are all series rad caps the same internally?

julianf · Aug 20, 2015

I have a 3rd party rad on my 101, with, what looks like, a s2 rad cap - the one with the two bumps on the edge.

The issue is that these bumps conflict with the rad mounts when the cap is turned (crap design of mod) and have resulted in the cap getting a bit twisted.

The s1 caps are round. This would miss the mounts fine, but are they the same in other respects?

julianf · Aug 20, 2015

Some photos to explain further -

This it the top of the rad - the cap conflicts with the mount -

The other issue is that, every time, the rad ends up being this empty (finger on pipe shows depth below internal neck) -

This, i think, is because the cap has a seal missing -

I think there should be another seal - ie three in total -

First seals the tank against expansion, and releases so as the fluid rises into the neck, and flows down to the overflow bottle.
Second (the little one in the middle) opens when the rad contracts, so it does not implode, and
Third (missing) seals against the top neck, so that, when the second seal opens, the liquid is sucked back from the overflow tank.

I think that, on mine, the tank pressurises, overflows to the overflow, and then, on cooling, because seal #3 is missing, sucks air in, rather than the coolant back from the overflow.

Im thinking they should look like these (photo off internet) -

Blackburn · Aug 20, 2015

Can you not cut a small amount of the mounting bracket .
You are right about the seal I made one from some thin DPM rubber.

mrchurchill109 · Aug 20, 2015

Yes on the seal, not necessarily on the caps being the same.

You need to make sure the pressure is correct - the early Series caps are only like 7 pounds pressure. With the 101 I'd expect it to be 12 pounds or so but I don't have a manual here to confirm (working from memory of an early RRC I had with the same engine).

This could also be the source of your coolant loss - cap is opening WAY too soon and not maintaining proper system pressure. Combine that with the missing gasket and it's a recipe for coolant loss and a cooked V8...not a great idea.

Alan

julianf · Aug 20, 2015

I should have said - its not got the v8 any more, but the hs2.8 (300tdi a like)

The system on my 300tdi disco is completely different (expansion, rather than overflow) and I do wonder if it wouldn't have been better to do the conversion like this.

I've tried to look up 300tdi coolant pressure with no success.

julianf · Aug 20, 2015

PS.

I figure I can chop one of the bumps off the cap, as its not as if it seals on them.

mrchurchill109 · Aug 20, 2015

julianf said:
The system on my 300tdi disco is completely different (expansion, rather than overflow) and I do wonder if it wouldn't have been better to do the conversion like this.

I'd have been tempted to do so personally, but i still think the cap you have is opening way too soon. The old Series cooling system setup was a throwback to the Dark Ages

and is very low-pressure. I'd suggest a 10 or 12-pound cap would be a good idea - and I know those can be had at the local FLAPS (Friendly Local Auto Parts Store) for short money.

This way you can kill two birds with one stone - get a cap with the right pressure and one with a gasket as well.

Alan

honolulujoe · Aug 20, 2015

iirc some s1 caps are only 4 lb's, my s3 has a 10 lb cap

julianf · Aug 20, 2015

Ive read that theyre ment to be stamped with the pressure - the only number on mine was "15" but i dont know if that means anything.

Anyhow, today i got a chunk of rubber and cut a seal for the existing cap, fitted it, and ran the vehical up to temp. Water was certainly dripping out of the overflow bottle's 'overflow' (as it should do - i brimmed the rad, and the bottle)

Ill see what the job is like tomorrow morning, when i can be sure its stone cold. Of course, im hoping that the rad will be air free, and the overflow tank almost empty.

I also chopped off one of the 'bumps' on the cap, so it turns fine, and misses the rad mount.

I dont mind buying a new cap, but this was the quickest option for now.

julianf · Aug 21, 2015

Checked the rad this morning - some air in it, but not as bad as before. The overflow (which I had brimmed too) was a bit emptied, so the setup had partially worked with my makeshift seal.

I went out today and purchased a new cap - 15psi, but still no rubber seal, just a metal one. I'm not sure how much confidence I have in it, but it was worth a gamble. If its not much better I'll mail order one with a rubber seal.

Blackburn · Aug 21, 2015

The rubber seal is sold as a seperate part

julianf · Aug 25, 2015

Blackburn said:
The rubber seal is sold as a seperate part

It seems pathetic to ask, but, as I've not seen them by themselves, do you have a li k, or a part number?

Blackburn · Aug 26, 2015

part Number 564999
Do a web search for Smithies landrover will come up with a NZ website of interest including parts and optional parts manuals.

are all series rad caps the same internally?

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