Bent intake valves - non zed content

[Brian H]

Looking for a bit of advise from the mechanics we have on board, my sons car suffered a timing chain guide failure which in turn loosed the chain and allowed the inlet cam to slip (3 cyl, 12valve VW Polo). All 6 inlet valves are bent and I have ordered replacements.

Question:

Do I try and straighten the bent valves to release some pressure on the valve springs to allow removal or is there another way to do this? I’m worried if I try and straighten them I will damage the head.

Thanks

B

 

[t-tony]

An old school way of removing the collets is to use an 1/2" deep socket (say 3/4") and a large hammer. You put the socket on top of the valve and smack the socket with the hammer. With luck the shock will release the collets and let the spring go.

Tony.

 

[Brian H]

An old school way of removing the collets is to use an 1/2" deep socket (say 3/4") and a large hammer. You put the socket on top of the valve and smack the socket with the hammer. With luck the shock will release the collets and let the spring go.

Tony.

Good lad Tony, just the sort of advise I was looking for

 

[t-tony]

You have to be fairly brutal Brian but I hope it works for you. I definitely wouldn't try to straighten the valves or you stand a chance of cracking the guides or damaging the seats.

Tony.

 

[Pingu]

Tony's method is the method that I usually use for loosening the collets before removal. Sometimes it is enough to remove the collets completely. You will have to be careful as the collets can fly out and can be easily lost.

Top Tips

Use a spark plug socket (as it is nice and deep) and a lump hammer.
Use a piece of cloth to cover the head - it will keep the collets and springs under the cloth.
Put a small piece of wood in the combustion chamber under the valve head - it will stop the valve going into the combustion chamber when you hit the socket.

Don't forget to port and polish before refitting.

 

[Stevo7682]

Brian if the valves are quite badly bent you have probably cracked the brass valve guides .
Once the valves out ( Tony method will work fine) just watch you don't loose the 2 collets when it pops.
If any of the guides are damaged you will have to take the head to an engineer's as changing the guides specialised and you won't be able to do it yourself.

 

[t-tony]

Use a spark plug socket (as it is nice and deep) and a lump hammer.

A spark plug socket is 13/16", we going to bicker over 1/16"?Large (lump) hammer, I think Brian has the knowledge to know what I meant.

Tony.

 

[Stevo7682]

Oh and in reply to the other part of your question Brian.
Don't try straighten the valves you will end up making things worse instead of better .

 

[Pingu]

A spark plug socket is 13/16", we going to bicker over 1/16"?Large (lump) hammer, I think Brian has the knowledge to know what I meant.

Tony.

Not quibbling over diameter, but it's easier to strike and hold a deep socket than a standard one.

 

[t-tony]

Not quibbling over diameter, but it's easier to strike and hold a deep socket than a standard one.

Yes mate, it is. That's why I said use a deep socket.

Tony.

 

[Brian H]

Bent valves now out, I did have st straighten then a little to release the compression on the valve spring. The trick with the deep socket worked a treat, thanks

 

[Lee]

This is the same engine i have. I bought a fixer upper last year with the same problem. For £75 I managed to find a new head.

 

[Brian H]

This is the same engine i have. I bought a fixer upper last year with the same problem. For £75 I managed to find a new head.

It may end up that way if all does not go to plan.

 

[Stevo7682]

How do the guides look Brian

 

[Brian H]

How do the guides look Brian

The guides looked fine, the valves were bent right at the end, the main shafts are straight and true. New valves will hopefully arrive early next week.

 

[Stevo7682]

The guides looked fantastic he, the valves were bent right at the end, the main shafts are straight and true. New valves will hopefully arrive early next week.

Good stuff that's an exspense spared

 

[t-tony]

Just double check for a full seat on the valve itself when you lap them in Brian. Sounds as though there was some good luck involved I'm happy to say.

Tony.

 

[Brian H]

I'll bring this to a close, 6 new intake valves lapped in, needed to buy a valve spring compressor to get the collets back in, new timing chain, sprockets, guides etc. Engine assembled, engine timed, car started on the key first time.
I ran into a bit of an issue as the car was throwing a few codes, amongst them was a misfire on cylinder 3, I removed the spark plugs to run a compression check to make sure that the valves were seated right and I did notice the spark plug gap was nearly non existent on plug no3, Ran the compression check and this showed 9.5-9.7 bar on all three cylinders (10bar when new). I reset the gap on the plug and ran the car, touch wood all the codes have disappeared and is running smother than is has for a while. Note: sometimes its the simple things!

Happy Chap

Thanks for everyone's input

 

[t-tony]

I'll bring this to a close, 6 new intake valves lapped in, needed to buy a valve spring compressor to get the collets back in, new timing chain, sprockets, guides etc. Engine assembled, engine timed, car started on the key first time.
I ran into a bit of an issue as the car was throwing a few codes, amongst them was a misfire on cylinder 3, I removed the spark plugs to run a compression check to make sure that the valves were seated right and I did notice the spark plug gap was nearly non existent on plug no3, Ran the compression check and this showed 9.5-9.7 bar on all three cylinders (10bar when new). I reset the gap on the plug and ran the car, touch wood all the codes have disappeared and is running smother than is has for a while. Note: sometimes its the simple things!

Happy Chap

Thanks for everyone's input

Good news Brian, we sometimes miss the basics.

Tony.

 

[Stevo7682]

Great news Brian that you got it all sorted out