Mike M Posted October 3, 2008 Share Posted October 3, 2008 Just a quicky. My stock top pipe from the rad to the engine seems to suck in on itself once the cars cool and if I undo the rad cap it becomes a pipe again. Its fine while the engines running but have to admit it looks a bit bloated. I'm guessing the blitz 1.3bar rad cap is showing up the hose as being knackered. Anyone seen this before? Cheers Mike Quote Link to comment Share on other sites More sharing options...
wile e coyote Posted October 3, 2008 Share Posted October 3, 2008 That dont sound right Quote Link to comment Share on other sites More sharing options...
magictorch Posted October 3, 2008 Share Posted October 3, 2008 Thought it was advised to use a stock 1.1 rad cap as well? Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 3, 2008 Author Share Posted October 3, 2008 (edited) Its on a Koyo rad so cant use a stock cap. I know these pipes can sag with age and have heard of them hitting the fan belt but not heard of them doing this. The hot cooling system must be pulling a vac as it cools, certainly shows theres no leaks in the system at least. Edited October 3, 2008 by Mike M (see edit history) Quote Link to comment Share on other sites More sharing options...
heckler Posted October 3, 2008 Share Posted October 3, 2008 Its on a Koyo rad which so cant use a stock cap. I know these pipes can sag with age and have heard of them hitting the fan belt but not heard of them doing this. The hot cooling system must be pulling a vac as it cools, certainly shows theres no leaks in the system at least. but thats why you have an expansion tank, when the coolant gets hot, the coolant expands and flows into the tank, and as it cools, it should suck it back in - so if you ask me, you rad cap is only doing half its job! Quote Link to comment Share on other sites More sharing options...
Ben-san Posted October 3, 2008 Share Posted October 3, 2008 Apologies for guessing, but if there's too much vacuum, I would think it's some sort of blockage to the expansion bottle. Is the level on the bottle going down after you switch off? Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 3, 2008 Author Share Posted October 3, 2008 but thats why you have an expansion tank, when the coolant gets hot, the coolant expands and flows into the tank, and as it cools, it should suck it back in - so if you ask me, you rad cap is only doing half its job! Yeah but the port for the expansion tank is between the sprung seal in the cap and the top seal of the cap. Under pressure the sprung part lifts letting coolant to the exp tank so how does coolant get back from the tank. Quote Link to comment Share on other sites More sharing options...
heckler Posted October 3, 2008 Share Posted October 3, 2008 Yeah but the port for the expansion tank is between the sprung seal in the cap and the top seal of the cap. Under pressure the sprung part lifts letting coolant to the exp tank so how does coolant get back from the tank. dunno, but it gets sucked back in!! erm... teleportation? Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 3, 2008 Author Share Posted October 3, 2008 Apologies for guessing, but if there's too much vacuum, I would think it's some sort of blockage to the expansion bottle. Is the level on the bottle going down after you switch off? Never looked that closely to be honest but i'll have a look next time. I always check theres a level of coolant in there whenever the bonnets up. dunno, but it gets sucked back in!! erm... teleportation? I'll patent it then if it is. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 3, 2008 Share Posted October 3, 2008 Either the valve in the rad cap is faulty or the hose from the rad filler neck into the expansion tank is blocked or kinked. Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 3, 2008 Author Share Posted October 3, 2008 Either the valve in the rad cap is faulty or the hose from the rad filler neck into the expansion tank is blocked or kinked. Cheers Chris I'll check it out, the rad cap is only a few months old. How does the coolant get back into the rad from the expansion tank, I know the rad cap spring lifts off its seat to let coolant out the rad but cant think how it goes back. Cheers Mike Quote Link to comment Share on other sites More sharing options...
imi Posted October 3, 2008 Share Posted October 3, 2008 there should be a pipe that will syphon it back into the rad.... Quote Link to comment Share on other sites More sharing options...
heckler Posted October 3, 2008 Share Posted October 3, 2008 taken from "how stuff works" "When the pressure reaches 15 psi, the pressure pushes the valve open, allowing coolant to escape from the cooling system. This coolant flows through the overflow tube into the bottom of the overflow tank. This arrangement keeps air out of the system. When the radiator cools back down, a vacuum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow tank to replace the water that was expelled" Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 3, 2008 Author Share Posted October 3, 2008 Thanks for the help guys, I'd best have a look at the expansion tank tomorrow hopefully just a kinked hose somewhere. Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 4, 2008 Author Share Posted October 4, 2008 Had a look today, Rad cap spring is ok and you can see that its sealing on the lower seal face inside the rad. I removed the hose from the rad and tank and blew through it which felt blocked initially before clearing. Almost had the tank removed just to check underneath for another hose but couldnt find any so somehow the coolant gets back into the rad. That'll be why the tank top cap has the pipe going to the bottom of the tank. Does the rad cap also have a vacuum spring too as well as pressure relief? Quote Link to comment Share on other sites More sharing options...
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