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Just a quick note about rattly pumps. Mine had been knocking for ages and I'd been on this forum looking at various ways of sorting it.I'd just about decided to get a genuine VW one after all the horror stories about the cheap ones on fleabay and then got some info about the angle they're fitted isn't the way Pierburg (the manufacturers of the pump) designed them to be fitted. Evidently because of the angle they're fitted oil gets behind the piston over a period of time and stops the piston returning fully so more clearance for the pump pushrod.........and we know what that means................nasty rattle!! Anyway decided to do it yesterday so pump off and to the bench.Took the 6 Torx bolts out and took the plate off, it's not under load or anything but there's some seals and valves there so either take a note of what goes where or take some photos.When you've got that lot out of the way put a 15mm socket in the vice,put the end of the piston rod in it and undo the nut on the other end(11mm spanner) Leave a few threads to go then just take the tension off by clamping it up in the vice. Now you can remove the nut,open the vice and remove the piston rod and spring. The only thing now holding the piston is friction so either clout it on a wooden surface or poke it out from behind. The piston has a stepped nylon seal so take care of it.Now the interesting bit, mine had less than a teaspoon of oil behind the piston so I wasn't convinced that oil was the problem but I carried on and cleaned the oil up.Putting it back together is just a reversal of the way it came apart,making sure you get all the valves in correctly(I think they'll only go in the right way). I realised that something had changed when I started to fit it back on.............because the piston was now returning fully the overall length of the piston rod and the separate pushrod was now longer making it just a little more awkward to fit!! Got it all back together and fired it up and............rattle's gone!!!!! Acess is a pig so it's not the easiest job to do but so far so good. Maybe it'll get oil behind again but I reckon it's worth a try for the money I've saved!!
 

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Any pics? T:
 

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Discussion Starter #7
Any pics? T:

Sorry mate, I didn't take any. If you've got any mechanical aptitude it's fairly straight forward, all you have to do is take care removing the lid. There's nothing under load under it but just make sure when it comes off you make a note where everything goes.T:T:T:T:
 

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Just thought I'd add to this, I've done 4500 miles since I stripped and cleaned the vac pump with not even a hint of a noise.
Until I did a service yesterday, now it's rattling again! I'm in 2 mind about if it's worth cleaning again or to get a new one? It's a bit of a bugger if I'm going to have to clean it every time I do a service.
 

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Any update on this?

I imagine if you catch it early enough, then you won't cause too much wear to the pushrod/ mechanism. If it's rattling for a long time then something has to be wearing/ deforming so the longer it rattles, the more damage will be done.

Time to give mine a go it seems!
 

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Hi, I'm a new chap to posting but having trawled the site looking for solutions to the rattling vacuum pump I decided the best option was to buy new. As budget is tight (as always) I opted for eurocarparts Dansk unit about £140 all in. Made by Mechanex which could be "made in China" for all I can tell. The casting looked OK and the fit was near perfect so hoping for the best. However, push rod/tappet bar was bought from VW main dealer at £40. It was whilst I was speaking to the parts guru he mentioned that it was unlikely that this rod would wear considerably and to that end they rarely change it but do change the pump. I still bought it just in case and after fitting the rattle has gone. I guess its up to you guys to decide whether buying a new rod is a waste of money or not. Back to the other issues with the good old VW.;)
 

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T: Further to the excellent First post, a few pictures.

NOTE. I have not fitted or proved the strip / rebuild yet, but a bench test showed a Vacuum IS being drawn :D

****Pump now fitted, all good, no 'tapping'***


Cleaned ready for strip down.



Cover removed (T25 Torx x6)



Close up of uncleaned seal (stuck in place) and NRV's



Seal removed



Seal and NRV's removed with piston removed



Piston, pushrod and spring assembly removed but in order



Cleaned and reassembled (note: I did not clean the NRV assemblies, I don't know how fragile they are)



Block side (seal requires replacing)



How I 'THINK' it works.


Spring pressure draws piston back 'Drawing Vacuum'



Cam acting on on pushrod moves piston out preparing for 'Vacuum draw'


I think the cam and push rod are supposed to be in contact at all times using spring pressure to maintain contact. When it fails, oil gets trapped behind the piston and stops the spring short of full extension, creating a 'break' in contact between pushrod and cam, the 'Tap' is the contact forming again on the next cycle (I 'think' LOL: )


Hope the pictures compliment the excellent initial post.


Chris

***Pump now fitted, all good and no 'tapping' since fitting***
 

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T: Further to the excellent First post, a few pictures.

NOTE. I have not fitted or proved the strip / rebuild yet, but a bench test showed a Vacuum IS being drawn :D


Cleaned ready for strip down.



Cover removed (T25 Torx x6)



Close up of uncleaned seal (stuck in place) and NRV's



Seal removed



Seal and NRV's removed with piston removed



Piston, pushrod and spring assembly removed but in order



Cleaned and reassembled (note: I did not clean the NRV assemblies, I don't know how fragile they are)



Block side (seal requires replacing)



How I 'THINK' it works.


Spring pressure draws piston back 'Drawing Vacuum'



Cam acting on on pushrod moves piston out preparing for 'Vacuum draw'


I think the cam and push rod are supposed to be in contact at all times using spring pressure to maintain contact. When it fails, oil gets trapped behind the piston and stops the spring short of full extension, creating a 'break' in contact between pushrod and cam, the 'Tap' is the contact forming again on the next cycle (I 'think' LOL: )


Hope the pictures compliment the excellent initial post.


Chris
Great post. That's also how I think it works.

I can confirm that cleaning does stop the tapping however I've done it twice and both times it's come back after 5-7k
My vans done 245k and I've no record of it ever being changed or for how long it was tapping before I got the van.
I suspect my pumps to worn for cleaning to work as a permanent fix. But if your van has less miles or you do less than my 12-20k a year it's well work the time and effort to try cleaning it first.

Gavin
 

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Just a question / thought

All the inlet/exhaust valve stems have an oil seal on them. Is there a similar seal on the vacum pump push rod that needs replacing as well as a clean/de-oiling of the pump itself
 

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What an excellent how to, now with pics - always makes it so much easier for us to see what's going on and whether we like the look of doing it.

I had mine off a while ago due to a bit of an oil leak from the "seal" onto the block, which had failed. As already said it's a daft design/application for the pump, being mounted with oil collecting down into/onto it.

I wonder whether I should get it off again for a strip/cleanup... ? Does leaving it getting oily inside actually cause the problem to occur/get worse? I don't think mine is actually noisy, yet - done 155k.
 
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