timing questions

[trucker677]

I am finally putting the car back together and have a few questions that are bugging me, I looked through the other threads and can't seem to find the naswers to what I am asking.
1) I have the crankshaft at TDC and am trying to line up the camshaft marks with the little notch in each cog with the notch on the block, but they either go just before it or just after it. What would cause this to happen?

2) If I rotate just the crank by hand until the OT is on the timing mark will it be at tdc and if I roatate it again 360 degrees will it still be at tdc, (I hope that question makes sense because I don't know how else to word it) I am just making sure I have everything in order before I go any further and have to undo something again because of a stupid mistake.

I know 1-4 is on the passenger side and 5-8 is on drivers side, I made that mistake before. my crank is OT on the timing mark.

[Landseer]

Sounds like you are close.

Two turns of the crank will result in the timing gears being back on or about their marks. (crank turns twice to get 1 turn of the cam gears).

At TDC (O/T on the harmonic balancer*) one timing gear might be perfectly aligned with the mark on the back cover, while the other could be nearly 1/2 tooth or so off the mark when the belt is tightened. That's normal in my experience. Get it close and make several crank rotations each time you check the belt tension, a total of 4 or 5 times of rotating and checking belt tension. Should be at the lower 1/3 of the window of the Kempf tension tool.





* when standing in front of car, facing the harmonic balancer, the O/T and numbers must be visible and directly readable to you, not visible and upside down

[trucker677]

I can read the numbers while standing in front of the car so I know that is right, but if I don't have the TB hooked up then all I have to do is rotate the balncer until it is at TDC and then put the pther two marks on the camshaft on, is the a chance that the crankshaft can be 180 degrees out from the camshafts. It is hard for me to explain it in words. without the TB being hooked up is one rotation one rotation on the crankshaft, as long as it is at tdc it shouldn't make a difference, Right???????

[Danglerb]

Timing is three things, crank, cams, and distributor. Cranks turn twice per full cycle, cams and distributors only once. Make sure Distributor rotor is pointing where it should be, #1 I think.

[trucker677]

so I got everything back together and went to start it, and as it was rolling over (probably 5 seconds or so) the timing belt spilt right in half width ways. so now I am back to square one, need a timing belt, I still have the old one but it was soaked in oil when the crank seal let go.

[Danglerb]

Was this a new belt? What kind from who?

Turned fine by hand several revolutions?

Split? Like into two belts?

I like either a Gates or last one I got was a Flennor. Gates also has a fancy racing belt, but I plan to wait until somebody breaks one to see what breaks first.

[trucker677]

yes it was a brand new belt, I bought it from 928 intl. it split crossways like clean straight across, I have to pull the balancer off tomorrow and see if anything is damaged and to get the belt out, I a think it is wrapped around the crankshaft cog. I will take pics and post them, if the belt was too tight would it cause that, I didnt think it was too tight, I dont have a tensioner tool

[harborman]

Originally Posted by trucker677

yes it was a brand new belt, I bought it from 928 intl. it split crossways like clean straight across, I have to pull the balancer off tomorrow and see if anything is damaged and to get the belt out, I a think it is wrapped around the crankshaft cog. I will take pics and post them, if the belt was too tight would it cause that, I didnt think it was too tight, I dont have a tensioner tool

You need the tensioner!!! I think I paid about $50 for it. I also bought the flywheel lock. You need both of these tools.

I used a Gates belt on mine and they have one for about $135 which is stronger as well. There is a complete write up on the Rennlist site you can down load for the TB job.

Hope you did not damage anything. On something like this you cannot take short cuts. You need the right tools and time. Especially a critical item as the timing belt. You must use the tensioner tool and set the belt correctly and have the proper gear alignments.

[aluminum]

Most likely You got a bad belt . Don't know what engine your working on ? 16 0r 32 valve but I expect It's a 16 Valve .
Yes it's hard to get the belt to line up on the Cam Marks with the Crank Pulley on OT because the valve Springs are trying to push the cam off the mark .
You need to relax the tensioner to help install the belt in case you did not do that. Install the drivers side first and clamp the belt to the Gear with something that well not damage the belt ( C Clamp or Vice grips with padding or perhaps a helper <> that's a big help )
You want the OT to be Lined up with the Distributor Rotor pointing at Number 1 cylinder ( toward the front ! ) then set your Cams .
After installing the Belt rotate the Motor at least 2 times and check the tension.
You well need a Kemp Tool to set the Tension at the Low side of the Window with the 16 Valve Motor and the high side with the 32 Valve Motor .
I don't install the Upper Cam Covers but rather run the Motor for a day or 2 and keep checking the tension a few times as they well most likely get loose . Some tensioners work with Oil Pressure not sure what your running in that area ? .
I expect if you state your area someone may loan you a tensioner if they live close .
You can use mine but I am in Northern California ? Mendocino County so look for your area .
It seems like you can just guess the Tension but you can't because if It's not correct it well brake the Drivers side Cam off on start up at some point > be sure you check the Key way if you have a early type Cam Gear with a Key way that slides on the Cam. Look for wear of the Key way on the Cam Gear.
You can check the Tension with the Crank Pulley on OT and the Cam's on the notch >> not just anywhere You move the Kemp tool Handle back until it just hits the Housing then take a reading .
The Housing well flex if you push hard so don't do that as it well change the reading just make it touch >> It's very easy really .
Be Sure you install the Crank Pulley and Crank Oil deflector correctly lip out not in .

[trucker677]

I am working on a 16 valve. L jetronic, I know I had everything lined up correctly, the only thing I didnt do was take off the dist cap and see where the the button was pointing, honestly I didn't think of it, I asked the question about OT being at tdc without the TB on it. I guess I should have asked does the dist spin off the crankshaft, if so then I could see a difference then. it could be 180 degrees out. I am going to shop around locally tomorrow and see if I can buy a belt and take everything off again and go from there.

[Mrmerlin]

there is a possibilty that you didnt position the 2 thrust washers on the timing gear on the crank the correct way,
the flanged edges should both face away from the timing gear so when the crank turns the belt will be guided onto the gear.
otherwise having a timing belt split means that something else isnt correct in the belt run possibly a damaged water
pump or a frozen idler bearing. Please post pictures of the belt run and how the belt looks before you take the belt off

[trucker677]

I will post pics for sure tomorrow, I did position the two thrust washers on correctly, I am thinking it was just a ****ty belt, either that or it was on too tight, when I take everything off I am going to see if something got seized, it was all running free before I put it all back together. hopefully everything is good.

[Landseer]

Forget shopping locally.
You want a fresh belt from stock that moves
Gates standard belt from 928srus is one known-good pathway.
Its the exact same belt as the Porsche branded unit.

Tensioning tool is really required or you risk a great deal more than the belt, including but not limited to camshaft snouts. There is a lowside limit to the investment in parts and tools necessary to play with these things.

Would like to see pictures of each pulley.

[Danglerb]

The timing belt is pretty strong, last 32v motor I bought the guy used the old timing belt as a lifting strap to pull the motor, and first couple times something got hung up and the whole front of the car lifted up. I've never heard of one just snapping either, so my guess is you have something frozen/locked up.

[MPDano]

[MPDano]

The Kempf Tool is what we all use for Tension. Best $59 you'll ever spend



928 Specialists - Tool 9131 - Timing Belt Tensioner Tool

[harborman]

Look at this site for a real nice description and with great pictures of doing the timing belt. There is also one on Rennlist you can look at.

Timing Belt and Water Pump Procedure w/pics

I think you mentioned doing the job with crank on TDC. However read the following from the above site:

"Now we need to set the crank at 45 degrees BTDC and lock the crank in place. In this 45 degree BTDC position, it is safe to work on the timing belt as none of the valves can contact the pistons if the cams move during the procedure." This might be for the 32V engine only.

[harborman]

Originally Posted by Danglerb

The timing belt is pretty strong, last 32v motor I bought the guy used the old timing belt as a lifting strap to pull the motor, and first couple times something got hung up and the whole front of the car lifted up. I've never heard of one just snapping either, so my guess is you have something frozen/locked up.

Funny story: A friend of mine has a Harley Davidson which uses a belt to drive the rear wheel, looks like our timing belts. He is a big guy and had one of his big girl friends on the bike one day. Well, he got on the throttle pretty good one day as they took off. 15 minutes later he walked back with a broken belt! I never heard of one breaking, but he managed to do it!

[trucker677]

here is the pics of the motor and the belt as it was when it broke, it looks like it is wrapped around the crankshaft,

[lfausty]

928 tensioning tool part 1 ( 2 ,3 ) You Tube, real pros. loaded info/hands on/picturiol.