Air lock somewhere

Post by **paul72** » Fri Jan 03, 2014 8:06 pm

Still not solved this problem yet any ideas people .
Car warms up fine an have fitted new thermostat but when u put heater blower on its hot for a min then goes cool then if you turn off for few mins an back on it does same hot then cool . Still freezing my ass off

Post by **GreenyUK** » Fri Jan 03, 2014 9:18 pm

I think it's still an air lock mate, try bleeding it through again.
Had this problem with my mrs BM had to bleed it 3-4 times before it was ok. It's now toasty inside

Air locks can be a right c***
Good luck.

Post by **paul72** » Fri Jan 03, 2014 9:57 pm

Which way do you bleed it as been told a couple ways one with cap off an running or cap on an bleed nipple on thermostat undone?

Scott560 · Post by **Scott560** » Sat Jan 04, 2014 11:37 am

normally, on older cars, the small heater matrix just gets clogged up with silt, this is my experience with 'tracking down heater problems' when things have been disturbed.

When the coolant is drained, by virtue of its position and hose routes, the heater matrix generally tends to get left with all the crap and silt in it.

I've never had an airlock that couldn't be removed (in various scenarios on lots of cars) by running with the cap off or squeezing hoses, few heat up cool down cycles etc (you might say i dont believe in airlocks!).

my knowledge of 4th gen is slim, but i would check (with a hose pipe) that the valve works as it should, and then flush (in both directions) the heater matrix. Not the most pleasent of jobs, youll get water all over yourselv and engine unless you have an assistant on the taps!

I've seen cars where new coolant is added, goes in and comes out all clean, flush the heater matrix, and tons of rust coloured crap comes out.

Also, if you bought your thermostat of ebay, can't hurt trying another one, as some times thermostats ive purchased have been 'lazy' out of the box, and dont keep the car at the right hot temperature (eg over cool, get stuck open a little).

Post by **GreenyUK** » Sat Jan 04, 2014 4:14 pm

As a few have said dude, can't go wrong with cap off. I too have never failed with this method. Air wants to get out it always wants to get to the top and this is the radiator cap on most

Good luck with it mate hope you sort it soon

Bludge · Post by **Bludge** » Sat Jan 04, 2014 4:51 pm

Good call on double checking the hoses too, its worth a good old look as i didnt notice i had refitted one of my coolant hoses on the mondeo badly when i did the thermostat and it was causing very similar problems.

bb1boy · Post by **bb1boy** » Mon Jan 06, 2014 3:08 pm

For what it's worth, it took me AGES to properly bleed my coolant system after fitting a new rad.. and the cooling system on a Prelude is very efficient, I thought my fans/switches etc were screwed, turns out I was just impatient.

Post by **paul72** » Mon Jan 06, 2014 6:24 pm

Cheers it will probaly work wen its summer