service c/chain tensioner, engine locked up!

[Guest]

Replaced o rings in leaking auto cam chain tensioner and I suspect I may have turned the engine too far counter clockwise. Turning the crankshaft (socket at ignition side of crank) the engine will continue to turn counter clockwise but will only move 180 degrees clockwise before stopping. Motor ran fine before my adjustments. Knowledegable expertise appreciated.

[Nessism]

Either the cam timing jumped and the valves are hitting the pistons, or the cam chain is bunched up on the crank sprocket keeping the engine from turning over. Worst case, the cam timing is messed up and the valves are bent now. Did you turn over the engine with the starter? Hopefully you verified the engine will turn over by hand before hitting the starter button.

I'd verify the cam timing. Is the tensioner working properly? Did you wind up the spring tight and make sure it pushes out the plunger with full force when the lock screw is released? Did you release the lock screw after installing the tensioner?

[2whldreams]

Thank you for the quick response.
I checked the engine using the socket only.

If by chance the tensioner is malfunctioning could that prevent the crank from turning in the clockwise direction? Will the cam chain hang up?

[BassCliff]

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[Big T]

Thank you for the quick response.
I checked the engine using the socket only.

If by chance the tensioner is malfunctioning could that prevent the crank from turning in the clockwise direction? Will the cam chain hang up?

Pull off the valve cover and check your cam timing to find out

[Nessism]

Pull off the valve cover and check your cam timing to find out

Yes this! Goes without saying that the valve timing should be checked each time the tensioner is removed.

[bwringer]

The engine should be set to TDC before monkeying with the tensioner. I've added a stern warning to my writeup.

You really need to get your mitts on a shop manual -- there's a precise procedure for checking and setting cam timing.

And one of the first warnings you'll see is that you should never turn the engine backwards...

[cowboyup3371]

The engine should be set to TDC before monkeying with the tensioner. I've added a stern warning to my writeup.

I wish I knew that before taking mine off. Hope I won't have issues.

You really need to get your mitts on a shop manual -- there's a precise procedure for checking and setting cam timing.

And one of the first warnings you'll see is that you should never turn the engine backwards...

I'm curious about this last statement Brian as the GS550 service manual says to do the exact thing:

p. 61
"While turning the handle (1) counterclockwise, slowly rotate the crankshaft in reverse direction (thus causing the chain to push back the tensioner).

Release the handle and slowly turn back the crankshaft in normal turning direction (to slacken that portion of the chain extending along the tensioner). See if the handle rotates by itself as the chain becomes increasingly slackened; if it does, then the pushrod inside is obviously moving forward under spring force as it should, thus signifying the tensioner is in good operable condition. If the handle rotates but sluggishly, it means the pushrod or lock shaft is sticking and, in such a case, remove the tensioner and service the pushrod and lock shaft to make them move smoothly."

The handle in this case referring to the round knob on the tensioner.

Is the service manual wrong in this case?

[tkent02]

Is the service manual wrong in this case?

No .

[salty_monk]

I believe Brian means never rotate it backwards with the Tensioner removed.

I did mine straight in and out. Didn't check cam timing, didn't TDC it first I don't think.

I've done two that way now.

Maybe I was just lucky. I'm sure there are better practices. Mine was for an oil seal change too.

I certainly didn't mOve anything with it out though!

[GateKeeper]

I did what you did as well, to clean it up and to change the seal, moved nothing while it was out, so hopefully, all is good.....

I believe Brian means never rotate it backwards with the Tensioner removed.

I did mine straight in and out. Didn't check cam timing, didn't TDC it first I don't think.

I've done two that way now.

Maybe I was just lucky. I'm sure there are better practices. Mine was for an oil seal change too.

I certainly didn't mOve anything with it out though!

[Nessism]

Depends on where the engine stopped before the tensioner was removed. If a couple of the cam lobes are near the peak the cam could rotate when the tensioner is removed. You are taking a chance by not checking the timing after the job.

[GateKeeper]

OK, well I guess I have to do some more work then, it's OK I have to take the head cover off anyways, gotta clean it up, plus I have to check the clearances as well, I guess I can do it all and then put it back together the correct way.

Thanks

[bwringer]

I'm curious about this last statement Brian as the GS550 service manual says to do the exact thing:

p. 61
"While turning the handle (1) counterclockwise, slowly rotate the crankshaft in reverse direction (thus causing the chain to push back the tensioner).

Release the handle and slowly turn back the crankshaft in normal turning direction (to slacken that portion of the chain extending along the tensioner). See if the handle rotates by itself as the chain becomes increasingly slackened; if it does, then the pushrod inside is obviously moving forward under spring force as it should, thus signifying the tensioner is in good operable condition. If the handle rotates but sluggishly, it means the pushrod or lock shaft is sticking and, in such a case, remove the tensioner and service the pushrod and lock shaft to make them move smoothly."

The handle in this case referring to the round knob on the tensioner.

Is the service manual wrong in this case?

Good point. Let's say that on the GS models I've worked on, there's a warning that you shouldn't rotate the engine backwards. I haven't done much GS550 work.

Of course, the procedure describes something more like changing the tension on the cam chain (likely less than 1/8 turn) rather than rotating the engine backwards through a complete revolution.


One other bit of info: to check the cam timing on a GS, remove the valve cover and look at the rectangular notches in the ends of the camshafts. When the engine is at TDC, the notches will be parallel with the cylinder head surface and either pointing directly at one another or 180 degrees away.

Like this:
>______<

or this:
<______>

[2whldreams]

Cam chain, engine lock up part 2

If the tensioner has been removed, and the engine is turned counter-clockwise/backwards, the cam chain can jump the cam sprockets. Reset the cam timing.
Shop/Factory manuals are written by engineers for qualified mechanics. I'm neither. The Suzuki factory manuals idea of loosening the tension on the cam chain upon reassembly and my idea are different.
The combination of GSR and not panicking, eveything has been resolved.
After correct reassembly, the engine turns freely forward and backward. Nothing is broken or damaged. This is simply a case of gaining experience.
The morale of the story is this. When your cold, tired and uncertain-just walk away. With rest, caffeine and new information just start at the basics.