Overheating & Juddering?

[DBofficial]

I seem to have two issues, possibly unrelated.

1. When the car is idle (usually when I wait for the oil check and put away my phone etc) before pulling away, sometimes it starts bouncing around until I drive.

2. I have issues with the car overheating. I'm driving the 1.6 auto, I never had a single issue until I changed the cambelt/water pump at 70,000 miles. After that it immediately had issues overheating (110 within 2 minutes of driving and the fan would lose the battle). The car was repaired again, turned out to be a load of rust and gunk backing up against the thermostat. System was flushed, new thermostat and refilled. Problem solved.

A year later and my car randomly overheats driving home. Coolant seemed slightly on the low side, I topped it up. No more issues.

Now today it overheated AGAIN. I'd been stuck in traffic and noticed it was gradually rising over 100 (it did this a few days before but never topped 100 and dropped back to 80/90 once moving) however once we got moving and I climbed a hill it hit 120 and the lights came on to pull over. I cranked up the fans to blow out the hot air from the engine but they just blew colder than ever before... I could not get it to blow hot air. I pulled over and rested the car and managed to finish my journey but the temp was constantly around 115 and would drop to 80/90 and climb back up quickly before dropping (guessing when the fan kicked in?).

Any ideas? Coolant level is good?

[gazza82]

Temp senders have a habit of going wrong and mis-reading. Swap that out first as I had one and it would hit max when driving only to "feel" ok when the bonnet was opened. Swapped out the sender and all was OK again.

[Capncol]

"I cranked up the fans to blow out the hot air from the engine but they just blew colder than ever before... I could not get it to blow hot air."

Heater fan???
Would suggest an airlock. When you topped up coolant, how much did you put in?

[DBofficial]

"Heater fan???
Would suggest an airlock. When you topped up coolant, how much did you put in?"

Yeah, it would only kick out ice cold air, colder than usual despite being set on max, meanwhile the coolant/engine temp was sky rocketing from 90 to 120. Usually if my engine is hot, the air is very hot when on hottest. That did seem very odd. I didn't top it up too much, but the level seemed at min or possibly under (hard to see through the foggy/dark bottle), on a day it had overheated for the first time in almost a year. After that top it, it didn't overheat ever again or even top 90 degrees until the other day, which is 3-4 months worth of daily trips.

Does that still sound like an airlock could be a possibility despite taking 3-4 months to show up? If so, do I need a mechanic to fix that or is it do-able at home?



"Temp senders have a habit of going wrong and mis-reading. Swap that out first as I had one and it would hit max when driving only to "feel" ok when the bonnet was opened. Swapped out the sender and all was OK again."

Ok thanks, I'll get my mate to fiddle with that as he is a qualified mechanic and I don't even know where the sensors are haha.

[Capncol]

If the heater is putting out cold air, then either it is full of air (needs bleeding / low coolant level) or no circulation.
If you don't check the coolant level often, it can drop low enough to draw air into the system and cause problems such as this. You usually can't fill it back up fully unless you bleed the air out.