Overhead and Oil Change Questions?

[Papa Rick]

Appreciate the reply with the web site for freightliner. Really learned alot off of this. Thanks much.

[heavyhaulerss]

if your in n al. mayfield trucking is great. i-65 exit 321 & 325 falkville al 256-784-5998 ask for don. shop manager. he is the most corteous & honest mechanical person i have ever met. been dealing with them for 7 years. tell em troy sent ya if ya ever visit them...

[BanditsCousin]

Rev-

I think you meant the pistons become close to valves, not the heads. Piston/head clearance should always remain the same, even with worn crank bearings, which would allow very VERY minimal deviance in the stroke of the cylinder.

And, to my undersatnding, "piston slap" is the result of badly worn rings, in which you can hear slight rattling of the pistons in the cyclinders due to rings that are wayyy out of spec, and excessive blowby exists.

8) Fashionably late on this post!

[special k]

Actually an overhead is usually a term for adjusting the valve lash. If anything gets tight it's the clearance between the end of the valve and the rocker arm. If the clearance gets too tight the valve might not seal on the valve seat in the head thereby causing low compression and possibly burning a valve. This is usually caused by wear on the valve seat or the valve itself. Sometimes the valve lash is too much due to wear on the valve stem or rocker arm this usually causes valve clatter and possibly a little loss in power due to the valve not opening as far as it should. There is a similar adjustment on the injector itself to make sure the plunger is travelling the proper distance. Piston slap is when the skirt on the piston gets worn and the piston starts to rock slightly. Thats what you hear, Once the piston is rocking it's hard for the rings to seal well so it becomes a downward spiral and you lose power and start using oil. These guys that always lug their engines right down with heavy loads are really hard on piston skirts and can end up with piston slap. Bear in mind I'm not a professional mechanic so a few details might be off a bit.