When to do a overhead run?

You noticed that too.

 

Does anyone one know the reason why you do an overhead?

 

Setting the valve lash clearances.

 

Because over time the distance the valves open and close may slightly change and if they change too much it could hit the piston. So they need to be in spec. Something like that. Typically fuel mileage improves after it's done on an engine that is out by a bit also.

 

I don't know about hitting the piston. Parts wear, meaning looseness. Means less valve open. Also causes ticking.

In order to hit the pistons. The valves need to go tighter. Generally speaking. I've never seen a diesel head though. But i can't imagine valves hitting pistons when valve clearance generally gets looser.

My experience from never having the overhead done in the time i drove that truck. ISX motor. Motor ticking really bad. Eventually one of the cylinders quit working. Oil was diluting with fuel. I was never told what the problem was but the fix was only $300 and the motor got quieter. I"m assuming that's what the problem was. It's also what the shop charges for an isx overhead.

 

I am baffled by the shops that say doing an overhead would "make things worse". Perhaps they are speaking of their own customer experiences, when they screwed up???

 

Never heard of that.Checking your overhead on a regular interval is a good idea.Set your valves,injector if needed,and Jake brake lash to factory specs.I'm a mechanical person,always did my own overhauls,just good sense to have a peak in your engine every now and then,make sure everything is A OK.

 

No oil samples are no help here. As a tech and driver, 100k is a great time to reset overhead. You all so wanna watch your hours for guys that idle, or run pto alot. Compute hours to miles, 100k on odometer may be to long. And if you have a ISX. I would do it once a year just to look at camshafts.

 

I'm curious....so what material at what PPM on the chart from an oil sample tell you that your tolerance is out by a couple thousands on your intake valves and that you need a overhead ran.

If a mechanic screws the adjustment up while running an overhead, will the oil sample reveal this immediately or do ya have to wait 10 to 15 thousand miles for your next oil change to know?

 

I have done my overhead every 100000 miles. Every time I do it I notice a slight difference in how smooth it runs.