Cat 951c engine, oil in exhaust manifold

[tctractors]

To undo the Drive Cookies can be a fair struggle as sometimes the bolts need a spanner all the way off, plus to crack them free can take a good arm full of power, your engine seems to be in fare condition piston wise, have you measured the piston ring gap,you will need to mark the 2 top rings for TOP position if you remove them, the valve guides looked to have massive wear so will need a new set of springs, valves and guides, also the valve seats will need a trim on the 2 angles, tctractors

 

[sergioannis]

you will need to mark the 2 top rings for TOP position if you remove them

Hello .
What do you mean ?
How should the position of the new rings be?

 

[kshansen]

Hello .
What do you mean ?
How should the position of the new rings be?

I think what TCtractors was getting at is assuming the rings were installed correctly the first time the markings for top might not be visible now with a little running time. So just use something like a marker pen to mark which side goes up.

There is an up and down to many piston rings that might not be easy to see or measure without lots of effort and knowing what to actually look for as the differences would be near impossible to measure but if installed wrong would cause all kinds of problems!

 

[Cat977]

Hello .
What do you mean ?
How should the position of the new rings be?

tctractors is quite right right about marking the rings and checking the end gap.

Whether you replace the rings or not, I think some one said to be sure to hone the cylinder out so the rings will seat themselves properly in the bore. Also if there is a ridge at the top that should be removed so you don't damage the top ring unless you put back the same used ring in the same used piston in the same bore.

If your going to get new piston rings you should measure to see if its been bored over size. If it has get the rings to fit that bore.

When you get the rings put each of them one at a time in the bore (preferably in the same bore you'll be putting it in). Use a piston to push them in straight. The Cat book will tell you the end gap, you measure it with a feeler gauge.

I think most all piston rings have a top and bottom and should be marked by the maker of the ring.

I'm still concerned why a short time engine could be so screwed up? Like kshansen said, the rings could have been put in upside down by the guy before you. See if you can find the root cause. Could be it was run with 10W and a bad sensor. lol!!!
Best of Luck

 

[tctractors]

The 2 top rings are marked from new for position, after 10 minutes of running the etched Top marking would be gone, the oil control ring is not usually marked for fitting but depending on make can be narrow or wide so the ring needs to fill the grove totally, the possibility of the liners being bored over size is not really on the cards as the liners are very low cost, plus a piston part number check will soon cover this point, the piston has a V mark on the top that will point to the V mark stamped on the cylinder block, I have already said the Con Rods are marked for front so make sure they are fitted correctly as the piston pin is off-set from mid position to stop reverse start up. tctractors.