Help needed: Boxter fails to restart after rebuild / windows no longer work - Page 2 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

healthservices · 01-13-2014, 05:39 PM

not to be a pessimist, but your motor cranks kind of funny

Jake Raby · 01-13-2014, 05:46 PM

That engine has compression all over the place.. I can hear it based on the load on the starter.

Did you have the entire engine apart? Explain how you carried out cam timing.

healthservices · 01-13-2014, 05:53 PM

meaning that the cranking pulses are not at a even pattern when you crank it.

Jake Raby · 01-13-2014, 06:37 PM

Quote:

Originally Posted by healthservices

meaning that the cranking pulses are not at a even pattern when you crank it.

Absolutely. That tells the story when you have a trained ear.

seningen · 01-13-2014, 06:52 PM

Quote:

Originally Posted by Jake Raby

Absolutely. That tells the story when you have a trained ear.

Check Cam timing and do a compression and/or leak down test.

Sounds uneven.

m

Jake Raby · 01-13-2014, 07:11 PM

Lifters may be sticking to create this…

But I have another idea after he replies to my previous questions.

BYprodriver · 01-13-2014, 07:54 PM

Sounds like both banks are timed the same instead of being 180 degrees opposite.

Jamesp · 01-14-2014, 03:02 AM

[QUOTE=Jake Raby;380855]That engine has compression all over the place.. I can hear it based on the load on the starter.

I had the engine completely torn down for an IMS shaft replacement.

I locked the engine at TDC and timed both banks using a factory built timing tool and the instructions from the 987 manual

It has the original lifters in it.

Both banks were timed the same way, meaning engine locked at TDC and timing tool used.

The picture below shows bank 1-3 timing

seningen · 01-14-2014, 05:48 AM

[QUOTE=Jamesp;380902]

Quote:

Originally Posted by Jake Raby

That engine has compression all over the place.. I can hear it based on the load on the starter.

I had the engine completely torn down for an IMS shaft replacement.

I locked the engine at TDC and timed both banks using a factory built timing tool and the instructions from the 987 manual

It has the original lifters in it.

Both banks were timed the same way, meaning engine locked at TDC and timing tool used.

The picture below shows bank 1-3 timing

Still worth a quick double check that your still in time.

pull the oil scavenge covers and make sure the cam sprockets didn't slip.

left and right bank do get timed 180 out of phase. Been a while since
I personally checked but the cam holder gets rotated such that
when timed both camshaft sides are slightly on the outside of the case.
Double check that as it's been a couple years since I did it myself.

mike

Walter White · 01-14-2014, 06:25 AM

Bummer. I have been looking forward to your engine running.
Have you left anything off or unconnected, like the tranny?
When I do my bearing I hope to be able to start the motor without the tranny installed. I was wondering if you are trying that.

Is it possible to see if the throttle body motor is working? When I start my Box it always starts with a little blip on the throttle ( from the ECU, not me).

Those windows are bugging me. Are all your grounding straps installed?

healthservices · 01-14-2014, 11:35 AM

Not that you did it wrong but if I remember correctly the timing tool for one head is not used for the other when the motor is at TDC for number one.

Am I correct?

Jamesp · 01-14-2014, 02:52 PM

Quote:

Originally Posted by BYprodriver

Sounds like both banks are timed the same instead of being 180 degrees opposite.

I think you are right. So do I expect bent valves at this point? Seems like I would not because the valves are opening and closing exactly opposite on one bank.

healthservices · 01-14-2014, 03:17 PM

Id just make sure none of the pistons on that side of the motor is at TDC when you rotate the cams to where they are suppose to be, that way they will not touch the top of the pistons when you do rotate the cams.

Just rotate the crank about 30 degrees from TDC, put the cam where its suppose to be then rotate back to TDC and put the chain on.

then do a compression test.

Easier said than done.

Jamesp · 01-14-2014, 03:19 PM

So, off the top of my head here is a fix for this screw up. please review and comment:

Step:

1) Lock the engine at TDC with the 4-6 side cams in the position where they can be locked

2) Remove cam chain tensioner for the 4-6 side

3) Pull the oil scavenge pump in the engine compartment

4) Remove the cam sprocket

5) lock the cams with the cam locking tool

6) Unlock the engine and carefully rotate the crankshaft clockwise 360 while feeding the cam chain over the inlet sprocket - likely get a piece of plastic to put between the chain and inlet sprocket teeth while rotating

7) With 4-6 cams locked into position, re-install exhaust sprocket

8) remove cam locks and torque sprocket

8) tighten up tensioner

9) replace scavenge oil pump

10) replace cam plugs

So - what's missing? How can it be improved?

Jamesp · 01-14-2014, 03:25 PM

I'll take the easy missing piece - unlock the engine!

Jamesp · 01-14-2014, 03:31 PM

Quote:

Originally Posted by healthservices

Not that you did it wrong but if I remember correctly the timing tool for one head is not used for the other when the motor is at TDC for number one.

Am I correct?

The timing procedure seems to go like this - Lock the engine at TDC and set the valve timing using the timing tool. Head 4-6 is shown first in the repair manual, but I dont see a difference in which head gets timed first as there is only one TDC sr=etting on the crank. Now for the part I missed - Roll the crank 360 degrees (that's half a rev of the cams) and see the other side. Now the cams are set 180 degrees out from one another. I have one set of cams out 180 degrees. BYprodriver hit it on the head.

healthservices · 01-14-2014, 03:38 PM

its sucks how we sometimes just miss one simple step and it totally fubars everything.

seningen · 01-14-2014, 03:42 PM

Quote:

Originally Posted by Jamesp

The timing procedure seems to go like this - Lock the engine at TDC and set the valve timing using the timing tool. Head 4-6 is shown first in the repair manual, but I dont see a difference in which head gets timed first as there is only one TDC sr=etting on the crank. Now for the part I missed - Roll the crank 360 degrees (that's half a rev of the cams) and see the other side. Now the cams are set 180 degrees out from one another. I have one set of cams out 180 degrees. BYprodriver hit it on the head.

Go get a boroscope and insert it into the spark plug hole
You'll need the more expensive, smaller one to fit into the spark plug hole.

You can see if there is valve strikes in the pistons

It will typically show up as a shiny half moon arc

If it's there, you probably have bent valves.

You really don't want to risk starting with bent valves

They could stick and break off
Which obviously would not be good.

Mike

Jamesp · 01-14-2014, 03:59 PM

The question I have is do you bend the valves 180 out of time? Surely this has been done before.

BYprodriver · 01-14-2014, 04:26 PM

Quote:

Originally Posted by Jamesp

The question I have is do you bend the valves 180 out of time? Surely this has been done before.

NO, I'm thinking you just forgot to spin the engine 360 degrees after setting cam timing on 1-3 cyl bank, & prior to setting 4-6cyl bank. If that's what happened the valve to piston clearance is as designed but DME is not programmed to send spark & fuel at the appropriate time for 4-6cyl combustion stroke.