Club 80-90 Forums

Hi all, we could do with a bit of your knowledge...

Our van (1.9 water cooled petrol engine) started running a bit lumpy, which turns out it was only running on 3 cylinders. The spark plugs had oiled up - so we replaced them. Also we replaced some worn tappet screws as the same thing happened about a year and a half ago, and we replaced some worn tappet screws then and it seemed to resolve the problem.

Our van has 4 x10mm tappet screws on the right hand side and 4 x 9mm on the left. Now I'm not very knowledgable on engines/mechanics but I'm guessing this isn't right and some parts have been replaced at some point. Does anyone know which size tappet scerws would have been the correct size as standard for our van/engine?

Also the 9mm tappet srews have worn quite severely in about 18 months (see image) - does anyone have any idea what could be causing this?

Unfortunately this time around replacing the tappet screws hasn't resolved cylinder 3 not working

Cheers
Mark

If thats a wbx engine then those are not tappets

tappets should be hydraulic and are located in the engine case, if you have had solid tappets fitted in the past then you need to adjust the screws (which I think you have shown) to have a clearance.
If Hydraulic they are adjusted to have a preload

Sorry, I meant tappet screws. I've changed my original message now so it should actually make sense. Trying to figure out which size tappet screws would have been standard on our van and what could be causing them to wear away so badly?

My mate (helpful mechanic mate) who is used to dealing with Aircooled vw's rather than watercooled, tried to get the actual tappets out to check if they are hydraulic, but couldn't seem to get one out. He said he tried dangling a strong magnet down there to pull one out to see.

so you have telescopic push rod tubes do you? can't get to them with standard push rod tubes.
You can get them out just need to get a very small flat screwdriver and bend the end over, you can then hook them out from the circlip groove, turning the engine over helps to push them up to cam max.

Adjuster screws are worn because you have a gap, bet it's making a right din.

I wonder if you have the wrong valve gear/ rocker shaft on one side?

Them screws have been beaten to death.
Has your mate set the valve gaps for you?
Because there should not be gaps!

AFAIK all wbxs after 1988 had 10mm adjusters. Prior to that, dg/df had 9mm. Same preload setting on both types - 1.5 turns in from touching.
If you have both sizes, most likely someone has swapped a head in the past. You could convert all to 10mm if you wanted. Easiest way is a good complete rocker shaft off an old head (fit new screws where needed), most expensive is to buy the rocker arms, screws and locknuts individually (about £150 for 4).
Possible reasons for hammering the ends of the adjusters include incorrect adjustment /assembly causing misalignment, bent pushrods, a badly worn camshaft (with flat spot causing hammer effect) or non-hydraulic cam fitted?

marandali wrote: My mate (helpful mechanic mate) who is used to dealing with Aircooled vw's rather than watercooled, tried to get the actual tappets out to check if they are hydraulic, but couldn't seem to get one out. He said he tried dangling a strong magnet down there to pull one out to see.

Why didn't he just look at them in place?

I would also add that the tappet screws supplied by some outfits are not made of very stern stuff, I replaced some of mine with screws from a well known place that only does stuff for Kampers and they were like cheese. The replacements from Brikwerks are still looking perfect. It could have been a bad batch I suppose. If you want to be able to get at the tappets just in case get a set of SCAT BIG MOUTH telescopic tubes and buy the silicone seals (8 of the smaller ones) Dont use the seals that come with them. £65.00 a set and do the job well. Use a bit of silicon grease around the seals.

ajsimmo wrote:AFAIK all wbxs after 1988 had 10mm adjusters. Prior to that, dg/df had 9mm.

Didn't know that, thanks for sharing

I have bought a few sets from VW Busshop (Gunzl) before now. OEM stock.

Thanks for all the input.

ajsimmo - from what you've said I think our van (being an F reg 1988) has the 1.9 dg engine and therefore originally would have had 9mm tappet screws.

As it happens further probing has uncovered that cylinder 3 has no compression and it looks like the exhaust valve is burnt out. Cylinder 1 was also showing signs of wear.

Now we need to decide on whether to A) try and get the engine taken apart and fixed, or B) get a replacement bare engine.

I've heard these engines can be trouble to get apart and fix! Any advice on which option go for? And where to look for a good replacement bare engine?

Cheers

Correction. 'Cam followers' are in the engine case. The screw adjusters are tappets.

itchyfeet wrote:tappets should be hydraulic and are located in the engine case, if you have had solid tappets fitted in the past then you need to adjust the screws (which I think you have shown) to have a clearance.
If Hydraulic they are adjusted to have a preload

Okay go it now. I think. Ta.

I'll start a new post with the last two questions I asked, as they don't really relate to my initial post anymore.

CovKid wrote:Correction. 'Cam followers' are in the engine case. The screw adjusters are tappets.

not according to this...
https://en.m.wikipedia.org/wiki/Tappet" onclick="window.open(this.href);return false;

https://en.m.wikipedia.org/wiki/Tappet wrote:The name arises because it is the clearance of the tappets that is being adjusted, even though the adjustment is not made to the tappets themselves.

Strictly speaking, the tappet, also termed a cam follower,[3][4] or lifter,[5] is that part that runs on the camshaft and is made to move vertically by the action of the rotating cam.