Drippy Rad Cap

[halloween]

Just got the tractor fired up and left her ticking over for a while when I noticed coolant dripping from the filler cap. The coolant was full to the top before I started, but started dripping out within a minute or two. Any ideas on what could cause this? I know about the thermal expansion of liquid but could it be a duff cap??

[Mervyn Spencer]

Hi Halloween

My experience with a drippy cap turned out to be the seat of the radiator neck where the rubber washer of the cap sits or makes contact which had an uneven/raised spot. My leak was actually out of the overflow pipe. I used some emery paper to flatten it off and have not had a further problem. It could also be the rubber wqsher on the cap or a weak spring. What pressure cap do you have?

Mervyn

[halloween]

As far as I know Mervyn, it's the original one. I'll have a better look tomorrow.

[Brian]

The answer lies in your"full to the top". She will blow that out of the cap if it does not seal well, and the overflow pipe until she reaches a level she is happy with. I would not think you have a reason to worry until you have tried her in work and noted the temperature gauge.

[halloween]

Where should the overflow be Brian? I can't say I've noticed one.

The temperature gauge is on the 'to buy' list

[Brian]

From just behind the filler neck, little short pipe with a plastic one pushed onto it and running down the side of the radiator.

If the plastic pipe is missing/split it could be the source of your leak rather than the cap.

[halloween]

Thanks Brian, I'll have a look this afternoon whilst tinkering.

[halloween]

Ah, found the pipe Brian. It appears to be blocked though and the plastic pipe seems to be missing. Noticed also that the coolant level seems to have dropped an inch or two presumably through contraction of the now cold fluid.