Don't repair what's not broken advise please

[Richiebhoy]

Never had a problem with overheating until now. Had rack refurbed so while fitting that replaced all hoses and connectors with act silicone and stainless. Decided to put upgraded temp sensor and new thermostat. All good so far. Distiller water, water wetter red anti freeze. Now blew on expansion cap running about 103 degrees, and both fans kicked in at about 68 degrees. Usually fans come in at 80 and 90. Confused? I might have air in system so going to bleed again tomorrow following advise on here. What throws me is fans kicking in so early, any ideas? Thanks in advance :-(

[phillpot]

Sounds like air lock to me.

without proper circulation fan switch could have been sensing a different temperature to the temperature gauge sender

[Richiebhoy]

phillpot said:

Sounds like air lock to me.

without proper circulation fan switch could have been sensing a different temperature to the temperature gauge sender

Sounds like good advise. Had an inkling of air in system but the fans threw me.

[Byker28i]

Air lock, almost certainly. It helps to put it on a slope so the bleed points are the highest.

[Richiebhoy]

Byker28i said:

Air lock, almost certainly. It helps to put it on a slope so the bleed points are the highest.

Got some air out this morning. Fans kicked in at 80 bleed it 4 to 5 times. Radiator bung constantly under pressure so can't put fluid in through that plus the water is ice cold combining up from bung and bottom hose cold has well and cat at 90 degrees. Could the thermo be not working. Thanks

[Supateg]

Just to clarify, you have bled at the water rails taps.
If you have and still got the airlock a washer tube slips on from these to the expansion tank with them open may force it out while running.
Also the expansion coolant level likes to be low in the tank. Anything over 1/3 on mine and it blows it out until it's happy!

[Supateg]

I've never had any major issue bleeding, as long as the nose is up a touch.
Best test the thermostat the old fashioned way!

[Richiebhoy]

Really sure virtually all the air is out. Fans kick in@ 80 but engine still gets hot. Top hose hot bottom ice cold.

[Supateg]

This adds more complication to the issue....

http://www.pistonheads.com/gassing/topic.asp?t=119...

Looks like a straightforward replacement thermostat is a minefield.

[MoonMonkey]

Supateg said:

Looks like a straightforward replacement thermostat is a minefield.

Agreed! I had a seized thermostat so I replaced it with a brand new Quinton Hazel QTH221 made by Wahler (original part?). Checked it in a bucket before fitting, and it worked ok, fitted it and it didn't work. Took it out and checked it again - didn't work.

Had to replace with a pattern copy made by Gates but opening temp was too low - 78oC

In the end I eventually replaced it with the Racetech Direct one. Expensive, but it works ok and at the right temperature - 84/85oC