From: Jerry J. McMurry [jmcmurry@pacbell.net] Sent: Sunday, February 20, 2000 2:57 AM To: 928 Subject: [928] T-belt Adam, I just got done with that job. 1. I got a rebuilt water pump from Devek and got back something like $100 for the old pump, so I wouldn't just throw the old one away. The rebuilt one was done in Germany, (not rebuilt at Mert's Two-Car Garage Water Pump Rebuilders of south Texas), so I figure it's a pretty goot one. 2. Main seal replacement: good. 3. Take the belt tensioner apart and replace the o-ring (selected from the stock at NAPA auto parts) in the bottom of the cylinder around the piston and also replace the rubber boot (purchased from Devek) at the end where the thing pushes on the tensioner roller. This all costs $17 versus a new tensioner for over $500! Seal the tensioner to the block with gasket sealer, and refill with 90 weight gear oil per the manual. 4. Take the tensioner roller and the other smaller roller above it apart, clean out old grease and put in new grease. 5. Replace the belt guide that goes below the sprocket on the crankshaft, part# 928 105 067 00. Porsche says you gotta replace the plastic cover that goes behind it too (part# 928 105 147 05), but I just cut two little teeny pieces out of the old one and saved $45. It's easy. The new guide has a ball bearing roller rather than just smooth plastic. It is held in place by two little teeny Jesus clips* and washers on two pins coming out of the front of the engine block. 6. Rent the belt tension tester from Devek or 928 Specialists. Set tension at 4.5 on the tester. You must use the tensioner. Did you hear me? I said you MUST use the tensioner. 7. Recheck tension after 2000 miles or 3000 km. have fun/ --jer 83s a/t From: eds928gt@freewwweb.com Sent: Monday, June 19, 2000 5:56 AM To: 928 Subject: [928] Re: Timing Belt Here's a Timing belt replacement tip passed onto me by Pete Loedding. Before taking the tension off the old belt, set it to the TDC position as detailed in the Service Manuals. (Make sure all the marks line up as they should.) Then, turn the crank to the 45 degree mark. Make a paint mark on each of the cam-shaft gears directly across the reference marks. Rotate the crank again to 45 degree to verify that the new marks line up with the reference points. If so, place the engine lock in place and remove and reinstall the belt at the 45 degree mark. The reason for doing it this way is to avoid any movement of the cams, since there is no additional spring load on any of the valves while at the 45 degree posistion. YMMV. ~ Merry motoring ~ From: Jim [jim@928intl.com] Sent: Friday, July 21, 2000 5:38 PM To: 928 Subject: [928] RE: T-belt warning light question. The belt tensioner for all 928s is mechanical --it does not self adjust , does not use oil pressure , is not connected to the engine oiling system --- the "warning System" is a wire attached to the tensioner metal arm - as long as the arm is grounded to the pin sticking out of the tensioner the "system" is happy . Or if the plastic shoulder bushings where the arm pivots have disintegrated it is grounded and happy or if a prior "technician" became frustrated and attached the wire to any , any , any ground the "system "is happy. Yes the tensioner is oil filled but only if someone fills it !! yes it does compensated for thermal expansion using 35 to 50 cupshaped bi-metallic washers . Yes , later versions act as a vibration damper with a baffle and valve , if they have had oil added to them . The tensioner only tensions the belt from the point where it leaves the crank shaft and travels to the passenger camshaft drive gear - it is basically just picking up the "slack" on the portion of the belt where it is being pushed from the crank gear up to the passenger cam gear - the rest of the belt is being pulled around it's path by the energy from the crank shaft gear . Since the belt has teeth and the crank gear and camshaft gears have teeth the length of the belt between them never changes unless it jumps teeth . The tension of the belt between these gears varies with the compression and relaxation of the valve springs but has little to do with how the "tensioner" is set . If you want a simple example of how it works examine the chain on a bicycle with gears -- the chain is tight only from the front sprocket to the rear sprocket -- the rest of the chain is under little tension ...... so repeat after me "the tensioner is mechanical , the tensioner is not supplied with oil by the engine" The tensioner warning system is very unreliable --if you get a warning always get it checked but do not rely upon it to warn you before the belt breaks . Just my observations on this subject . The belt is affected by use , age , oil contamination etc. -- Which brings up another question if I drive around in 2nd gear at 4,500 rpm does my belt wear out twice as quickly ??? Do GTS with a 2.75 ring and pinion need belts changed more often than an 86 with a 2.20 drive ratio ?? the 86 spins at 80 % of the speed in 60,000 mi it may have only traveled the equivalent of 48,000 miles or is the Porsche 60,000 recommended interval just an estimate of how long most belts will last for most people ???? I recommend 45,000 mi. as a safer alternative Jim Bailey 928 International jim@928intl.com 79 928 5spd 80 928 5spd 68 911 5spd From: Jay Kempf [jkempf@tds.net] Sent: Thursday, September 14, 2000 5:03 PM To: 928 Subject: [928] New Low Cost Belt Tension Tool Hello all, If you go to the 928 International site and look in the accessory area there is a new product called "Aftermarket Belt Tension Tool". Those of you that know me know that I can't stand taking my car to somebody when there is a way to accomplish a maintenance job myself. Those of you that really know me know that's an understatement ;) That's how this tool was born. If interested use the link below. http://www.mailordercentral.com/928intl/products.asp?dept=102 It's a faithful but updated copy of the original cam belt tensioning tool. The construction is entirely stainless steel so it can't rust or go out of calibration. The tool is elegantly simple and comes with detailed instructions with clear pictures featuring my 79 WIP and also an S4. Thanks to Mark Anderson for helping to get this going and for putting the finished product in the virtual catalogue. Contact me with any questions or follow the link above. Regards, Jay Kempf 79 US 5 speed silbermetallische From: thom ross [tross2@nc.rr.com] Sent: Saturday, November 03, 2001 1:08 PM To: 928 Subject: [928] Water Pump and Timing Belt Replacement Essentials: Hi John, Since you are asking about timing belt issues, I worked up a revision to one of my earlier posts for you. See below: Water Pump and Timing Belt Replacement Essentials: Removal: You have to remove or loosen everything from the front of the engine including: Fan and Throttle Linkage Console/Carrier Alternator Compressor Smog Pump Power Steering Pump Front Timing Belt Cover Distributors Distributor Timing Belt Covers Tensioner - Rebuild it Tensioner Console Rollers Pulleys Water Pump You can easily break off water pump bolts by over-torquing or removing stuck ones. It would be nice to have the engine cleaned first - without losing any original factory stickers. However, I would not drive the car for that after receiving a belt tension warning. I heartily recommend that you or your mechanic replace everything on this list while you are in there. Rollers have bearings that will become fowled by anti-freeze or mileage. Special Tools: Buy the aftermarket belt tension tool for around $50, and the flywheel holding tool for around $20. Socket for front main pulley Metric Allen Wrenches with 3/8" drive fit Breaker bar and cheater bar for pulley socket (not really special tools) Metric deep sockets (not really special tools) Universal, ratchet, and extensions for sockets (not really special tools) Tool, Part, & Manual Suppliers: 928 Specialists at 828-766-9280, Devek, and 928 International 800-634-6117. Those "Big 3" can hook you up with about anything for the 928. Tweeks, Pelican, Automotion, etc. can also help with your needs. See the Rennlist site for contact information. The other tools are available from Sears, and most auto parts stores. Online Support: Join the free Rennlist 928 Web Board. The web interface is the most effective that I have used. The email groups give an additional audience, but less sophisticated interface. See: http://www.rennlist.org/ New Parts & Supplies: Water Pump - maybe Porsche rebuilt, not new Water Pump Gasket Timing Belt All other Belts Rollers (3) Aluminum Safe Antifreeze Distilled water (to be used with antifreeze) Thermostat Thermostat sealing ring Radiator Hoses (2) Timing Belt Idler bushings (2) Radiator Drain Plug Block Drain Plug O-rings - metal (2) Tensioner needs: O-ring Gasket Boot or rubber end cover - looks like a hollow half doughnut Boot Clamp 90 weight gear oil Optional Parts & Supplies: Front Seals: Main, Oil Pump Clutch (pulley driven) Fan Bearings Silicon Fan Clutch Fluid - from Toyota Timing Belt Tension Check: You will need the belt tension tool to check tension after approximately 1,500 miles and 10-15k mile intervals afterwards. Remove the passenger side timing belt cover (at the cam gear, remove distributor first), and check the tension. Timing belt and/or water pump failure is common after 60k miles on the 928. Take belt tension very seriously. That is the Achilles heel. Useful Manuals: The Parts and Technical Reference Manual is a great source of diagrams, part numbers, etc. The factory manuals provide procedures that are very helpful. There are parts microfiches and CDs. Optional Work: While you have the pulley driven fan off, you may want to replenish the silicon with Toyota supplied fan clutch fluid. You may also wish to replace the front main seal, and the oil pump seal while they are relatively exposed. Those seals are tough to change. May replace the Clutch Fan Bearings. Detailed Procedure & Photo Links: Greg Nichols' page has troubleshooting procedures for the timing belt light and more at: http://www.nichols.nu/tips.htm Tony's page has pictures and procedures: http://members.rennlist.com/v1uhoh/index.htm John Pirtle's site goes into great detail, with awesome pictures: http://members.rennlist.com/pirtle/svc.html Good luck, Thom Ross The Great Dark Blue 86.5 928 S3, 4 Speed Auto From: Ian Firmin [mailto:ianf@ijfirmin.co.uk] Sent: Saturday, May 11, 2002 8:27 AM To: john.pirtle@rennlist.com Subject: Tbelt changing - Comments on your website article Dear John, first of all a thousand thanks. I have your "Timing Belt Procedure, in only 175 easy steps!" in front of me. Without it I would never have attempted the procedure myself but with it I'm confident of a successful conclusion. I'm a competent mechanic but any problems will be of my own making so I would never dream of critisising your write up or holding you responsible for anything. The reason for this mail is that I think some small changes to the write up would help future referers. I have a Euro '88 S4 A/T. If you don't mind me making comments I'll make a note of any as I go along. I'm only at the belt removal stage at the moment but I thought I would put things down whilst they were still fresh in my mind. Under items 20-23 in the section "Remove the front of the engine" I have the following comments. The PS belt cannot be removed without first removing the AP belt. The AP will not loosen enough without the AC compressor being loose as well as the AP binds on the body of the compressor. The procedure that worked for me was to loosen the AP pivot bolt, lock bolt and loosen off the adjuster. Then... loosen the AC compressor. There are two 17mm pivot bolts, one front and one at the back. With these and the lock down and adjuster bolts loose the compressor pivoted easily (the rear pivot bolt was VERY tight). With the compressor loose and pivoting the AP can be easily moved enough to get the belt off and the AC belt follows after the PS belt. The main point being that if all three items are loosened, PS, AP and AC (including pivot bolts) then the belts will come easily. I hope this helps, Kind regards Ian Firmin I J Firmin (Contractors) Limited Tel. +44 (0)1474 350503 Fax. +44 (0)1474 564600 Mob. +44 (0)7860 217500