'87 928S4 105K miles.

I am replacing my water pump and timing belt after the water pump failed. Having just got the timing covers off, and following John Pirtle's excellent instructions, I am on step 2 of REMOVING TIMING BELT. When the engine is at TDC, the notches in the Cam Sprockets should line up with the notches in the backing plates........Well, horror......Mine DONT!!! The Right side is about 2 sprockets away and the left is about 10 sprockets away.

About 3 weeks ago, my car suddenly died at a traffic light, It would start and "idle" very roughly, but would ignore any attempt to rev, the gas pedal could be pressed to no avail. All i could do was idle it to the curb. When I checked, Water was leaking from the pump.....and so here I am on my way to dismantling the engine.

1) Where is the timing mark to line up with the marks on the crank pulley. I gather it is the pointed plastic piece on the center timing cover????
2) What is the procedure now My timing marks are not aligned? Can I correct this? Is there any way to check if I have damaged the valves etc?

Please help.!!

Having just spent $2700 getting the Torque tube And torque converter bearings replaced....then another $1000 for new tires, I hope the engine is not damaged. If it is, you can look forward to seeing a 928s4 being sold for parts pretty soon.

I love this car and it is in excellent shape, but I only bought it to drive until I could afford my next 911, turbo.

 

before you even think of moving the camshafts back to the correct position,refit crankpulley with the timing marks on it,turn crank to the 45 degree mark(is belt still on)very slowly,you can then remove belts,make sure you have some help to hold camshafts,they will spin.when refitting belt,set crank back to tdc mark,start fitting belt from crank,oil pump,this is the fun part,turn cam on bank 2 (cyl 5-8)until timing mark lines up,fit belt,need to ho;d belt in this position,get friend to do this,water pump next then do the same on other cam.

chris

 

Hi Pooch,

Do alignment at 45btdc crankshaft position. Need to align cam gears at 22.5 degrees before the tdc (top dead center) notch on the cam gear to correspond to the 45 btdc crankshaft setting. My analysis of this is: 22.5 degrees before the cam notch corresponds to 3 TEETH. The reason being: There are 48 teeth on the cam gear. 3/48 = .0625 = 22.5/360. (Adjust the math if the number of teeth on your cam gear is different.) BTW there are 24 teeth on the crank gear. Therefore, 2 to 1 ratio with the cam.

HTH,
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

 

pooch,
once you've done the above, you need to do a compression and leakdown test to see if you have any valve damage. if you do, it would be an opportunity to upgrade to larger valves at least.
good luck

 

Yes, the pointed plastic piece lines up with timing marks on the crank.

You can do a compression check or leakdown check to see if you have valve damage.

As previously stated, slowly turn the crankshaft clockwise only with a 27mm or 1 1/16" socket, 2” extension, and ratchet on the crankshaft bolt to the 45btdc mark. At this setting the valves will not hit the pistons. Lock the position with flywheel locking tool. Slightly loosen timing belt. Turn each cam to 3 teeth before the notch on the back of the cam. Tighten belt. Remove flywheel lock. Do compression check. If compression is good and uniform, you got lucky. Then service the front end with new belt, pump, rollers, etc. See the timing belt… essentials document I provided on this earlier post.

<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001607" target="_blank">http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=14&t=001607</a>

HTH,
Good Luck,
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

 

A further check is that the rotors point left at TDC. Does anyone know what direction they point at 45btdc? Nevertheless, reinstall the rotors at the 45btdc setting to verify that they both point the same direction before moving to the next step.
<img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

 

Thanks for the suggestions so far.
I have not removed anything yet. The belt is still on and all is as I found it when removing the timing covers.
I have to wait to recieve the flywheel lock tool before I can continue and remove the pulley.
I had a peek behind the center timing cover, and there is a lot of debris there from the broken pump I guess.
Do you think it is a good idea to remove the valve covers as well to check the valve stems for bending while turning the motor?

It seems that the belt must have slipped some teeth wjhen the pump went south. The motor ran in the bad idle mode for a while whjile I was trying to get the car out of traffic. I guess I will have top wait and see (and pray).

thanks Again
Leon

 

Hi Pooch,

I don't know of any way to avoid piston contact with valves while you turn the crank to 45btdc -without a lot of work. You could pull the cam covers, and camshafts to avoid that contact. I don’t know if it is worth the effort. Perhaps someone else could answer that. I imagine that any valves would already have been bent at their current orientation, and turning the crank (and therefore, the cams) slowly to 45btdc would cause no further harm. Another option is to turn the cams counterclockwise, but that could be one of those GREAT mistakes. When I removed my heads, I had to replace nearly every piece of rubber on the upper engine to get the intake sealed again. However, you don’t have so many intake sleeves on that engine. You still might have to get a cam cover gasket kit, and new hoses if you remove the cam covers.
<img src="graemlins/icon107.gif" border="0" alt="[icon107]" />

 

Thanks again.
Maybe i should explain a little more. I have already turned the crank a few times to see if the timing marks would line up, so I can turn the engine. It seems ok but of course who knows what is going on inside.
I am going to Autozone to get a compression tester. BTW, how do I do a leakdown test?
What are the specs for the compression?

I will search the posts but it will be nice if someone can syupply them.

Thanks again

Leon

 

Hi Pooch,

I would not turn the engine anymore than enough to get it to 45btdc. It seems like a special tool at around $100, and a compressor are required for leak-down test. It is supposed to be more reliable than the compression test. I would not bother with it now personally. I have not purchased the tool. I don’t know your compression values. If you get uniform values around, I think, 150-200 psi for all cylinders, e.g. pressures fluctuate very little between cylinders, you should be fine.

 

Follow the directions given above to get the cams at the proper timing.

Do a compression test - the results will be VERY clear. If the valves aren't bent, you should have more than 125 on each cylinder. If the valves are bent, you will have essentially zero on that cylinder.

Good luck!

 

Thank you again. I am waiting for the lock toolsbefore removing the center timing cover and hence the pulley and belt. I tried to track down a leakdown tester today but no luck.
Tonight, I fashioned my own device from an old spark plug shroud that sealed just enough to allow me to blow some compressed air into the cylinders. Turning the crank to a Guessed TDC point on each cylinder made the shroud pou out of the spark plug hole or atleast bulge when blowing air in......and also allowing free flow of air after TDC......so in my humble opinion ..(maybe just wishfull thinking)...the valves may have survived....
I will report back again once I have seen the damage behind the center cover. Thanks for all the help.
If anyone has any suggestions about what other tests to do and how to proceed when I have completed the replacement, Please advise.

Leon

 

Why risk futher valve damage by turning the crank when the cams are not aligned???

Valve damage can be a $6000 repair. Multiple people have tried to advise you on this point!!!

Just curious, did the timing belt tension light come on? Did you ignore that too?

Trying to lead a horse to water.
<img src="graemlins/nono.gif" border="0" alt="[nono]" /> <img src="graemlins/soapbox.gif" border="0" alt="[soapbox]" />

 

Thom
I appreciate your comments.....if you see my intro, you will see that this motor ran after the damage for at least 3 minutes while I was trying to get out of traffic. So I guess any damge would already have been done more than what I could do by turning it by hand for 4 or 5 revolutions.
But I appreciate your input.
The motor is now standing at TDC waiting for the lock tool.
No, the belt light did not come on, the belt is still on and tight.
Thanks again

Leon

 

Pooch,

Yeh, I kinda' said the same thing to you about the damage being already done at the current orientation. My bad.

Valve damage is about the most devastating financial catastrophe most of us have ever encountered. If the cams are currently way off, the valves can interfere with the pistons. If you turn the crank, you can bend the valves. Why pour salt on a wound?
<img src="graemlins/icon501.gif" border="0" alt="[icon501]" />