about ready to start the IMS project

[JFP in PA]

Originally Posted by Jamesp

Well then you should be using 2 cam locks, not a cam lock. It would be interesting to understand what would you think could drive the cams to move independent of the chains as there is no driving force to rotate them at TDC to lose timing. I've had my 3 chain apart and set the timing without the cams locked, all that was needed was TDC as there is nothing to cause the cams to rotate independent of the chains. Tearing the engine down for the first time after an IMSB failure, I made the choice not to be at TDC because I thought I might have valve to piston interference if I rotated it. A poor choice as I can confirm through personal experience the valve springs will rotate the cam independent of the chain if not at TDC, and they will not, and indeed can not if the engine is at TDC. I prefer to complete jobs without unnecessary parts (cam plugs) and time (messing with the cam locking tool).

As I have always been brought into the issue after it has already happened, I can only surmise what is causing it. That said, I would put my money on the removal of the tensioners, and perhaps the order in which that is done. Removing the tensioners has a similar effect as valve spring tension would, only to a lesser degree. When one tensioner is removed, the load on the chains is asymmetric due to the released tension. I have discussed this problem with other shop owners that have encountered it, and that seems to be the general consensus of what happens.

You also have to ask yourself why Jake even developed and LN produced three chain cam locks at all if they are not required during an IMS retrofit.

[Jamesp]

Originally Posted by JFP in PA

As I have always been brought into the issue after it has already happened, I can only surmise what is causing it. That said, I would put my money on the removal of the tensioners, and perhaps the order in which that is done. Removing the tensioners has a similar effect as valve spring tension would, only to a lesser degree. When one tensioner is removed, the load on the chains is asymmetric due to the released tension. I have discussed this problem with other shop owners that have encountered it, and that seems to be the general consensus of what happens.

You also have to ask yourself why Jake even developed and LN produced three chain cam locks at all if they are not required during an IMS retrofit.

My experience has been that tensioners in or out, or going in or out, won't make the chains jump timing on the cam sprockets. I messed with the tensioners with the engine out on a stand, they do tend to rotate the cams a little but don't cause the chain to jump teeth on the cam sprocket. Not sure what the folks did who brought you their cars, but it would not surprise me if they fibbed a little to save face.

The Cam locks are used in disassembly, assembly and final adjustment. The factory tools are pretty basic. Why Jake developed his is a good question, they may be superior in some manner to the factory tools.

[JFP in PA]

Originally Posted by Jamesp

My experience has been that tensioners in or out, or going in or out, won't make the chains jump timing on the cam sprockets. I messed with the tensioners with the engine out on a stand, they do tend to rotate the cams a little but don't cause the chain to jump teeth on the cam sprocket. Not sure what the folks did who brought you their cars, but it would not surprise me if they fibbed a little to save face.

The Cam locks are used in disassembly, assembly and final adjustment. The factory tools are pretty basic. Why Jake developed his is a good question, they may be superior in some manner to the factory tools.

Well, I can tell you the others, including some shops that have gotten themselves into trouble not using them, would not agree with your assessment. After you hear the same scenario for the third or fourth time, particularly from someone you know fairly well, you have to consider it as a potential fact. We have never encountered this issue in my shop, but my guys always use the cam locks, regardless of how many chains the engine carries.

[flaps10]

My amateur observation is that you can only be at zero valve spring load on one cylinder head at a time. If you've assembled the M96 you may recall two TDC locations. You install one bank, rotate the engine 360 degrees then install the chain for the other bank.

While you're on that second bank the valves for that head are unloaded, but at that moment there IS spring pressure on the first bank. In short, there is no position of zero valve spring pressure. A five chain motor, set correctly, will lock the head with valve spring pressure, allowing removal of all three chain tensioners

[amagalla]

OK. First I'd like put a damper on the tech battle brewing. I respect everyone's opinion, but I know that Jeff has done a LOT of work on P cars. I trust his judgement. As I understand it, the only time you don't need to use the cam lock is if you're not removing the tensioner for that bank. Even at tdc, there may some tension in the valve train. It's always better to be safe than sorry.

More importantly; I found the spreadsheet where I saved the cam deviation values. It was .3(8) not 3 deg of deviation on bank 1. I was able to get the cam lock on, but the front crank lock wouldn't wiggle into place. I ended up locking the crank from the rear. Everything came apart and went back together easily from there (with the exception of the transmission not wanting to go in...that's another story). I fired it up for the first time this afternoon. Everything seems to be running perfectly. I rechecked the cam deviation again. Bank 1: .38 (again) bank 2: .22.

I'm going to call it a success for now.

Thank all.
Tony

[sgt brad]

Good on you for getting it done. Glad it seemed relatively drama free.

[particlewave]

Fan-frickin-tastic!

Do you have a lift, or did you do it shadetree style with jacks and stands?

[amagalla]

Jack and jackstands, baby!

Sent from my SM-T800 using Tapatalk

[BFeller]

Congratulations on a job well done.

[amagalla]

A bit of an update. I just finished changing my IMS over the weekend. My 03 S had 55300 miles on it. I ran into a couple of glitches, but for the most part, it went well. The old bearing was in good shape, but I'm not sure it was original (is there a way to tell?). In any event, there were a few things that needed to be done on it anyways. There was an oil leak. I thought it was the RMS, but in the end, it looked like more oil was coming out of the IMS flange than the RMS. Since the oil was out of the car, I decided to add the LN oil filter spin on adapter.
It also needed a new clutch. Although the clutch wasn't slipping yet, it was really rather stiff. It was still the original clutch I believe and at almost 60k I figured it was time for a new one. I also installed a new dual mass flywheel. The feel on the new clutch is SOOO much lighter. Compared to the old clutch, it now feels like it's not even connected. While the transmission was out, I decided to change it's oil as well. I decided to go with Royal Purple 75W-90. It feels a little smoother, but that could be the clutch.
Since I had to remove the exhaust to get to everything, I replaced it with a Manzo muffler/TopSpeed test pipe system. All I can say is....WOW. The sound is so fantastic. At 5K RPM, it sounds like a supercar. It's really incredible. There is fiberglass all over the car though. I'll have to hose the car off sometime this week.
I'm so happy to have all of this done. It's like having the car make it though a successful open heart surgery.

The next project will be the brakes and repainting the calipers.

Tony

[EJ-Fresno]

Congratulations!

[JayG]

Tony, what is your hourly rate. Ill bring my car to you for a new clutch and IMSB

[amagalla]

No way. man! There is no way I want to do this on a regular basis. The most nerve racking part is hammering the new IMS bearing home. Get it wrong and kiss the bearing good-bye. It was hard as hell getting the extra 120 deg onto the flywheel bolts as well.

[JayG]

Originally Posted by JayG

Tony, what is your hourly rate. Ill bring my car to you for a new clutch and IMSB

Originally Posted by amagalla

No way. man! There is no way I want to do this on a regular basis. The most nerve racking part is hammering the new IMS bearing home. Get it wrong and kiss the bearing good-bye. It was hard as hell getting the extra 120 deg onto the flywheel bolts as well.

LOL