Community Forums

radams · 10-07-2010, 01:19 PM

I took the C9 in to get the valve lash adjusted at 40k miles. They just called the DW and said it was ready to be picked up. They told her that that the valves were tight when they got in there. What does that mean? Good, bad, ugly?

Vegasdan · 10-07-2010, 01:50 PM

Probably means they didn't have to adjust them.

RustyJC · 10-07-2010, 01:52 PM

Generally speaking, tight valves result from valve/seat recession - the valves pound themselves into the seats and therefore move higher in the head (closer to the rocker arms) which tightens up the rocker-to-valve tip clearance.

This isn't necessarily as bad as it sounds. Some valve/seat recession is to be expected. It all depends on how tight the valves were as to whether or not the recession is excessive.

Rusty

radams · 10-07-2010, 02:01 PM

Well now I'm really glad I got it done. It was one of those things where nothing seemed broken so I was hesitating getting it done. Thanks for the explanation.

radams · 10-10-2010, 08:49 AM

Thought I'd give you guys an update. CAT dealer performed a "run the overhead", changed the air filter, lubed the chassis, changed the oil and filter, changed primary and secondary fuel filters. And what did I end up with? I absolutely can't believe how well it runs. It is amazing. I thought it was running okay before and I've only got 37,500 miles on it so I figured that any improvement would be slight. Absolutely couldn't be any happier. That engine is running so smooth now you can't tell it from a gas.

sailor_lou · 10-19-2010, 07:59 AM

It's good you had it done. If the valve lash is too tight, they will not sit properly on the seat and in addition to performance loss, they will not tranfer the heat from the valve into the head. This will result in burnt valves and an expensive repair. Engine manufacturers specify maintenance activities for reason and too often owners ignore their recommendation because everything appears normal.

Lou
05 Travel Supreme 38DS04, CAT C-7

radams · 10-20-2010, 03:56 AM

Ah, I can see the logic on that Lou and appreciate the info. In my case it's less a matter of wanting to get the maintenance done and more a case of knowing everything that needs to be done. That's why these forums are such an invaluable resource for me.