....

[mike.perry]

Side valve Minors run perfectly well without a thermostat or a heater

[bmcecosse]

And could easily top 40 mph - downhill with a tail wind.......

[robby]

It could be a few things. I`m going for the thermostat, they pretty much always stick shut these days, the older types stuck open, so no overheating, but the new designs don`t. Check a couple of simple things first though. Is your fan belt tight enough? Is there anything blocking the front of the radiator? If those check out, then take the thermostat out. It will do no harm to the engine whatsoever. If you had a heater, you would notice it blowing colder than usual and you may have to leave the choke out a bit for longer than if you had the thermostat in, other than that no problem. If all works OK without the thermostat, then replace. If there is till a problem, then I`d go for the water pump.

Rob

[kennatt]

you are getting all sorts of advice,all different, and by now are probably totaly confused. so do this before taking anything off.

make sure there are no leaks,you say not.

From COLD,take radiator cap off,and start engine. give it a couple of bursts of revs,look for excessive bubbling in the water...........indicates head gasket trouble.If no,
now just let the engine warm up ticking over , . Watch the water in the top of the radiator it will initially be still, it will be sort of jiggling about,if the thermostat is working,as it opens you will see that the water is now flowing through the rad.and the top hose will now go from cold to hot as the water is now able to circulate through the engine and rad.If all ok.................
still watching the water in the rad,and assuming the above shows thermostat open,rev the engine(From the carb or get an assistant in the car) if the water pump is ok you will see the level of the water drop down slightly into the rad as the pump draws water down and through the rad and engine...............
Now SWITCH OFF and quickly,feel all over the radiator vanes,everywhere,with the palm of your hand,it should be warm all over,if you feel a SIGNIFICANTLY COLDER area(the bottom will be slightly colder that the top in anycase) that indicates that the rad is silted up and will require flushing or replacing.You need to do this quickly because it will all warm eventually by heat transfer .................
do the above and report back Good luck

[bmcecosse]

Some poor advice two up. Thermostats don't fail shut - they always fail open. Running an A series without a thermostat risks serious damage to the engine - the water will just 'short circuit' around the front two cylinders and the rear two risk serious overheating. Yes - circuit cars run without a thermostat - but they then fit a 'blanking sleeve' which sends the water round all the cylinders. It's fine to ditch the stat for a short test - not for every day. Most likely your radiator is silted up - and a good reverse flushing will do no harm. But if the engine has been at 120C - and possibly short of water - the cylinder head gasket will now be seriously compromised - if it was my engine - I would change it.

[les]

Yes there is a blanking sleeve available for running without a 'stat. Bmc/Leyland wouldn't produce one if it wasn't detrimental to run without.

[Bidz]

Most likely your radiator is silted up - and a good reverse flushing will do no harm.

Take it out, stick a hose on it? Shake it a bit maybe, if it's silted? Doesn't get got at the bottom really...

[bmcecosse]

Hose in the bottom connection..... You can of course use 'Rad flush' - or just some drain cleaner/sodium hydroxide (take care with these) and only leave them in for 30 mins max while you run the engine to generate heat - then flush out very thoroughly.....

[Bidz]

So, we didn't drive the car back up to Liverpool tonight. Instead we left it with a very old family friend, who is going to take it apart piece by piece until he finds the blockage...

[Bidz]

Update - a brand new radiator has solved the problem entirely...

[bmcecosse]

Good thinking - well done for coming back to us.

[Bidz]

I'm hoping to replace the head gasket soon too - I have one waiting - as you said, it will have been compromised at the high temperatures...

[bmcecosse]

It is a worry. You could try just tightening down the head - and resetting valve gaps.... But the ONLY time I blew a gasket was the day after the MOT place boiled up my car by leaving it idling throughout the whole test -when it had no fan.....