83 GS 550ES Please help engine trouble

[Anonymous]

My 550es has been making a bad knockin/ metal on metal sound so I took the valve cover off and removed the spark plugs. ON the number 2 cyl piston I coul see an outline of the spark plug opening a circle on the piston and a marking of the ground side of the electrode ie that little arm that sets the gap. ALso every spark plug was running rich except number 2 cyl which leads me to thing the piston is commin up to far and causein more compression. Please let me know what you think and how do I fix this prob

[tfb]

Reem98,

Are you sure you have the correct spark plugs installed? If you are using a set with too much 'reach', then that is one obvious reason why they will be connecting with the piston crowns.

Mike.

[RJ]

It could also be that the wrist pin/connecting rod joint is wearing out causing the piston to rise higher in the bore. I had the exact same thing happen to an old Datsun 240Z.

[Anonymous]

Hears the weird thing the spark plug itself isn't smashed at all maybe I'm wrong and it was an illusion what I was looking at. But there is a definate metal on metal sound

[tfb]

Yes, I can't see how your engine would keep running if the piston(s) had connected with the sparkplugs -- the plug gap would probably get knocked to zero and then the engine would stall because you wouldn't have any spark.

Have you tried cranking it over with the spark plugs removed? If there's still that knocking then we can properly rule them out.

"Metal on metal" sound, you say? First, what sort of sound? If a cyclical ticking, could merely be camchain. Irregular clattering, might be fractured valve train hardware. Dull knocking, might be conrod big ends or crankshaft. Without further info., it's so hard to say.

Second, whereabouts in the engine do you think the sound is coming from? From the top end, or does it sound like it's coming from the bottom end? Gearbox perhaps? Is there any metal appearing in the oil (either as fine flakes suspended in the oil, or larger fragments)?

If you can't narrow it down you just may have to pull the whole engine apart. :roll:

You'll find many knowledgeable folk here at the GSResources only too happy to help, but the clearer and more specific you can be, the more likely you are to get help with the problem!

Mike.

[Anonymous]

Well thanks for the insight I took the motor completely apart last night heads, cyl block and found that the #1 cyl has about a 1/4" play on the crankshaft connector rod bearing. I E my knockin noise and then I'm guessing it hittin the head (the really bad metal to metal noise). Now I need to look at the bottom of the crank and I figured I'd change the timin chain while I have it all apart. Is the only way to do this is to pull the motor out of the frame. Do you think if my piston had that much slop could it have bent my valves without me knowing
thanks

[tfb]

When you say 1/4" play, do you mean vertically or laterally? A bit of 'lateral' play is OK... but if you're talking about vertical, ie. your piston could rattle 1/4" up and down in the cylinder, then yes you have a problem.

1. You can remove the head and cylinder block and the pistons, as well as renew the camchain, with the engine in the frame. If you want to do much more than that, eg. remove the crankshaft and the conrods, or do stuff in the gearbox, you will need to get the whole lump out so that you can split the crankcases.

2. You could check the crankshaft etc. from beneath by removing the sump plate, but I'm not sure if you could get to all the conrod bolts, ie. of cylinders 1 and 4 from there. Maybe someone here on the forum can give a more definite verdict on this.

3. You could well have bent the valves. Check the stems for straightness, and whether the valves seat properly in the head.

Mike.

[SqDancerLynn1]

If you have problems with the rod THE engine has to come out & the cases split. You will be looking for a new crankshaft

[duaneage]

Might be time for that 550 to collect social security benefits and watch TV all day