T25 flat 4 hydraulic tappets - the learning curve continues!

[ghost123uk]

So, my "new to me" VW recon (at some time in it's past) has passed it's 2000 mile confidence test
Uses no oil or water and the inside of the (new) tail pipe is still perfectly clean ! (running on LPG helps )

So, time to check the hydraulic tappets and do an oil & filter change.

I knew how to do it, back them off at TDC to barely making contact, then 2 turns in, but I double checked in my Haynes anyway.

All went OK, only took 30 mins, until I tried to fire it up !!
No compression at all, it just span over like there were no plugs in it !!

I nearly pood myself, thinking I had done summat wrong and bent a load of valves

Checked on the WIKI on here and read that they should be done with a warm engine !!
It did not mention that in the Haynes !!

Set them to barely making contact again and ran it at tickover for 15 mins.
Set them 1 point 5 turns in (as recommended on the write up in the link from our WIKI) and all is OK
Seems to tick over better and is generally quieter and smoother sounding.

Big sigh of relief !!

I write all this purely for the benefit of any future "searches" on here re this.

.

[toomanytoys]

I use 1/4 to 1/2 turn from touching... and I am sure thats the setting VW changed to later on... less wear and tear and no little fear of the valves being held open...

[ghost123uk]

It's odd that there seem to be so many opinions on what is correct.
You would think VW would have a definitive answer !!

From => http://www.ratwell.com/technical/HydraulicLifters.html" onclick="window.open(this.href);return false;

Bentley (both Bus and Vanagon versions) say the adjustment should be two clockwise turns after the valve adjusting screw makes contact with the valve stem. Some folks think the adjustment should be 1/2 turn. If the lifter was dry and you were to preload the lifter 1/2 turns,In practice what happens if you don't preload the lifter enough is it will take too much time to pressurize and you won't get enough valve lift. This will cause the engine to labor and sound noisy. The noise is often heard coming from the camshaft (center of the engine).

The lifter will pump up to the correct oil level no matter what you set it to but a sufficient initial setting is important in order to prime the lifter: two turns of the 10mm valve adjusting screw with 1mm threads will preload the lifter ~1.5mm (remember the 1:1.3 rocker ratio). This is about half the distance that the piston inside the lifter can travel. If you use too little preload you will be stressing the lock ring that holds the lifter together. If you use too much preload, the plunger may bottom out at first, then if the lifter pumps up the valve may not close properly and compression, performance and valve life will suffer.

How about 1.5 turns instead of 2? In practice, this seems to be as acceptable as the factory recommendation and a feel good insurance against the ills that other people have experienced over the years following the factory recommendation. In my experience, 1.5mm of adjustment after the engine has run for a while ends up as 2mm. This is good news because it continues to support the ease of valve adjustment vs. solid lifters.

What happens if you only adjust them 0.5 turns? The lifter won't achieve 2mm of travel and you then upset the rocker geometry accelerating valve train wear.

Then =

When I first learned to adjust hydraulic lifter I used the following procedure before following the steps in Bentley:

1. Run engine at 11pm for 30 minutes to pump them up
2. Adjust valves cold first thing in the morning

Over time through research and experimentation, I realized that it's best to adjust them with the engine warm (VW even says that a solid lifter engine can be adjusted up to an oil temperature of 50ºC/122ºF).

The steps I prefer to follow are:

1. Change the oil and filter
2. Run engine for 5 min and let it cool for 5 min
3. Perform a valve adjustment sequence. For each valve...
* Record # of turns that keep the screw is in contact with valve (save for comparison later)
* Perform leak-down test on each cylinder with no tension on springs (record state of valves)
* Adjust valves to 1.5 turns

[Fritz]

John , I thought you would have learned at least one thing after all your troubles recently,,,,,,,,,,if it isn't f**ked don't try and fix it.

It's a pity the Axel Knutt trophy isn't featured anymore coz you would have won it hands down....



Regards


Fritz,,,,,,,,,,,,,

[T'Onion]

John
Why ? you say its running sweet as so why mess with it ???

oil and filter mate thats all you needed to have done. the tappets if set correctly shouldn't need touching.

[toomanytoys]

If you are daft enough to try and fit hydro's without filling them with oil first then the only way to clear them properly is with 6thou of clearance (as per normal solids) but they will make one hell of a racket and prob break........

[ghost123uk]

John
Why ? you say its running sweet as so why mess with it ???

oil and filter mate thats all you needed to have done. the tappets if set correctly shouldn't need touching.

I didn't say the tappets weren't a bit rattly tho did I - I have highlighted in bold the relevant bit above

That's why I was doing it

(Anyway, a quote from the article in WIKI "It is prudent is to adjust the valves upon purchase of a new vehicle regardless of whether or not you are told the engine has hydraulic lifters."

If you are daft enough to try and fit hydro's without filling them with oil first then the only way to clear them properly is with 6thou of clearance (as per normal solids) but they will make one hell of a racket and prob break........

No No No - I was not fitting them, I was adjusting them !!

.

[kevtherev]

Some super info here John
I used the top method from Ratwell
I used it to do my valve lifters... and it worked!

http://www.thesamba.com/vw/forum/viewtopic.php?t=151300" onclick="window.open(this.href);return false;

scroll down the page to the relevant links.

and here's a good step guide

http://www.thesamba.com/vw/forum/viewtopic.php?t=331065" onclick="window.open(this.href);return false; ( Bleeding lifters! )

[T'Onion]

Sorry John , I thought you got a second hand running engine , not a new one

I didn't say the tappets weren't a bit rattly tho did I - I have highlighted in bold the relevant bit above

So, my "new to me" VW recon (at some time in it's past) has passed it's 2000 mile confidence test
Uses no oil or water and the inside of the (new) tail pipe is still perfectly clean ! (running on LPG helps )

So, time to check the hydraulic tappets and do an oil & filter change.

I knew how to do it, back them off at TDC to barely making contact, then 2 turns in, but I double checked in my Haynes anyway.

All went OK, only took 30 mins, until I tried to fire it up !!
No compression at all, it just span over like there were no plugs in it !!

I nearly pood myself, thinking I had done summat wrong and bent a load of valves

Checked on the WIKI on here and read that they should be done with a warm engine !!
It did not mention that in the Haynes !!

Set them to barely making contact again and ran it at tickover for 15 mins.
Set them 1 point 5 turns in (as recommended on the write up in the link from our WIKI) and all is OK
Seems to tick over better and is generally quieter and smoother sounding.

Big sigh of relief !!

I write all this purely for the benefit of any future "searches" on here re this.

anyway glad you now up and running again

[ghost123uk]

Sorry John , I thought you got a second hand running engine , not a new one

Oh dear Oh dear Mr T'Onion (what is your real name - I am sure I have been told and forgotten - E D I T = Mark perhaps ? )

rtfm as they say

To clarify :-

It's a second hand motor I got off billy739 about 5 months ago.

It had been a VW recon at some time in it's past, and judging by it's general nick, not that many miles before I got it.

However it had been stored un-run for more than 4 years, so I flushed the oil system, changed the filter and refilled, bobs your uncle

However, I recently decided to check the tappets as it was a bit tappety.

My error, as in the first post above, was only a minor glitch and all was OK 30mins later.
It was all just a routine servicing / checking / familiarising thing really.

It is definitely quieter and smoother now, so I expect it might be better on the gas as well
Time and maths will tell !

[T'Onion]

Happy days then John , glad its running correctly now
rtfm .. erm which manual do you refer to
cheers
Edward