Full Answer
What valves does Continental use?
Do aircraft engines run at high power?
Does a burned valve affect the valve?
What causes pitting in valve?
Valve and valve seat are peppered with tiny craters resembling the "moon's surface". CAUSES: Primarily contaminant fouling temporarily trapped between the valve face and seat which encourages hot gas blow by/acid etching/metal tongue detachment and adhesions.
How do exhaust valves get damaged?
Exhaust valves burn when they fail to seat properly and, as a result, can't efficiently transfer heat to the cylinder. Ultra-hot gasses scorch these valves beginning at their thin rims. This damage erodes and weakens the valves, exacerbates the poor seating problem, and dramatically accelerates wear.
What causes an exhaust valve to warp?
Exhaust valves burn when the heat transfer path from the valve to the cylinder head is compromised. If the valve loses its heat sink, it can overheat and start to warp and possibly start to crack around the edges.
What does white crusty exhaust valves mean?
It is caused by small amounts of oil coming past the intake valve seals and mixing with fuel and being burned.
How do I know if I have a bad exhaust valve?
0:093:27Leaky and Burnt Exhaust Valves Signs & Symptoms - YouTubeYouTubeStart of suggested clipEnd of suggested clipYou can see the cloth being pulled right back in and then blown back out by the exhaust gasses. ThisMoreYou can see the cloth being pulled right back in and then blown back out by the exhaust gasses. This is a telltale sign that you have cracked burnt or leaking exhaust valves.
How much does it cost to replace exhaust valve?
That is bad news, but you'll want to take care of this urgent problem as soon as possible. The average full car valve replacement cost is between $900-$2,000. A single valve replacement cost is about $100-$200. A valve replacement job is often expensive due to labor costs.
What causes too much exhaust back pressure?
7:269:00Stop Saying Car Exhausts Need Back Pressure - YouTubeYouTubeStart of suggested clipEnd of suggested clipHappens with these exhaust gases. So when they open up and it sends out that high pressure exhaustMoreHappens with these exhaust gases. So when they open up and it sends out that high pressure exhaust pulse that exhaust that air has inertia to it because it's traveling at a very high speed.
Do exhaust valves wear out?
As durable as most engine valves are, they won't last forever, particularly exhaust valves.
What is the most common cause of failure on the exhaust system?
There are essentially three different areas that common causes of damage or wear fall under: rust, vibrations and incorrect use, with rust usually being the main culprit. Depending on the severity, it can lead to complete exhaust failure or structural damage.
What color should exhaust valves be?
A symmetrical, circular pattern shows a healthy valve. Red and orange deposits are harmless. Don't be alarmed by the bright color, or deposits around the edges. The symmetrical pattern shows this valve is just fine.
What color smoke comes out of the exhaust if your head gaskets blown?
White Exhaust SmokeWhite Exhaust Smoke White smoke billowing out of your exhaust means that coolant is likely leaking into the cylinders. This usually happens when there has been a breach in the head gasket, which makes the coolant create this white steam.
What does a corroded valve look like?
Corroded shut – off valve and pressure reducing valve Shut – off valves that are corroded usually appear to have a white and green powdery substance on them.
Do exhaust valves wear out?
As durable as most engine valves are, they won't last forever, particularly exhaust valves.
What is the most common cause of failure on the exhaust system?
There are essentially three different areas that common causes of damage or wear fall under: rust, vibrations and incorrect use, with rust usually being the main culprit. Depending on the severity, it can lead to complete exhaust failure or structural damage.
What are the major defects in exhaust valve?
uneven build up of hard debris on seat. hard products of cylinder lub oilcombustion. reduced compression and cylinder power. high exhaust temperature.
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The valves in your cylinder head are a vital component of your engine and undergo enormous stresses, opening and closing up to 2500 times every minute under normal operating conditions. When one or more of these valves are damaged, the result can be anything from reduced power and poor fuel consumption, to complete engine failure. […]
Exhaust valve pitting-What can cause it at low miles?
So in doing more research on my current truck project, I find that the GM 6-60 V6 engines have a reported tendancy to be really rough on exhaust valves, lots of pitted valves and seats at relatively low mileages.
Re: Exhaust valve pitting-What can cause it at low miles?
That is a good question.
Re: Exhaust valve pitting-What can cause it at low miles?
It's carbon trapped between the seat & valve that does it - Subaru's are chronic for it. Often wider exhaust seats will trap more carbon, the carbon gets pounded into the seat. The usually seal just fine until you clean the carbon out!
Re: Exhaust valve pitting-What can cause it at low miles?
Hondas do the same thing. Looks terrible but usually runs fine. I thought it was from being lean.
Re: Exhaust valve pitting-What can cause it at low miles?
Just witnessed the same thing on my Chrysler V6 with 105,000 miles. Intakes looked fine, exhaust seats were very pitted. Didn't really see anything on the exhaust valves.
Re: Exhaust valve pitting-What can cause it at low miles?
It has to do with nickel or chrome migration out of the valve and into the seat or vice versa. It was documented in an engineering book but i dont remember the name of it.
What valves does Continental use?
Continental uses solid valves and the heat is rejected primarily through the valve seat to the head. Lycoming favors sodium filled valves and much of the heat is rejected through the valve guide to the head. Mechanical defects that can disrupt the cooling are several:
Do aircraft engines run at high power?
It seems obvious that that the exhaust valve leads a pretty tough life bathed in extremely hot exhaust gasses. It's not fair to compare aircraft engines with automobile engines since aircraft engines run continuously at high power during cruise and cars cruise at very low powers (maybe 20 hp or so).
Does a burned valve affect the valve?
In that motor a "burned valve" doesn't affect the valve itself, but the seat burns away and leaves a gap when the valve is "closed" and reduces compression. This is a very soft failure, in that engine performance gradually decays and the low-speed operation becomes rougher than usual.
What Is Pitting Corrosion?
Pitting corrosion is a type of corrosion that can affect any materials, including metals, that have a protective coating, film, or unprotected surface.
The Top 5 Causes of Pitting Corrosion
Pitting corrosion occurs for numerous reasons and with varied impacts, depending on the materials involved, but the top five causes include the following.
How to Prevent Pitting Corrosion
The cavities caused by pitting corrosion are, in many ways, similar to dental cavities. As with teeth, appropriate preventative care is the best way to avoid pitting corrosion.
How to Repair Pitting Corrosion
More difficult to combat than uniform corrosion, pitting corrosion is harder to anticipate and detect. Once pitting begins, it tends to accelerate quickly, causing severe damage. Interrupting this process involves acting swiftly to repair the pitted areas.
Conclusion
When pitting corrosion has caused damage that you cannot reverse, you must simply replace materials. While costly, this approach maintains the safety and integrity of building materials.
What are the two things that are machined in a valve?
During a valve job, there's two basic things which get machined: the valve face and the seat. In this image, you can see which part of the valve is the face: Getting the face recut will in and of itself cure the issue with the pitting.
How to fix pitting valve?
All they do to accomplish it is to put the valve in a mounted motorized stand which rotates the valve at a specific angle. They line it up to a grinding stone and take a little bit of material off of the valve face to make it look just like new.
What is interference valve job?
Because of manufacturing costs, coming from the factory, most manufacturers will do what is called an interference valve job. They will cut the seat at 45° and the valve face at 46° (or I guess it could be reversed ... don't remember off the top of my head). On startup, the two come together and mate forming a relatively good seal. This is a cheap way to seal valves and get the consumer something which can work for the life of the engine, but really, there's nothing in the performance aspect of it.
What is the meaning of "back up"?
Making statements based on opinion; back them up with references or personal experience.
Can a valve be salvaged?
This valve can absolutely be salvaged. You just need a valve job. You can have a look at what's entailed in a valve job by watching this Jafromobile video.
What valves does Continental use?
Continental uses solid valves and the heat is rejected primarily through the valve seat to the head. Lycoming favors sodium filled valves and much of the heat is rejected through the valve guide to the head. Mechanical defects that can disrupt the cooling are several:
Do aircraft engines run at high power?
It seems obvious that that the exhaust valve leads a pretty tough life bathed in extremely hot exhaust gasses. It's not fair to compare aircraft engines with automobile engines since aircraft engines run continuously at high power during cruise and cars cruise at very low powers (maybe 20 hp or so).
Does a burned valve affect the valve?
In that motor a "burned valve" doesn't affect the valve itself, but the seat burns away and leaves a gap when the valve is "closed" and reduces compression. This is a very soft failure, in that engine performance gradually decays and the low-speed operation becomes rougher than usual.
