An Engine Clack with Loss of Power

[Bookmon]

Started having a clacking sound associated at the same time with loss of power. Gas is open wide and it's crawling up a slight incline. (I could hop off and push it faster)
I know my gs450 automatic is no speed demon and hills are its worse nightmare, but this is more extreme.
Read some archived posts pointing out vacum lines, or clogged fuel source.
Any other suggestions?

[BigD_83]

Be careful,

Although it doesn't sound as bad as it could be, keep in mind Toejams1's scenario.

http://www.thegsresources.com/_forum/showthread.php?t=194613

Wouldn't want your problem to lead to a tale of misfortune.


So, back to the topic at hand. Can you tell at all where the "clack" is coming from? Do you hear it or "feel" it. Can you replicate the clack in any gear?

A really loud clack could be a plug lead arcing out to the cylinder head, causing you to drop a cylinder, but I don't think you'd hear it over the engine.

I can't think of a scenario where fuel starvation would cause a "clack" and still let you run, even at reduced power.

Does the 450A have a single coil with lost spark, or individual coils for the two cylinders?

[SqDancerLynn1]

I would start by checking the valve adjustment / Maybe a Adjustment screw backed out ??

[Bookmon]

I thought about that, seeing as we did the valves. Possible "slapping of the valves" is the clacking and thus loss of power.

[Mekanix]

Few things come to mind that cause a clack.

Piston slap from lugging it at low rpm,

Crank case over filled, possibly from gas and that cylinder is being flooded.
If one cylinder is weak or dead, then its possible that its just rattling that piston around while washing the cylinder with fuel.

Or a shim has poped out.



To do:

Check shim's

look for a shim or bucket that is lower than the others, That would indicate a bent valve or stuck bucket.

check plugs for signs of debree or fouling.

Do a compression test.

[Charlie G]

When my cam chain tensioner lost the nut for the knob, the cam chain jumped time and it had the same symptoms.

cg

[Bookmon]

Charlie G- was just thinking last night- hmmmm, could this be the tensioner, thus a way too lose cam chain. The tensioner was lose before.
Possible to tighten w/o much ado; er taking heads off, etc....
It idles well, both cylinders firing, cranks ok.... before getting into shims and head ... I think I shall start there.
Thanks bunches

[Charlie G]

Charlie G- was just thinking last night- hmmmm, could this be the tensioner, thus a way too lose cam chain. The tensioner was lose before.
Possible to tighten w/o much ado; er taking heads off, etc....
It idles well, both cylinders firing, cranks ok.... before getting into shims and head ... I think I shall start there.
Thanks bunches

You'll need to check the timing if the tensioner has gone wack-o. My thread "Lost a nut" http://www.thegsresources.com/_forum...light=lost+nut
cg

[AngeloBj]

How did this turn out? Could it be the torque converter as well?