Pressure testing cooling system-what pressure?

[John_D]

Lads I've tested my coolant pressure tester cap and it works a treat! Delighted with it.


What is the maximum safe pressure I can go to without doing damage?
I went up to 1.8 bar and couldn't see any leaks(warm engine)

Cheers,
John.

[rebel.ranter]

The cap is rated to release at 2 Bar so I definitely would be going above that. In normal service it shouldn't really hit 2 Bar, otherwise you'd be constantly topping up with coolant.

Here's my photos/write up of my pressure tester:

I made this nifty little device, a coolant system pressure tester. I used an old radiator cap & a car tyre valve. I I used a hacksaw to remove the pressure relief valve from the radiator cap. I retained the top portion of the relief valve for two reasons:
- it has a rubber seal so I can still have an air tight seal
- the outer cap still spins independently of the piece with the rubber seal

I did have to separate the outer cap from the pressure relief valve in order to do the mods but I think it turned out really well. I tried it out on the e36 & it picked up a leak straight away. I knew it had a slight leak but I thought it was a lower hose, in fact it was the upper one. It was not a strong enough leak to detect without this piece of kit, you could see an odd drop on the ground after a drive (which is a rare event these days).
Anyway here's some action shots:

[John_D]

Yeah I totally copied your idea and did a writeup too, it's in the DIY section.

http://www.bmwhaus.ie/forum/showthread.php?tid=83

Cheers for the info ill have another go later.

[John_D]

Tried again but this time with a cold engine and instantly I spotted the leak.
It's the thermostat! It appears not to be sealing properly.
Ill have a go at re-sealing or replacing the o-ring. Ideally I don't want to replace as they are around €100
The leak started to show at around 1-1.5 bar

[Gar]

Try otto john if you have no luck fixing it they do them for around 50/60

[John_D]

Will do cheers Gar!