Timing belt alignment question
 

Ok, I am to the point of checking the marks. I set the crank at top dead center "0" mark on damper. The right cam mark is in the valley with the cam pointer but the left cam gear mark seems to be on the tip of the gear, not aligned with the little hole in valley of gear. So maybe a half tooth off. I turned the crank several turns and it still looks to be about the same alignment. I took 3 pictures but the camera will not focus so close on those little holes in relation to the pointer on casting of cam housings. What should I do now?? http://forums.pelicanparts.com/uploa...1266007201.jpg
http://forums.pelicanparts.com/uploa...1266007291.jpg
http://forums.pelicanparts.com/uploa...1266007310.jpg

My camera batteries are going out and could not take better pictures at the moment.

That is most likely as close as it gets as far as timing the gears is concerned. The next step beyond that would be to actually degree the cams them selves. this could be done the old PITA way with degree wheels and a dial indicator or through the use of Porkerns engenious device the PK32V'r, which greatly simplifies the opperation.

Also for taking close-up pics if you didn't set you camera to "macro" (the llittle flower symbol), you should try it. It will greatly reduce the focal distance, and will help greatly in getting decent clase-up shots.

Well, its fine for now.

Next you will be rotating just shy of two crank revs to get the unit at 45 BTDC
Thats where the belt will be removed and replaced. (flywheel lock in place / crankbolt removed)

Then, after putting on the new belt, lower cover and retightening the crank bolt, you will rotate the crank clockwise facing motor (always clockwise facing motor) the remaining short distance to O degrees for the check. You will probably be a hair closer to the alignment at that point.


Then, you will want to consider using the 32Vr tool to do your fine timing adjustment. Its a separate operation best done before the r and l covers go back on.

(edit / looks like 76' and I are giving you same input)

You guys are wonderful!!! I figured it might be a bit of belt stretch possibly. Anyway I will do some more checks and mark those 45 degree positions carefully. I have not removed the center cover yet. I am taking my time no rush on this. I might take a few more pictures. I would say I have about 4 hours in this so far but time is NOT of the essence on this job!!! Actually kind of a fun job, not that intimidating, I am actually enjoying doing it and feel I am accomplishing something! I appreciate all your assistance and advise!

Very methodical, symphony. Gotta hold-out through the end and not rush, though.

I'd get some new batteries and post some pictures.

And be sure your doublechecking any advice here, including mine, with some sort of WSM pages or write up. Am not waffling at all on you, just being cautious.

I have some new batteries for the camera and will try and get better pictures. This belt must have been replaced as it is a Uniroyal not Porsche! But now that I have gone this far, I will put the new Gates one on along with the water pump which I am waiting to receive next week. The maintenance records did not show a previous belt replacement, but the car has been sitting for many years.

Tiny amounts of wear / wobble in the pivot bolt bushings and associated tensioner roller are important to remedy, I mean very small amounts.

Here are some better pictures.[img]http://forums.pelicanparts.com/uploads16

Right side. Lined up over tooth, valley with hole just to the left of tooth below mark.
/IMG_36971266077615.jpg[/img]

Left side. Lined up in Valley with marking hole.

http://forums.pelicanparts.com/uploa...1266077723.jpg

And my work bench of parts layout.

http://forums.pelicanparts.com/uploa...1266077987.jpg

I may remove the center cover today. No rush, water pump is not here yet.

Right side mark line up.
http://forums.pelicanparts.com/uploa...1266078301.jpg

Aren't there little tiny notches on the backs of the cam gears? Their alignment with the backing plate notches was what I was expecting you to show.
How's about a camera shot on each side shooting downwards behind the gears?

I think the front notches on the 86 align with the actual cam covers so you can check without removing the covers. Look inside your cover vent holes for a similar feature to mine on this 86 cover:http://forums.pelicanparts.com/uploa...1266086052.jpg

If you look at my pictures of the cam gears, I have put a BLUE pen mark on the side of the gear facing out. On the INSIDE of that exact tooth, or should I say the VALLEY, is a small hole on both gears. I have brought the crank to TDC, 0 mark when those two little holes are each about under those "V" s on the backing plate. My concern was there is a slight variation of the alignment under each V mark. One was maybe a half tooth off from the other. I took a straight edge and marked the exact center of the V mark on each gear. Maybe I am being too exact because of some wear on the belt possibly. Guess I will know when I go to put the new belt on in a few days.

I have now brought the crank from the TDC possibly 3/4 revolution (clockwise) to the 45 degree mark and I have now put marks on each gear. So I think I am ready to install the flywheel lock. (I did turn the engine 2 more revolutions and the 45 degree marks aligned again. Then I can remove the harmonic balancer and remove the center cover.

Ok so I need to turn it almost TWO revolutions AFTER I set it on TDC with the cams lined up NOT directly to 45 degrees from when I set it the first time. In other words you want it at 45 BTDC on Number 1 piston if I understand correctly. Glad I caught this.

Gotcha. No difference: re, notches: just wanted to point out the inner and outer markings, in case you weren't looking at the inner notch. Also, for future when you want to look down the vent holes and ensure timing is approx right.

I normally rotate 1 3/4 before flywheel lock. That way, after putting on the belt, I'm close to coming up on TDC again for a notch check when I remove the flywheel lock.

Looks like we cross posted.

Back to my steering pump rebuild.

Many thanks for info!!!! Will do!

Belt seems like its tracking too far forward, right at the edge of the gear.

I noticed the other gear is out farther for some reason. But it's been running fine. I think this belt is almost new and was not original because it is Uniroyal. Did Porsche use these at the Factory?? Anyway, I am about to remove the center cover soon and then can examine the rest.

I wonder how long its been since Uniroyal sold timing belts.

Good point.
Changing this one was long overdue by standards of 32V enthusiasts, be they right or wrong.

Just to add a little info to the thread. As you note the marks are not lined up identically on the left and right cam gear. this couldbe partially due to design and partially due to build tollerance.
Ideally the cams will be degreed in so the slight varience you see at the V notches is just an visual artifact.
By design with a cold engnine the passenger (rigt) cam will be slightly retarded relative to the driver (left) cam. this is due to the cam timing beingdesigned for normal opperating temp. as the engine warms up it expands which slightly advances the cam timing as the timing beld run from the crank to the left head is increases. the distance between the left and right heads also increases with tends to ad vance the right cam. therefore the righ cam has a cumulative advance of both the belt runs.
Also when degreeing the cams the notch positions will not change. the notch positions are dictated by the location of the teeth on the belt which is static when the crank is locked down during belt replacement. the cams however can be rotated slighly (degreed) relative to the gears to effect tuning.
So essencially the marks are there as a reerence for gross positioning, and beyond that the cams will need to be fine tuned bu degreeing by one of the previosly mentioned methods.

Here's what appear to be the beginnings of the reveal of the ingenious little cam degreeing tool.
I have one (loaned out somewhere) and it helped wake up the 32V cars.
Basically it tells you to where to reset the camshafts on the left and right banks independently of each other to achieve the timing you want.
The gears are slotted where they attach to the camshafts so, in essence, you can hold the notches in place, but turn the underlying camshafts slightly for fine tuning. That's not exactly how you execute the changes, but that's the effect.

The same thing is accomplished with the techniques in the workshop manual, but that method requires fancy dial gauge arms and removing the intakes and valve covers on teh 85/86 cars.

(So, consider doing this later after the job is done and you've come back to retension your belt in 1500 miles.)
Adjusting Cam timining 86.5 - Rennlist Discussion Forums

Now that make sense for sure!!! Well, with my limited experience on the 928 and my first time replacing the belt, I am going to leave well enough alone. It was running fine, so I will be HAPPY just getting the new belt and water pump on. I am not going to race the car or do any drag racing as those days are over and behind me, but I do like to give it the gas once in awhile! However here where we have more cops per capita than any where else on Earth and a crime rate of near zero, one needs to be cautious on speeding. Even the Tribal police can issue tickets on public roads and not just on casino land! Sorry, got off topic.

I have the fly wheel brake installed and now to remove the balancer. I just bought an impact wrench and may try it or put a pipe extension on my braker bar to get that bolt off..

Careful of the radiator.

With the timing thing you are just trying to ensure its at the proper factory setting.

There are also certain sensors, if malfunctioning, also, that will cause electronic resetting of the timing or prevent it from being advanced properly.

Also, there is a set of wire plugs taped to the brain harness. Octane loop. Dials the timing to accept low octane gasoline, downside being robs power. Sometimes mechanics have plugged them together.

Yours is running fine, thats good. Lots of them, though are sold because they just don't run right. Trick is to buy these and fix them.

I hope you are going to take excessive pictures of the belt tracking and the tensioner and closeups of the gears and as you disassemble. Dangler is hinting to you that something is causing that slight front tracking. My guess is the front edge of the belt will be very close to the tensioner arm, maybe rubbing, which would probably indicated need to replace pivot bolt plastic bushings, tensioner roller and maybe pivot bolt itself. Also, look for the little bump/touch idler wheel down below the crank pully, under the cover, to spin freely. If not replace it. The bearing can be matched at napa, and you need the little spring clips.

Yes, I plan on taking more pictures and I sure will look at those items you mentioned. I will look at that belt tracking again, will have a better idea when the center cover is removed. Ok on radiator, oh yes, I am very careful!!!!! I use to build RC airplanes, so I am not a Bull in a China closet!!!

Here is a picture with the center cover now off.

http://forums.pelicanparts.com/uploa...1266176120.jpg

I wiped off the tensioner boot a little. You can see it looks just like new, no cracks. The radiator hoses are originals from date stamped on them in 1985 and they are very flexable, not hard. I don't as yet have the water pump here. The only thing I saw inside the cover was some kind of sandy looking material but it was not like sand, kind of soft stuff. It was also around the bottom outside of the radiator and a few other places.

Ehhh, try building an RC Helicopter. Lol. Got out of it as I couldn't afford it anymore. It was actually a more expensive hobby than my 928.

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nice flying i hear they are a nightmare to get right

You have 5 servos to control at once. You have to get the pitch and blade speed just right and if you want to do tricks (3D), then that's a whole other nightmare. I've gone through many helis while I was learning and that's using a simulator too before flying the real rc heli. Once you get them dialed in, it's a real rush to do basic tricks. Loops, Rolls, Inverted Flying. Fun stuff, but way too expensive.

way too complicated for my dumb ass but looks great fun

Yes, I heard those copters were something to fly, never got into that and have not really built any planes in years. Naturally the electronics is vastly improved for them.
Right now the 928 is my hobby besides the Harley and Ham Radio.

Nice work.
Looks to be in good shape as you expected for a low mileage car.
Looks to be tracking ok, a little forward maybe.

I marked your picture.

Things of interest are the oil pump gear possible teeth erosion, the distance between the belt and the pivot arm, slight forward overlap of the tensioner pulley. On the peripery, OT, are those rotor edges corroded or clean?

I'd be considering on one hand replacing / reworking the tensioner, on the other hand, leaving it alone, filling the oil and putting a new belt on.

If its a Porsche water pump, I'd almost consider leaving it.

Now that you know how to go in, you can go in any time.

Again, very nice shape, clearly cared for, nice find.


__________________http://forums.pelicanparts.com/uploa...1266183812.jpg

Well, the water pump is most likely original. I have ordered a new Laso one so guess it goes on. Yes, it's very clean although someone else got on me for mentioning this too much, did not believe me. All I am trying to do is say it like it is, no BS on this car! Think I am going to leave the tensioner alone. Looks too new to screw with at this point. I mean the darn radiator hoses look good, original.

Well the original owner was German, owned his own company here in Elkhart, In., bought the car in West Palm Beach, Fl. and kept it in good condition, his third or forth luxury car. You don't find this kind of thing often and I was not really looking for it, but a friend called me and said you better look at this car. I did, thought about it over night, made the call, wrote the check, next day car here, title in hand. So now I am in Porsche Club, well sort of in the back door you might say! Lets face it, most wealthy people do not fool with these things, they go to the dealer. Like a friend of mine who owns a Mayback, paid $389,000 for it. Way out of my league. I think I am just as happy, maybe more so, I like it better!!!! I have not worked on cars since I was young and actually I am having a lot of fun on this, especially with your help!

May I say, I really appreciate all your advise and experience with the 928S.

Should I replace those rotors????? I saw your arrow on that. I think gears are OK, will clean and check them. Should I keep Laso new pump as back up or just replace now since I have ordered it and paid for it. Still not delivered here, but expected soon.

On the rotors, use your judgement, its pixalated so I couldn't see clearly, mine have generally cleaned up well with some 600 paper. Inside the caps, if corroded, I might delicately touch them with a dremel wire brush. Like on any car, they just need to be clean.


On the water pumps, read this, especially post #18 in this attached thread.

If its a new Lasso from Roger, I'd say replace. If you bought it somewhere else, then I don't know how to know if its the new generation new Lasso or not. That's why I was steering you to him, he's on the cutting edge of this.

Water pump replacement - Page 2 - Rennlist Discussion Forums

If you leave the tensioner, then be sure to remove the top passenger cover every 6 mos or so after your initial retensioning and watch the tracking for migration. Does the tensione hold oil? If so, you would probably be ok for a while. Depends too, how close the belt is running towards the pivot arm.

On the pump, I won't know until I get it. I think he had to order it from his supplier because it still was not shipped. Yes, I cleaned up the caps, not too bad, I have not messed with the rotors but will clean them up. I will remove the belt today and check things out. I don't see any oil leaks anywhere near the tensioner but will give it a good look over.

The tensioner has a pair of fill holes on it, right? It should be full of 90wt gear oil, or, as Mr. Merlin suggests, STP instead. Easy to open it and check level / refill. It provides dampening (oring/piston internal arrangement). The back of the tensioner assy gets a gasket and is mounted against the block. The oil in the tensioner is separate from the oil in the block. Not related, I think one of the tensioner mounting bolts actually passes into a block oilway.

Did you speak with Roger?

I will check that oil in tensioner. Yes, I understand it is not engine running oil. I will look in manual and check posts on how to fill. I read one here before from someone. No, have not talked to "Roger" but read that post on the other site. I saw where two new Laso pumps failed, some what disturbing. I will see what I get here on the Laso when it arrives. I know one usually replaces the water pump with belt on most engines, but this one is more frequent at 40K miles. I bet my pump is original. There are some numbers on it. Will try and read them today. I will turn up heat in the garage and work on it later today, remove belt. So far so good on this!

One of them was on a stroker motor. The other one a while back.

And the problem is fixed now with the upgraded new lasso metal version, with the plastic version coming soon.

Very low torque on the wp bolts, remember that. They will strip in a heartbeat if you go past snugging them past that value.

Looks like you've got it under control, though. Cool.

BTW, I'm not dealing with anybody on parts that doesn't own and operate one of these, and am selective beyond that too.

I was missing the one special bolt in the middle of the RIGHT cam cover. Someone mentioned it was a special one since I have not seen it and it was not on the cover when I removed it. I believe there are only two bolts holding it on, so would like to have both.

Do you have a source for this bolt by chance?