What causes exhaust valve failure?
In the failure analysis of a valvetrain, valve failures represent the most common problems. The major causes of valve failure are distortion of the valve seat, deposits on the valve, small tappet clearance, burnt valve, erosion of valves, heat fatigue, pitting, breaks, and wear [1, 2].
How do you fix a bad exhaust valve?
A “burnt exhaust valve” cannot be “fixed”; it must be replaced. This is achieved by removing the cylinder head and physically replacing the damaged valve(s) with new or reconditioned parts installed on a properly machined and/or resurfaced head.
What happens when an exhaust valve fails?
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.
How do you test a worn valve guide?
So to test the seat, take a new valve–or one that you are certain is good–install it in the guide, give it a good push and see if it bounces back off the seat. A bad seat tends to damp the action, so the valve will feel like it sticks in the seat.
What happens when valve guides are worn?
Worn guides can also contribute to valve breakage. The guides support and center the valves as they open and close. A worn guide will allow the valve to, wobble slightly as it opens. This will cause it to drift off-center with respect to the seat.
What causes 80 percent of turbochargers to fail?
While there are many types of turbocharger failures and reasons for these failures, the law of 80/20 applies as it does to most statistical situations. About 20 percent of the failure reasons cause 80 percent or more of the failures that occur.
What causes damage on the exhaust side of a piston?
The piston above shows the most common severe piston damage we see – the exhaust side has damage caused from excess heat. This damage looks similar to piston damage caused by running straight gas shown in the first image, but with this piston, conditions under the piston looked normal.
When does bad filtration lead to piston failure?
The important thing to learn is this damage can happen quickly when the filtering system is leaking debris. Piston damage is not the only consequence of bad filtration. This debris can also collect in the bottom end of the engine. This leads to premature bearing and seal failure.
What causes the turbine wheel inducer to fail?
If the compressor wheel inducer shows no sign of foreign object damage, but the turbine side inducer has impact traumas on the blade tips, it can be a sign of internal engine damage that resulted in turbo failure, but not always. Valve or piston fragments are possible turbine wheel eaters.