internal combustion engine stuck valves 1

[Luis_Villacres]

We own natural gas engines (Waukesha), sometimes the exhaust/intake valves were stuck in the valve guides, Do you guys know the causes and solutions to solve that issue?

 

[mfgenggear]

As said before, tear down and Inspect, but I have not worked on these engines .
Is there a procedure like gas engine . Edit
Removed comment.
Inspect with bore scope

 

[gruntguru]

The first thing that should be done after a failure like that is to measure valve stem diameter and valve guide bore diameter and compare to specification.
I assume this was done.
What were the results?
If clearance is less than it was when it was last assembled you have contaminant buildup.
Are these engines lean-burn or stoichiometric?

 

[TugboatEng]

There may be a clue here. Rusty ports are an abnormal condition.

 

[CWB1]

Are you running wet gas? Landfill, digester, and many wellheads have high sulfur/other content that's very corrosive.
Its been a decade since I did this work, but I'd start by sending a fuel sample analysis to Waukesha and asking if they had any concerns or part upgrades if necessary.

 

[TugboatEng]

None of those conditions should be a problem for a running engine. Condensation can't occur below 212°F (250°F is preferred as a design condition). An idling engine can maintain port temperatures below that level. Are you idling your engine for hours? The only other way to achieve this condensation is a common stack shared by other engines

Also, don't idle your engines to operating temperatures. Load them as soon as they'll take it.

 

[LittleInch]

That's pretty ropey "natural gas" you have there. Looks like gas from a first stage separator on a well site or GOSP.

Very high calorific value and high levels of pentane etc.

So it won't take much contamination of your supply to add in some benzene or other high C number gas component.

And a whole pile of CO2 so any free water will corrode things rapidly.

That gas analysis looks very odd in that there is 1.9% C6, but 0.000% C7.

Has the manufacturer seen this gas spec?

 

[dgallup]

The oil was identified as Mobil Pegasus which is specifically formulated for natural gas engines and widely used so I wouldn't expect that to be the source of the problem. That gas analysis looks almost suspiciously too good, zero sulfur. But something is causing a lot of deposits. Do these engines run any EGR?

 

[TugboatEng]

There are a lot of digester gas engines around here. The siloxanes accumulate on the piston crowns to the point of that heads need to be pulled and needle scalers used to clean piston crowns. They don't get stuck valves. The rusty ports here are the key.