1983 Timing Belt Change Help Needed
 

All,

I started my timing belt change today. I need to know from this robust group if I have created a problem.

I placed the engine at perfect TDC and then removed the started and placed the fly wheel lock in place. I noticed that I could not get the flywheel lock to fit into the teeth of the flywheel and line up with the bolt holes so that I could secure the lock. So, I went back to adjusted the TDC a small tweak. I used the CamShaft mark as my guide in this adjustment. I then went back to the install the fly wheel lock and it engaged with no problem. I tightened down the bolts to hold it in place.

So, the engine has not moved a single bit.

I then changed the timing belt. It is installed and looks great.

However, after I installed the nice new timing belt, I went to check on TDC before I moved on to install the new balance belt and set tension. This time I checked the TDC mark at the back of the engine near the firewall where the OT mark is located. I noticed that the mark is off a bit. I should have done this earlier but I did not. Again, the engine has not moved.

Do I now have a problem with the timing?

The only thing that has moved were the balance shaft rollers a bit when I removed the balance belt but I put the rollers right back to where the marks line up with the marks on the belt housing.

Thanks,
JBC

with the flywheel at TDC is the cam gear within half a tooth of the TDC mark?

You're fine. Those flywheel locks will often move the motor a squidge.

The flywheel lock is engaged and has been engaged since I started. So, I cannot move the flywheel back to TDC to see what happens with the cam gear. However, I noticed that the when the Flywheel was at precisely TDC the cam gear was about a tooth off from its mark for TDC mark. The cam gear was just to the left of the mark.

Right now, the cam gear is spot on the it mark. The TDC on the flywheel is off so that the OT is hidden under on of the reference sensor but the engrave line is just passed the metal reference mark in the window.

What is the relationship between the balance shafts and TDC? With the crankshaft and cam gear locked by the flywheel lock, the balance shafts can still rotate. Do the shafts have a rotational balance that matches piston movement?

That was my thought also but since this is my first timing belt and balance belt change I'm going slow and I want to be sure.

The key is that I locked the flywheel with the flywheel lock. Then I changed the timing belt. No relationships changed between the cam gear and the crankshaft because nothing moved.

With a new belt, you're going to have to tension it and rotate the engine at least 2x anyway. If you're off by less than 1 flywheel tooth, it's fine. Just line it up with TDC again after installing the belt and see how the cam is. You'll find that depending upon the temperature of the engine and the belt-tension, the cam's position will vary +/ a slight amount, even though the flywheel is always exactly at TDC.

Danno, that was my thinking last night as I reviewed how the engine worked in my head. When I had the engine at perfect TDC on the flywheel with the OT perfectly placed, I noticed that the cam gear engraved line was not perfectly lined up with the mark on the cover. I was off by about 1/2 to 1 tooth counterclockwise. This was before I removed the timing belt on a perfectly good running engine.

v2rocket, I'll let you know tonight after work when I get back to working the car. Thanks much for helping out - everyone. I hope I can be of help to someone on this forum one day soon.

This is a link to how to get them to line up. This is how every trained mechanic installs a belt on any car. They should line up perfectly or you will be noticeably down on power.

924Board.org :: View topic - How to set the timing and balance shaft belts on a 924S/944

+1

the relationship between the Crankshaft and Camshaft are the primary issue and the reason you use a flywheel lock. The balance shafts relate to the crankhsaft. timing of the cam is irrelevant to the function of the bal shafts. If you have any question as to which timing mark is technically more important, go with the crankshaft TDC mark (the bal shafts offset the rotational mass of the engine). But as the others have mentioned, no need to worry, it sounds like you did it right. Being cautious on your first time is a good thing though. Good work getting in there and tackling this yourself!

Excellent information! This is something I need to tackle this winter, and this has been very helpful.

Thanks!

My 83 has never lined up perfectly. IIRC, if the cam is dead on, the crank is shy of OT. Angle vision maybe, but it's close enough. I've only used a flywheel lock one time, and I think I remember it would not engage the flywheel when the cam was spot on.

What works for me is having the OT mark just shy and the cam dead on.

Rasta and Everyone,

First, thanks a million. Second, for V2, once I removed the flywheel lock and then removed all the spark plugs so that I could have good feel for the engine, I slowly tweaked the crankshaft. When I mean slowly, I mean very slowly. I first removed the little slack in the belt. Removing the slack does slightly move the crank. The Cam Shaft stayed TDC. Went to check on the Flywheel OT and grove and everything was perfectly matched up. So, V2, I'm not even 1/2 a tooth off. Big relief. The flywheel lock is vital.

And, the balance shafts are perfectly on their marks also.

So, lesson learned for all the Porsche 944 Pelican folks - the Flywheel lock could cause the flywheel to move slight amount when you lock down the lock with the starter bolts once you get everything TDC. If you check and it moves a slight bit. No worries. Second lesson, taking the slack out of the belt means the crankshaft moves ever so slightly without the cam shaft moving and the OT and grove in the flywheel window will move.

So, now I have to replace the slave cylinder and I'm going to go ahead and get at the master cylinder also.

Then a coolant flush, new oil, new gas filter, and maybe new plugs. I already put on a new rotor.

Again, thanks to this forum and this group for sharing their collective knowledge on these great cars.

I will get some pics soon. Black on black with fuchs all around 7s up front and 8s in the back. Now I need to find good 15 inch tires.

Oh yeah, no cracks in the dash - none. Perfect seats too. Been in a temperature controlled garage for years. All factory, everything, even the Blaupunkt stereo and original speakers and it all works. Incredible.

Fly wheel lock is optional, just like the tensioning tool. You don't need either one. Can't wait to see pictures.

Matt is right on (I haven't done mine in a while and was mistaken). You can absolutely change the TB without the lock as long as you aren't replacing the front crank seal. It's actually the 155 ft/lb for the crank pully bolt that requires the lock.

Sure, I can see doing the job without a flywheel lock. However, it is not bad to have someone or something "checking six".

I don't know why one would strip the front of the engine that far and not renew the crank seals...

Helpful yes, required no. I changed all the seals on the front of the motor without one. Just like the oil cooler alignment tool, helpful, but not required.

This is prime for trivia question. The first person to post a correct answer will be the winner and the next time they are in the DC area, I will buy them lunch.

The scene:
One evening, You're doing a timing belt, water pump, front seal job on your 944. The job needs to be done before midnight, otherwise your car turns into a pumpkin. You look in your tool chest and discover your flywheel lock tool is missing. Suddenly a leprechaun named "Matt" appears and says, "if you can finish this job without your flywheel lock tool, I will give you my pot of gold...and by pot of gold I really mean a kick ass sandwich or burger. The catch is, you cannot remove the starter motor and you must use this triangle shaped block of wood (about the size of a wheel chock)."

Mattdavis is obviously excluded from eligibility but I'll be happy to buy Matt lunch the next time he rolls through DC anyway.

Hmm, place car in reverse, set hand brake, wedge wood triangle between brake cables and torsion carrier to get it hella-tight?