When something in your diesel engine fails, we know you want the problem solved as soon as possible.
There are a lot of components that can cause diesel engine failures, and proper diagnosis is key to a successful repair. That’s why it’s our goal to give you the best information about your diesel engine possible, to help you look for parts more confidently.
In this post, we’re going through one of the components that can cause issues in your diesel engine: cylinder liner flanges. We’re taking a look at how and why they fail, as well as what that means for your engine.
What Are Cylinder Liner Flanges?
In the cylinder block, there are circular plane recesses called flange seats or counterbores. This is what holds the cylinder liners in the block.
It’s important that the flange of the cylinder liner fit exactly into the recess, so the liner rests its entire circumference on the flange seat.
Next, the head gasket is placed on the cylinder block. It’s vital that the sealing of the combustion chamber (a metal border on older models and a profiled surface for newer metal gaskets) fit exactly on top of the liner flange.
Why the Fit Must Be Perfect
When you tighten the bolts, the cylinder head presses firmly against the block.
To get the correct, firm connection, the head bolts and tightening instructions are precisely designed. Enormous forces are introduced, via the gasket, to the liner flange, from the bolts. To avoid damage, it’s crucial that this force is transmitted vertically to the liner flange.
Damage From Inclined Force Lines
It’s necessary that the force travels vertically because of the material of the cylinder liners.
Diesel engine cylinder liners are made from grey cast iron. While this material has many positive properties, flexing is not one of them.
Because it’s very brittle, if the force lines are even slightly angled through the cylinder liner flange, you can get flexing. This results in a fracture of the flange.
Why Bending Occurs
One of the main causes of bending moments is dirt particles. It’s crucial to avoid contamination between the flange and seat in the block like dirt, chips, gasket residue, and sealing material.
Cleanliness should be a top priority during the fitting, and sealing paste should only be used when specifically instructed by the manufacturer.
If the cylinders are pre-machined, it’s a good idea to stop a few millimeters from the block and remove any material that may have scraped off with compressed air.
Damage From Uneven Surfaces and Warping of the Flange Seat
It’s possible that uneven surfaces or warping at the flange seat is from increasingly lighter engine designs. The thinner the wall of the block is, the more potential there is for warping.
As engines become lighter, the power output, combustion pressure, and torque are all increasing. This means that engines that have been run for 350,000 miles can already see warpage excessive enough to warrant remachining of the seat in the block.
Remachining the Counterbore
Remachining the counterbore should be done on a boring mill or using a hand-operated mobile flange facing unit.
It’s important that the surface is not slanted and the sharp edge of the seat surface should be chamfered after machining. (About 1X45). Failing to do this can result in fracture damage.
Before fitting, ensure the specified liner protrusion. It’s possible to adjust the protrusion by placing a metal shim under the flange.
If you resurface the cylinder block, you’ll have to redress the flange seats by the same amount.
Using the Wrong Head Gaskets
It’s important to use the proper gaskets for your engine. The wrong head gasket can lead to angled force from a too small diameter at the combustion chamber or an inaccurate gasket thickness.
Use the type of gasket that was originally intended for your engine.
Damage From Incorrect Machining
In some cylinder heads there is a full perimeter groove where the fire ring of the cylinder liner projects. Certain Volvo engines, for example, have this.
It’s vital that the cylinder head and cylinder liner do not come into contact.
If you resurface your cylinder head because of damage or warping, make sure you also machine the perimeter groove by the same amount. If you don’t, angular forces might be introduced via the fire prevention edge of the liner, rather than vertically from the gasket.
Taking Correct Measurements
Correct measurements are vital in this kind of repair. Incorrect measurements can lead to future, expensive repairs. A broken liner, for example, will move gradually toward the crankshaft when the engine is started.
When the location of the liner break is level with the first piston ring in TDC, your piston ring will spring open above the break location.
The downward piston movement will then pull the cylinder liner downward, and the crankshaft can shatter the liner, connecting rod, and piston.
HHP Can Help!
Highway & Heavy Parts can help you fix failures in your diesel engine. We have the expertise to get you what you need to get the job done.
Our on-staff ASE Certified Technicians can answer your questions and help you diagnose your engine problems. We’re here to take the risk out of buying diesel engine parts.
From diagnosis through delivery, we’re Highway & Heavy Parts!
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DIESEL CYLINDER LINER FAILURE ANALYSIS: COMMON FAILURES, MAINTENANCE, AND CAUSES
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