[Mk2] [NA] Weird overheating problems

[quazmo]

Hey guys had a post about this before but didn't get farther the car is a 1992 rev 2 n/a . the car is overheating randomly.i mostly do short ten fifteen min journeys to work and back but if I do a lengthily journey on the motorway when I come off it and slow down a bit the gauge climbs to about 3/4 of the way. If I coast it it drops and if I pick up speed again it will drop back down slowly I have just changed stat and bled it twice and it seems to be still doing it and my rad fans seem to never come on but j have found no faults with circuit and fan comes on if I pull plug on fan switch . Any ideas would help greatly

[Ryan S]

sounds like an airlock, have you (not meaning to sound patronising) read the correct way to bleed it??

[quazmo]

Yea I have my only problem with bleeding it is that it seems someone changed to rad at some point and I have nowhere to attach the hose too on the rad I just have a screw type valve on it which may be stoping me from bleeding it properly

[Ryan S]

Yea I have my only problem with bleeding it is that it seems someone changed to rad at some point and I have nowhere to attach the hose too on the rad I just have a screw type valve on it which may be stoping me from bleeding it properly

are you jacking the car up while bleeding it??

[quazmo]

No will try that tomorrow when I have another does it make a big difference then jacked up

[Ryan S]

No will try that tomorrow when I have another does it make a big difference then jacked up

i believe you have to jack up the rear, but yes, jacking it up is the correct way to do it, otherwise the air won't move, think of a spirit level, if it's level, the bubble won't move

[quazmo]

Cool thanks will do that tomorrow and let you know how I get on xxx

[quazmo]

Well tried bleeding it again and with rear end jacked up and got some bubbles out but car still gets to about 3/4 up gauge and I found that the driver side of radiator is stone cold while drivers gets hot I am guessing there is an air lock still in it somewhere any ideas on where to narrow it down a bit

[abovetherim]

Well tried bleeding it again and with rear end jacked up and got some bubbles out but car still gets to about 3/4 up gauge and I found that the driver side of radiator is stone cold while drivers gets hot I am guessing there is an air lock still in it somewhere any ideas on where to narrow it down a bit

I would be flushing out the rad first

[quazmo]

Right will take it out tomorrow and flush it as well and start again

[abovetherim]

whilst you have the coolant drained, when was the last time you replaced the t-stat. This can also have a massive effect on the cooling. I always use OEM t-stats as i have had too many motor factor patern ones not last or fit properly. And whilst your flushing ; flush and back flush the engine also

[quazmo]

I fitted an oem stat last week which has got the car getting up to temp quicker but it overheats sooner as well but never more than 3/4

[quazmo]

Right quick update to the rad out flushed it fitted a new bleed valve to top flushed system bleed it again for the 89th time and got the exact same result the temp gauge goes to just under 3/4 and stays there could the stat I have be wrong I bought it off a guy who said it was and it was genuine but it seems to be running a tad warm but never overheats properly also the pipe behind it never gets hot it just stays cold when running

[moscoworbust]

Minw was ovewrheatign randomly.

I go a thermostat from UNIPART, 7 quid. Get one to remove doubt? as it worked for me.

Drained it from rad, under the car pipes and the engine drain plug.

Filled, bled.

Took it for a drive, overheated again. It was an air lock, put more coolant in on the side of the road and has been perfect.

If it's staying at 3/4 i would get the correct thermostat.