Valve Rotator Not Rotating

If it isn't urgent, forget it!

Changing it at 'the next available opportunity' is just fine.

Keep an eye on the exhaust temperature though, assuming you have one for that unit.

If the rotator fails to rotate, in time tiny leaks might grow, and as the grow, the rate of growth increases because contact with the head is impeded, allowing that part of the valve to over heat, and lose compression on the cylinder and that leads to loss of symmetry in the operation of the engine.

The contact allows for some cooling. The rotation is intended to average this wear = longer valve life.

As to why it has failed?? examine the rotator mechanism to see if some sort of accumulation or a broken spring or? has caused the problem.

Thank you for the replies.

"If it is not replaced, it is any body's guess when it will fail or how it fails"

1. It will fail sooner, rather than later.

2. If it didn't need to rotate, the engine manufacturer would not have gone to the expense of putting it in the engine.

3. When it fails, not if, it will damage the valve seat also tripling the cost of repair.

That very much depends on engine loading.

It engine is running at part load most of the time, you can safely bet, nothing would happen!

Point 2 obviously has a point, but, that's only when the engine is screaming or there about.

Valve rotation is more common on the "intake" valve to keep carbon build up to a minimum. Intake valves run cooler than exhaust valve by nature. Intakes draw in cool intake air/fuel, thus allowing the potential of carbon build up. Exhaust valves run hotter due to the expelling hot exhaust gases, thus less tendency to build up carbon.

All ICE intake and exhaust valves should rotate to a certain degree, if they don't then the valve clearance is to tight and just a matter of time before your introduced to, "The Kiss of Death". "The Kiss of Death" is when the valve, (Intake or Exhaust) seizes in the valve guide and the valve face kisses the piston, thus breaking the weakest link.

Being your dealing with a diesel engine and like what Lyn said, "you will triple your repair costs", if not replacing the entire engine, if a valve touches a piston.

So, now that you've been fore-warned, you decide.

Correction DJ, rotator priority is for Exhaust valve.

In fact, some models have these for only exhaust, and reason is, for precisely what you correctly observed - inlet valve runs cooler, no help needed there !

Whereas for exhaust valve, rotation helps it to adjust itself and seat properly at all times.

On and off same spot on valve seat can cause burn-through, i.e.: seat getting cut, hence need for rotater.

I'm not going to get into a peeing contest with you, but when I worked for General Motors, a good portion of our "valve jobs" was because the intake valve runs cooler and not burning the carbon build up off the intake valve stem, to the point that the carbon holds the intake valve open and burns the valve and seat. The exhaust valves run hot enough to burn the carbon off the valve stem. Most off the "valve jobs" only required replacing the burnt intakes and re-facing the exhaust valves.

None intended, but, could you provide detail of the GM engine model which has rotators only for the inlet valves ?

Because these are either fitted on all four valves or only the exhaust valves - to save cost.

I have never seen engines where only the inlet valves are fitted with rotators.

Members/visitors, and I, could learn a thing or two from this verification, don't you think ?

The old Buick 455cid's were notorious for carbon build up on the intake valves and it's not just limited to the big old G.M. engines, take a look here.

Part Load operation causes the bulk of this.

Think silt laden river water which flow slows down, at any point, on its way to the sea.

Silt/mud settles to the bottom, i.e.: becomes sediment.

Same here.

Reason why it's good to blow the cr.p out of the engine, every now and then

"Reason why it's good to blow the cr.p out of the engine," Yeah well, if your not careful about "blowing the crap" out of an engine ---- you can blow the said engine up, (sucking valves and or breaking pistons, bending connecting rods and ....... the list can go on".

The bottom line is, --- If it's not to spec's,--- then bit the bullet and fix it right while you have the chance, with out the extra expenses of replacing parts that were destroyed while waiting for someone on this anonymous forum to justify your lack of intelligence. penny pinching or what ever the reason maybe.

Completely with ye!!

My opinion was simply reply to OP's doubt if rotator replacement is an emergency op., i.e.: get it done right now or you lose the engine sorta emergency.

It's not.

Agree too, on the danger of leaving engine in pieces, with indiscriminate 'floor it' stunts.

But, I meant that as part of normal engine operation.

I certainly would not recommend that to a piece which sat idle for 50 years.

When I walk through the door of CR4®, it wasn't to impress anybody. I stayed here because I found a group of people, (Women and Men) I can relate to. I started working on ICE when I was 11yrs old and now I just turned 61, so I've been up and down a few blocks along with an A&P license, MAC (Mobile Air Conditioning) license and Universal Freon/ Recovery license. I am not bragging about anything, just when you start handing out advice-- be-careful. I'm sure you wouldn't intently steer someone wrong, but, this is a world wide forum and there are people here that English is not their first language which could lead to a major brake break downs in translations

aye aye, sir!

The greatest take away from advice, from a guru(master)........... ego stays intact !!

If the inlet valve is held open by carbon deposits it must leak, I wonder how the engine builds up enough peak pressure for 'dieseling' work, ie, ignition.

Apologies for ignorance, but I can't say I have heard of a valve rotator. What is it? I can guess what it does from the replies above, but is it a 'thing' in the engine?

Exhaust valves rotate, usually, by design.

state of the art of engine valve and tappet rotation

Anatomy of a Valve Failure - AOPA

MARINE ENGINEERING: VALVE ROTATORS

Mostly I have been working on diesel engines, four stroke engines in recent years. Have not worked on any automotive gas engines yet. In the old days, the diesel engines that I had worked on, two stroke or four stroke, did not have any valve rotators. Worked on some engines that had the valve rotators (on both intake and exhaust) added to the valves as a modification but later removed as they were considered too costly.

I am not sure the design criteria differences between the two (with and without the rotator), physically and metallurgically. Or the savings in the long run. One thing I am sure is that if the valve is stuck, open or close, it probably will give a disastrous consequence, likely breaking some component(s) of the engine. Not to mention to the operators and operations. So I think it should be replaced at the earliest opportunity.

1. Valve getting stuck is, mainly, a matter of lubrication failure.

Whether that is caused by lack of supply or stem getting too hot is a separate issue, nothing to do with rotators.

Otherwise, no engine should exist prior to rotator technology !!!!

2. At the basic level, rotator is added to extend TBO, that's it, since it allows for more even wear, and prevents hotspot from building up, i.e.; prevents cut-through.

3. There're usually more corrosion related pitting on inlet valve - acid related, since it runs cooler.

Ramm, I tend to agree with you and would be glad if my boss thinks the same. If for some reason, the valve that does not rotate is stuck, there is always the doubt that because of not rotating, it has experienced uneven heat, thus deformed or lacked of lubrication, and finally got stuck.

That's fine with me. Wait till it seizes.

By waiting you will risk catastrophic failure of the entire engine.

<Beam me up Scottie>

Here are some aspects of Valve Rotators