Der Treiber

With all the help on this site, and a few others, I decided to tackle the belts on the S2 (since they were nine years old). Going fine, so far, but wanted to turn to the experts here for some advice. https://rennlist.com/forums/graemlins/bowdown.gif

These four pics show the position of cam and crank shafts; e.g. existing engine timing. These pics are from as straight to the reference marks perspective as I could get, so they reliably reflect what you would see if you were looking yourself. But, as you can see, the marks on the flywheel are sort of all over the place, depending which reference port you look at. The cam and balance sprockets lined up perfectly after using the lower, driver's side (U.S.) crank port as reference (2nd pic), so this is where I locked it all down before pulling belts and tensioners.

But now that 6:00 reference mark (pic 3) is starting to bug me. Should I rotate the crank slightly to get that mark closer to center? Engine ran pretty smoothly, before, but I wouldn't say it purred. Or should I just leave well enough alone, since I don't have the dial gauges and brackets necessary to measure piston peak, cam lift, etc.?

Van

I can's see the pictures, but there is a little blade inside the bellhousing... that is what you line up with the OT mark on the flywheel.

car_slave

I think the best way to get TDC is with a dial indicator through #1 spark plug hole.
The balance shaft marks are not a very precise reference for timing.

Der Treiber

Der Treiber

Der Treiber

So, to simplify, which one of these reference marks matters the most?

Van

The line on the flywheel with "OT" should be at the spot of the blade where I've drawn the green arrow.

Der Treiber

Assuming that the starter ring is fitted to the center of the flywheel (manual transmission), I just can't see anything that remotely resembles the |OT marks on the right side (toward rear of vehicle) of the starter ring (or on the left side for that matter) - at least not anything that looks like the sample on the C-G web site. If anyone has an S2 and could snap a pic of what I might find in that square bell housing port at TDC...that would be great. Otherwise, I'm just going to stick w/ all the other reference points, and leave well enough alone.

I could have sworn, though, that when I pulled the distributor cap, the rotor was pointing directly at the point for piston 3. If P1 was TDC, shouldn't the rotor have pointed to the point for P1? Also, there's only one reference sensor at this position...I guess the other one was repositioned to the Cam housing on the S2's? Apologies for all the newbie questions.

dillon410021

just dont mess with the cam gear setting as its adjustable and you will need a dial gauge to get it back to normal. I did this on my 944S and it was a huge headache to get it good again. as far as tdc, just pull the #1 spark plug and stick a long screw driver down the hole. you will see when the piston comes to the crest. a dial gauge is best but most dont have them.

Der Treiber

Van - or others,

I noticed about 1.0 - 1.5 mm lateral movement on both of the balance shafts, and actually the seal shifts about 0.5 mm, too. Is that normal?

TL

Der Treiber

OK, next noob question: how firm is the compression from the pistons when you rotate the crank manually?

I just finished replacing both balance and the crank seals, as well as timing belts and a couple of rollers...everything went smoothly, and everything back in place, torqued to spec, w/ all marks aligned.

I locked the flywheel and cam sprocket before starting any work, so they never moved throughout the above work (engine was well-timed prior to work).

Now, I just wanted to run the crank through a few rotations to make sure all is well, before putting on the accessory belts, and starting at around four cam teeth clockwise I am getting a compression-like pushback...pretty firm on my 18" breaker bar. Any further and it will actually push counterclockwise back when I let go....no belt binding, or anything like that.

Is that normal, or am I pushing pistons into valves?

Van

As long as your "timing" is correct - e.g. the belt is on, the crank is at TDC and the cam gear mark lines up, you can turn the engine over without any interference.

There will be a bit of compression. I know that with a 12" long socket wrench, it takes a lot of force to turn.

If there's bounce back, that's probably just compression. A valve/piston collision would be more like a solid hit.

Arominus

Well with the plugs in thats pretty normal, pull them and then do your rotations.

Fara

When you're trying to turn the engine through the revolutions, do you have the spark plugs in?

Der Treiber

OK, thanks team. I was just being too cautious. I pulled all but the 2nd plug, because the strut brace blocks the plug, and I didn't want to go through the hassle of pulling everything off the stands to remove the brace...once I got past compression on cylinder 2, it wall went around smoothly. Awesome.