TDC and mystery flywheel

mytrplseven · mytrplseven's Garage

Resto project continuing on barn find '86 944 turbo and now replacing everything on the front of the engine. In setting up the TDC so I can lock the engine in place I haven't been able to find proper OT, line; or when trying to locate flywheel marks on the bottom of bellhousing, I have run into a quandary. As you may see from the pictures attached below, Unless I've once again lost my marbles, it appears that there may be a non-OEM flywheel so I can't see the TDC marks. Since there's no history on the car, I'm looking for info someone may have on this. Lightweight wheel perhaps? Where there should be a solid flywheel, the one that's inside the bellhousing tapers out from the hub and doesn't line up under the viewing square on the bottom.

mytrplseven · mytrplseven's Garage

Second photo: Note the taper at top and bottom of photo

Arizona_928 · 04-27-2018, 02:44 PM

get it close with the cam and see if there's anything marked. remember cam is always 180 off the crank. so you will have to rotate the cam twice to get the tdc

mytrplseven · mytrplseven's Garage

Did all that. Because it looks like an after market flywheel to me, there's no apparent markings. I've rotated the crank several times and They simply aren't there. I was hoping someone has seen a flywheel shaped like this and could direct me to a solution short of going through a clutch procedure to sort it out.

mytrplseven · mytrplseven's Garage

I'm beginning to think that this lightened flywheel may be typical of what may have been installed on the car since it has the big angled recess (shown in the outline) vs the thicker, full mass flywheel.

grendiers · 04-28-2018, 04:31 AM

I'm in the process of completing the FOES on my '83 track car, and aligning the cam marks works perfectly. To satisfy the 180 degree off-cam possibility, I removed the number one spark plug to verify.

v2rocket_aka944 · 04-28-2018, 06:59 AM

951 flywheel has a similar "cone" shape to it like you're seeing, vs the "flat" 944 NA.

mytrplseven · mytrplseven's Garage

But the flywheel surface should be viewable through the small square notch on the bellhousing bottom but this one doesn't (see the pics above). Additionally, when I rotate the engine where the timing marks should show up in the upper viewing port, there is no OT prior to what I think is a faint line. I've seen no references in my shop manuals that say the marks are different for the 951.

mytrplseven · mytrplseven's Garage

Quote:

Originally Posted by v2rocket_aka944

951 flywheel has a similar "cone" shape to it like you're seeing, vs the "flat" 944 NA.

Thanks, that clears up some of the difference but still can't find the standard OT/line marks on top nor on the bottom.

87m491 · 04-30-2018, 02:11 AM

If you can't see any marks through the top or bottom of the bell housing, I'd swear at the previous mechanic then go with the cam mark and position of piston #1.

Assuming the old belt is still on, you've basically assumed it is already oriented properly by turning the engine a bunch.

When at TDC the balance shafts should also be aligned. I'd go off that combined with the crank and piston #1

Quote:

Originally Posted by mytrplseven

Thanks, that clears up some of the difference but still can't find the standard OT/line marks on top nor on the bottom.

mytrplseven · mytrplseven's Garage

I guess the flywheel is aftermarket but I finally managed to verify TDC and now on to pulling EVERYTHING off of the front of the engine. Even though the timing/balance belts looked good visually and the rollers feel good, I found other stuff that's not. So, since there's not maintenance history on the car, I'm doing it all and eating the $$. Aux belts were cracked, balance shaft seals leaking and broken back side timing cover broken (looking for a replacement). Crank pulleys came off without having to rent a puller (whew). Thanks everyone for your inputs.

87m491 · 05-01-2018, 11:04 AM

Congrats on the crank pulleys coming right off. Just did mine a few weeks ago and they slid right off. Went in there yesterday to double check the crank seal and I had to use a puller on the balance belt cog and the T belt crank cog!

full quack · 05-16-2018, 11:54 AM

Why are you looking for the TDC mark on the bottom? The timing mark is viewed from the top of the engine, right next to the crank speed sensors, through the factory window.

Mark

87m491 · 05-16-2018, 12:00 PM

Not sure how clean your view is from the top but mine is covered with wires and I can't see athing etc whereas the view on the bottom is totally unobstructed!

Quote:

Originally Posted by full quack

Why are you looking for the TDC mark on the bottom? The timing mark is viewed from the top of the engine, right next to the crank speed sensors, through the factory window.

Mark

full quack · 05-16-2018, 02:12 PM

Mine is a dead stock '88 turbo, view good enough that with a flashlight I can clearly see what needs to be seen without moving anything.
Just replaced the cam tower gasket, so had to do the TDC shuffle myself.
So,
1.) View from on top, seeing tab and mark on to the flywheel lineup.
2.) Rotor orientation to plug wire #1.
3.) Line on cam gear lined up to mark on head, as viewed thru removable rubber plug on cover.

And your there 100% of the time, no guess work involved.

Mark

87m491 · 05-16-2018, 05:13 PM

6 of one, half dozen of the other I guess. Much easier for me to see the flywheel mark through the bottom factory window than even get into position to see the top.

mytrplseven · mytrplseven's Garage

I finally resolved the TDC issue and now that EVERYTHING on the engine front has been replaced, I chose to do a little "macho" trimming on the cam tower with red wrinkle paint. I'm sure it'll make it go faster.