advice needed re water level when removing rad cap.
recently had a leaky rad which is now repaired, (and pressure tested!). when i check water level, which is frequently at the moment i find that it is always in the horizontal section of pipe before it curves up to the rad cap. i can top it up as much as i like, but it always returns to this after being run! i know the rad cap is working as i took it off with engine hot...ouch!! some water blew off as expected. i put cap back on and waited for engine to cool, then checked expansion tank and level had dropped, so the water must have been drawn back in to replace what i let out.
looking at the way the water flows and the pipework, is this section supposed to have air in it as it is not part of the circulation "loop"?
i'm taking it to devon next week and i'm a bit paranoid about cooling problems!
regards.

- (#5142) eddie arrowsmith, 15 Aug 02

Eddie, if you've a cap with the spring- loaded valve, that's normal. It's out of the circulation loop as you say, and as long as the level's constant, don't worry.
The toyota rad cap opens to let the water back in at less vacuum, as it doesn't have a spring. It'll purge any air out of the system every time you start.

- (#5143) david miller, 16 Aug 02

thanks david! yep the level seems to be constant. no matter how much i put in it always returns to same level. rad cap is genuine toyota for the vehicle.
whilst i've got your attention i'd like to ask more advice, maybe rob drinkwater would like to comment as well.
i am thinking of changing to electric fan later in year.whilst i was at my local electrical wholesalers today i asked about strap om stats for hot water cylinders. these are only £10 and are adjustable from 40 to 90 degrees.
i was considering getting a dual fan, (i've seen them on some cars). using one stat set at 90 to bring both fans on and one at say 60 to bring one fan on.
i would mount the "hot" stat on/near top hose on rad and "cool" stat on/near bottom hose.
i'd be grateful if you would comment on this, even if only to tell me it won't work!!
regards
- (#5144) eddie arrowsmith, 16 Aug 02

Because of the temperature differential accross the system, you'll find that the cold end of the rad is the right place for both stats. I'm running my system at 55c and 90c, with the "safety" of the aircon fan cutting in at 105c at the outlet elbow.
With this setup, and four 1/8" holes in the coolant stat, the 90c fan only comes on after a hard run, and I haven't noticed the 105c one coming on yet...

Before all my experimenting of the past week, normal running temperature was 102c in the head, now it's averaging 96c.
- (#5145) david miller, 17 Aug 02