944 180 degrees out of time??? Help

thill944 · thill944's Garage

I bought an 87 944 NA a few weeks ago. I drove it home , about 150 miles. I wanted to check everything out before I started driving it daily. I posted a few days ago about how at idle I get a lot of vibration and asked for comments. Most said it was probably due to bad motor mounts. I thought it might be the balance shafts out of time. Anyway I decided to check the balance shaft timing.

I jacked the car up. First thing was to get the number one cylinder at TDC. Turned the crank until the timing mark on the camshaft sprocket centered in the little round hole. Then checked for the flywheel timing mark at the back of the engine near the speed sensor. It wasn't there.

I then turned the crank over until the timing mark on the flywheel appeared in the rectangular hole at the back of the engine. I aligned it with the timing mark. I put my screwdriver in the number one sparkplug hole to see if the piston was at TDC. It appeared to be. Then checked to see if the Timing Mark on the Camshaft Gear was visible. It wasn't. I thought this strange so I pulled the camshaft cover off to see just where the Sprocket Timing mark was. It was 180 degrees from the Timing mark on the camshaft housing.

Is this possible and would the car run. Like I said the car runs great. Just the vibration at idle. When the RPMs go above idle the car smooths out. I don't know what to do. My first thought was to remove the Timing Belt from the Cam gear, rotate the Cam Gear to where the marks on the gear and housing align, and then put the Timing Belt back on. Would this be the correct thing to do.

kdjones2000 · kdjones2000's Garage

Remember that on your engine the crankshaft/flywheel rotate 2X for every 1X the camshaft does. You are now 180 off from TDC.

Rotate until the cam sprocket is back near the hole, then move the flywheel a little bit until the TDC mark shows up. Sounds like everything is fine.

+1 on the motor mounts causing the vibration....

mikepellegrini · mikepellegrini's Garage

+2 on the motor mounts.

It wouldn't even run at all if it was 180 out.

Nottom · 07-22-2009, 07:32 PM

Yes, he was 180 degrees out the second time, but his initial check does seem like something is wrong.

I'm pretty new to the 944 scene, but I was a mechanic in another life. The flywheel is balanced is it not? Is it possible to install it incorrectly? Maybe someone left the dowel out?

Just throwing that out there...

kdjones2000 · kdjones2000's Garage

Quote:

Originally Posted by Nottom

Yes, he was 180 degrees out the second time, but his initial check does seem like something is wrong.

I'm pretty new to the 944 scene, but I was a mechanic in another life. The flywheel is balanced is it not? Is it possible to install it incorrectly? Maybe someone left the dowel out?

Just throwing that out there...

The first time he just missed the mark for TDC. Cam position mark is not as accurate. Everything is fine on his engine.

Nottom · 07-22-2009, 07:56 PM

Good point. A small rotation of the cam pulley equals a large rotation of the flywheel.

To the OP; the advice these other guys gave is sound.

Always go with the simplest things first. It will save you money in the long run.

moorepower · 07-22-2009, 10:10 PM

I was just explaining this to a guy at work the other day. There are actually two TDC's. There is a TDCC (top dead center compression), and a TDCO (top dead center overlap). They are at the same place relative to crank position, but 180 degrees away from each other (as you discovered) relative to cam position.

Schumi · 07-23-2009, 01:47 AM

Did you end up checking the balance belt? If hte balance belt is off a little, it will rev fine and seem normal at driving speed but will vibrate at idle.

Otherwise, what others have said may be true- motor mounts will be shot. They are not too difficult to replace IMO. Put a hoist on the motor to hold it and disconnect one, and inspect it. A bad mount will be squishy. They are fluid filled rubber mounts. If there are large crack in the side of them, the fluid can leak out and they will 'go flat'.

I think the factory manual recommends replacement if the rubber starts to crack even if they still seem OK.

HondaDustR · 07-23-2009, 07:59 AM

Just crank over until just before the cam timing mark lines up, then watch through the hole for the flywheel mark as you slowly roll the engine. 2 revs for the crank for 1 rev of the cam, so chances are, if the mark lines up with the cam 180 deg out of time, it probably lined up very near 0 degrees as well. Because of the diameter of the flywheel, the mark will travel a relatively very large linear distance for a small amount of degrees of rotation. Given that there has been proven a rather significant variance in the machining of the cam gears, and that the 944 motor can run without damage with as much as +/- 1 cam tooth out of time, it's probably just off a little. You may be 1 tooth off, or it may just be normal manufacturing variances of the cam sprocket. You'll learn which "side" of the cam mark your TDC mark is in time.