Hi any hints and tips much appreciated. Trying to fit the main fuel pump into the undercar housing. It is one of the pro alloy ones which I have got. I am struggling with fitting the o ring. I believe that the o ring is place above the flange on the pump housing. However the o ring does not want to go down into the housing far enough to enable the plastic retaining clip to sit flush with the housing. I have tried grease on the o ring and gradually righting each of the three retaining screws to get the retaining clip to push down the o ring . There is a slightly narrower diameter above the reservoir surface which I believe is where the o ring should sit and I am struggling to manoeuvre it into that so looks like o ring sitting to high? Any experience would be much appreciated thanks
They are a pretty tight fit even in the plastic housing,have you confirmed the o ring is the correct size ?,if you have measured it and still not sure buy a genuine one . From memory o rings seal on 10% of the diameter meaning that they will be 10% larger if that makes sense ,also in some applications they can be a differance in hardness so compare the old one and see if they are same,from experience this can have a lot to do with how they fit/seal. IMO I would fit with a little soapy water rather than grease ,good luck,cheers.
Thanks for the reply and useful info. Pleased someone agrees it’s a bit of a pain. Info. It’s a new Bosch pump and green o ring came with it. It does look slightly bigger than the black o ring which came out of old housing. I will have a better look now. Tried fitting with o ring above and below the flange on the pump. Do you know which is the correct position? Doesn’t seem to make a lot of difference in how retaining ring sits cheers
Have just looked at some images on-line of the Pro-alloy version and it's hard to gauge it's inner profile where the pump sits from them. I've a bog standard 8v one, so may or may not be differences that I'm not able to see as a result and all the below is of no use to you. This is a new (8v if it matters) pump still in it's vac. sealed bag, you can see the position of the ring as it was supplied by Bosch. It looks black in the image but is a very dark olive colour in reality. I re-fitted my original pump (the one you see in the other images) and do recall it was a tight fit, suppose because it has to be a strong seal and that initially it made the pump sit a little proud, however that was overcome as you progressively tightened down the collar. Maybe I just wasn't looking hard enough, but wasn't able to get a new, genuine 'O' ring at that time 2 years ago, didn't want to risk re-using the original 29 year old one. The originals an odd size but there was a guy on eBay doing some of the correct material that were so close as to be of no consequence. Fitted perfectly and still working/sealing perfectly a year later. It's important that you use a ring of a specific compound, one that's designed not to perish in petrol. Could stand to be corrected, but there's something in the back of my mind about that being why it's coloured green, helps to identify different properties. I'd guess (hope!) that the 'O'' ring you have and came with the new housing is of that material and they've covered that angle for you.
Thanks for that and the pictures which are useful. The o ring that came with the Bosch pump is that green colour. I’m going to measure and see. I’ve got an original coming as well so I see how that compares . Was surprisingly not a lot of money. Cheers
I feel your pain with the new seal and pro alloy housing. It's a right mare. They will go eventually. Just a case of carefully and evenly winding the securing bolts down. I ended up tapping out the holes slightly to use some more robust fixings as my first attempt ended up gnarring one of the threads and hairline cracking the plastic lock ring
If you've found a source for the real McCoy can you post up a link, be useful to know plus someone else might need some? The ones I got were from this outfit - https://www.ebay.co.uk/usr/worldofbearings Just had a look and they're still trading but those particular 'o' rings aren't listed at the moment, two years ago they cost £9.75 for four including postage. Also found a post I made at the time, a cut'n'paste below - "7Zap gives the original as N 90312402 for my '91 8v PB and a spec. of 42 x 5.3 mm, no mention of anything else about it unfortunately. Apparently green is a generally used / recognised colour for a material called 'Viton', though that's not a hard and fast rule so only use it as a guide. I did try to find some genuine ones at the time though they were either no longer available or that Greek seller on eBay had some, but postage was astronomical. I found a German place that supplied 42 x 5.3 rings however they turned out to be 'Nitrile' (also known as NBR) which has different properties and depending on what you read may or may not be reliable in fuel enviroments. I still can't properly get my head around all the differences and suitabilities of the various materials. Then there's something called 'Shore', which I think is basically how flexible they are, adding to the confusion. If it's too hard, won't seal properly, too soft and they tear. Upshot was I could find rings of the correct measurement, but not material and rings of the right material but ever so slightly smaller (0.3 mm) diameter. 'Viton' is apparently ethanol resistant - though E10 wasn't a consideration back in 1991 I'm guessing VW intentionally specced it and the fact it still exceeds standards is a happy coincidence. Like I said above, my original ring seemed quite hard (steady!) but now that I've gotten new ones of the same material, they're as equally so. The new ones are 42 x 5.0 and 'Viton' - they fit with no effort and seem to seal perfectly, but I've yet to run fuel through it on the car... I can fall back on the original if needs be." Interesting too when you look at the 7Zap schematic, if you didn't know better the order of the parts doesn't seem correct and could be confusing.
Thanks everyone. Pleased its not just me then! I emailed pro alloy to see if they had any suggestions and have come back as below “thanks for your message. You will need to apply a smear of grease to the O ring, they are a tight fit but the assembly goes together easier with a bit of grease on the surfaces. Are you using a genuine VW pump and O ring? We have seen small differences in pump diameters, the OE ones are fine but some of the pattern ones will make fitting very difficult.” pretty much what you guys are saying. I ordered the oe ring from ve classic parts so coming from Germany 4-10 days they say. Never used them before so fingers crossed.cheap I thought but you have same again for postage https://www.volkswagen-classic-parts.com/catalog/en_uk/search?q=Golf 16v fuel pump seal like jmsheahan says I’m worried about stripping the threads when trying to compress with the plastic restraining ring. One more question!! Are we happy the o ring goes below the flange on the pump so o ring sits between the top of the strainer and the flange. That’s the position I have come closest to persuading it to go in . Thanks guys
Managed to find time to get the fuel pump install finished last night. Using some grease and better bolts I got the fuel pump to sit better in housing and the retaining clip sitting as it should. The bolts supplied with the housing just didn’t have enough to push the seal into place. Then Had fun getting a Barb fitting on the feed to the engine bay to go into the pipe. Used boiling water without much success to soften the pipe so reluctantly and carefully and got there in the end. Managed to fire up last night and much to my surprise no leaks!! Just wanted to post and say Thanks everyone for the hints and tips which kept me going when I was stumped. A coolant change and oil change now and then present for mot . Hope I can get her back on the road soon for the summer.
