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350se dies when warm

Started by milo, 03 April 2020, 06:55 AM

Randys01

Gee mate I'm struggling on memory here and don't have one on hand to refresh my jaded memory BUT you should be able to remove the needle piston from the main body and inside you should find the small O ring.
Keep the photos coming.

revilla

Hi Milo and Randy,

The baby o-ring you're looking for is in the chamber covered by the hex screw inside the main valve body.

See picture below.  There's a C clip that can be removed to reveal it.

There's also this document from Bosch showing every model where this regulator is used.  Every model using K-jet is there, including every W116 model.  There's only one pressure regulator F 026 T03 010.  I can't see two types.

My guess is that the orings supplied in the kit are for the plunger, based on the size I can see.  The squared profile ring supplied is just a 'holder' of the assembly.

http://www.bosch-classic.com/media/bosch_classic/teile_1/nachfertigungen/motor_2/druckregler/Mini-Katalog_Systemdruckregler.pdf

Cheers


revilla

all those shims supplied in the new kit won't do anything to the Primary Pressure if the large spring shown in the previous picture is absent. The shims have to be in contact with the bottom of the large spring which will transfer the axial force to the plunger which will increase the Primery Pressure as it'll push against the return orifice with more force. 

milo

OK needle dismantled ,im looking at the taper shouldered seal to be a new replacement for the one still fitted to the rusty old needle in the pic.
So far so good but where do the two different style ones go? Im guessing the one with the more rounded body should be fitted to the inaccessible piston.
If I could just get to the piston...

milo

Last pic is poor image of piston looking into fuel return port
Looking into PFPR port the brass fitting shown in an earlier post holds a spring which bears onto the piston.
Thanks for continued support from all, it really does help.

revilla

Quote from: milo on 13 April 2020, 07:48 AM
Im guessing the one with the more rounded body should be fitted to the inaccessible piston.
If I could just get to the piston...

Hi Milo,

Im confident you have tried running the pump for a millisecond while the PR is out to get the piston out. If yes, try a bit (just a bit) longer as it might be stuck in there. Careful, Place rugs around and under as fuel will will drain out with significant flow/force. Maybe a job for 2 people! One of them watching closely if the piston comes out so you don't lose it!  There should be the larger spring too.

Good luck.

Please keep us posted.

Cheers

revilla

Every outlet (9 in your case, 8 + 1 for the cold start valve (CSV)) of the fuel distributor should be connected so they hold the pressure and push the piston/spring assy out.

milo

Its not the same as the design your familiar with, that's the whole problem, I have owned other k jet cars with the usual big spring piston type deal , this isn't like that, the brass fitting in the needle port retains a spring which bears onto a piston.
Yes Ive ran the pump many times and tried 150psi air pressure ,it seems to me there is a mechanical arrangement holding the brass fitting I just cant see how.
Looking at the proportions of items in my hand do you think any of those seals would fit on a more normal piston? they look a bit titchy to me.

revilla

Ok I see. Not the same PG design then. Interesting why Bosch would supply shims with the kit that aren't useful in that design to push a spring/piston couple into the return orifice. The shims in your design push on nothing. So I can't see their function.  While in the design I'm familiar with they actually push on the spring/piston couple.

Yes, to answer your question, proportionately speaking, the size of those orings at the tip of your new needle qre about the same size of the oring that goes on the piston in the design I'm familiar with.

Cheers

milo

Hi Rab
im guessing its to cover both designs, just need to find a way in then without doing any damage .
Looks like im on my own with this one unless aussie man Randy can cast any light ?

revilla

I see Milo. It could be that's why they added those shims on both kits. Could be.

I wonder (in your design) what procedure should be used to adjust the System Pressure if it's not the documented one of adding/removing shims.  It's certainly nowhere in the k-jet documentation that I have seen.

milo

Hi Rab
I need to find out how to access the piston , and suppose the needle part somehow bears on  the piston  buried in there.
Ill post more pics.
cheers for responses   

Randys01

Milo

Hold the phone....take a deep breath.............I am going to go across to the other side of the city to get a spare FD and I will bring it back home..dismantle it and walk u thru it. just bear with me.   I have a lot going on.......just park it and find something else to play with. We will sort this...I will make it my personal project.!
Ok?

milo

Randy
Music to my ears man , bloody marvellous and I bet more than me are curious to know the secret of the cast iron block.
Thanks.

Randys01

OK..............The new FPRV is correct for your application. Note that the new valve kit does not include a new piston.
I gather the old piston is stuck in the FD. If it is so stuck as to not come out that's a potential operational issue in its own right.
Firstly let's clear up principle of operation.

Ordinarily the piston slides out freely. I  used a small bore magnet to get mine out. It is about 1 inch long with a small O ring on the tip.
The piston is held to the seat of the FD by the main spring which seats inside the bore of the piston. The spring comes into contact with a fixed washer [ferrule ] on the main valve body ... the spring's tension is varied by the no of shims between the seat of the spring and the aforementioned fixed washer.
This sets system pressure.
When operating, fuel  pressure in excess of the set value..5.6 bar...causes the piston to lift off its seat  just enuff for fuel to flow thru an annular in the piston and thus pressurises thru the bore, the inner needle which lives in the main valve body. As the needle is forced off it seat [internally sealed with a small O ring within the main valve body ] a drilling in the annular just below the thread on the main valve body is exposed and thus surplus fuel is returned to the system completing the circuit.

Now to the immediate problem. Stuck piston in bore. It's stuck for one reason I'd guess. It's been full of water. ie rusted in. I'm surmising this FD sat idle for a long time and either moisture/grunge in the fuel has glued the little buggar in.
I note you used hi air pressure which  did not budge it.  Not sure what this would have done to the main diaphragm which is designed to handle 60 psi BUT I think from here you undue the hex nipples to the immediate left on the FPRV and fill it up with your favourite Penetrene or equiv. In other other words we want to get derusting lubricant behind the piston as well as fill the piston because it will ooze out thru the drilling in annular in the piston. Leave it o/n on its back or side.

Next trick is to find a rod which makes for a tight fit in the bore of the piston. it will need to be tight.I'm think a piece of wood which is tight when dry and will expand a bit when wet. It will go in about half an inch.
Gently heat the proximate area tapping with a metal hammer. Then  spray into the piston bore with  aerosol Freeze it or equiv. Repeat this procedure several times. Insert the wooden rod screwing it in as you go..spray it with Freeze it or water to expand it so it's a tight fit but not because you rammed it in..because you threaded it.
At some point you should start to feel the piston come loose and start rotating with the rod. .with draw as necessary. If this does not work you will have to have the piston precision machined out. There is little room for tolerance here. ..the piston wall is about .75 of a mm so an Ezyout solution won't do it lest you mangle the parent bore in the FD.

Once you get the piston out we can go thru the reassembly protocol .
Keep us posted.
Cheers