Found rough idle lack of power problem.

[fatboybell]

I finally narrowed my problem down to 2 cylinders.I checked the compression on these 2 and it was 50 pounds less than the other 6,so I feel I have a head gasket blown between those two cylinders.It is on the left bank.Has anyone done this in frame.Any suggestions would be appreciated.As soon as my hands heal from the injector changes,I am going to start this job.I cannott find any posts on this job.Mainly what I am curious about is working around the timing chain without having to remove it.Thanks in advance for any help.

[DAEDALUS]

I wonder if there is any way to confirm the HG being the problem. You do not want to tear into it unless you're certain.The head can be removed with the engine in the car. Keep in mind you'll be lifting 50 lbs up from the alignment pins and out of the bay. I recall that even with the tensioner removed there is not enough slack to get the chain over the cam sprockets. The slack-side guide has to be removed as well. You may be able to unbolt the cam caps and rotate the cam upward (lowering the sprockets) to get more clearance, but you'll still have to devise a way to keep tension against the crank, or you could jump time and not even realize it.In the grand scheme of things, removing the front cover is not that much more work.

[elwesso]

I wonder if there is any way to confirm the HG being the problem. You do not want to tear into it unless you're certain.The head can be removed with the engine in the car. Keep in mind you'll be lifting 50 lbs up from the alignment pins and out of the bay. I recall that even with the tensioner removed there is not enough slack to get the chain over the cam sprockets. The slack-side guide has to be removed as well. You may be able to unbolt the cam caps and rotate the cam upward (lowering the sprockets) to get more clearance, but you'll still have to devise a way to keep tension against the crank, or you could jump time and not even realize it.In the grand scheme of things, removing the front cover is not that much more work.

Truth be told, it may be easier to swap out the engine if your going to be tearing it down that far... That way you could really rehab the engine.. but at that point you consider if its worht putting in the old engine...?

[fatboybell]

I think this engine is deserving of new gaskets,it has good compression on all but the 2 problem cylinders.It also has alot of new parts,and the timing guide updates have been done.If the front cover is not that bad to come off i will just do that.I have done a few turbo changes on z32's so hopefully it will not be as bad as that.I noticed the heads only torque to 69ftlb do you suggest new head bolts?

[maxnix]

I noticed the heads only torque to 69ftlb do you suggest new head bolts?

Since they go into aluminum, I do not see why. But I would clean them and the the block threaded receptacles and lubricate them wiht anti-seiaing grease to ensure the correct and even torquing upon reassembly.

[DAEDALUS]

I would not lubricate such a critical joint unless the FSM tells you to (it doesn't). Lubrication completely changes the preload calcs and puts much higher tension on the bolt than what is designed. The bolts work as they should dry.