Importance of checking valve clearance.

[sawtooth]

I have a massive 461 with the Perkins engine in the valve Clarence has never been checked. Engine has under 700 hours on it but thought I might have it checked. Looks to me that someone hard to get things removed in order to check the clearance so I'm wondering is this really worth doing? Engine starts up and has a slight tapping sound when cold which seems to go away as it warms up. Thoughts?

 

[Phillip w]

I have a massive 461 with the Perkins engine in the valve Clarence has never been checked. Engine has under 700 hours on it but thought I might have it checked. Looks to me that someone hard to get things removed in order to check the clearance so I'm wondering is this really worth doing? Engine starts up and has a slight tapping sound when cold which seems to go away as it warms up. Thoughts?

Well, here is my take for what it is worth. Do you have blow by? Does your muffler/

 

[Phillip w]

Well, here is my take for what it is worth. Do you have blow by? Does your muffler/

I hit the wrong button so I will try this again. As I was saying do you have any blow by? Is there an oil film in the muffler/exhaust pipe? How hard have you been pulling it. Diesel engine are kind of a funny breed of cat. (To a point) the harder you pull a diesel the better they will run. I have seen more than one doggy farm tractor you take out and pull a plow or disc to give it a work out. My allis Chalmers 185 wants to smoke a bit when you first get her started. After she warms up a bit she does alright. I've pulled her so hard a few time she was blowing coal black smoke. Generally a diesel doesn't run good you get her warmed up. In the winter I let her warm up 20-30 minutes before I use her. Another thing about diesels is they are made to run at least a
"Fast idle" usually at least 1000 rooms or so. Don't know a lot about the Perkins, but I watch out for blow by, make sure she is strong and blowing black smoke. If she is blowing white or blue smoke that tends to indicate problems or problems brewing. Hope this helps.

Well, here is my take for what it is worth. Do you have blow by? Does your muffler/

Well, here is my take for what it is worth. Do you have blow by? Does your muffler/

 

[SPYDERLK]

I have a massive 461 with the Perkins engine in the valve Clarence has never been checked. Engine has under 700 hours on it but thought I might have it checked. Looks to me that someone hard to get things removed in order to check the clearance so I'm wondering is this really worth doing? Engine starts up and has a slight tapping sound when cold which seems to go away as it warms up. Thoughts?

It is unlikely that your valves need any attention. It is normal for a diesel to quiet a little as it warms up. Both pistons and valves may make noise but its probably the pistons you hear that quiet when warmed. Valve clearance in a healthy engine tends to be very stable, and to an extent self correcting to stay within a safe range.

This is due to the way the cam is ground to lift and lower the valves. At begin lift the valve is eased slowly off its seat before being driven much more quickly to full open. On closing its the reverse, falling quickly to near the seat, then slowed and eased onto the seat. A valve with more clearance will leave the seat quicker/faster going up and hit the seat faster as it comes closed. This little abuse causes the seat and valve to wear more quickly. This wear reduces the valve clearance toward optimum. ... Conversely, a valve going tight will move so gently off and onto its seat that there will be almost NO valve or seat wear. But there will be more wear in the valve lift mechanism. The valve is staying open a tiny bit longer, opening a tiny bit higher and being forced to slow down to almost zero before it meets the seat. Valve lift mechanism wear will increase clearance.​

There is a point between too loose and too tight where the two wear mechanisms balance and the engine runs huge hours maintaining a near perfect valve clearance.

Your engine sounds healthy from your description. I would be attentive to how it behaves when started cold, how it idles normally, how it coasts to a stop when turned off, how evenly it cranks. This can give an idea of differences in cylinder compression. Watch for it and if you detect a change that continues - then investigate. Until then, probably thousands of hrs, enjoy.​

 

[sawtooth]

Ok so no blow by, smoke is perfect, engines runs good and cranks fast in cold weather. The only think I noticed is that when you quickly let down the throttle it sounds like its going to die but never does. Other than that all is fine. Just read in manual that it should be checked or inspected but hadn't done it yet.

 

[Phillip w]

That is typical for a diesel to sound like it is about to die when you throttle her down quickly. Also if you idle along about 700 rpm. It is best to idle about 1000 rpm or so. A diesel engine relies on high pressure fuel injection and comprsession to fire. What spider was saying is right. He sounds like he has a better handle on things than I do. With a diesel there is no spark, spark plug, coil etc just fuel and compression.