hot and cold

[super8simon]

Hello again.

At what point should the expansion tank start filling with water? I just got back from a short journey, the temp guage had just reached the normal, just below half, point on the guage, and as I was topping up my window washer fluid I noticed that the water level in the expansion tank was above the max level (It's at max when engine cold.) The top of the radiator felt cool on the left side and only slightly warmer near the top hose. The top hose, bottom hose and all the hoses to the heater matrix were all warm to the touch. I'm pretty sure there are no air locks in the system as I've been running it with heaters working fine and no change in the coolant level for weeks. I did put the aircon on for the first time in a while a couple of days ago. Could that cause an air lock? Could it be a dodgy thermostat?

Cheers

Simon

[Koi]

Hello again.

At what point should the expansion tank start filling with water? I just got back from a short journey, the temp guage had just reached the normal, just below half, point on the guage, and as I was topping up my window washer fluid I noticed that the water level in the expansion tank was above the max level (It's at max when engine cold.) The top of the radiator felt cool on the left side and only slightly warmer near the top hose. The top hose, bottom hose and all the hoses to the heater matrix were all warm to the touch. I'm pretty sure there are no air locks in the system as I've been running it with heaters working fine and no change in the coolant level for weeks. I did put the aircon on for the first time in a while a couple of days ago. Could that cause an air lock? Could it be a dodgy thermostat?

Cheers

Simon

As soon as water starts to get hot it expands, as you don't say by how much water the level in the tank had rose its hard to say.
If say it was full up then I would say problem, possibly air lock, dodgy stat, head.
If it was only a little possibly air lock, stat.
Air can get in the system even if you haven't flushed it for ages, eg if you had a small water leak (not even noticeable to see) the water that gets out has to be replcaed and it will be replced with air. Air expands far quicker and greater than water.

[super8simon]

As soon as water starts to get hot it expands, as you don't say by how much water the level in the tank had rose its hard to say.
If say it was full up then I would say problem, possibly air lock, dodgy stat, head.
If it was only a little possibly air lock, stat.
Air can get in the system even if you haven't flushed it for ages, eg if you had a small water leak (not even noticeable to see) the water that gets out has to be replcaed and it will be replced with air. Air expands far quicker and greater than water.

It could well be an airlock, I'll squeeze my pipes when the engine's cold and try and get rid. The water level was I guess only about a third to half an inch above the max line, but the motor had not long been to temp. Just out of interest how far above the max would you expect the level to be after a run on a healthy motor?

Thanks again

Simon

[Koi]

It could well be an airlock, I'll squeeze my pipes when the engine's cold and try and get rid. The water level was I guess only about a third to half an inch above the max line, but the motor had not long been to temp. Just out of interest how far above the max would you expect the level to be after a run on a healthy motor?

Thanks again

Simon

12 mile or 242 mile doesn't matter once it up to operating temp it should be the same unless you got a problem. Mine rises about 2/3rds up the expansion bottle and once cooled back down to the max mark.
I would say as long as it don't overflow any level should be OK.

[super8simon]

12 mile or 242 mile doesn't matter once it up to operating temp it should be the same unless you got a problem. Mine rises about 2/3rds up the expansion bottle and once cooled back down to the max mark.
I would say as long as it don't overflow any level should be OK.

Cheers Koi, set my mind at rest again.

Simon

[da SLUG man]

12 mile or 242 mile doesn't matter once it up to operating temp it should be the same unless you got a problem. Mine rises about 2/3rds up the expansion bottle and once cooled back down to the max mark.
I would say as long as it don't overflow any level should be OK.

so long as it covers the botom of the pickup pipe when cold! else it will suck air back in.