Cayman S 3.4l Engine Rebuild Problems

[ken52]

Hi,

After engine failure I've completely rebuilt the Cayman S 3.4l engine (2006 Vario Valve). I identified a dmage piston and damaged cylinder liner, a new liner was professionall fitted and I've rebuilt the engine from there myself.

However once the engine was back in the car it wouldnt start correctly. It seems to try to start but appears to backfire, therefore suggesting the cam timing is incorrect

I've been back to check the photos i took while rebuilding and as far as i can see the timing appears to be correct, as per the manual:

Pin was put in crankshaft pull at U6

inlet and exhaust camshafts were installed with cylinder 4 cams pointing inwards:


camshafts were aligned with DIY aligner tool (photo taken on side of banks 1-3):


Ends of cams for banks 4-6


as per manual, chain tensioner installed and moved engine to TDC:
http://i166.photobucket.com/albums/u103/Georgy24-7/IMG_5933_zpsvp9ijkmy.jpg

both camshaft sprokets tightened as per manual

DIY Aligner tool removed, and crankshaft pulley rotated clockwise to U6 position

Operation repeated for the other side:
Cylinder 1 exhaust cams pointing downwards and out:


Cylinder 1 inlet cams pointing downwards and out:





Any help much appreciated as to why the engine may not start or where I may have gone wrong with the timing

[Sapientoni]

If you have an OBD reader, check for the faults it's seen. Maybe the coils aren't properly plugged in, or not completely plugged in. Especially this can happen if there were 2 people working on it. There are two harness plugs, one for each bank if I remember correctly.

[Sapientoni]

is your DIY alignment tool properly machined with the offset? Thats' mucho important. Have you access to a "factory manual" or instructions? The procedure is almost fall off a log simple compared to dial indicating a 32 valve 928 engine.

[Boiler Inspecto]

Did you do this after installing the 4-6 camshafts (this is the first step in installing 1-3 camshafts):

Turn the crankshaft by means of the pulley or vibration balancer clockwise (running direction of engine
further still until the marking U6 on pulley or vibration balancer coincides with fixing bore in crankcase
(60° before TDC). Fix with locating pin P 9595/1.

Essentially you must rotate the engine an entire 360 degrees and I suspect that you may have missed this step, resulting in the cams being out of time. Hope this helps. You can get a service manual off eBay for $13.

[ken52]

Thanks for the replies, We tried using OBD reader but there were no faults.
We're now taking the engine out (again) to check the timing!

[Sapientoni]

Hi Ken, I didn't see a response to my query about the DIY cam tool being machined with the proper offset. And for all the work removing, I'd have tried resetting them in the car before all that work taking out again.

[ken52]

Thanks for the replies, we decided the only way to check the timing was to take the engine out as we couldn't remember turning the engine over 360degrees before doing the timing on banks 1-3.

It turned out the timing was incorrect, but thankfully no valves have been bent.

Thanks

[ken52]

Just incase it helps anyone, heres the photos for timing the 987 engine:
note; that's a DIY aligner tool and the ends of the camshafts have been marked with tippex for my reference.


Cylinder 4, cam lobes pointing in:






Cylinder 1, cam lobes pointing out:


Cylinder 1, cam lobes pointing out:


Cylinder 1, cam lobes pointing out: