flushed coolant, seems to be an air lock?

[2001ultima]

All, I flushed the coolant yesterday and changed the thermostat (US car LSD). I took it for a drive today and the car heated up and the temperature continued to climb. I then reeved the engine and the temperature immediately returned to normal. I thought I was fine and continue to drive. Then I noticed the temp going back up again after continued driving. Revved the engine and that helped.

At cold start the passenger side of radiator remains cool for a good time then finally once the thermostat opens the car will cool. Thermostat is working (also tested the thermostat, put it on the stove and heated the water and watched it open at 160+.

Seems intermittent.

Note: the thermostat I removed had no internals, basically the coolant would always flow. One other, it is an LS engine and the heater hose ports on the water pump are blocked.

Any ideas, have you had this problem? Either a bad water pump or air lock. Also, I have no heater hoses (I read you could get an air lock if you don't open the heater valve after flushing and adding the coolant back in)

[Storer]

Never had this problem myself so probably not much help.

Is there a reason you wanted to replace the thermostat and do you need one anyway?

I suspect you will need to bleed the system a few times to sort the problem.



Paul

[RoBe427]

I thought that if you are not using a heater you should link the connections at the pump with a length of hose and not just block them off. Think that's why the "H" piece is in the heater circuit so that if the heater valve is closed there is still a return.

Yes you are correct the heater valve should be open when filling system, a length of hose across the connections would achieve the same effect.

Also jack up the rear of the car when filling with coolant.

Edited by RoBe427 on Sunday 22 June 21:28

[kev b]

I don't know if it is practical for you to borrow or buy one but a vacuum bleeder is an amazing piece of kit and will sort this problem in a few minutes.

[ROWDYRENAULT]

I also have no heater but have had several mid engined cars and bleeding the water system after a coolant change is problematic. Although the presence of a heater or a hose between the in and out of the water pump is not necessary. I am sure that the vacuum device would hasten the process but the other way to do it is raise the back of the car as high as practical. fill the car with coolant run the motor until the thermostat opens this well be apparent by the sudden change in water level in the tank. shut down the motor fill the tank back up, repeat. 2 0r 3 times of this will purge the system of air. Lower the car check the water level and take a quick trip far enough to open the thermostat and all should be in order. If it overheats at this point you still have air in the system. The tell sign to me of an air bubble is that the temp goes up very quickly. Lee

[2001ultima]

Thank you all. good suggestions. I'll keep you posted.

[macgtech]

We tend to have to top up the coolant a couple of times after a flush or engine out. Run it up to temp, leave it for a minute or so for it to pump round, let it cool then top up.

[Nabbott]

Also had reasonable success with 'water wetter' products as these help break down the surface tension (that would be present in 'bubbles') of the water in the system.