Thorny Posted March 18, 2010 Share Posted March 18, 2010 Is it possible to change the valve stem seals on a 300tdi without taking the head off? Cheers. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted March 18, 2010 Share Posted March 18, 2010 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. Quote Link to comment Share on other sites More sharing options...
Thorny Posted March 18, 2010 Author Share Posted March 18, 2010 Hmmmm, thanks for that. Looks like I'm going to have to take the head off again. GRRRRR! Quote Link to comment Share on other sites More sharing options...
discomikey Posted March 18, 2010 Share Posted March 18, 2010 itd be a nice experiment fer someone if they had the time to see if its possible. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted March 18, 2010 Share Posted March 18, 2010 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 Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted March 19, 2010 Share Posted March 19, 2010 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. Quote Link to comment Share on other sites More sharing options...
cieranc Posted March 19, 2010 Share Posted March 19, 2010 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! Quote Link to comment Share on other sites More sharing options...
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