MK1 Golf K-Jet Ramblings...

Starting to take an unhealthy interest in K-Jet (specifically MK1 Golf) and pleasantly surprised to be finding plenty to read on the inter-web and elsewhere.

Trouble is I'm prone to half remembering things and even I do bookmark stuff, nine times out of ten I can't find it again when I go back to look.

I'm creating this thread then as somewhere to post up (read that as save) random info. as and when I find it, somewhere I'll have half a chance of finding it again if needs be.

So expect it to be unintelligible ramblings, along with random or disjointed thoughts, plus likely other very odd but vaguely related stuff.

By way of a disclaimer - I'm just getting into K-jet so don't take any of what follows as accurate or correct, I'm very much learning as I go along and bound to get quite a bit wrong before I get even some of it right.

To the one or two other members who stumble on this thread and may even actually read any of it - watch this space!

 

You'll find a lot of other publications / info-sites will have regurgitated this official Bosch publication in whole or in part, and no wonder as it covers all the basics plus gives you a handle on the correct names / terminology of the various components.

Very good starting point / reference material and does away with the need to pay through the nose for a hard copy on ebay!

https://www.club911.net/divers/32tech/docKJetronic.pdf

 

To do anything with KJet, you need good fuel pressure gauges.

 

Good advice... accurate system and control pressures are all.

 

Bit of a follow on from something that was touched on in another recent thread.

Primary pressure regulator, it's screwed into the lower half of the fuel distributor.

Seems there's slightly different versions described by some as 'old' and 'new'.

Not sure of the exact differences other than one seems to have a different tip to the piston at the end and needs it's own sized 'O' ring as a result.

Some of the refurb. kits seem to give you both (so there's 3 included, of which you use 2 and discard the last one), other sellers ask you to specify which kit version you want so presumably have to identify which piston yours is.

I've only found one seller who goes a step further and provides the 'O' ring for the pin inside the main regulator, all the others seem to gloss over the fact there even is one.

The ad / seller - T&S Technik.

(also shows the 2 x piston types / their unique 'O' rings.)

The 'O' ring I'm talking about here is the one, second from left on the lower row... it goes into that gap on the nail like looking pin pictured immediately above it.



Like everything within K-jet it plays a crucial role - below are images from the Bosch tech. instructions above.








Apparently pre. 1978 the sealing this added 'O' ring subsequently does was problematic.

Fuel could seep back into the primary pressure regulator from the Control Pressure Regulator when the engine was switched off causing a loss in residual system pressure.

As an aside, Control Pressure Regulator seems to be the correct name for what's generally called the Warm Up Regulator, though to confuse you even further Bosch also refer to it as both.

I've an old Volvo 240 fuel distributor and it's Primary Pressure Regulator is the same as the MK1's (Bosch F026T03010)

VW use 035133422A

That's the VW on the bottom and Volvo above in bits (piston is missing on that one, got stuck in the fuel distributor).

You can still buy these new from Bosch with all the 'O' rings / washers and even a few shims but they're a shocking price for all that they are.

When I realised their worth gave the Volvo one a clean up and it came out like new... it was quite bad so shows you what's doable, a half decent one should take no effort at all.

 

Image of a NOS KE-Jetronic (electronic) air flow sensor...

Shows off nicely the sticker that highlights the different sensor plate 'zero' settings it has from the regular K-jet's (plus the black plastic wiring connection where the part number plate would've previously been).

 

Reluctantly joined Facebook a few months back, but it wasn't much of a surprise to find that it's not for me.

There's maybe one possible exception, a Bosch Kjet group that seems to have some very knowledgable members.

Going to stick up a few posts and see how it goes, if it works out and anything's learned I'll update on here.

First post was to try and get the contents of the Peugeot dealer workshop kit properly identified.

With some luck might be able to figure out how to replicate a few of the tools.

 

Have you managed to uncover the size of the o-ring for the pin/needle?
I believe the piston is 2x4 and the larger one that seals the unit is 2x7 but I haven't found sizes for the pin o-ring anywhere (and mine has disintegrated so I have no reference point to measure!)

 

Didn't really look as I'd intended using this seller (the one mentioned above) and it's part of a kit along with some other consumables, doubt I could source things any cheaper, plus presumably these are guaranteed to be the correct materials / sizes.

My reading of it is they're also throwing in a shim (but doesn't say what thickness) that assuming it's the size you just happen to need can be used to adjust the system pressure if required.

If you do use this lot, let us know how you get on / quality / fit etc... cheers.

https://www.ebay.co.uk/itm/385328851274?var=653217726759

 

I've used them.
You get what is in picture 1/2 (old/new version). Pic 4 isn't actually what you get annoyingly. Very misleading given clicking new version takes you to the picture with everything.

Edit: the quality/fit for what you do get is absolutely fine.

 

My understanding is there's 2 x types of primary pressure regulator and that the design changed around 1978, hence the old/new kit choice.

The original pre '78 one didn't have the push valve part, that's the portion I previously described as being nail / pin like (and with the 'o' ring you're after on).

Prior to the improvement there was a tendency for control pressure from the control pressure regulator to dissipate after switch off causing re-start issues.

Is it possible you ordered the kit for the early regulator (pic. 2/3), as it would have no need for that particular 'o' ring?

Pic 1/4/5 are the post '78 version... I'm guessing he included the images of a pre/post '78 fuel distributor (with the red arrows pointing at their respective primary pressure regulators) to help identify which version you need.

(Edit - just looked again at his auction and he could've ordered the images a bit better, I can see how it'd be easy to mix one version up with the other.)

 

I definitely ordered "new". The sticker on the bag confirmed as such on receipt too

 

Give him a shout, errors happen... seems bizarre he'd go to the trouble of describing the two types / putting up different photos then not to then supply one of them!

Ebay.co.uk has automatically translated the auction, maybe the problem lies there?

Having said that I've looked at the same auction on eBay.de and I still read it as offering a choice of either version, they're even priced differently with the newer kit costing more.

 

Got the tester in one of the images below quite awhile ago and true to form just had to dismantle it for a clean (read that as really to see how it worked).

Problem was I should have left well alone as it leaked like a sieve afterwards, plus it had a non-standard gauge that was probably to allow diesel and not petrol injectors to be tested as the range was so high.

It's not just a case of pumping away (oh err!), there's a series of set steps that takes you in an order through the 4 x tests it does.

Luckily found some random Merc. pdf that shows you what to do, it's not difficult, but I doubt you'd be doing things as intended unless you read it first.

https://www.tonk.ca/r107CD1/Program/Engine/107/M117_45/073-135.pdf

Couple of interesting things mentioned - the basic leak test is to be carried out at 1.5 Bar, even though the injectors are expected to open at a minimum of 3 bar.

Another is that 'new' injectors are expected to open at 3.5 bar, not the 3 bar of used ones.

The tests are done in sequence and each finishes in such a way that the tester is set up for the next -

1. 'Coarse' test, that's the basic 1.5 bar one mentioned above.

2. Checking opening pressure.

3. 'Precision' leak test - done at 0.5 bar above whatever you find your opening pressure to be - so potentially at 4.0 bar for a 'new' injector.

4. 'Buzzing' test to evaluate the spray pattern. Other tests I've read describle the noise made as 'chirping' which isn't that far off the mark and descibes it better

So with instructions / new washers / seals and a gauge later had a go at my original injectors plus a second set that came included with a spare fuel distrubutor / airflow regulator.

All were pigging but as it turns out they all also work 100%, which was a surprise... my own had been sitting of 14 years attached to dried out fuel lines, very bad news for k-jet.

The spares came from an Audi 80 GTE and if anything looked in even worse a state.

The tester can be used to just straight forward flush injectors, in this case all but one ran clear from the get go, the last one 'popped' after a few seconds and then ran clear after a few more.

Don't know if I was lucky, but if not it suggests to me that at the price of the things new you shouldn't write off any old injectors too soon... even they've been sitting a long time / potentially varnished up, at least try to flush / test them first.

The image with the copper coloured pintle surround is a brand new injector, the other is 40 years old!

Apologies for the dodgy image quality, don't know why but it just doesn't work for me some days.

 

This caught my eye on eBay - it's for amongst other models the 1.6 MK1 GTI.

The silver slotted screw with nut / washer and the separate brass fitting aren't standard and have been added.

The screw/nut/washer is a known mod. done to allow you to adjust the bi-metal spring beneath without having to take the casing apart every time... that I understand.

The placement of the brass fitting is where there'd be an atmospheric pressure vent (usually with a black domed plastic cap) on the more advanced WUR's with vacuum advance connections, of which this more basic type wouldn't have had any.

On the basic WUR there's a hole on the bottom face that would perform that task instead, but this one appears to have had its intentionally sealed up, hence presumably the need for the brass adaptation.

Someone has done it for a reason, though from what I can see it's just replacing one way of doing the job with another that does the exact same thing... unless you know differently?

 

Quite possibly it is a vacuum connector. Some of the older WURs had a manifold connection there. I’ll try to find an image. The resources on k-jet.biz are quite useful for identifying your version.

 

Yeah, sort of throwing me this one as on the surface of it there's no obvious advantage to doing that mod

Your very top diagram shows the inlet manifold vacuum connection on the top of the unit (at '3') and the atmospheric port on the side (at '9').

There's likely different versions out there but the one I'd in mind has a black cap on that top pipe and a hose goes on the side one, the opposite way about from what the diagram implies.

It's the sealing off of the standard atmospheric opening that makes me think the new brass connection replaces that function, but to what end?

Maybe whatever the WUR was originally from had work done necessitating it to be repositioned, meaning the original port wouldn't work as intended... just guessing?