P38 heater o-rings: draining tips?

Datatek said:

How to turn a quick easy job into a slow difficult one

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Yeah, but the thing is there's never just one job to do behind the dash...

DrBunsen said:

Yeah, but the thing is there's never just one job to do behind the dash...

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That is not something I have encountered. I did the O rings on one of my P38's over 10 years ago, the blend motors and flaps needed no attention and that is still the case today.

Getting closer to changing the o-rings, subject to Royal Mail ever condescending to drop a new pair of the little blighters through my letter-box.
To give the fixing screw little or no chance of declining to release the pipes from the matrix, I have ordered a 12” 1/4 hex extension and will use a Wera PH3 bit, as the screw (pictured) seems to be Philips, not Pozi. Is that correct?

P38 Monkey said:

Getting closer to changing the o-rings, subject to Royal Mail ever condescending to drop a new pair of the little blighters through my letter-box.
To give the fixing screw little or no chance of declining to release the pipes from the matrix, I have ordered a 12” 1/4 hex extension and will use a Wera PH3 bit, as the screw (pictured) seems to be Philips, not Pozi. Is that correct?

View attachment 331251

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Can't remember if it's Philips or POZI but I threw it away and replaced with a SS Allen head screw to make removal easier next time.

Datatek said:

Can't remember if it's Philips or POZI but I threw it away and replaced with a SS Allen head screw to make removal easier next time.

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exactly so… correct size stainless Allen screw (M5 x 25 mm) is on order … and will use copper grease too. Just wanting to remove the screw cleanly before binning it.

They protrude out the back, that bit goes rusty and then it can bind up just as you think you are winning.
Get something on that before you start. My new genuine O rings started leaking again sometime, can't remember how long, after I did the job. Got fed up and ordered the audi matrix, started the job and when I got to that screw...it wasn't particularly tight! Tightened it up some more and it hasn't leaked since. I think the hot and cold coolent cycle slackened things a bit or I'm a bit limp wristed.
Audi matrix still in its box.

P38 Monkey said:

Getting closer to changing the o-rings, subject to Royal Mail ever condescending to drop a new pair of the little blighters through my letter-box.
To give the fixing screw little or no chance of declining to release the pipes from the matrix, I have ordered a 12” 1/4 hex extension and will use a Wera PH3 bit, as the screw (pictured) seems to be Philips, not Pozi. Is that correct?

View attachment 331251

Click to expand...

That screw head is a pozidrive,
phillips does not have the little bits between the cross.

Job done..
Set up with polythene sheet, absorbent mat, fluid guide (cut-away plastic bottle), washing-up bowl, safety bund consisting of a suitably pink bath towel.
Following the tips and guidelines, I used an “I’m not asking” screwdriver with PZ2 bit, very carefully lined up and applied super-smooth pressure.
To find that the screw was not even hand-tight… D’Oh!
But that wasn’t the cause of the leak - see photo - both o-rings very hard, brittle and cracked.
Having syphoned coolant out of the overflow tank, about 1/2 litre, when I pulled the tubes off the matrix, nothing came out of the top one, and only a very small dribble out of the lower one.
Re-assembled with copper grease on the stainless Allen screw, Lucas red grease on the o-rings.
Checked for leaks and refilled the system - all looking good.
I have left the trim off for the moment, with an absorbent pad tucked in place to show any drips and leaks.
I’ll check the bolt for tightness in a while.
Thanks again for the tips and advice..greatly appreciated.