Xu10J4Rs Have I Possibly Bent A Couple Of New Valves?

[Emmy Seize 8]

Right, I've put my GTI6 engine back together today after a cambelt snap (with the usual bent valves).

 

The head has been reworked by an engine builder.

 

The last thing I wanted to do today was to remove the crank pulley in order to fit the new cambelt tomorrow.

 

I had pinned the cams and the crank. Before putting the head back on I made sure the psitons were all halfway up the liners as I had read about slipped pulleys somewhere on here before.

 

As none of my locking tools fitted the flywheel, I asked my wife to lock it with a chisel as I undid the screw on the pulley.

 

After loosening the screw we just left the chisel in place while turning the screw out of the crank completely.

 

A long story short: I missed the moment the pulley came off the crank and as the screw was quite hard to turn I must have moved pistons 2 and 3 towards the open valves.

 

Now I've got two questions:

 

1. Is it possible the I already bent the new valves again? and

2. What is the best way to move the crank into its proper position again?

Edited August 25, 2012 by Emmy Seize

[dcc 855]

if it were me I would take them out and get them checked. for the sake for the small extra work, could potentially save you hours of engine in and engine out...

[welshpug 1,666]

How far did you move the crank?

[Emmy Seize 8]

How far did you move the crank?

 

I don't know really. I presume a quarter of a turn until one of the pistons 2 or 3 met the valves.

 

Don't think that I actually forced the piston past the valves. Turning the screw ant-clockwise it felt like the crank was stationary.

 

Only turning clockwise gave me the idea that something had gone wrong anyway.

[Emmy Seize 8]

I've turned the crank back clockwise. As I had guessed, it was about a quarter turn.

I took a caliper to measure the distance between the top of the plug hole and the top of the piston.

All four are now ~89 mm away from the top of the plug hole.

 

As they all seem to be the same height, is it safe to assume that this is the position the crank is meant to be with the crank pulley pinned?

 

If so, I would put the timing belt on, rotate the engine by hand and then do a compression test.

 

My idea behind that is that if a valve is seriously bent, it should show in the readings (I'll squirt oil into the cylinders to avoid the readings to differ because of ringwear).

 

Any suggestions?

[Liquid_106 97 1 Cars]

As you're nearly there, I'd do what you suggested - get it timed up and do a compression test. Might have been lucky and will have saved yourself the cost of a new head gasket or the valve(s) are bent and you're no worse off that you were previously, bar a few hours(?) work.

 

Fingers crossed for you!

[welshpug 1,666]

Due to the valve springs a compression test rarely highlights a bent valve.

 

Only two things to do i think, carry on and hope it doesnt tap, or take it apart.

[Liquid_106 97 1 Cars]

Due to the valve springs a compression test rarely highlights a bent valve.

Can you elaborate for both mine (and guess OPs) benefit? Do you mean the springs are so 'strong' that the valves are held closed even though they are bent?

[Cameron 16]

Only one thing to do in my opinion - take it apart.

 

Imagine you get it going and it taps / drops a valve head, how will you feel then? Or if it doesn't, will you ever feel secure driving it or will you constantly have a thought in the back of your mind, waiting for a funny noise?

 

Take the head off and lightly lap all the valves in, that will tell you immediately if any of them have been bent. (If the valves have already been lapped, you could use a light coating of engineer's blue instead) The seat on the valve should be the same all the way round, if it's bent you will see that only part of the seat has been cleaned.

 

It's a couple of hours work for peace of mind, don't be lazy and take chances.

[CosKev 16]

I know its abit late now,but you should have unpinned the cam pulleys and let the valves sit in the closed position before undoing the crank pulley

 

Think I would carry on putting it together and hope you did not put too much force into the valves?

 

Presume you put the cams in the correct position for instalation,and have not turned them around too far when locking them?As this is how most new valves get damaged.

[Emmy Seize 8]

Presume you put the cams in the correct position for instalation,and have not turned them around too far when locking them?As this is how most new valves get damaged.

 

Actually, I pinned the cams before putting the head back on as I was afraid of turning the cams without being able to see the valves.

 

My measuring of the piston position seemed to be accurate enough: The crank pulley alligns nicely when I put it back on and pin it.

 

As soon as the thunderstorm and rain outside cease, I'll put the final bits on and give it a try.

 

Thanks to all of you for the advice. I'll post the outcome later....

[CosKev 16]

Actually, I pinned the cams before putting the head back on as I was afraid of turning the cams without being able to see the valves.

 

There is a set position for the cams to sit at for when you are installing the head so the valves are all closed.

Valves can get damaged fitting the head with the cams pinned,as you can catch them on the block if not carefull when lowering head into position.

 

How did you get on anyway?!?!?!?!?

 

Fingers crossed for you!!!

[welshpug 1,666]

There isn't a position where all the valves are fully closed, when the cams are pinned they are open slightly more though.

[Cameron 16]

I think when the cams "relax" they sit in a position where the valves are open an even amount, that's how I managed to get away with a cam pulley vibrating loose on the dyno with no bent valves! I still took the engine apart as a precaution though, 'cos I'm sensible like that.

Edited August 26, 2012 by Cameron

[Bas 6 1 Cars]

I think when the cams "relax" they sit in a position where the valves are open an even amount, that's how I managed to get away with a cam pulley vibrating loose on the dyno with no bent valves! I still took the engine apart as a precaution though, 'cos I'm sensible like that.

 

Sensible or chicken...

 

Cameron is right. Take the engine apart and check the valves. GTi6 valves are extreme easy to bent!

 

I learned the hard way:

http://forum.205gtid...ra&fromsearch=1

[petert 600]

I'd time it up and give it a compression and leak down test.

[Emmy Seize 8]

A TAPPER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

But only until the tappets were filled with oil completely :lol: :lol: :lol: :lol: :lol: :lol:

 

 

THANKS (caps is ok for big thank yous, I guess) to everyone for giving advice and keeping their fingers crossed.

 

It helped a lot!

Edited August 28, 2012 by Emmy Seize

[Liquid_106 97 1 Cars]

And relax........ Glad all is ok, I bet it was squeaky bum time on the first turnover!

[CosKev 16]

Glad its worked out ok for you

 

There isn't a position where all the valves are fully closed, when the cams are pinned they are open slightly more though.

 

Even when the lifters are totally drained?(as they should be when cams are bolted down)