Chalkboss

Here we go again... finally started tearing into my 87 to change an old belt and pump and who knows what else rears it's head during the process. Last I can tell the belt was done many years ago but only 20K miles, and a new WP was replaced but not much else during that job. I must first say I have not done a 928 TB but have on a few other cars, so this is new to me and this list has helped me greatly over the last year to understand various issues and fixes.

I wanted to see where the old belt was sitting at tension-wise and learn to use the Kempf tool. First, seems to me the belt was too tight...? I have the Kempf tool in the right orientation and it is hitting the timing belt cover just like the directions say. Is this correct?

Second pic just shows the timing marks. Pretty darn close on the drivers side and a little off on the passengers. Is this reasonable? I know the pics don't show it well but maybe a half tooth off on the left cam gear.

Third showing some nasty wear (I think) on the passenger cam gear. All the coating is gone, very shiny, and the teeth might even be dished. The other side not as bad but not elegant one bit.

Is this a result from the tight belt? Don't know what I will find on the other gears but I will update with pics as I venture forth.

Finally, enough 928 for one night! A sweet McLaren P1 spotted on the Coast of Ca this weekend. Payoff for reading this post!

MainePorsche

The tension reading on the tool seems OK - it is still within the window, but the tool seems a little close to the cam pulley. The measurement should be taken halfway between the pulleys. Being to close to the pulley can give a slight 'tense' reading which is what you are approaching. Do again at the midway point and see the difference.

Timing marks are OK.

Yes, the pulleys appear to be beat up.

Chalkboss

Thanks. I just went out and rechecked it at the midway point of the roller and gear. Now the pointer is right in the middle of the window.
One other point I wanted to make is the belt was not tracking perfectly straight and had a slight wobble. I imagine this can accelerate wear as well on these surfaces.

MainePorsche

Don,
When you get into the whole disassemble, the idler and roller may have a worn bearing causing less than optimal rolling - could be part of the belt wobble - important to check these - may need to replace. Also be sure to do a disassemble and rebuild of the tensioner (unless you are going with the p-tensioner).
Craig

jcorenman

Don, how many miles on the car? Are the cam gears original? They are probably just worn out, that looks like normal wear after 100K++ miles.
New ones are pricey but should wear better, from Porsche (check Sonnen) or from your friendly 928 specialist. And I think Roger was having some made that might be more reasonable.

For the timing marks you need to check the alignment of the small "v" on the back side of the cam gear, compared to the "v" in the rear belt cover. Look down from above, at right angles to the belt surface.

Cheers, Jim

Chalkboss

Thanks Jim. The car has 88k miles, and I have full service records and they are likely the original gears. I need to get everything apart and make yet another list. Wife just shakes her head...
I will check those timing marks again after work. I was using Dwayne's write up on this matter.

z driver 88t

Hard to tell from the pics but the gears look like the coating is worn but teeth still look straight. Check them with a straight edge. May just need to have them recoated.

Good luck. I'm accumulating parts for my first 928 Tbelt job in the next couple months. Like you, I've done other cars, but the 928 looks to be a bit more of a challenge to tackle.

dr bob

I'm not sure that the 928 is any more "difficult" that other cars, but there's a lot of stuff to keep track of. And with all the parts that come off and go back on, more chance of missing something. The Good News is that many who have walked this path before you have documented their work, including some "what not to do's" along the way. I did my first T-belt project with John Pirtle's excellent guide. The Kelly manual is great, with every step detailed for you. Perhaps the best first-timers guide to a calm and relaxing project. Duane's excellent guide is perfect for someone already comfortable with the tools, ready to dive in. The best comfort is that you have a whole network of experts at your service here.

On the parts... My first time at this was guided by the Pirtle manual, and also depended on the great support of our vendors. Before I pulled the hood release, I called Jim Bailey (then with 928 International) and asked him to assemble a "care package" with everything I'd need. The box contained everything I already knew I needed, plus a lot of interesting bits that I didn't previously know I'd need. Cam seals, oil pump o-rings, the little circlips that hold the lower guide bearing console, new water pump bolts and washers, coolant block drain plug seals, a new radiator drain plug, coolant reservoir cap, dipstick o-ring, and much more. Since this was the second belt change on a car with about 75k on it, all the coolant hoses were part of the package by my request. I'm happy to say that only a few little pieces were not needed. Bottom line is that your favorite 928 parts vendor has a knowledge base of all the parts typically needed for any 'project'. Rather than search PET yourself and guess at what you might need, let someone else's fingers do the walking for you. You'll have everything at hand as you start your work, with much less chance of that Saturday afternoon "aw shucks" moment when you discover that a critical piece isn't there, and won't be available to even ship until Monday (!!!). Support our vendors, and in turn let them support you.

Chalkboss

Well this has been a day of infamy when it comes to stuck, broken bolts. Finally got the water bridge off after three frozen, stripped bolts. Of course the worst one was nearest the intake. That one took a few hours. I slightly nicked the water bridge so I might just get a used one from Mark. There was a long-term leak that had created some corrosion...

Which leads me to the water pump. Despite following excellent advice here and soaking bolts I snapped 10 of 13 right off, I was very gingerly trying to remove them, they just snapped right off near the bolt head. The three I amazingly got out intact looked terrible with corrosion, I assume from the persistent coolant leak above. Next fun was I simply cannot get the WP off- I tried prying from the engine number block area but it is frozen on. What do you guys recommend? I stopped because I was so exhausted and frustrated. Did not want to blow it.

The last time the TB/WP was done was in the late 90's I think. The tensioner boot is petrified and mostly gone, and I am certain when they did it they just slapped a belt and pump on and called it good.

Also, once I get the pump off I should have the broken bolts standing proud of the block face a bit. Are these easy to get out? HAHAHAHA. I only have 10 to deal with.

Thanks

linderpat

wow; just went thru this and broke only one, and it was a real pita. I finally had to fix with a keen sert because I ovalled the hole, but now it is good. I can't imagine 10 of them. Jeesus, new engine time!
Just kidding. Be pateint, remove each one carefully and be prepared to use time serts or the like on the holes to repair them. Make sure you get every last peice of the old bolt out of the hole in each case, or you will oval the hole when you drill out to repair. and do not use heli coils - they are crap.

Chalkboss

Very comforting. Not!
I believe I may have set a record. Since they broke at the head I hope I can soak, heat, vise grips. Not hopeful though. I need to get the wp off first.

Bilal928S4

Don,
Sorry to hear about all the trouble this job is giving you. On my first TB/WP job I broke one bolt and it was a pain to drill out and re thread the hole.
I feel your pain. There is a device that electrically heats the bolt up quickly and that makes it lose its bond to the surrounding metal. It might be worth investigating if that is available locally for rent even if it comes with the operator. Might be the cheaper and less painful path to take.
Best of luck.

dr bob

Good News is that, once you find the bolt that's still holding the pump on (seems like I have to look 6x to find it...) and you get the pump off, you'll be able to soak the actual threaded part of the bolt with Kroil or ATF/acetone mix for a while, and get the rest of each bolt out hopefully intact.

Patience is key.

linderpat

try cnc freeze as well. opposite of the heat(obviously) but it works well too.

tlister67

This might be too late for you, but this video shows water pump bolt extraction for steel bolts in aluminum water pump housings. The principles might help with extraction as well.