How to change your cam follower inside. (Now with debate about failures and their cause.)

[magilson]

Quote, originally posted by GolfRS »

This is exactly the kind of early damage that leads to all those missing center piece photos.

How did you reach that conclusion?

[xxxfast]

shue get some lotion on those hands........ouch

[NoRegrets78]

I'm hosting the TSB here http://hardwired.homeip.net/VW...r.pdf

When I had my pump installed, my follower looked like the picture with the scuff marks.

[Issam Abed]

I thought the 2.0 motor was testing for over a year before VW released it!How is it that all these stupid failures are still happening in 2008!?

[Audi4u]

Quote, originally posted by Wizard-of-OD »

I thought the 2.0 motor was testing for over a year before VW released it!How is it that all these stupid failures are still happening in 2008!?

And its a big problem, 9 pages in 6 days. damn

[blackvento36]

Quote, originally posted by shue333 »

when i reinstall the pump, just start it up? or do i have to do something to prime it?

You don't really have to do anything. Just let the key set to "on" for a second before starting it, I'm pretty sure that's what pressurizes the hpfp. Opening the door primes the lpfp

Quote, originally posted by NoRegrets78 »

Just be very careful when you bleed it...there's a lot of pressure in there! Don't let yourself get caught in the stream.

I didn't notice alotta pressure at all when I bled mine. I'd just keep a rag under it cuz it does let some fuel out, as does cracking the lines on the pump

Quote, originally posted by NoRegrets78 »

No pressure? What was with all the warnings about high pressure, run it with the fuse out or you'll die blah blah blah?

IIRC the early pumps (those before the "F" pump) did not have bleeder valves these may have to re run out the old fashioned way, by pulling the fuse and stalling the car

[shue333]

Quote, originally posted by xxxfast »

shue get some lotion on those hands........ouch

those are working man hands, sonny

i do hvac and was glueing together pvc pipe yesterday. got the glue all over my hands. so that's not dead flakey skin, it's pvc glue i haven't pulled off yet. it dries them out a bit also.


Modified by shue333 at 9:00 AM 3-29-2008

[rbradleymedmd]

can someone inform my stupid ass how to get that second fuel line off? I have the two metal lines running into the pump...first line was a breeze (17mm wrench)...second line (12 pt...not sure what size)? Thanks.

[jc@douglas]

8mm 12 point

[Mohudsolo]

I do not own anything with a 2.0T in it and have no stake in this whole discussion but am an engineer and find this to be an interesting technical problem.

Followers that look like the one that Shue333 posted that show a small ring near the holes could be tested with magnaflux or dye penetrant to see if that is cracking in the metal or only wear in the coating.

To get the follower to rotate, the cam will have a very slight cone shape to it with a very small difference in the circumference of the lobe across the face. This could tend to cause the scuffing seen in the coating on the follower face.

Most followers that fail are becoming concave on the face that contacts the cam lobe then the face fractures off the rest of the follower and carnage happens. My question is: does the metal of the follower wear off, get forged thinner, or does it stay basically the same thickness and get formed to the concave shape?

If it wears, the problem is a failure of the oil film. That can be from poor oil, prolonged oil changes, overheating of the oil, or simply overloading the surface. A spring that is too stiff could do that, but stock pumps are also causing failures. Is the coating on the follower for break-in or is it supposed to hold oil to give better load carrying capacity? In a properly designed follower, there should not be metal to metal contact; they should always be separated by an oil film. Maybe a better surface treatment would do it.

If wear is not the cause of the concavity, then that points to poor design of the cam lobe itself causing the pump to float. Pushrod engines can have issues of the closing side of the lobe doing a poor job of decelerating the follower as it gets back to the base circle and having it bounce when it stops. This causes very rapid wear. As Harley people with Evolution motors who had certain aftermarket cams about valvetrain issues in just a few thousand miles.

If stress is the main cause of failure at the holes, that also points to a basic design problem. The center of the follower transmits force from the cam to the pump. The only load that should be through the outside of the follower should be to resist rocking and to keep the surface touching the cam from rotating with it. Is there any chance the "skirt" area of the follower can hit something at either end of travel? How close to the oil holes does the cam lobe actually hit? Could it be a simple as being too close to the holes and being a stress riser?

Adapting a roller follower is not that easy. Roller cams usually require a different material for the lobes than flat tappet cams. Pushrod engines generally have to switch from chilled iron to some variation of steel and the cam lobe shape is very much different.

Simply making a follower thicker/heavier could make it worse as it would make it float at lower rpm. Better knowledge of the exact failure mode is necessary before anything concrete can actually be done.

I fear this could become another of those nagging problems that dogs VW. I'll be interested to see how this eventually turns out.

[rbradleymedmd]

Quote, originally posted by jc@douglas »

8mm 12 point

Thanks JC...started pouring on me once I got back from lunch, so I put everything back quickly and will have to give it a look next weekend.

Quote, originally posted by Mohudsolo »

If stress is the main cause of failure at the holes, that also points to a basic design problem. The center of the follower transmits force from the cam to the pump. The only load that should be through the outside of the follower should be to resist rocking and to keep the surface touching the cam from rotating with it. Is there any chance the "skirt" area of the follower can hit something at either end of travel? How close to the oil holes does the cam lobe actually hit? Could it be a simple as being too close to the holes and being a stress riser?

This is extremely interesting. Would moving the 4 holes to the side of the follower help this? I'm not sure if oil would be able to circulate through it then, but if these holes were drilled very low (towards the base), seems like it could be a good idea.

[SuckSquishBangBlow]

Pulled the vac pump apart and found that I have the two piece B cam. 3/2006 build date w/ engine #07XXXX. Tried to pull the HPFP but just couldn't get at the second metal line coming off the bottom. Guess I'll jump back into it next weekend...

[enginerd]

Quote, originally posted by GolfRS »

This is why i said what i said above about your suggestion. I guess no one noticed the stress marks forming an inner circle at the weak points connecting the lubrication holes.... This is exactly the kind of early damage that leads to all those missing center piece photos. My advise would be to change the follower ASAP to avoid cracking and all the known consequences.... But then again...its up to you....

Those do not look like stress cracks. If you can look at it at high magnification you can look for cracks. I have not seen any stock pump, or OEM pump spring retainers/wobbler cause stress cracking. From the picture it looks like coating wear. Stress cracks are never a perfect circle .. lol

The pumps with stress cracks are from autotech pumps that have poor contact geometry with the inner part of the follower. The origin of the stress cracking appears to be the contact point with the autotech pump tip, not around the holes. Here is a picture from a greek site with good details on this particular failure mode.

When GolfRS is done rolling his eyes he may take a step back and realize that he has been completely wrong about the importance of the OEM spring retainer. He just has it out for APR due to European pricing and will support anything else.

http://www.carsinspections.com....html

The wear marks on the above photo shows wear marks away from the center. These are from the follower making contact with the edges of the cam due to tilting of the follower. The cam has a crown to it to contact in the center, but some tilting can cause this edge contact. If you measure the width of the cam you will find that is matches the diameter of these contact marks.

Everything is worn in together if you change the follower you risk damaging the coating from high contact stress. I would not change it unless those are indeed cracks.

The follower has a DLC coating. I have SEM data showing this, and I have worked with the supplier that applies this coating on the VW parts.

TiN coating is gold colored BTW, and very aggressive - it has a high coefficient of friction and would eat the cam.

When the coating is worn through the base material can not support the contact loads and wear rate is very high.

Modified by enginerd at 10:37 AM 3-31-2008


Modified by enginerd at 10:39 AM 3-31-2008

[2zzge]

thanks for your post enginerd.

you state that once the coating is worn, that metal wear happens much faster....
i looked at my CF when installing my pump and the coating was nearly worn completely off...in a somewhat square pattern (basically straight lines from hole to hole).

the cam looked fine and so did the pump-side of the follower.
there was some light sratches/scaring on the face of the follower but VW shows that to be "normal".

it looks as tho' my follower -after only 20k+ miles- is about to die.

pfft...i'm ording an new one today.

[magilson]

Quote, originally posted by enginerd »

The wear marks on the above photo shows wear marks away from the center. These are from the follower making contact with the edges of the cam due to tilting of the follower. The cam has a crown to it to contact in the center, but some tilting can cause this edge contact. If you measure the width of the cam you will find that is matches the diameter of these contact marks.

Which is exactly what I told GolfRS via PM. He just doesn't listen...

Quote, originally posted by enginerd »

The follower has a DLC coating. I have SEM data showing this, and I have worked with the supplier that applies this coating on the VW parts. TiN coating is gold colored BTW, and very aggressive - it has a high coefficient of friction and would eat the cam. When the coating is worn through the base material can not support the contact loads and wear rate is very high.

I'm sure syntrix thought this was TiNi because he owns some knife with that coating. You are correct that it's gold, it's just that a gold colored knife doesn't sell as well as a gray or black one.

As a side note, I'm sure you will have to explain a bit more since I'm sure this last statement will make a few unbelievers perk up as it would appear that we are seeing that there is a high wear rate (although I'd be interested if anyone still believes it's occuring before the coating wears off.)

[twinkers]

Just figured I'd post pics of mine. 10,000km stock pump Apr S1. Another 10,000km Apr S2. Another 10,000km Apr S2+Apr pump. 500km Apr pump + GT30.

[goin2fast]

Hopefully I will be able to show how the VF pump treats the follower in the next few weeks.

[glydingsoul]

i havent begun to read this whole thread, but i figured i'd add my experience with this engineering blunder.

i was driving in first gear when i heard a *pop* and a *wizz*. it sounded like a rapid depressurization. boy was i surprised when i got under the hood.

Cam Case:

MY Fuel Pump Cam Follower:

Cam Damage:

Fuel Pump Damage:

No other damage was found as of today, but who knows what this could have caused that is not yet visible. i just hope their fix is a permanent one. i guess i'll start looking at the aftermarket replacements after VW gets the car back to me.

[shue333]

^ it's good to hear they're taking care of it. and letting you get pictures!!!

[rbradleymedmd]

Shue,
Did you ever figure out your hesitation issue? Since you know that it's not fuel issue, where are you going to turn now? Also, when your hesitation occurs, does the car's RPM drop at all?

[enginerd]

Looks like a "B" Cam failure on all stock parts

[rracerguy717]

Quote, originally posted by enginerd »

Looks like a "B" Cam failure on all stock parts

Hopefully the Aftermarket cam companies will have a solution. Bob Q said that CAT cams is coming out with a cam for the 2LTFSI hopefully with a follower solution . Bob.G

[NoRegrets78]

I'm sorry but that's just unacceptable.

We shouldn't have to buy parts to fix a design flaw on these cars. We paid to get a fully functional vehicle and from what I'm seeing, even completely stock, we're not getting what we're paying for.

Why do I have to spend another thousand or so dollars just to make sure my car that I spent so much money on is reliable???

If I didn't just buy a bunch of parts for this thing, I would have traded in for another Honda. This has been my first and will be my LAST VW.

[crew219]

Quote, originally posted by enginerd »

Looks like a "B" Cam failure on all stock parts

What do you make of the follower?

IMO it looks as if the follower failed, not the cam.

Dave

[jc@douglas]

follower was deff. what failed here causing the pump to take out the cam

[magilson]

Quote, originally posted by NoRegrets78 »

If I didn't just buy a bunch of parts for this thing, I would have traded in for another Honda. This has been my first and will be my LAST VW.

lol. I think that's probably for the best! The MkV generation has brought into the fold a large number of people that will never be dubbers.

[goin2fast]

Quote, originally posted by magilson »

lol. I think that's probably for the best! The MkV generation has brought into the fold a large number of people that will never be dubbers.

x535436546

[OOOO-A3]

Quote, originally posted by magilson »

lol. I think that's probably for the best! The <INSERT VARIABLE HERE> generation has brought into the fold a large number of people that will never be dubbers.

If YEAR=1975, then VARIABLE=watercooled

If YEAR=1985, then VARIABLE=Mk2

If YEAR=1992, then VARIABLE=MkIII

If YEAR=2000, then VARIABLE=MkIV

If YEAR=2008, then VARIABLE=MkV

[OOOO-A3]

Quote, originally posted by enginerd »

Everything is worn in together if you change the follower you risk damaging the coating from high contact stress. I would not change it unless those are indeed cracks.

So, you're saying that we *shouldn't* change the follower as a routine preventive maintenance item? There's nothing to be done except hope for the best? I'd change the damn thing myself every 10k if it meant never having to worry about getting stranded, or spending $$$$.

[NoRegrets78]

I would have loved to have committed to dubs for the rest of my life...eventually going the way of Audi. I was IN LOVE with german engineering having come from reliable yet soulless hondas/acuras.

But how can you expect any newcomer to the dub scene to really invest emotion/time/money into it when the drivetrain even stock is unreliable?

[fastconti]

Quote, originally posted by jc@douglas »

follower was deff. what failed here causing the pump to take out the cam

I don't know about that. From what I can see, the follower's contact face has been sheared off. This could be due to wear on the cam that allowed improper lubrication or contact angle between the cam and follower. The increase of tangential force against the follower could have sheared the face from the follower. However, this failure would be expedited by concave deformation of the follower face.

[NoRegrets78]

For those who've seen failures...what kind of oil have you been using?

[magilson]

Quote, originally posted by NoRegrets78 »

But how can you expect any newcomer to the dub scene to really invest emotion/time/money into it when the drivetrain even stock is unreliable?

Again, proving my point. Even if I had to change this cam and follower every 30k I still wouldn't sell it for any other make. I like to have fun when I drive!

Just be patient for the aftermarket. This feels a bit like the great PCV and DV scare of 2007. And if there isn't any aftermarket, then keep a good eye on the parts and be ready to buy new ones. From what enginerd has been saying we should all be good at cam swaps eventually!

[OOOO-A3]

Edit: nevermind, dumb question


Modified by OOOO-A3 at 1:26 PM 4-1-2008

[NoTsipa]

Can someone please post a photo , of the pump out of the car with the follower nearby just to see how it '' sits '' on the pump's spring ? Wouldn't be a solotion of making the spring sit directly on the followers inside base and let the pump's pin get in touch with the followers base diameter somehow .
I 'll try to post a drawing of what iam saying later


Modified by NoTsipa at 9:23 AM 4-1-2008