Money shift., Help me figure this out. Options

[ottox914]

A friend of mine, whom I would trust with my life or my wife, was taking the 914 for a little test beating with me the other day. At about 7k rpm and 15 psi he money shifted me from 3rd to 2nd. He WAS very quick to throw the clutch back in, but...

I now need a new fan belt, as the OEM one was thrown and is slightly mangled at present. More concerning, is the noise it makes now. It isn't the 1 in 4 cycle "thump, thump" of a rod bearing. I can pull plug wires and rev it up and the sound remains. Its more of a tic-tic-tic-tic-tic thing. Due to the speed of the tic tic tic and that it goes up and down with rpm, I'm thinking valves. Not that i really want to think that.

Any other thoughts or trouble shooting to be tried that anyone else can think of?

I'm thinking to start with compression test, move to leakdown, and submit some of the oil for testing of metallic ick. I can do the compression test and send in the oil, but I don't have the tools for the leakdow.

[r_towle]

A friend of mine, whom I would trust with my life or my wife, was taking the 914 for a little test beating with me the other day. At about 7k rpm and 15 psi he money shifted me from 3rd to 2nd. He WAS very quick to throw the clutch back in, but...

I now need a new fan belt, as the OEM one was thrown and is slightly mangled at present. More concerning, is the noise it makes now. It isn't the 1 in 4 cycle "thump, thump" of a rod bearing. I can pull plug wires and rev it up and the sound remains. Its more of a tic-tic-tic-tic-tic thing. Due to the speed of the tic tic tic and that it goes up and down with rpm, I'm thinking valves. Not that i really want to think that.

Any other thoughts or trouble shooting to be tried that anyone else can think of?

I'm thinking to start with compression test, move to leakdown, and submit some of the oil for testing of metallic ick. I can do the compression test and send in the oil, but I don't have the tools for the leakdow.

Use a compression tester threaded hose hooked up to a 125 psi compressor in each cylinder.
Listen with a hose to your ear and the intake, exhaust and oil filler holes for sound.....you can hear it right through a muffler pipe if it's leaking and you can hear well enough...

[ottox914]

Use a compression tester threaded hose hooked up to a 125 psi compressor in each cylinder.
Listen with a hose to your ear and the intake, exhaust and oil filler holes for sound.....you can hear it right through a muffler pipe if it's leaking and you can hear well enough...

I can probably rig something up. I thought the "right" way to do this was with gauges and such, to measure the rate of leakdown. I get how this process would at least identify leaking at the valve, and which valve it might be. Don't I need to have the motor at TDC with both valves closed, and them find some way to "lock" it in that position, so the pressure of the air does not push the piston down and rotate everything, opening a valve? Any BTDT to set this process up and get it right? I'd hate to do it wrong, think I have a bunch of bad valves, rip it all apart and find a simple fix rather than the valve thing.

Should I be able to visually inspect the head for other damages, or if I can see the bent valve just replace it and be good enough. I put a bunch of $$$ and Len put a bunch of time into those heads... they were perfect.

[76-914]

Use a compression tester threaded hose hooked up to a 125 psi compressor in each cylinder.
Listen with a hose to your ear and the intake, exhaust and oil filler holes for sound.....you can hear it right through a muffler pipe if it's leaking and you can hear well enough...

I can probably rig something up. I thought the "right" way to do this was with gauges and such, to measure the rate of leakdown. I get how this process would at least identify leaking at the valve, and which valve it might be. Don't I need to have the motor at TDC with both valves closed, and them find some way to "lock" it in that position, so the pressure of the air does not push the piston down and rotate everything, opening a valve? Any BTDT to set this process up and get it right? I'd hate to do it wrong, think I have a bunch of bad valves, rip it all apart and find a simple fix rather than the valve thing.

Should I be able to visually inspect the head for other damages, or if I can see the bent valve just replace it and be good enough. I put a bunch of $$$ and Len put a bunch of time into those heads... they were perfect.

Harbor Freight has one that is pretty good and cheap. Towle is right in his method but if you want to know the percentage of leak down you will need gages. If looking for the bent valve you wouldn't need gages. Listen thru exhaust for the bent exhaust valve and thru the TB for an intake valve. (IMG:style_emoticons/default/beerchug.gif)