Engine timing Problem

[HerbieJ]

This is a follow up to my "Bad Engine Knock" post dated Oct. 4th. Much thanks to emckelvy and j martin for their thoughts and suggestions. I still haven't gotten it running, but I did drain the oil, (two full quarts over!), but no water in the sump, thankfully. I also finally located a compression gauge with a 12 mm thread and ran a test. Got 115 on three of the cylinders and 118 on the fourth one. The head stays on, at least for now. Then I did a timing check. With number 1 plug removed, I can see the piston at TDC. At that time the pointer under the flywheel is right on the TDC mark, AND the "#1" on the cam pulley is right on the pointer for cyl. #1, where it should be. But, the flash of the timing light illuminates nothing! I moved the timing light around the turning flywheel and found the mark for TDC --approx. 90 or 100 degrees PAST where it should be. What has happened here? I don't think this 50 hp, 4 cyl. 4 stroke jumped timing because the piston at TDC aligns with the flywheel and cam pulley marks. Any thoughts and suggestions would be appreciated. Gotta get this running to see if there's still an engine knock to contend with.

 

[CharlieB]

Re: Engine timing Problem

Do you have the service manual for this engine?

It will spell out the timing procedure.

Depending on the motor and ignition system, timing may be adjusted by the computer referenced from the crank, distributor ignitions often have timing adjustment but there again you really should have the manual for the proper procedure, depending on your particular motor.

If the motor will run, then check timing running and see what it is, it shouldn't be too far off TDC at an idle.

 

[j_martin]

Re: Engine timing Problem

This is a follow up to my "Bad Engine Knock" post dated Oct. 4th. Much thanks to emckelvy and j martin for their thoughts and suggestions. I still haven't gotten it running, but I did drain the oil, (two full quarts over!), but no water in the sump, thankfully. I also finally located a compression gauge with a 12 mm thread and ran a test. Got 115 on three of the cylinders and 118 on the fourth one. The head stays on, at least for now. Then I did a timing check. With number 1 plug removed, I can see the piston at TDC. At that time the pointer under the flywheel is right on the TDC mark, AND the "#1" on the cam pulley is right on the pointer for cyl. #1, where it should be. But, the flash of the timing light illuminates nothing! I moved the timing light around the turning flywheel and found the mark for TDC --approx. 90 or 100 degrees PAST where it should be. What has happened here? I don't think this 50 hp, 4 cyl. 4 stroke jumped timing because the piston at TDC aligns with the flywheel and cam pulley marks. Any thoughts and suggestions would be appreciated. Gotta get this running to see if there's still an engine knock to contend with.

120 degrees = wrong coil wire. Is there a chance the ignition wiring got mixed up?

John

 

[HerbieJ]

Re: Engine timing Problem

Service manual is ordered and due any day. Ignition system on this 1998 Mariner 50 appears to be electronic and I need to see the manual to know if it can be manually adjusted. 100 or so degrees seems like a lot for it to self-adjust. It won't start so I can't re-test the timing with it running. Also, the large nut on top of the flywheel looks like it hasn't been touched, so I don't think the coil wire (is this the "stator"?) has been changed. The spark plug wires are such that it's physically impossible to confuse them.

 

[j_martin]

Re: Engine timing Problem

Service manual is ordered and due any day. Ignition system on this 1998 Mariner 50 appears to be electronic and I need to see the manual to know if it can be manually adjusted. 100 or so degrees seems like a lot for it to self-adjust. It won't start so I can't re-test the timing with it running. Also, the large nut on top of the flywheel looks like it hasn't been touched, so I don't think the coil wire (is this the "stator"?) has been changed. The spark plug wires are such that it's physically impossible to confuse them.

Naw, timing is pretty much mechanically locked, except for trigger travel.

It's real easy to mix up the trigger wires, or the coil primary wires. When you get the book, carefully compare color codes and wire routing.

Or alternately, mark the flywheel at 120 degree increments from TDC, and using the timing light figure out which plug is firing where, then chase down the wiring.

hope it helps
John