Need a coolant cap

Post by **Alan8086** » Wed Apr 17, 2019 2:57 pm

Can someone point me in the direction of were to buy a new coolant cap for my 24V? Its the one to the lower right of the engine bay - that overflows into the reserve reservoir.

I cant see anything convincing on eBay - the filler cap to the upper left of the engine is different to the cap to the lower right of the engine bay IIRC. None of the listings mention that difference.

I made a rare long journey in my Probe yesterday to see my parents in Cheshire.
I checked the coolant levels before leaving - the overflow tank was near empty so i topped it up. Checked again before I left from Cheshire and had to top up again. Fearing some 'event' on the way home, I watched the temp gauge with hawk eyes and kept the heaters on full so I could tell if the level in the engine was dropping. The air remained hot all the way but the temp gauge went up ever so slightly - reduced speed to 60 and opened the windows! I was only 5 miles from the Mway exit at this point so I took the A roads for the remaining 10 miles and took it easy. Temp gauge back to normal by now.

This morning I checked again, the overflow tank is down but still water there, looking into the rad cap. Noticed water below the rad cap around the outside and sure enough, a crescent shaped bit of rubber nestled on the 'tank' bit that the cap screws into. Engine is running as well as ever, oil etc looks good.

Need a new rad cap but from whence will it come?

Thanks for any pointers.

Post by **Probeman** » Wed Apr 17, 2019 3:47 pm

I had a similiar issue a few years ago. The 2 caps are different but you can use spring loaded caps on them both now as the non spring one is difficult to source.

Secondly dont top up the plastic tank, it is simply an overflow tank. The way to top up a 24v is remove the 2 radiator caps and then fill from the left hand side one until the right hand side overflows.

Hope this helps

Post by **Alan8086** » Wed Apr 17, 2019 3:54 pm

'it is simply an overflow tank'

- didn't know that, thankyou - how come it has a dipstick in the overflow tank?

Post by **jrh** » Wed Apr 17, 2019 4:48 pm

An overflow container ?
Well, yes, but a little more sophisticated than that.
Look closely at that dipstick in the overflow container and you will see a 'ladder of slots'.
Ideally, the level of coolant should be about half way up the slots.
If the cooling system is fault free, then exactly the same amount of expanding (hot) coolant will flow into the container as flows back when
it cools down.
NEVER run the engine with the container empty.

Post by **mojo98** » Wed Apr 17, 2019 5:39 pm

You will be luck of find a filler cap (left hand without a loaded spring) I buy them from Australia

the right hand is the pressure cap and that the one you need, plenty on ebay,
again I buy them from the usa (if you can find them (motorcraft)

Post by **Alan8086** » Thu Apr 18, 2019 7:44 am

Currently considering this:

https://www.ebay.co.uk/itm/282083640616

- before I go ordering from the US. I just paid a load of import taxes on some vintage computer parts from Jameco - our HMC wanted taxes for some 40 year old RAM ICs!

Both caps seem to have the spring so I assume a previous owner gave up looking for the correct cap.

Post by **Alan8086** » Thu Apr 18, 2019 7:46 am

So far, I've assumed that dipstick is for some purpose - always kept the water level at least half way up the dipstick.

jrh wrote: ↑
Wed Apr 17, 2019 4:48 pm
An overflow container ?
Well, yes, but a little more sophisticated than that.
Look closely at that dipstick in the overflow container and you will see a 'ladder of slots'.
Ideally, the level of coolant should be about half way up the slots.
If the cooling system is fault free, then exactly the same amount of expanding (hot) coolant will flow into the container as flows back when
it cools down.
NEVER run the engine with the container empty.

Post by **Alan8086** » Thu Apr 18, 2019 7:50 am

I cant seem to get rid of this car! Tuesday was my 3rd nail biting ride home from Cheshire, waiting for something to go wrong, watching temp gauges etc. I had made up my mind to sell, missing the days of my C180 or my wife's Saab - get in and drive without fear of incident. As soon as I get home and realise it was just the cap - oh, its ok - such a nice looking car too, and that sound - and it did 35mpg. Back to square one again - its a keeper for now!!

I am considering a slight career change that will involve a lot more commuting - IT contracting. What will I do then? Turn up in a Probe??!! That wouldn't be a bad thing but the fuel costs could be a killer. My Probe continues to turn heads and be a source of compliments at work. There are a couple of higher - ups that turn up in 19 plate Porsche/BMW M4s. I probably glean more interest for my £1280 investment than their devaluing £40000+ ever will! I never wanted a new car and now I haven't got one! Contentment!

If only i had a drive/garage!

Post by **Jon G 24V** » Thu Apr 18, 2019 3:55 pm

jrh wrote: ↑
Wed Apr 17, 2019 4:48 pm
An overflow container ?
Well, yes, but a little more sophisticated than that.
Look closely at that dipstick in the overflow container and you will see a 'ladder of slots'.
Ideally, the level of coolant should be about half way up the slots.
If the cooling system is fault free, then exactly the same amount of expanding (hot) coolant will flow into the container as flows back when
it cools down.
NEVER run the engine with the container empty.

Personally i always fill mine to the Full Mark on the dipstick.
If you put to much in it will just overflow what it doesn't need under the Car on the 1st couple of warm ups.
During normal routine checks it stays just about where it should be with only a very occasional dribble added.

As said never run with the Tank empty

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