As the title says, anyone? how difficult a job was it? Did it improve running, idle, boost, economy?

read a bit in ukmkivs so got one coming tommorrow ready for the weekend.... have a boost leak that I cant find, economy has never been good, idle not stable when warm, brakes poor (fluid been changed and all bled OK - didnt do the ABS thing though?) so this looks to be one possible culprit.

At £16ish seems a good place to start and I remember how coked the Crankcase valve was when I changed the pipes when I first started.

The only suction jet pump I know of is the one in the left hand side of the fuel tank,are we taking about the same one?

Maybe he means the Suction spray pump under the manifold? Karl are you on about number 19 on the following diagram?

Ian

Ahh yes its the smal valve on the vacuum pipes that split under the manifold.

Just googled it and some interesting reading. Apparantly if it fails boost leaks into the pcv system, might be a possible cause of the 17705 dtc that some have had no joy in fixing.

Good find Karl.

Ian

Makes sense.

I've been trying to find out what this little doobry does for a long time!

As far as I can tell, it helps the crank case breathe when your idling. Using the vacuum from the manifold to 'boost' the flow of vapours. But when there is pressure in the manifold, I recon it should shut off due to an internal valve.

If the valve dies then I suppose it would pressurise the crankcase, or blow around the PCV system back into the turbo intake. Makes sense that this would cause the 17705. If the spray pump is split/leaking, then it would show up as a vacuum leak. Causing rough idling, and maybe a weak vacuum to the brake servo.

Some of the mk4 boys have 'deleted' this system, and just run a plain hose off the crankcase breather to a catch tank, and simplify the brake servo vac line by removing the lower line (I've seen a vRS with this done also). Seems very sensible to me, but I worry about why it's there in the first place!

Does anyone know why this engine needs it's crankcase vapours 'sucked' out on idle?? Could it be an emissions related thing??

It is exactly that.

Fueling is very tightly monitored at idle for emission based reasons, vapour from the crankcase can and does alter the mixture if you like, burning the oil vapour. This isnt an issue when running at revs, infact the engine ECU has an apative figure from the MAF that compensates for it (thins is why the emission light comes on with the 2.0 petrol engine when the rings start leaking) but at idle its not such a good idea.

Does anyone know why this engine needs it's crankcase vapours 'sucked' out on idle?? Could it be an emissions related thing??

Definitely for emissions only. Had a quick glance at wiki and it comes up with thisregarding PCV systems.

Before the invention of Crankcase Ventilation in 1928 the engine oil seals were designed to withstand this pressure, oil leaking to the ground was accepted and the dipstick was screwed in. The hydrocarbon rich gas would then diffuse through the oil in the seals into the atmosphere. It is therefore an emissions requirement as well as a functional necessity that the crankcase has a ventilation system. This must maintain the crankcase at slightly less than atmospheric pressure and recycle the blow-by gas back into the engine intake. However, due to the constant circulation of the oil within the engine, along with the high speed movement of the crankshaft, an oil mist is also passed through the PCV system and into the intake. The oil is then either burnt during combustion or settles along the intake tract, causing a gradual build-up of residue inside the inlet path. For this reason many engine tuners choose to replace the PCV system with an oil catch can and breather filter which vents the blow-by gases directly to atmosphere and retains the oil in a small tank (or returns it to the sump), although this technically fails to meet most engine emission legislation.

It is exactly that.

Fueling is very tightly monitored at idle for emission based reasons, vapour from the crankcase can and does alter the mixture if you like, burning the oil vapour. This isnt an issue when running at revs, infact the engine ECU has an apative figure from the MAF that compensates for it (thins is why the emission light comes on with the 2.0 petrol engine when the rings start leaking) but at idle its not such a good idea.

What do you think about removing the suction pump then? Bad idea, or no problem?

I can't see it causing an increase in crank case pressure, as the breather will be nice and free flowing still. So what's the drawback? Less oil in the intake seems like a good idea!

I've been trying to find out what this little doobry does for a long time!

As far as I can tell, it helps the crank case breathe when your idling. Using the vacuum from the manifold to 'boost' the flow of vapours. But when there is pressure in the manifold, I recon it should shut off due to an internal valve.

If the valve dies then I suppose it would pressurise the crankcase, or blow around the PCV system back into the turbo intake. Makes sense that this would cause the 17705. If the spray pump is split/leaking, then it would show up as a vacuum leak. Causing rough idling, and maybe a weak vacuum to the brake servo.

Some of the mk4 boys have 'deleted' this system, and just run a plain hose off the crankcase breather to a catch tank, and simplify the brake servo vac line by removing the lower line (I've seen a vRS with this done also). Seems very sensible to me, but I worry about why it's there in the first place!

Does anyone know why this engine needs it's crankcase vapours 'sucked' out on idle?? Could it be an emissions related thing??

yes ,if you dont suck them out blowby gases will pressurise the crankcase and blow out (via dipstick or any other route ) a mix of combustion products and engine oil adding to emissions .Taking this off and feeding the hose to a catch tank does mean unfiltered air could be drawn into the crankcase.

What do you think about removing the suction pump then? Bad idea, or no problem?

I can't see it causing an increase in crank case pressure, as the breather will be nice and free flowing still. So what's the drawback? Less oil in the intake seems like a good idea!

My 20VT in my Golf ran just fine without it.

Some of the mkiv and vwvortex guys say they replace this every 30k, I think the early versions used to split apart at the widest bit causing boost leaks etc. whereas I think mine is just ful of gunk. should be picking mine up today the deciding factor for me was when I read a thread about boost leak + rough idle + poor economy + poor braking = jet pump

as it such a cheap part I though i'd start with that before lookin at things like N75 etc.

Let us know how you get on changing it mate, looks like a pain to get to!

Try and get some pics if you can, we all love a good engine photo!

"Anyone fitted a "Suction Jet Pump"????"

I say Matron:rofl:

Interesting reading, when i replaced the leaking pipe under the inlet manifold i noticed this pump leaking a bit of air on idle. Would this also be leaking on full boost?

Anyone seen this? VWvortex Forums: -= 1.8t Technical Forum Guide { FAQs | Tuning/Modification Assistance | Troubleshooting } =-

Check out the PCV flow diagrams about quarter of the way down. They indicate that there is no pump on the AWD engine, and that the valve is in the T-piece.

Interesting....

Interesting reading, when i replaced the leaking pipe under the inlet manifold i noticed this pump leaking a bit of air on idle. Would this also be leaking on full boost?

A good chance esecially if the check valves are all gunked up as well. when I did the lower breather hose on mine I stripped out the Crankcase breather with all the other bits and the PCV valve stuck open. on mine there is a pipe from the manifold down to this valve so boost leaking through and into the crank case or the TIP (path of least resistance) I imagine that the same amount of gunk must be flowing through the rest of the system and all the little check valves etc.

OK

firstly, appologies for the lack of photos but it was Pi55ing down.

changed the valve on Friday night, what a PITA.

didnt remove the engine cover as I never put it back on after the LPG.

removed the SAI pipes out of the way.

removed the metal plate full of vac cr4p and folded up to the right.

I decided based on past experience to remove the dipstick tube (wise move as it makes access easier)

I decided while I was at it to remove the crank case breather and the replacement silicone hoses just to check the crankcase breather check valve, I had cleaned it when I did the silicone pipes in the begining but not with anything like carb cleaner so I thought it might have got stuck again. blew and the valve shut, sucked and it opened, so all OK.

I then tried to remove the suction jet pump by removing the pipe from above the manifold, that goes to the brake booster, took the one use clip off (eventually) and then spent 30mins and all my energy trying to get the pipe off.

similar story trying to take the one off the under side of the manifold.

I then unbolted he metal pipe that runs back to the TIP and disconnected it at the top of the manifold and fed the pipes down under the manifold and removed it all out of the big hole where the dipstick used to be. taking it all out in one lump like this was a lot easier than trying too remove the clips under the manifold.

once it was all out I moved the pipes one at a time to make sure I had the shape right to be able to put it back together, the only difference is the hard plastic pipe I cut off an replaced with some silicone fuel line. Lots of jubilee clips later and it was all back in.

the result: it doesnt drop into limp as quick, but it still does. I still get the 17705 (even at idle)

the brakes do seem a bit stronger. The block 32 readings are -0.4% and -4.6% so looks like the vac is no longer leaking. but still not sure about boost leak.

All in all, one more step towards getting it sorted (crosses fingers) might try N249 bypass next.....