Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 02-27-2020, 08:58 AM   #1
Registered User
 
Join Date: Oct 2018
Location: North Cali
Posts: 182
Garage
IMS timing question

Hey All,

I asked this question a while ago somewhere here but I had no answer so I thought I ask again before I assemble the engine. My understanding is that the crankshaft has to be lined up with the 4 camshafts, and the IMS position with respect to the crankshaft shouldn`t really matter. However, there`s a punchmark on the IMS sprocket, am I right that I can just ignore that?

If you know the answer or you have assembled a Boxster engine and paid/didn`t pay attention to this alignment I`d appreciate if you could chime in.

Thanks
Greg

Homeoboxter is offline   Reply With Quote
Old 02-29-2020, 05:17 PM   #2
Registered User
 
Join Date: Aug 2005
Location: Sanford NC
Posts: 2,370
Start reading here...http://lnengineering.com/files/IMSR-Pro-Manual-03-23.pdf
mikefocke is offline   Reply With Quote
Old 02-29-2020, 07:42 PM   #3
Registered User
 
Join Date: Oct 2018
Location: North Cali
Posts: 182
Garage
Quote:
Originally Posted by mikefocke View Post
Thanks for sharing this, it`s useful. Basically they just lock the crank and camshafts at TDC. Does not say anything about IMS timing with respect to crank position though, but probably it does not matter anyway.
Homeoboxter is offline   Reply With Quote
Old 03-01-2020, 04:15 AM   #4
Who's askin'?
 
maytag's Avatar
 
Join Date: Mar 2018
Location: Utah
Posts: 1,936
Quote:
Originally Posted by Homeoboxter View Post
Thanks for sharing this, it`s useful. Basically they just lock the crank and camshafts at TDC. Does not say anything about IMS timing with respect to crank position though, but probably it does not matter anyway.
I refrained from replying because I am not a Porsche engine expert. Frankly, I've only ever had the m96 down to its nuthin's once.
But I am somewhat of a very knowledgeable engine builder in my own right. And based on my experience, and even more on what I've read, there's really no reason that it should matter.

So I'm voting with you.

Sent from my SM-G970U using Tapatalk

Last edited by maytag; 03-01-2020 at 04:10 PM.
maytag is online now   Reply With Quote
Old 03-01-2020, 10:32 AM   #5
Registered User
 
Join Date: Oct 2018
Location: North Cali
Posts: 182
Garage
Quote:
Originally Posted by maytag View Post
I refrained from replying because I am not a Porsche engine expert. Frankly, I've only ever had the m96 down to its nuthin's once.
But I am somewhat of a very knowledgeable engineer builder in my own right. And based on my expressive, and even more on what I've read, there's really no reason that it should matter.

So I'm voting with you.

Sent from my SM-G970U using Tapatalk
Yeah, it should not matter. My guess is that it`s for the alignment of the three sprockets on the IMS, as they are three individual pieces and the teeth are not in line. It`s confusing, because it really looks like a timing mark. Here`s a picture just for reference.

Homeoboxter is offline   Reply With Quote
Old 03-01-2020, 10:56 AM   #6
Who's askin'?
 
maytag's Avatar
 
Join Date: Mar 2018
Location: Utah
Posts: 1,936
Quote:
Originally Posted by Homeoboxter View Post
It`s confusing, because it really looks like a timing mark.
Boy it sure does.
You're likely onto something about it being for assembly onto the shaft. Those sprockets would indeed need to be indexed somehow when they're installed on the shaft.

Sent from my SM-G970U using Tapatalk

Last edited by maytag; 03-01-2020 at 04:08 PM.
maytag is online now   Reply With Quote
Old 03-01-2020, 01:24 PM   #7
1202021
 
piper6909's Avatar
 
Join Date: Jan 2019
Location: PA
Posts: 902
If the chains have marked links, it's probably to help you during chain installation. I.e. so you don't have to count the links between the sprockets. Timing belts have marks that line up with marks on the sprockets, so you don't have to count teeth. Maybe these chains do too?

I'm surprised no one on here who actually takes these motors apart has chimed in yet. But, like others who have replied, I believe the IMS sprockets are not timed.
piper6909 is offline   Reply With Quote
Old 03-02-2020, 09:09 AM   #8
Registered User
 
Join Date: Dec 2009
Location: Orange County, CA
Posts: 1,314
Quote:
Originally Posted by piper6909 View Post
If the chains have marked links, it's probably to help you during chain installation.
Yes, the timing chain has one link with a different color that you are supposed to align with the dot on the sprocket
I am really sorry, I did not put attention and assumed that the picture was from one of the Cam Sprockets...
.

Last edited by Gilles; 03-02-2020 at 01:33 PM.
Gilles is offline   Reply With Quote
Old 03-02-2020, 09:30 AM   #9
Who's askin'?
 
maytag's Avatar
 
Join Date: Mar 2018
Location: Utah
Posts: 1,936
Quote:
Originally Posted by Gilles View Post
Yes, the timing chain has one link with a different color that you are supposed to align with the dot on the sprocket
Interesting.
What purpose does that serve? What is it "timing" that way?
maytag is online now   Reply With Quote
Old 03-02-2020, 10:53 AM   #10
Registered User
 
Join Date: Oct 2018
Location: North Cali
Posts: 182
Garage
Quote:
Originally Posted by Gilles View Post
Yes, the timing chain has one link with a different color that you are supposed to align with the dot on the sprocket
Apart from the two small chains in the heads, I don`t remember seeing any other chain marked, but I`ll take a second look.
Homeoboxter is offline   Reply With Quote
Old 03-02-2020, 11:53 AM   #11
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,405
Garage
Quote:
Originally Posted by Homeoboxter View Post
Hey All,

I asked this question a while ago somewhere here but I had no answer so I thought I ask again before I assemble the engine. My understanding is that the crankshaft has to be lined up with the 4 camshafts, and the IMS position with respect to the crankshaft shouldn`t really matter. However, there`s a punchmark on the IMS sprocket, am I right that I can just ignore that?

If you know the answer or you have assembled a Boxster engine and paid/didn`t pay attention to this alignment I`d appreciate if you could chime in.

Thanks
Greg

The IMSB external flange is just a mount for the bearing to spin on. If it's a LN bearing just torque the bolts to spec & you are done. I would guess the punch mark is from the machining process.
__________________
Jerk that is constantly criticzing new forum members and overly advertising my rebuilt engine for sale for a highly inflating price along with other miscellaneous parts accumulated over my 20 years of ownership.
BYprodriver is offline   Reply With Quote
Old 03-02-2020, 12:18 PM   #12
Who's askin'?
 
maytag's Avatar
 
Join Date: Mar 2018
Location: Utah
Posts: 1,936
Quote:
Originally Posted by BYprodriver View Post
The IMSB external flange is just a mount for the bearing to spin on. If it's a LN bearing just torque the bolts to spec & you are done. I would guess the punch mark is from the machining process.
I know you'll think this rude of me, so I'll be extra sensitive.
I don't think anything in this thread is about the external flange, and so your post is likely to confuse some future reader. (As it confuses me)

Sent from my SM-G970U using Tapatalk
maytag is online now   Reply With Quote
Old 03-02-2020, 12:31 PM   #13
Registered User
 
Join Date: Aug 2019
Location: Texas
Posts: 177
My guess is that the punch has significance if it is lined up to other components. I.E.: you could tell the orientation of other components without seeing them.
Just a guess.
BYprodriver could be right about it being an artifact of manufacturing, though (although seemingly being confused about the component in question).
Having worked in a machine shop, I've put marks in seemingly odd places, either for our use, or to help with assembly in some way.
The way these engines were manufactured in the original facility could have had an important use for that mark. German sophistication often goes much deeper than what is apparent at surface level.

Ultimately, though, I do not think the orientation of the IMS is functionally significant, as it appears to be radially symmetric other than the mark.
__________________
'97 - Silver (rebuilt/stripping)
'99 - Black (rebuilt/sold)
'01 S - Rainforest Green (daily)
'03 S - Orient Red (sold)
Fiddlebog is offline   Reply With Quote
Old 03-02-2020, 01:35 PM   #14
Registered User
 
Join Date: Dec 2009
Location: Orange County, CA
Posts: 1,314
Quote:
Originally Posted by piper6909 View Post
If the chains have marked links, it's probably to help you during chain installation.
Yes, the timing chain has one link with a different color that you are supposed to align with the dot on the sprocket
I am really sorry, I did not put attention and assumed that the picture was from one of the Cam Sprockets...
Gilles is offline   Reply With Quote
Old 03-02-2020, 03:23 PM   #15
Registered User
 
Join Date: Oct 2018
Location: North Cali
Posts: 182
Garage
Quote:
Originally Posted by Gilles View Post
I am really sorry, I did not put attention and assumed that the picture was from one of the Cam Sprockets...
No worries!

Homeoboxter is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 12:04 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page