Jump to content

Valve stem seals


Recommended Posts

I'd say yes, but you need the right tools.

Either you pressurise the cylinder to hold the valve closed, or perhaps you might get away with having the cylinder your working on at TDC so the valve cant drop down when your remove the retaining collet and valve spring.

Link to comment
Share on other sites

If you do decide to have a go without taking the head off sealey do a tool for about £20 which looks like it might release the valve collets. I guess if you were to use the compressed air method you need an adaptor for the injector hole - sort of dummy injector with an airline attached or even a rubber bung that fills the hole with an airline connection through, but it does need a lot of pressure. I have changed seals on a vauxhall petrol engine successfully (adaptor made from old spark plug with middle knocked out, and air connection brazed in)using air so it's not too far fetched. Borrowed a special Vauxhall valve tool for that.

Regards

Nigel

Link to comment
Share on other sites

I'd say yes, but you need the right tools.

Either you pressurise the cylinder to hold the valve closed, or perhaps you might get away with having the cylinder your working on at TDC so the valve cant drop down when your remove the retaining collet and valve spring.

I've done 300Tdi and 2.5NAD valve stem seals without taking the head off. As Aragorn says, make sure the cylinder you are working on is at TDC.

  • Remove the rocker shaft.
  • Compress the valve spring with a home made tool (lightly load the spring cap and give it a tap with a hammer to unstick the collets).
  • Fully compress the spring and extract the collets - a magnetic retriever is handy for this. Remove spring and cap, extract seal.
  • Fit new seal and reinstall the collets (tweezers or fine nosed pliers are useful) - don't drop a collet into the engine!
  • Put it all back together and set tappet clearances

The home made valve spring compressor was a length of 50mm angle that I had lying around, with a ~20mm (IIRC) hole drilled to go over the valve stem. Other holes allowed me to drop a bolt through in to a rocker shaft bolt hole for a bit of purchase. It's a bit fiddly working through a hole, but a lot quicker than removing the head.

IIRC, the valve to piston clearance is ~1mm, so the valve can't drop far so long as the piston is at TDC.

Link to comment
Share on other sites

I've used the compressed air method on engines, a bit of a mess on and not 100% guaranteed to work in my opinion.

Method I prefer to use now is, I feed a length of string down the injector hole, as much as I can get into the cylinder. Then wind the engine until the piston is as close to TDC as it will go. This jams the string between piston and valve, the valve can't drop at all now.

Obviously, don't lose the end of the string!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy