X-xyk Member 37 Member For: 3y 10m 12d Posted 14/05/21 11:13 AM Share Posted 14/05/21 11:13 AM Hi all again, after looking around online for a couple of hours I'm stuck, Im in the process of replacing my valve stem seals, and after my first replacement seal I can't hold pressure in the cylinder as the valve is letting air through exhaust. Valve guides seem to have very minimal play so I'm not sure. Any ideas? Cheers Link to comment Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 15,116 Member For: 9y 2m 20d Gender: Male Location: South Australia Posted 14/05/21 11:19 AM Share Posted 14/05/21 11:19 AM (edited) Turn the motor over until both the intake and exhaust valves are shut. Edited 14/05/21 11:20 AM by Puffwagon I edit for fun Link to comment Share on other sites More sharing options...
X-xyk Member 37 Member For: 3y 10m 12d Posted 14/05/21 11:31 AM Author Share Posted 14/05/21 11:31 AM Forgot to mention I don't have cams on Link to comment Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 15,116 Member For: 9y 2m 20d Gender: Male Location: South Australia Posted 14/05/21 12:21 PM Share Posted 14/05/21 12:21 PM Of course lol. Maybe it is leaking down flat out? Check the others and see how you go. 1 Link to comment Share on other sites More sharing options...
X-xyk Member 37 Member For: 3y 10m 12d Posted 14/05/21 11:56 PM Author Share Posted 14/05/21 11:56 PM Sorry what did you mean by flat down? lol Link to comment Share on other sites More sharing options...
Puffwagon Puff Gold Donating Members 15,116 Member For: 9y 2m 20d Gender: Male Location: South Australia Posted 15/05/21 12:11 AM Share Posted 15/05/21 12:11 AM When a valve is bypassing air between the valve and the seat, generally due to wear and carbon build up, it is referred to as "leaking down". There is a test you can do called a leak down test and it measures how much air is being lost from the cylinder through the valves and or rings. Flat out is a fast as possible lol. Leaking down flat out makes sense now Link to comment Share on other sites More sharing options...
JETURBO ...JD TUNING ADELAIDE... Gold Donating Members 23,708 Member For: 15y 10m 19d Gender: Male Location: Adelaide Posted 15/05/21 07:20 AM Share Posted 15/05/21 07:20 AM OP Are you sure you got the Valve locks ( Collets )on correctly ? Link to comment Share on other sites More sharing options...
X-xyk Member 37 Member For: 3y 10m 12d Posted 15/05/21 08:17 AM Author Share Posted 15/05/21 08:17 AM Yep collets were in properly, but found I had the same problem on a few other valves. Rotating the valve when closed seemed to do the trick I guessing there was some carbon build up, I've got some headstuds to go in so I'll give her a clean underneath. Thanks for tips fellas Link to comment Share on other sites More sharing options...
4321 Bronze Donating Members 257 Member For: 10y 23d Posted 15/05/21 10:23 PM Share Posted 15/05/21 10:23 PM put some string down the spark plug hole & turn the motor over by spanner not starter until it stops. the string push's the valve up which should close it. if it dont seal you got problems ! remove the string when your finished Link to comment Share on other sites More sharing options...
X-xyk Member 37 Member For: 3y 10m 12d Posted 16/05/21 04:57 AM Author Share Posted 16/05/21 04:57 AM Cheers mate, took head off turned out was just really bad carbon build up on top of cylinder head and valve seats. Link to comment Share on other sites More sharing options...
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