Saturday, 29 October 2022

Schoolboy Error.....The 32cm Solution

Sometimes you take the lazy way. And really wish you hadn't.

As part of the process of repainting the engine bay (you can read about that HERE) I needed to remove the metal hydraulic return pipes from the 'tunnel' under the engine bay. This is two pieces joined by a short 10cm section of LHM hose. Everything was covered in grit and grease and dirt and space was cramped under the car. 
Return pipe join under the engine bay
I wrestled with the two Ligarex buckles and belts and got those off. But then couldn't get my hands into the narrow tunnel and around the pipe ends to pull them free from the old and hardened rubber hose. Although all parts have specific part numbers, (this one was 'DXN 394-147') a quick inspection convinced me that the hose was just common hosing. You probably know the kind of thing: it has a  green stripe and three ribs along it. It was just a simple Citroen solution to a simple assembly problem. I thought once about it (but not twice): it could be replaced with a short section of standard replacement LHM hose.  Out came the Stanley knife and I cut the hose in two......What harm could it do? Job done. All pipes removed.

I checked the hose I'd cut. Yep - standard LHM hose with a 14mm outer diameter and a 7mm internal diameter.
10cm of trouble (to come)
No problem. Easy to replace. I'd just need to order some......

Fast forward couple of months and I was at the point of putting all the other pipework back. All the other pipe and hose work had been removed and sat in a pile. Needing a 'donor' piece of LHM pipe in a hurry, I found a pipe with a short (24cm) length of 14 x 7 LHM hose. This piece.
My first 'donor' hose
I cut myself 10cm, leaving 14cm. Job done. 
New pipe join fitted
No problem. Easy to replace. I'd just need to get round to ordering some......

Fast forward to last weekend. I was gradually putting all that other pipework back. One of the first things I needed was that pipe that had the 24cm length of hose on it. Damn! It was now cut down to 14cm! I looked at all my pipework and found another group of hoses of the right diameter, connected to a 'T' joint. It had several branches. Planning ahead, so that I didn't need to buy too much replacement hose, I picked on the shortest branch (32cm long this time!) to be my donor. Here it is.
My second 'donor' hose......
I removed the hose. I noticed it was fatter at the end that fitted to the 'T' piece. But that was alright - I only needed 24cm of it and so wouldn't need to use that fat end. 
Fatter at one end.....
Without thinking much (enough!) about it, I cut 24cm off the end and used it get on with my plumbing job. 
Good progress on the pipework
Satisfied with progress, I chuckled to myself, thinking how the need for 10cm of hose had now grown to a need for 32cm of hose.....Still, no problem. Easy to replace. I'd just need to pull my finger out and order some......It probably comes in minimum lengths of 1 metre anyway. 

But something was niggling me. It wasn't the bit I'd cut off and used - but the bit that was left. I went back and looked more carefully at the remaining 8cm piece form the 'T' junction and was suddenly struck by a sickening discovery. The hose end wasn't just fatter where it had been squeezed over the 'T' junction. It was fatter for more of the length of the hose. Almost as if it was moulded that way......
8cm of trouble
Surely it wasn't a special part was it? I grabbed a parts manual and started thumbing through. Oh dear. The part was indeed 'special'. It's size was given as '7-10' which I very quickly translated as 7mm inner diameter at one end, but changing to 10mm inner diameter at the other.
Part 8: internal diameter 7mm (going to) 10mm......
Examining the plastic 'T' piece, it suddenly looked enormous. Why manufacture a 'T' join with a 10mm end for 7mm hose? Something to do with creating pressure for the return flow perhaps? It got better: as well as being 10mm diameter, each branch also had a bulbous end making it 13mm diameter! 
My nemesis
Other people do wholesale replacements of LHM hose as part of full restorations. Some must have navigated this problem  before (or never noticed it?). I would expect that putting the end of standard 7mm size hose in boiling water would soften it enough to go over the 'T' piece nozzle, but I had no confidence that modern rubber hose would not begin to split once it had cooled down. That was not my 'Plan A', but might need to be my 'Plan B'..........(Plan C was to try and use a four-way 'spider' connector).

Sure - taking 24cm as a donor hose hadn't been a problem, but finding a replacement 32cm hose with two different sized ends just might be! Bugger! What started out as a simple and easily met need for a 10cm length of generic hose had rapidly turned into a global search for a very specific piece of specialist 32cm long hose. It was the kind of thing 'Citrotech' might re-manufacture, but I never got that far. Some bad-tempered Googling turned up one genuine Citroen part in the USA........
.......and one in Europe
I also investigated 'Plan B' - the cost of generic replacement hose. It was indeed sold by the metre. At £19 per. Plus there was postage on top of course. The Ebay USA part looked to be a good buy, but postage was high for just a small hose that could fit in a Jiffy bag and I'd been stung by unexpected American import duties (and added Duty collection fees!) before. All things considered, I bought from Citroen Andre. It wasn't a hard decision as I've bought there before. I also used it as the excuse to buy something else I'd had my eye on, to justify the cost of delivery. So I got away with it. Next time it might not be so easy to find an original part. 

As a bonus, the parts arrived very quickly. Less than a week between order and delivery and here for the coming weekend. And here it is: the expensive 32cm solution to a quick and easy 10cm problem.
Lucky Find!
You can see quite clearly that the diameter of the hose changes towards the left and 10mm hole end.  And of course the two different sized plugs in the end are a dead give away!
All smiles now
It's just curiosity, but I may need to get a Vernier out and take some measurements as the difference in diameter seems to be more than 3mm. I can't see standard 7mm hose fitting over that very easily.
Well of course it's obvious now......
I'm expecting to fit the new part, and other pipes and hoses, this weekend. I just need to avoid the temptation to 'borrow' anything else.

Whats have I learned? Probably: "If it sounds like a bad idea - it probably is!"