Cooling system curiosity

I have my fill neck mounted in-line on the upper radiator hose because my rad sits a couple inches below. I put a 16 lb cap on the radiator and a 9lb on the fill neck and then hooked that to an recovery tank. After noticing it was getting alittle warmer than it had been and the tank was actually gaining on coolant and the system seemed to be emptying itself out , I had the idea to switch the high and low caps and re hook the tank to the lower overflow. I'm not sure if this manuver will gain anything or even makes any sense. I may have found the problem afterwards in a slightly loose lower rad hose connection, allowing the system to vent instead of pulling back thru the tank? Anyway, should it make any difference where the recovery tank is hooked to once the system is full?

It shouldn't make a difference as long as the recovery tank is connected to the lowest presure cap.

You would normally want the recovery tank conected to the highest point in the cooling system so air in the system will be blead off.

You might want the recovery tank to be below the conection. That way the tank won't drain every time you remove the rad cap. Like mine does.

M1D

Took it out as is today, hitting the flea market and a couple yard sales , ice cream stand, just a good round the really big block cruise, no sign of anything leaking or over heating, will pop the cover tomorrow and see where the level is at.

just currious about the 2 different pressure caps on a 2 cap sys.
they will work just like a chain, only as strong as its weakest link.
9 lbs of pressure will be all that sys will hold. I`d tee them togeather
and to a recovery tank with 16lb on both caps.
the higher the pressure the higher the temp before boiling over,
just something to think about.

I checked it cold the next day after the little tour, the fluid level was at the lower cap which was the 9lber, but i had gotten rid of the leak in the big lower hose , the temps were doing fine. I switched them back to the original positions
again for now 9 on top 16 on bottom, going to run it around some this after noon and recheck again. I think you may be exactly right on T-ing 2 16s together. I was thinking old school top tank rad with the 9lb cap, I am running a cross flow, it seems to make sense to me , my thinking was the 9lb on top would be the weak point but the pressure may be way to low for the set up , thanks for the suggestion, I will try that.

I made the switch to 2-16 lb caps and T'd the overflow hoses together. It is working the way it's supposed to now. The coolant is staying completely full in the system and the recovery tank is doing it's job. The temp holds steady at 185-190 right with the thermostat. Thanks for the excellent suggestion Panelmanrd !

was just a thought, glad it worked. always great to see one run
cool!!!!!!!!!!!!!

I've got an old mercedes that is a bear to bleed. Will overheat till it is bled. The trick, one of a few, is to drill about 3 little holes in the collar (don't know if that's the right word) of the actual thermostat. Allows it to bleed air and move just a tad of coolant while cold. Save a little overheating by waiting or it to warm up to bleed. Will try it on my van as the geometry for all the parts is about the same.

And, I use as low a pressure cap as I am to keep them running as the lower the pressure the less likely is a catastrophic failure like a hose blowing. Of course, if you aftermarket A/C it will be hard to get around low pressure caps. I leave high pressure to the race cars and new cars that are way overdesigned IMHO.

Happy motoring, Mark