Another expansion tank leaking ..

SpiggyTopes said:

Hi All,

This will be my third tank in 2 years.

Last one failed in the same place as this one - where the small pipe from the radiator connects.

I've done a quick search looking for genuine Landrover but only found Britpart so far (don't know what make this one is -- anything goes in Dubai!).

Any ideas on genuine without going to the dealer?

Cheers.

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Speedex750 said:

Not P38 RR but my son has had a similar problem with his BMW Z4, I've fitted 4 replacement tanks - I'm getting good at it! The last one was a genuine pre-loved BMW one and has been OK so far. The three cheapy replacements split easily, one even had a shrinkage crack in as delivered. I also suspected that the original cap wasn't relieving pressure and with a very small air space the pressure could have been popping the tanks. After trawling Beemer forums it transpires that most have a 2Bar pressure cap but some have 1.4Bar, and they look exactly the same as the P38's. The second hand tank fortunately came with a 1.4Bar cap and this could be helping the 'so far so good'. Try a new cap with the genuine second hand tank.

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Speedex750 said:

2 bar is fact. I agree with you, it seems high and would suppress boiling beyond where something else would happen. But there must be millions of various model Beemers around the world with 2 bar systems. I suspect initial over filling to compensate for air elsewhere in the system was part of the problem, getting the system primed and ending up with a good level in the expansion tank with a decent air space isn't straight forward. The P38 is much easier; the Beemer tank and water level is low down in the system, going up a steep hill is needed to get all the air back to the tank. I suspect the cap has had to relieve some water - and that our original may not have been doing that. Having a 1.4 bar cap fits better into my normal experience and will reduce strain the system when expansion takes the pressure up.

If the guy is splitting tanks, the cheapy new ones may not be as good and a second hand one may be better. And change the pressure relieving cap, it could be part or all of the problem. If it still splits it sounds like there's something more sinister going on.

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