Help! Is this correct? Valve open at TDC

[Franks944]

Hello all!

I’ve recently purchased a 1989 Porsche 944 NA that hasn’t moved in 15 years. I replaced the water pump, replaced the pulleys/gears, and have now replaced the timing belt. I noticed before replacing the timing belt that on cylinder 3, the valve is open while the others are closed. I put the new belt on and checked my timing and everything timed up correctly. The markings on the camshaft housing and fly wheel are in time with each other yet cylinder 3’s valve is open. The crank rotates with relative ease as well. The belt I took off the car had no damage either. Is this normal? I have not started the car and want to. I appreciate the help! I’m not a mechanic, it’s a hobby so sorry if it’s an easy question for some

[Legit Salvage]

Which valve on Cyl 3, intake or exhaust?

[Franks944]

[QUOTE=Legit Salvage;12426964]Which valve on Cyl 3, intake or exhaust?[/QUOTE

Intake!

[944 Ecology]

On a 4 cylinder engine, one intake valve and one exhaust valve (not on the same cylinder) are always open.

Looking at the camshaft will verify.

[walfreyydo]

It depends on what you mean by "open". Is it barely open or fully open?

I believe cylinder 3 would be about to start its intake stroke while cylinder 1 is at TDC so the valve being very slightly open would be normal.

Typically on the intake stroke the valve begins to open just prior to the piston reaching its top of stroke and is fully open when the piston travels down (and sucks in air). Cylinder 1 at TDC would be about to start its power stroke, so cylinder 3 would be about to start its intake stroke. (2 and 4 would be starting its compression and exhaust strokes respectively)

If the engine turns over by hand without interference you can be sure that you wont have piston/valve contact. You may want to try running a compression test just to be sure this isnt actually a bent valve or something bad.

[Franks944]

Thank you everyone! I attached a photo of it so you can see how open it is. My main thing was watching NC944er and noticing his were all closed besides 4 which he in turn said that it could be bent slightly and had the head rebuilt. The previous owner told me he wasn’t aware of any misfiring coming from the car when he did have it and drive it but it has been a long time since he has driven it. I also want to verify that it is moving when I put the balance shaft belts on and make sure it’s TDC and that it isn’t stuck

[Franks944]

Update - I had someone turn the crank while I examined all intake valves and can confirm they all move and don’t stick. I’m going to put it all back together and say a Hail Mary that the car doesn’t grenade itself lol. Balance shaft belts are on, torqued and at proper TDC in there respective spot

[walfreyydo]

You dont have to say a hail mary, all you need to do it crank the engine by hand a few revolutions first to ensure no piston to valve contact.

If after you do start it, you have some rough running issues, I recommend a compression test to confirm that the valve isnt actually bent. A bent valve would reveal low to no compression in that cylinder and likely cause a misfire.

[wwdwgs]

remove the spark plugs before you hand-crank the engine - easier to turn without excessive force. Some people managed to bent the valves, when the spark plugs were in.

[jkkarrow]

Do a compression test to confirm that the valve isnt actually bent..

[walfreyydo]

Originally Posted by walfreyydo

I recommend a compression test to confirm that the valve isnt actually bent

Originally Posted by jkkarrow

Do a compression test to confirm that the valve isnt actually bent..

Reported

[Franks944]

Wanted to thank everyone! Put everything back together, at a crank no start. Ran a compression test and I’m happy to report every cylinder is reading 220-235psi! From what I saw that’s perfect for the 2.7.

[Odin911]

Originally Posted by Franks944

Wanted to thank everyone! Put everything back together, at a crank no start. Ran a compression test and I’m happy to report every cylinder is reading 220-235psi! From what I saw that’s perfect for the 2.7.

That’s some great news

[Monkey Wrench]

Ideally there may be a proper procedure to use a porsch tool to check belt tension, Just realize it shoudl be about right otherwise if it should throw the belt you can have a piston and valve collision.

Yes its normal that the old belt looks ok, the point of failure is expensive so it should be changed on a somewhat regular basis to prevent ever reaching a fail point. since it sat 15 years, it was due, wheather it ran or not at all.

in an volvo of the 80's for example, you roll to a stop, no damage, you are just stranded and either being towed of doing a roadside repair. In a porche 944 however, it is an interference engine.