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Tag: Camshaft

Camshaft Failure: Causes of Excessive Camshaft Lobe Wear

IS IT CAMSHAFT LOBE WEAR OR DAMAGE?

We all know how important camshafts are to the function of your diesel engine, and when they fail it can spell big trouble. Whether you have a flat tappet or a roller camshaft, you’re at risk for one of the most common causes of camshaft issues: lobe wear or damage.

DID YOU KNOW EVEN .001 INCH OF WEAR ON A CAMSHAFT IS A PROBLEM?

Yes, just .001 of an inch of wear on the lobes can negatively impact your valve timing by as much as 3 degrees.  

This wear leads to a loss of horsepower and fuel economy, among other problems.  And that’s not even considering the impact of more extensive damage caused by mechanical interference or other serious issues.

If you notice wear or damage on your camshaft, it’s important to locate the causes of the problem before installing your new cam.

If you don’t, you run the risk of ruining the new camshaft as well and costing yourself even more money.

So What Might Be Causing These Issues?

We’re taking you through some of the most common causes of camshaft lobe damage.

HERE ARE 4 SIGNS TO LOOK FOR CAMSHAFT LOBE DAMAGE:

1. LOOK FOR PITTING ON THE CAMSHAFT

In many cases, pitting on the lobes is due to normal part wear from many hours of operation. Even so, it’s important to identify and replace the camshaft before it fails completely or causes damage to other components due to improper operation.

In other instances, the pitting might be caused by debris in the components. Make sure that everything is clean when the camshaft is installed, and that the oil passageways are clear and free of dirt or other particles.

This is vital to a proper install, as dirt and debris can cause major issues for the camshaft and bearings.

2. IS THERE A LACK OF LUBRICATION?

Proper lubrication is vital to maintain normal camshaft operation. When there is a lack of lubrication, whether due to blocked oil passages or too much clearance space, you’ll begin to notice wear patterns.

Increased friction from the rotating camshaft can cause these wear patterns. If left unaddressed, you run the risk of ruining your bearings or even breaking the cam cap because of the high amount of friction and heat.

The two main places you should ensure are properly lubricated are between the pin and roller and between the lobe and roller. This will help reduce friction, in turn reducing the amount of wear on the components.

3. DAMAGE FROM THE LIFTER/FOLLOWERS?

It is possible to have lobe damage caused by an improperly functioning lifter. You’ll most likely notice gouging on the lobes, as well as damage on the lifter itself.

This can be caused by a lifter being out of position and striking the lobe, weak valve spring pressure, lack of oil pressure, or stressful operating conditions like overspeeding.

4. THE CAMSHAFT MAY HAVE BEEN INSTALLED INCORRECTLY

There are other types of damage a camshaft or its associated parts can incur besides just lobe wear. Many of these result from improper install techniques.

To prevent install-related damage, ensure your camshaft is properly positioned and placed. Read our install guide for more information.

5 Potential Reasons Why Your Diesel Engine Camshaft Bearings Failed

In your diesel engine, it’s not just the camshaft that can wear or fail. You also have to pay attention to the health of your camshaft bearings.

Bearing failure can cause extensive damage to other engine components, so it’s important to identify the root cause of issues and repair them as soon as possible. Below are some common camshaft bearing issues and possible causes to help you better identify what’s going wrong in your engine.

CAMSHAFT BEARING JOURNAL DAMAGE

There can be several things that cause journal damage, including:

1. UNEVEN BEARING SUPPORT

For proper function, bearings have to fit correctly, be aligned, and be supported. When that is not achieved, you can have damage to the bearing journal.

The below image shows a bearing whose measurements and wear marks indicate that the camshaft bearing bore in the block was probably oversized. The wear marks are uneven, indicating a likely distortion.

There was probably too much clearance space, which allowed the camshaft to move, hurting both lubrication and support.

The following bearing became blackened due to overheating caused by misalignment:

2. LACK OF LUBRICATION

Not enough lubrication allows for increased friction, which in turn increases heat. The camshaft can then damage the bearing surface as it rotates, which, after further use, may eventually lead to a broken cam cap.

The image depicts the discoloration of a bearing journal because of poor lubrication. The blue arrows point to the extension of the issue onto the shaft.

3. IMPROPERLY INSTALLED BEARINGS

If your bearings aren’t installed correctly, the lubrication may be negatively impacted. This can lead to bearing failure, as shown in the below image. Note the partially covered oil hole in the second image.

If the oil holes aren’t aligned correctly on install, the oil cannot properly lubricate the camshaft, again leading to increased friction and wear on the bearings. The image shows the improper alignment of the bearings leading to partially blocked oil holes.

Installing bearings the correct way can help prevent these problems. Read our past blog, Camshaft Bearing Facts and Installation, for tips on properly installing your bearings.

4. EXCESSIVE WEAR

Too much wear can spell disaster for your camshaft bearings. Several things could be causing this, including:

  • Improper Install
  • Incorrect Bearing Sizes
  • Elevated Operating Temperatures

Again, with these issues we’d expect to see decreased lubrication, allowing for further damage to your bearings. If left long enough, you could experience total bearing failure.

5. CLEAN ENGINE BLOCK

Writing for the July-September 2018 issue of Engine Professional, Brandon Flannery points out that your engine must extremely clean before assembly. He finds that failed bearings are often caused by debris build-ups from poor cleaning and blowing with compressed air might only make matters worse.

Instead, rinse and wash them thoroughly to keep that debris from contaminating the oil that lubricates the camshaft and bearings. This dirt can either cause damage to the components’ surface, or block clearance space, both of which could lead to failure.

It’s also important to pay attention to specific cam types as you’re cleaning. The ISX Injector Camshafts, for example, are hollow, and sometimes debris collects inside the cam as it spins, like a centrifuge.

We have seen times when the cam is removed, the jarring from setting the cam on the ground causes the debris to break free. This debris can plug an oil hole, starving the bearing and ultimately failing the cam, bearing, and possibly the head.

Why Did My Diesel Cummins ISX Camshaft Fail? Causes And Prevention

Are you hearing a sudden engine knock? Is your engine running rough?

These can be signs that your camshaft is failing.

Replacing a camshaft can be an expensive and frustrating repair, especially if it needs to be done outside an engine overhaul.

You want to do everything you can to keep your engine running for miles to come and avoid unnecessary downtime. That’s why we’re taking you through some problems you could see with the camshaft for the Cummins ISX.

The ISX has gained a bit of a reputation for issues with camshafts. In this post, we’re looking at where you might be seeing these problems, and what you can do to keep your ISX running great!

WHY DID THE CAMSHAFT IN MY ISX FAIL?

If you’re experiencing a camshaft failure in your ISX, you probably want to know what went wrong so you can avoid it in the future.

CHANGES TO THE ISX CAMSHAFT

Cummins has changed the camshaft rollers multiple times to get more surface area between the roller and the cam. But the differences in the camshaft lobes are designed to spread out pounds per square inch.

That’s basically the load on the camshaft.

So, you would think that the widest camshaft you could get would be the best. The problem, however, is that the more surface area you have in contact, the more surface area there is to fail.

WHAT’S THE IDEAL CAMSHAFT FINISH?

There’s a lot to do with startup. You want to have a finish on the camshaft that’s coarse enough that when the cam starts turning for the first time, it gets the roller to turn with it and the roller doesn’t slide. That’s because you have a roller that has heavy down pressure on the camshaft.

So, if your roller doesn’t start turning  with the camshaft, it will slide, which is the starting failure point.

The way to avoid slide is to narrow the camshaft so your pressure is higher. Or, you make the surface more coarse. In the end, though, that can work against the longevity of the camshaft.

You might wonder, then, “How wide and smooth should I make it?” If you make it so wide and smooth that it doesn’t even roll, then you’ve gone too far.

That’s the biggest battle with the camshaft, and one of the big reasons gasoline engines have started to move away from camshafts. There’s just too much opportunity for wear.

LOOK AT YOUR ISX CAMSHAFT WHEN YOU’RE OVERHAULING YOUR ENGINE

It’s a good idea to take a look at your ISX camshaft when you have the engine apart for overhaul.

You might not think you need to take it in to get a valve adjustment done, because it’s running fine, but you might have valve clearances expanding or contracting. This can cause the cam rollers to beat on the cam.

INSPECT YOUR LOBES AND ROLLERS

When you’re doing an overhaul, take a look at your lobes and rollers.

Make sure they’re in good shape before you put it back together. They can and do fail, and it’s a lot of work to take it back apart to change a cam.

REGULAR DIESEL ENGINE OIL CHANGES ARE KEY

It’s also important to do regular oil changes to ensure everything is working properly. It can be tempting to try and push it a few more thousand miles, but this can cause damage to your camshaft. And it could end up costing you more money in repairs than if you’d changed the oil regularly.

Doing oil samples can also help you diagnose an issue with your camshaft. It gives you a chance to check for metal shavings.

These are often a symptom of failure and can damage other lobes on your cam. They can even travel downstream and damage other components.

ISSUES WITH ROCKER ARMS IN THE ISX CAMSHAFT

Some ISX engines have had an issue with rocker arms that have led to camshaft problems.

Some productions of rocker arms prevented the correct amount of oil from flowing, which starved the components. These rocker arms begin to stick and smack the camshaft, which leads to lobe flattening.

To fix this problem, both the rockers and cam will need to be replaced, otherwise the faulty rocker arms will damage your new camshaft as well.