Pelican Parts Forums

Pelican Parts Forums (http://forums.pelicanparts.com/index.php)
-   Porsche 928 Technical Forum (http://forums.pelicanparts.com/forumdisplay.php?f=15)
-   -   Is it possible to bend a valve doing the TB/WP job? (http://forums.pelicanparts.com/showthread.php?t=554979)

JE928sx4 07-24-2010 11:57 AM

Is it possible to bend a valve doing the TB/WP job?
 
Doing the timing belt/WP job. This is like my fourth time but first on a 32 valve model (MY 86). When I took the belt off the cams the marks for TDC moved about an inch both sides. The left went left, the right went right each about an inch. Moving the cams by hand is near impossible. Used the old belt to try to pull them into alignment but they just wanted to jump about 1/3 of the way well past the mark. And I kind of heard a "tink" sound as it did it. Can you bend a valve this way? How do you get and kep the 32 models aligned while you put the belt on? Never was this much trouble on a 16 valve model.

Regards,
JE

Dean_Fuller 07-24-2010 01:48 PM

Rotate one cam at a time to line up with mark then slip the new belt on. The new belt should keep that cam from moving too much then do the other the same way. You can bend a valve but its unlikely the way you are saying happened IMHO.

Mrmerlin 07-24-2010 01:59 PM

first you should read the WSM it will tell you to turn the engine to 45 deg BTDC .( the reason for this step is so if a cam does decide to turn freely the pistons will all be out of the way)
then mark the cams to the reference lines remove the belt and install the new belt then turn the engine to TDC.
The tink you heard was infact the valve hitting the piston.
Use the 30mm washers under the cam bolts to turn the cams , first remove the rotors then install small bolts to take the place of the rotor screws.
Dont turn the cams with 17mm bolt use the 30mm washer under the bolt

JE928sx4 07-31-2010 08:30 PM

So I may have bent a valve or two just by a 1/3 rotation of the cams?

Quote:

Originally Posted by Mrmerlin (Post 5470840)
first you should read the WSM it will tell you to turn the engine to 45 deg BTDC .( the reason for this step is so if a cam does decide to turn freely the pistons will all be out of the way)
then mark the cams to the reference lines remove the belt and install the new belt then turn the engine to TDC.
The tink you heard was infact the valve hitting the piston.
Use the 30mm washers under the cam bolts to turn the cams , first remove the rotors then install small bolts to take the place of the rotor screws.
Dont turn the cams with 17mm bolt use the 30mm washer under the bolt


Fredfox 08-01-2010 03:21 AM

Not likely, that tink sound was most likely a valve closing when the cam moved.
Just put the crank on tdc and then put the belt on and rotate the cams that little bit to bring the marks back.

Mrmerlin 08-01-2010 06:33 AM

So is the engine running , how is the idle??
if the engine runs smooth then the valves should be OK,
to confirm do a compression check

JE928sx4 08-01-2010 09:26 AM

Quote:

Originally Posted by Fredfox (Post 5483436)
Not likely, that tink sound was most likely a valve closing when the cam moved.
Just put the crank on tdc and then put the belt on and rotate the cams that little bit to bring the marks back.

OK. Thanks.

JE928sx4 08-01-2010 09:35 AM

Quote:

Originally Posted by Mrmerlin (Post 5483539)
So is the engine running , how is the idle??
if the engine runs smooth then the valves should be OK,
to confirm do a compression check

No, not running yet. Haven't done anything on it in a week. Been too busy. Last thing I did was rebuild the tensioner and put the H2O pump on. Still need to do some cleanup of old caked on dirt and oil and need to pull the small idler assembly under the crank and examine for rebuild or replacement. Also want to see if the crank seal is leaking. Hard to determine with all the old dirt and oil builup.

Mrmerlin 08-01-2010 02:03 PM

I suggest to use STP oil treatment for the tensioner, use a visen bottle to fill from the hole furthest from the crank and make sure both of the bleeders are out when filling


All times are GMT -8. The time now is 03:45 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.