Need help with Camshaft timing for 1999 Boxster 2.5 L
 

Hi

my 1999 Boxster 2.5 L only fires on Bank 1 after engine overhaul. Electrical connections on Bank 2 seem all good, and the injectors work too (found unburnt fuel in the exhaust manifold).

I had installed the camshafts exactly as per workshop manual and turned the engine many times to ensure that the markings stay aligned. But now I observe at least once cycle where all inlet valves are closed, which clearly should not be. Re-reading the workshop manual 15-20 I am now unclear if a full rotation is needed between adjusting each Bank, or not.

Grateful for any advice. See pictures below, showing the camshaft markings in TDC front (F) and rear (R). Thanks!
http://986forum.com/forums/uploads02...1681333300.jpg
http://986forum.com/forums/uploads02...1681333330.jpg
http://986forum.com/forums/uploads02...1681333356.jpg
http://986forum.com/forums/uploads02...1681333394.jpg

Did you take all these pictures while the crankshaft being at TDC? If so, you didn`t do the 360 degree crankshaft turn between setting the timing at the two banks. When the camshafts are lined up at TDC at one side, they need to be 180 degrees off at the other bank.

Yes, I did.

Can this be corrected this without removing the camshafts?

I have never had to do this and I wouldn`t recommend doing it, but theoretically, if you disconnect the sprocket from the exhaust camshaft and you insert a tool into the slot of the camsaft on the other side, you should be able to rotate the two camshafts together a complete revolution. Before doing this, you would need to turn the crank a few degrees to pull back the pistons from TDC to avoid piston to valve contact.

Again, this is theoretical, I`m not sure it`s doable and you may mess up something even more. The best is probably to pull the headcover on one side and redo the timing. Make sure to reread the manual and think over what you do before you proceed. Good luck!

Thanks. Yes, will pull the cover and play it safe.

Did this couole of months ago.
First you place the engine to TDC and time the Bank 1 cams. Then rotate the engine 360 degrees and lock it agian to TDC and time the Bank 2 cams.
Then test with hand tool from crank that engine rotates freely and only to the normal rotating direction (clockwise).
I had same dilemma from the factory manual and took several times reading it to be certain how to get this done right...

It`s pretty straightforward if you think it over. In the boxer engine the opposing cylinders must be in the opposite stroke, i.e. if cylinder 1 is at intake, cylinder 4 must be at combustion - at cylinder 1 intake valves open while at cylinder 4 all valves are closed. This can easily be checked if you look into the ports, or just inspect the camshafts' position before you put the cover back on. To achieve this, the camshafts at the opposite banks must be off by 180 degrees, hence you turn the crank a complete revolution. It does not matter which bank you time first, the combustion will be determined by the camshaft position sensor.

Thanks - I did that.

Has anyone checked this table from renntech?

https://www.renntech.org/uploads/monthly_04_2014/post-93239-0-95551000-1397312927.png

Hi - do you know of a table showing the different valve positions in OT? I am suspecting that the replacement cylinder head which I got on eBay came with the wrong camshafts. I found a table (https://www.renntech.org/uploads/monthly_04_2014/post-93239-0-95551000-1397312927.png), but it is for a different engine. Thnx

I don`t. The camshafts are labeled in terms of where they go (IN/EX) and which motor they belong to (2.5). So it`s hard to mix them up. What makes you think they are the wrong ones? If you need engine parts feel free to PM me, I have a bunch of cylinder heads for the 2.5.

I have no concrete reason to believe this is the wrong camshafts but am a little paranoid about the idea of possibly having to remove the engine for a third time. Since I bought the cylinder head used, I just assumed that the camshaft set which came with it is the correct one. But other than the grey bit at the solenoid cable (I think the one for bank 1 is black) I have no way of knowing that it's the right cams.

Are the camshaft assemblies interchangeable between Bank 1 and 2? Or would they only fit in the cylinder head of the bank they belong (and I am stressing myself out for nothing..) Thanks!

They are definitely not, as they are different. Check out post #140 on this thread: http://986forum.com/forums/show-tell-gallery/73917-blue-boxster-resurrection-project-3.html

One of the pictures clearly shows that it`s written on the camshaft: 1-3, meaning bank 1, and 4-6, meaning bank 2.

Ok, so they are different (but they would fit if accidentally installed in the wrong bank?) I guess i will have to pull the cover and look for the labelling on the shafts. Thanks!

You can time it with the engine in the car. Easy if you have a lift, but not impossible lifting it up with jacks. Worth it to jack it back up, take off the valve covers and readjust. Question, did you ever have both camshafts off at the same time?


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Thanks for remining me of the engraving! I was able to confirm that it is the correct camshaft by going through the middle spark plug hole with a bore cam.

I had several camshaft assemblies and wasn't sure which one I ended up using (because the whole overhaul project was interrupted for 1 year due to corona). http://986forum.com/forums/uploads02...1682599929.jpg

dramabean: I took the engine out and had to replace both cylinder heads which were bent when I got the car. So yes, I had pretty much everything off and taken apart at the same time...