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Leaking radiator
marting - 3/6/08 at 12:53 PM

Hi Everyone
first of all thanks for the help on the expansion tank cap i have on now.
i have another problem, the is a leak coming from radiator i'm loosing water every now and then. i think its coming from the cap or the bleeding nozzle next to it. i don't even know what car the radiator is from to replace bits. has anyone had this problem before, help

nick205 - 3/6/08 at 01:14 PM

MK usually supply a modified mk2 Escort rad as part of their kits so there's a good chance that's what you have fitted (assuming you bought a built car?).

A few pics will help identify the radiator for sure.

DaveFJ - 3/6/08 at 01:16 PM

Could you have fallen foul of the same trap I did?

I had a pressure cap on my expansion bottle and a pressure cap on my radiator. this seems to have led to air being sucked into the radiator leading to airlocks and overheating - at whcich point it dumped coolant from the radiator - hence it was not happening constantly...

I solved it by pulling the radiator cap apart and sealing up the pressure relief mechanism with that 2 part loeak stop glue stuff. Had no problems since (cross fingers~!)

02GF74 - 3/6/08 at 01:29 PM

as DaveFj points out, you have only one peressure relief cap; either on the radiator in whcih case there is a small tube that goes to a bottled vented to air or else have one on the expansion tank.

why you say you are losing water, do you know where from? antifreeze will leave a cryslline deposit. or get some white hand towels and put around warous parts of the colling system to trace the leak (obviously aeway from exhaust and hot spots).

don't discount the possiblity of the water could be leaving via the engine too

marting - 3/6/08 at 01:32 PM

Hi Dave thanks for the advice
i don't think i'm quite sure what you mean. are you saying the water is leaking out of the bleeding mechanism because the cap is not sealing properly and sucking air in

DaveFJ - 3/6/08 at 01:38 PM

I beleive that the presure caps are designed to release pressure at a certain point but the design also allows air to be sucked into the system... that was the explanation I was given anyway and teh advice seems to have paid off! I decided to keep the presurised cap on the expansion tank rather than the Rad because it was higher up.

marting - 3/6/08 at 02:07 PM

I Have just had a thought when i did a trackday at the weekend the cap off the expansion tank blew off and had to replace it because i couldn't find it i just thought i hadn't tightened it properly. do think it blew off under pressure and thats why i am getting the leaking. prssure caused by air locks maybe

DaveFJ - 3/6/08 at 02:12 PM

cap should have vented long before enough pressure built up to blow it off....

marting - 3/6/08 at 03:00 PM

i think i'll go with the sealing up the radiator cap first ,cheers

02GF74 - 3/6/08 at 04:38 PM

quote:
Originally posted by DaveFJ
I beleive that the presure caps are designed to release pressure at a certain point but the design also allows air to be sucked into the system... that was the explanation I was given anyway and teh advice seems to have paid off!


yes and no.

radiator cap with overflow tank. the water will expand and push the cap open overflowing into the tank. when water cools, it sucks water back into the radiator. you would normally fill the radiator up to the neck so there is virtually no air in the system.

expansion tank is different - and I may be wrong here - but there is ussually air in the tank. you fill the tank to some mark on the side of the tank and as the water expands, the water level rises. air inside the tank is compressed and once it reaches a certain pressure, I guess the cap has to vent. as the water cools air has to be drawn in or else the tank or hoses collapse due to negative pressure.

So one system draws in air and other does not.

DaveFJ - 3/6/08 at 04:46 PM

depends on the rad I suppose

I have a polo rad and the cap on that vents (did vent!) under pressure and just dumps the overflowing fluid onto the floor....