engine rebuild trouble

[itchyfeet]

Rotor arm position is dictated by the dizzy drive, looks like it could be a cog out so id pull tge dizzy and recheck with haynes pic
dizzy body looks way off, rotate it until the rotor arm points at the hole with cap when on tdc

[ermie571]

ok - this weekend we serviced the van. new rotor, cap, leads and plugs. All back together .... no start.

sparks on each lead.

Put everything back

still no start.

the leads were 90 degrees out....

Mate showed hubby (while I made tea frustratingly) how to get to Top dead centre....and at this position it was at 2, not 1 (or something like that) moved all the leads round one position....and it started. Dunno how many times we have serviced the van....problem was...I started off, then hubby took over.... d'oh!!

I knew mine had to be sommat simple.

Em
xx

[T25Convert]

In terms of the dizzy you should be able to check its in the right place.

First pick a cylinder, doesn't matter which one. Spark plug out, rotate it until it is on the compression stroke (check by using thumb over the hole as you turn - you should feel the compression. Check its at the top of the stroke (using a thin screwdriver). Your rotor arm will be point somewhere.

The rotor arm should point at the plug lead of the cylinder you have just been poking, so its a case of putting the dizzy cap back on, marking up where the 4 leads sit and then twiddling the dizzy body until the rotor arm lines up with one of the marks you made. Make sure this plug lead is the right one for that cylinder, then work round from there making sure each plug lead is in the right place to match the firing order.

You can do this using a small mark on the dizzy body and number one cylinder (as per the Haynes manual) but if you are not sure its all in the right place this way you will make sure that the dizzy is with a couple of degrees of where it needs to be so that it is providing a spark on the compression stroke.

Good luck!

Alex

[itchyfeet]

Good advice, i was thinking it doesnt really matter if you get the dizzy drive in one cog out as you can just turn the dizzy by the same amount.

[agnew1985]

Well I moved the dizzy driveshaft 1 cog and I have to say it doesn't look like the manuak says it should. anyway I've put a pic of it below. I have been twisting away at the dizzy for ages but to no avail. There is a mark on the body for no. 1 which was correct before i did the work so i should be lining it all up fine. I feel like it must be the compression issue still. I've bought a leak down tester to see what results that yeilds. Does that sound sensible?! Probably wont get a chance to do anymore now till after the weekend. Thanks again for all the advice.

[itchyfeet]

does the rotor arm point at the dizzy cap terminal when it's fitted? if so that's OK, but could be 180 degrees out , if you can't seel compession on no1 how do you know?
use Alex's method on 3 or 4 which have some compression to check

First pick a cylinder, doesn't matter which one. Spark plug out, rotate it until it is on the compression stroke (check by using thumb over the hole as you turn - you should feel the compression. Check its at the top of the stroke (using a thin screwdriver). Your rotor arm will be point somewhere.
The rotor arm should point at the plug lead of the cylinder you have just been poking,

Try taking plugs out then hold your finger over the spark plug hole, turn it over and see what compression you can feel with your finger
then remove rocker shaft and repeat, see if its any different , this may indicate if its valved being held open at the wrong time.

did you do this yet ^^^^^

[agnew1985]

Hi Itchyfeet, yes I did do as you suggested and I could feel no pressure with it on or off. I have checked a few times that the dizzy driveshaft is not 180 degrees out but I will double check with Alex's method asap!

[Ian and Lins]

Just a few thoughts on bent valves/compression loss;
Valves are usually bent because the crown has been clouted by the piston or something in the combustion chamber. It only has to be bent a very small amount for all compression to be lost. You will probably see no bending or damage on the valve stem itself.
Compression is lost due to; ring wear failure, hole in the piston, worn or damaged valves. It helps if you can deduce whether it's rings or valves. Take a compression reading; if it's OK well, whooho!, if it's low then the OLD method used to be to pour a bit of thickish oil down the plug hole and do another comp check. If it's improved, even if only for a few strokes, it indicates ring/piston wear as the oil provided a temporary seal. If the reading is still low it points to the head/valves.

Of course, it's a boxer so not sure how you would 'seal' the rings, spray grease?

Good luck and keep at it!

[itchyfeet]

If you read back its had new rings and compression has been checked, its low or missing
oil down the plug hole may not be much good on a wbx because of gravity as said

[agnew1985]

Hi everyone, managed to get some time on the van today. Did as alex suggested with the screwdriver and the dizzy was in the corret position for each cylinder. Also bought a cheap leakdown tester and while I don't think the gauge is the most accurate I found: little loss of pressure on 3 and 4 but 100% loss of pressure on 1 and 2. On cylinder 1 I could hear air rushing out the exhaust and on cylinder 2 out the exhaust and carb. I'd say pretty conclusive.valve damage?! Spose that means the heads coming off...

[itchyfeet]

Before taking heads off just try removing the rocker gear and do that again, just to be sure with nothing touching the valves they still leak.

[T25Convert]

^^^ WHS!

With the rocker shaft removed you'll know for sure if the problem is that your valves aren't sealing or if something is holding them open (like a pushrod that isn't quite right for example - took me a five goes to get them to seat when eth engine was in the van, ended up using some thick grease to hold them all in place, right pain).

On the up side (there is one if you look hard enough!) at least the air was coming out the exhaust and inlet, indicating it is most likely valves and not rings / cracked head etc...

Let us know how the leakdown without rocker shaft goes!

Cheers,

Alex

[silverbullet]

Unless I have overlooked it, you have got the earth strap connected between block and body haven't you?

If it's all been out and the inlet manifold off you may have an air leak. Had this on a carb'd wbx last autumn, wouldn't start for love or money and I was convinced that it was an ignition fault. In desperation I replaced the inlet gaskets and glued them on for good measure. It started first time.

[agnew1985]

well I'll be honest I'm a bit dissapointed! Taking the rocker shaft off made no difference - still had air coming from exhaust and carb. So I thought, well I'll take the problem head off and have a look. I fully expected to see something dramatic but.... no! I've attached pics but the valves don't look bent. I'll lap them in again because that looks like the only cause for the leak. Mind you, I haven't actually taken the valves out and had a really good look yet. Also there is a tiny crack between the valves on both cylinders which I hope can be made out in the second pic. Also noticed that cylinder 2 was slightly oily - left hand of the first pic. This one did seem to spill more air than 1 but only just - they were both really bad. Just expected it to look much worse given the results from the leak down! Silverbullet - the earth strap is a bloody good idea! It's been so long since the engine went in I haven't given it a thought-I'll double check tomorrow!

[Ian and Lins]

Could you lay the head horizontally and fill the combustion chamber with paraffin? Leave over night and see if any has leaked past the valve heads.
I've not done it on a VW but used this method before.