hydraulic tappets ceased?

[palmerw]

Hi Guys,

I've been having a reccomended mechanic look over my van due to power loss and poor performance. So far I have had carbs balanced and throttle cable tightened, that has helped a lot but still not near what performance I had before I started having these issues.

Firstly I have a 1982 Aircooled 2.0ltr CU.

I am expertiencing poor preformance, especially when cold (dipping clutch and dies at every junction) and high fuel consumption.

The mechanic has looked at the values and initially at TDC all 8 were closed with no give. He then put some clearence on and said monitor these as the gaps should close up after a run (I was doing a 90 mile trip the next day) and give a little when pressed. I vistited him again to ask him to have a look this weekend (2 weeks from inital setting and about 200miles) after a 90 mile journey and still had poor running issues. He again looked at the valves and said 7 out of 8 still had a gap and said the hydrolic tappets have probably ceased. He said that leaving a brick on the throttle for an hour could help as one of his friends had solved a problem liked this before.

He also said to mention my situation on a forum and ask for advice on this matter as he works with old Aircooled ususally without the hydrolic tappets.

I should mention oil change was 300-400 miles ago.

Would be great if anyone could help, I'm a mechanical novice but learning quickly!

Thanks,

Will

[Red Westie]

ceased? as in dead? or seized as in not moving?
Anyway, there is much debate about the exact settings for hydraulic lifters, one thing is clear though, you need to take out the clearance THEN pre-load the lifter: Haynes says 2 full turns (this is said to be too much and incorrect info) lots of peeps are saying anything between 1 and 1.5 turns, the odd person saying a quater to a half a turn pre-load after clearance has been taken out.
The nature of an hydraulic lifter means it takes out any clearance by filling with oil but if adjustment is wound out beyound the lifters travel it can no longer auto-compensate for clearance and may infact not be opening the valves suficiently (at least thats how I see it)
Martin

[palmerw]

Thanks for the reply,

Sorry to be ignorant but how do I tell if they are not moving or dead?

After my 90 mile run yesturday the tappets sounded like a machine gun.

I will ring the meachanic to ask how far he turned then out but he used a feeler guage to put the gap in; it could be that the gap was beyond the point this auto compensate point on all but one.

[dugcati]

Do you know for certain that your engine has hydraulic lifters? don't forget many of these vans now have a bit of chequered history!


It could be possible the tappets have been back off too far and cannot self adjust to the right setting?... To find out if the tappets have seized then a screwdriver in between the valve and rocker is the way I have found - you should be able to squash the spring up.

If you confirm they are hydraulic (and they are not seized and have oil in them) then I would set them up by backing them off completely then doing the 1.5/2 turns in pre-load pressure thing.

I'm not sure about the 2.0l engines - I hear the pushrod tubes can be removed with the engine/heads in place - the tappets are fairly easy to get out with a telescopic magnet - I think it is possible to pull them all the way up the pushrod tubes if you don't want to remove them but it's a reet fiddle!

I'm sure the 2.0 Aircooled crew will be along to confirm my ramblings and also add to the fault finding with you

[Ian Hulley]

With the ignition off and the rocker covers off turn the crankshaft with a socket and watch the rockers, they should rise and fall as the cam activates the tappets which in turn push the pushrods which will then be pushing the rockers via the adjustment screws which then push the valves open against their return springs.

If the rockers dont move the tappets have failed and it's back to the garage via the bank

Ian.

[palmerw]

Do you know for certain that your engine has hydraulic lifters? don't forget many of these vans now have a bit of chequered history!

I have what appears to be a volkspares engine that has hydraulic tappets (well the stickers on the rocker cover say they are!). I've heard that these arn't the best of replacement engines

I will have a look tonight at the van with advice given and report back.

Thanks for the help,

Will

[Red Westie]

It will sound like a machine gun if your mechanic has backed them off this much. As for seizing....hydraulic tappet elements don't usually seize (as far as I am aware) they are more prone to leak and not hold pressure which results in a clatter of tapping noise for the first 5 miles or so of a journey until properly warmed and self primed.
Martin

[jason k]

well if he has done that its wrong. they need to be pre loaded.

he has gapped em like a traditional tappet. this should not be the case.

grab a haynes or look in the wiki for the cu motor and look its all there.

or better still take it to a mechanic who knows what he is doing!!!

[kevtherev]

lots in the wiki on tappets

[Globbits]

I'm not sure about the 2.0l engines - I hear the pushrod tubes can be removed with the engine/heads in place - the tappets are fairly easy to get out with a telescopic magnet - I think it is possible to pull them all the way up the pushrod tubes if you don't want to remove them but it's a reet fiddle!

Sorry for the hijack, but can anyone confirm this is possible? I'm toying with replacing all the hydraulic tappets on my DG engine and don't fancy forking out for spring-loaded pushrod tubes if I can get away with it!

Richard

[Ian Hulley]

Sorry for the hijack, but can anyone confirm this is possible? I'm toying with replacing all the hydraulic tappets on my DG engine and don't fancy forking out for spring-loaded pushrod tubes if I can get away with it!

Richard

You would have to fit 8 telescopic pushrod tubes to do this without taking the heads off. What's wrong with your tappets that you'd want/need to replace them all ?

Ian.

[Globbits]

Long and boring story (if you're bored, feel free to read it on the Brickyard ) but I have hydraulic lifters that won't preload. They're definitely hydraulic, but if I wind them past just-touching, all that happens is the valves open and I lose compression