TDC crank pulley timing mark not a 0

[Kenepela]

Volvo AQ131D motors. When motor is at Top Dead Center, are the timing marks on the crank pulley supposed to be at 0 degrees? Mine are not, one is about 10 degrees before TDC and the other is about 14 before TDC. I am positive the motors are at TDC. Can I make a new mark at 0 degrees and then time the motors from there? Thank you

 

[Alpheus]

Re: TDC crank pulley timing mark not a 0

I am positive the motors are at TDC.

Can you explain your method for knowing you are at TDC?

Im not being a smart ***** I just want to make sure...

 

[TiredoleBoy]

Re: TDC crank pulley timing mark not a 0

TDC is when the #1 cylinder is at its top of the compression stroke. Be sure you know it is at the top prior to looking at the flywheel. I like to use the thumb over the hole then a brass pipe to verify it is at top when I manually turn the crank.

 

[JustJason]

Re: TDC crank pulley timing mark not a 0

How many timing marks do you have? I put a timing belt on an AQ131A today, and there is only 1 slit on the balancer.

 

[a70eliminator]

Re: TDC crank pulley timing mark not a 0

This is where a degree wheel and dial indicator come into play, depending on the cam profile the crank can travel several degrees before the piston begins it's downward travel.
If you set your timing mark to 0 TDC the piston should still be on top.

 

[Kenepela]

Re: TDC crank pulley timing mark not a 0

Thanks for the replies. I had to have the #4 exhaust ports on both heads (twin motors) welded and machined. Heads were off, #1 piston at top stroke with crank keyway and guide plate notch set with mark on block and cams set. Timing belt marks lined up fine with crank timing gear, camshaft gear and intermediate shaft. I don't have an air gun, so used the Crank Pulley holding tool to tighten the crank pulley bolt and the tool only lines up with the pulley one way and this is the closest I can get the ignition timing mark, using the holding tool. Only one mark on the pulley.

Brief history, I purchased boat about 1 year ago as a project, not knowing if motors would run and expecting to have to replace motors. Boat had sat in my neighbors yard for 8 years without being started. He had only used it about 5 times. I am the third owner. Got motors running in driveway but motors were running hot so tore into the exhaust manifolds and discovered corroded head exhaust ports. Motors seemed to run fine in the driveway, besides running a little on the hot side from plugged exhaust manifolds. Just telling this because I have never had a timing light hooked up to these motors and don't know how the timing was. Neighbor is good friend and in his few runs with the boat, never complained of timing problems.

Thanks

 

[Don S]

Re: TDC crank pulley timing mark not a 0

Not sure how you are setting up TDC, but I do know you are doing it wrong.
If you go to this link http://www.4shared.com/file/64741910/25295432/230_250_251_131151171.html and download the manual, then go to page 71 and 72 of the manual, it will explain how to install the timing belt (aka toothed belt)

Here is how TDC on the crankshaft is determined when installing the timing belt