Should the pistons move at tdc? Mine wobble a tiny amount but I would have thought there should be no movement at all?!

 

Move up & down or sideways?
BIG difference.


In theory, every degree, minute or second of crank rotation from TDC will move the piston down.
In reality there is a tiny amount of play in all the journals between piston & crank, but.. that play is filled with oil.

 

They move back and forward in the bore

 

There is a spec for it.

Piston-to Cylinder clearance:
Standard(New): 0.004-0.027mm (0.0002-0.0011in)
Service limit 0.04mm(0.002in)

 

they will definitely move, the question is how much movement, the specs listed above are to be used to determine that. Your method doesn't reveal much unless you are experienced with a number of new and used S2K engine blocks. Someone with Billman250's experience would likely be able to tell by eyeball or feel but I couldn't.

 

Thanks for your replies, I'll get my feeler gauges out

 

I measured at the top of the piston (looking at the service manual it shows measuring at the bottom) and they are all about 0.5mm! Seems odd they are ALL way, way over 0.04 by about the same.

Measured at tdc and about halfway down the bore, less further down but still about 0.4mm

Is the service manual correct?

 

Extract from service manual

 

The correct way to check piston to wall clearance is to use a bore gauge to measure the bore and a Micrometer to measure the piston 1/2" from the bottom of the skirt. It's going to be hard to get a solid measurement with feeler gauges.

What kind of mileage on the Motor? Pistons will "rock" at TDC since most are tapered at the top. Stock PTW clearance is so small that there should be very little "rock" at TDC.

 

It has done 100,000 miles

Maybe I should start a new thread with the symptoms as I'm trying to understand what the issue is, I thought head gasket but that seems ok, no obvious failure so I was thinking maybe pistons or rings