M42 overheating big help needed please!

Post Sat Jul 17, 2010 9:09 pm

I have a compact that i have fitted a m42 motor to, i took it for mot today and it overheated on the way.

I have driven the car around the yard many times and its been ok, but i did about 6 miles, 4 to get to the motorway, and 2 on the motorway, and the temp just shot up.

I stopped and let it it cool for a minute, then startd off again, where it then overheated about 1/2 mile later.

Problem is, its off for vic test on monday and i can t miss the apointment, and tomorrow is the only time to get it sorted.

WHat i did notice was that the water in the rad was on max when i startd, that about 3/4 the way up the side of the rad, when i got htere it was full, and when i got back it was empty, it took about a kettles worth. Im wondering if it has an air lock, but im not so sure as i i think i bled it right in the first place. that is heater on, bleed screw open on top of the rad, and waited for the heater to get hot, then closed the little valve and later topped it up.

Can it be a sticking thermostat or something like that?

thanks ;)

Post Sat Jul 17, 2010 9:24 pm

water?
why are you not using coolant?

Post Sat Jul 17, 2010 9:25 pm

how do you mean?

Post Wed Jul 28, 2010 5:04 pm

flush your rad out and put some quality coolant in the rad and let the car be cool lol

Post Wed Jul 28, 2010 5:07 pm

Coolant wont stop the overheating problem.

It could be the thermostat, radiator a number of things, its just a case of eliminating them.

Post Wed Jul 28, 2010 5:18 pm

You don't bleed it until the heater runs hot! Having the heater on full allows water to circulate throught the heater matrix, removing any air locks from there and doesn't show that the coolant system is properly bled.

You need to do it until coolant comes out of the bleed screw. You'll need to "massage" the top rad hose to help work any air out of the system. Once you've got coolant coming out when you squeeze the top hose you'll know that the system is full of water rather than air (watch out, it squirts a bit and is pretty hot).

Post Thu Jul 29, 2010 8:23 am

If the heater was blowing warm air, it was bled. Pull the top hose off the rad and add coolant/water via there slowly. By all means try it with the stat removed but if it still does it, it could be in trouble - M42's crack the head from no2 and 3 cyl exhaust valves to the waterway. But try it without a stat as a temporary thing and also make sure the water pump is okay.