Jun. 17, 2024
What is a valve grind?
Are you interested in learning more about Valve Seat Grinding Machine? Contact us today to secure an expert consultation!
The valves in an engine have several functions. First, they must allow the intake of fuel and air. Then they must seal the engine. As engine combustion takes place, the exhaust valve must also allow the burned gases to leave the combustion chamber.
A valve grind (commonly referred to as a valve job or valve lap) can be crucial for proper functioning valves/seals. It is the process of smoothing out the engine valves so that they are effectively able to seal in the valve seat in the cylinder head to completely seal the engine&#;s combustion chamber.
When do you need a valve grind / job?
As your vehicle&#;s mileage increased, the valves can degrade and need repair. This is due to constant movement and engine heat. Due to advances in valve metal technologies, most modern engines will never need a valve grind. However if there is a problem with the valve, valve seat or valve tappet or rocker arm, then the cylinder head might need to be removed to fit a new intake or exhaust valve. At this point the valve(s) may need to be lapped in, or have a valve job / grind.
Older vehicles (pre &#;s) where far more prone to burning valves, and often needed valve grinds on a regular basis.
A valve job gives mechanics the opportunity to thoroughly inspect the rest of your engine including the cylinder heads and engine block. Any cracks or leaks in these components can lead to oil leaking out of your car and overheating.
Symptoms of valve damage include:
Increased fuel consumption
Engine running rough
White exhaust smoke
Chuffing noise from the engine exhaust pipe
Lack of engine power
Learn more about engine valve failure >
What does a valve grind consist of?
During a valve grind, the engine cylinder head is typically removed to access the valves. The process involves the following steps:
The valve grind process aims to restore optimal sealing and improve engine performance by enhancing compression and reducing leaks. It can be performed as part of regular maintenance or as a repair procedure when valve-related issues are identified.
Engine Valve Grinding, Servicing & Maintenance in Hamilton
Proper engine maintenance can greatly extend the life of your vehicle. At Grimmer Motors, we can remove your engines cylinder head and organise reliable, high-quality valve repair and replacement. This will allow for your engine to run healthily.
For engine valve grinding and maintenance in Hamilton, contact Grimmer Motors today!
Please Note &#; we don&#;t generally stock or supply just &#;parts only&#; for this service. We are a general automotive repair workshop. If you are able to bring your vehicle to us, we can diagnose the problem, find and fit the necessary parts, or organise the appropriate service for you.
Book Now
Sep. 23,
Valve after long-term use, the valve and seat sealing surface will be worn, tightness reduced. Repairing the sealing surface is a large and important task. The main method of repair is grinding. The seal surface of serious wear is first welded by turning to process and then grinding.
Portable Gate Valve Grinding Machine
Valve function is not fully realized mainly due to internal leakage, external leakage, drive mechanism failure and other reasons. External leakage and drive mechanism failure can be eliminated by replacing the gasket and finding the cause of the failure. Valve internal leakage accounts for a larger proportion of corrective maintenance work of the valve, the main reason is the sealing surface defects, but does not exclude other types of causes, such as whether the valve closing torque is sufficient, whether the closing air pressure is sufficient, whether there are foreign objects stuck in the sealing surface and other factors that can be easily judged and excluded. Only when these factors are confirmed to be normal, the sealing surface problem is considered and the valve is disassembled for inspection.
Preventive maintenance and corrective maintenance for the seal surface inspection and defect handling are not the same. The former is only a periodic comprehensive disassembly inspection, the sealing surface is free of defects, then surface polishing treatment back to install. The latter is a targeted treatment of the valve door leakage, to find the cause of leakage, focusing on checking the condition of the valve seat and valve sealing surface, the defective sealing surface according to the grinding process requirements for processing. Grinding before the first to determine the size of the sealing surface defects. If the sealing surface defects are small, then directly grind. If the sealing surface defects are large, we should consider other means of processing such as turning before grinding to improve efficiency.
Want more information on Valve Grinding Tools? Feel free to contact us.
Commonly used grinding materials are abrasive cloth and abrasive paste. Abrasive cloth is a fabric backing with grit glued on top. The abrasive paste is made of lubricant and an abrasive blend. The lubricant can be used as machine oil, kerosene, butter, glycerin, oleic acid, stearic acid and paraffin wax, etc.
Valve and seat sealing surface due to different degrees of damage, can not be directly on the research. Rather, a certain number and specifications of the specialist prior to the fake valve flap (i.e., grinding head), fake valve seat (i.e., grinding seat), respectively, the valve seat, valve grinding. The grinding head and grinding seat are made of ordinary carbon steel or cast iron. Size and angle should be placed on the valve, valve seat equal.
If the grinding is carried out manually, it is necessary to configure various grinding rods. The grinding rod and research tool should be properly assembled, can not be skewed. To reduce human labor intensity, speed up the grinding speed, often using an electric grinder or vibration grinder grinding.
Items to check when deciding to grind:
&#;Visual inspection is performed immediately after the valve door is opened and before cleaning. This will provide a very accurate indication of the valve grinding operation.
&#;Visual inspection after cleaning.
&#;Blue oil contact between valve seat and valve flap.
&#;Visual inspection.
&#;Tungsten carbide layer thickness.
&#;For wedge-shaped valves, the wedge position before/after grinding.
Valve and seat sealing surface pockmarks, scoring, when the depth of 0.5mm or less, can be repaired using grinding methods. The grinding process is carried out in three steps: coarse grinding, medium grinding, and fine grinding.
Coarse grinding generally uses 240~W40 abrasive or No.2 abrasive cloth, and uses larger grinding pressure, mainly for grinding away the pockmarks and scratches. The middle grinding uses W28~W14 abrasive or No.1 or No.0 abrasive cloth, the grinding pressure is smaller, and the grinding tool should be replaced with a new one before grinding.
After the middle grinding, the sealing surface basically meets the requirements, and the surface is flat and bright. Fine grinding is done by hand, the valve and valve seat on the valve directly to the grinding. Choose a fine grinding paste (abrasive particle size W14~W5), and a little oil dilution, first clockwise and then counterclockwise, gently grinding back and forth. Grind for a while to check once, until grinding shiny, and can be seen in the valve and valve seat sealing surface of a circle of the black bright closed belt. Finally, gently grind several times with machine oil and dry with clean cotton yarn. When using abrasive cloth grinding, the abrasive cloth should be fixed on the grinding tool made according to the shape and size of the valve flap and valve seat. For large gate valve gates, usually use the scraping method to repair. When scraping and grinding the gate plate on the grinding plate with the coloring method, scraping the uneven parts until every 25px2 contact point reaches more than two points. Then scrape the good gate coloring scraping valve seat, the contact point should also reach every 25px2 contact point to reach more than two points. Welded-in the pipeline gate valve and shut-off valve, it is necessary to special research gate machine grinding repair.
After the valve overhaul, the hydraulic test should be carried out to check its tightness. Hydraulic test pressure is 1.25 times the working pressure, the test pressure is maintained for 5 min. and then the pressure is reduced to the working pressure for inspection. If a leak is found, it should be overhauled again until qualified.
Portable Gate Valve Grinding Machine
1. Blue oil test
Blue oil test is the most common and convenient test method, mainly to check the sealing surface fit, the thinner the coating of blue oil the better, for the wedge gate valve blue oil test, pay special attention to.
2. Knife edge ruler to check the flatness
Use the knife mouth ruler to check the flatness, the actual light transmission method of inspection, you can visually observe the flatness.
3. Monochromatic light interference method (spectrum)
Monochromatic light interference method is as follows: a lens flat on the sealing surface, next to the incident beam of monochromatic light (such as sodium lamp), the human eye above the lens to observe the appearance of light interference stripes. Principle: The incident light is monochromatic light, so the wavelength is the same. The light is reflected on the upper surface of the lens, and at the same time through the lens to reach the sealing surface and then reflected again, and then shot through the lens. The two rays interfere with each other. If it happens that the crest meets the crest, the brightness is the strongest, and if it is the crest that meets the trough, the brightness is the darkest. The brightest and darkest then form an interference fringe. The difference in height between two adjacent bright stripes is half a wavelength, and the same stripe has the same height. In this way, the flatness and roughness of the seal surface can be quantitatively evaluated by counting the interference fringes.
Grinding should only be performed when the valve's sealing properties must be ensured by grinding.
Unnecessary grinding can lead to:
&#;Risks when using grinding machines
&#;Shortened valve life due to removal of some hard surfaces
&#;High dose exposure due to working in high radiation area
&#;Increased environmental dose due to hard surface hot particles in the circuit (hard surface hot particles become cobalt 60 under neutron irradiation)
Over-grinding can lead to:
Excessive grinding will destroy the thickness of the carbide layer on the sealing surface, which will accelerate the wear of the sealing assembly and reduce its service life.
Insufficient grinding leads to:
Insufficient grinding does not effectively eliminate the defects to meet the sealing requirements of the equipment, and the residual defects will expand during operation and lead to the scrapping of the entire seal assembly.
Metals Kingdom offers both portable and benchtop valve grinders. Portable is suitable for in-line repair of valves that are inconvenient to disassemble and site valve repair. The benchtop type is suitable for site valve repair.
We also provide different models of valve grinders for different valve grinding. M-100 and MJ series are mainly used for repairing globe valves and safety valves. M and MZ series are mainly used for repairing gate valves. Finally, let us help you if you have any questions in shopping for the right valve grinding machine for your task!
For more information, please visit Valve Tightness Test Machinery.
If you are interested in sending in a Guest Blogger Submission,welcome to write for us!
All Comments ( 0 )