JamieP Posted June 6, 2011 Share Posted June 6, 2011 I think i lost a bit of water from somewhere as i could see some fluid on the undertray, everything has now been nipped up so hopefully thats the end of that, i was under the impression if the rad was low it would pull water from the overflow tank? this dont seem to be the case, brand new rad cap and also checked the overflow pipe is clear, any ideas why its not pulling water from the tank when needed or is this not the case? Quote Link to comment Share on other sites More sharing options...
Mace Posted June 6, 2011 Share Posted June 6, 2011 Mine hasn't either and my rad has a big hole in it.. Quote Link to comment Share on other sites More sharing options...
imi Posted June 6, 2011 Share Posted June 6, 2011 it should pull water from the expansion tank when needed. is the pipe in the expansion tank submersed in coolant? imi Quote Link to comment Share on other sites More sharing options...
JamieP Posted June 6, 2011 Author Share Posted June 6, 2011 Yeah fully submersed, stock cap and pipe. Quote Link to comment Share on other sites More sharing options...
sideexitsupra Posted June 6, 2011 Share Posted June 6, 2011 We found the same issue on SteveLs race car at Donnington a few weeks ago. Also mine was the same! Strange to say the least. Quote Link to comment Share on other sites More sharing options...
dwayne Posted June 6, 2011 Share Posted June 6, 2011 block in the expansion cap piping? maybe somethings blocking air flow so it cant syphon the fluid Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 6, 2011 Share Posted June 6, 2011 it wouldnt suck water back through from the expantion bottle if it wasnt getting preasurised, but i would expected you would see steam on a run or after you have stopped Quote Link to comment Share on other sites More sharing options...
JamieP Posted June 6, 2011 Author Share Posted June 6, 2011 We found the same issue on SteveLs race car at Donnington a few weeks ago. Also mine was the same! Strange to say the least. Well, at least im not alone. block in the expansion cap piping? Pipe was checked. Quote Link to comment Share on other sites More sharing options...
dwayne Posted June 6, 2011 Share Posted June 6, 2011 sorry, meant the small hole under the rubber on the inside of the cap next to the small length of pipe that goes into the bottle, either that or the overflow itself. i'd imagine that if either of those was blocked it would struggle to get water into the rad Quote Link to comment Share on other sites More sharing options...
Havard Posted June 6, 2011 Share Posted June 6, 2011 As a heating engineer I can't understand the cooling system in the Supra for one minute. The expansion tank seems to be only capable of topping up the rad at best and if you lose water from the highest point in the system (near the bulkhead) you would get airlocks that would stop the liquid from the expansion bottle entering the system naturally. I put a copper top up connector on my NA at the highest point and filled the system from there instead of the rad. Never had a problem after I fitted this, although I never had any more leaks after that. It did give me a very easy way of checking the fluid level as I didn't trust the expansion tank. H. Quote Link to comment Share on other sites More sharing options...
snake Posted June 6, 2011 Share Posted June 6, 2011 I thought that as the water in the rad was heated and expanded it would vent into the expansion tank, and as the rad cooled it would suck the water back into the rad as it created a vacum. I would imagine the the expansion tank also needs to be at the right height in relation to the rad. Quote Link to comment Share on other sites More sharing options...
Havard Posted June 6, 2011 Share Posted June 6, 2011 I thought that as the water in the rad was heated and expanded it would vent into the expansion tank, and as the rad cooled it would suck the water back into the rad as it created a vacum. I would imagine the the expansion tank also needs to be at the right height in relation to the rad. Granted, but if water is lost from the main system you can't create a vacuum. You would expect gravity to put the water back into the system but the expansion tank is only 3/4 of the way up the system. H. Quote Link to comment Share on other sites More sharing options...
DodgyRog Posted June 6, 2011 Share Posted June 6, 2011 Is this the Black beast or the V8, reason I am asking is I said to about a similar problem Fearless was having on his V8 Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 6, 2011 Share Posted June 6, 2011 Some aftermarket caps don't allow the coolant to be sucked back from the expansion tank properly, the return valve is incorrectly set. I would wager you have a none OE cap on it? If you are building a race engine you are better off running a big header tank, as a closed circuit system, with a bleed pipe off the system back to the header tank, and a stiff cap pressure. Be aware running higher coolant pressures can find weak spots like old heater matrices, not that a race car would have one. Quote Link to comment Share on other sites More sharing options...
JamieP Posted June 6, 2011 Author Share Posted June 6, 2011 Fluidine rad/cap Chris, its worked just fine for years but we did recently fit a new cap, maybe its faulty, will try another. Quote Link to comment Share on other sites More sharing options...
GazB Posted June 6, 2011 Share Posted June 6, 2011 Check the rubber seal inside your rad cap, i had this problem and tried lots of different thing (move res tank, new piping, etc) until it was noticed the rubber seal was to small and not giving a full seal Old inner tube and new seal was fitted, works perfect now I've got a PWR rad with the cap supplied with it, red lever type, odd size though, tried a Stant and i was wrong size. I've got a PWR dealership close by but as yet i've not tried them for a new cap. Quote Link to comment Share on other sites More sharing options...
JamieP Posted June 6, 2011 Author Share Posted June 6, 2011 Everything is pointing towards a dodgy cap then, cheers guys, will look into it. Quote Link to comment Share on other sites More sharing options...
dude Posted June 7, 2011 Share Posted June 7, 2011 I think people are missing the point here, the rad will only suck water back into itself from the exp tank that it has expelled into that tank, if JP has lost water from the rad it will not suck from the exp tank, does that make sense??? Bit how a re breather in diving works. Quote Link to comment Share on other sites More sharing options...
Westy Posted June 7, 2011 Share Posted June 7, 2011 Interesting - let us know how it fairs after a new cap is fitted. Quote Link to comment Share on other sites More sharing options...
dude Posted June 7, 2011 Share Posted June 7, 2011 Interesting - let us know how it fairs after a new cap is fitted. Didnt bother reading the last post then Quote Link to comment Share on other sites More sharing options...
JamieP Posted June 7, 2011 Author Share Posted June 7, 2011 Thanks dude, won't bother with a new cap for now in that case, Lee fixed the leak, I will keep an eye on the water level now, hopefully a simple fix. Quote Link to comment Share on other sites More sharing options...
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