How to Replace Your DD15 Crankcase Separator in 10 Easy Steps

If you have a diesel engine, you may have heard of the crankcase separator or crankcase breather. This is a device that filters the blow-by gases from the crankcase and returns them to the intake manifold. This helps to reduce emissions, improve fuel efficiency, and prevent oil leaks.

However, like any other part of your engine, the crankcase separator can wear out or fail over time. This can cause oil to leak from the bottom of the filter, or a check engine light to come on with a fault code for the crankcase separator speed too low.

If you notice any of these symptoms, it’s time to replace your crankcase separator. Don’t worry, this is a very easy and inexpensive repair that you can do yourself in your driveway or parking lot. All you need are some basic tools and a new crankcase separator kit. Here are the steps to follow:

Step 1: Remove the sensor

The first thing you need to do is to remove the sensor from the top of the crankcase separator. There is a little gray tab that you need to push down and pull out to disconnect the sensor. Then, you can cut the zip tie that holds the harness and hang it down.

Step 2: Remove the vent tube

Next, you need to remove the vent tube that connects the crankcase separator to the intake manifold. To do this, you need to push the top and bottom tabs in and pull out the tube. It should pop out easily.

Step 3: Remove the bolts

Now, you need to remove the four bolts that hold the crankcase separator to the block. You can use a 16 mm socket and a ratchet or an impact wrench to do this. Be careful not to drop the bolts or lose them.

Step 4: Remove the crankcase separator

Once the bolts are out, you can pull off the crankcase separator from the block. You may need to wiggle it a bit to break the seal. You may also lose some oil when you do this, so have a bucket or a pan ready to catch it.

Step 5: Remove the gasket

Behind the crankcase separator, you will see a gasket that seals the mating surface. You need to remove this gasket and clean any residue or dirt from the area. You can use a scraper and some brake cleaner or starting fluid to do this. Make sure the surface is dry and smooth before installing the new gasket.

Step 6: Install the new gasket

The new gasket may look different from the old one, but it will fit the same way. Just align the holes and press it onto the block. Make sure it is seated properly and does not move.

Step 7: Install the new crankcase separator

Now, you can install the new crankcase separator onto the block. It should come with a new vent tube and a new seal for the plug. If your old seal is leaking, you can replace it with the new one. Just push it into the hole and make sure it is snug. Then, align the crankcase separator with the gasket and the bolts and push it in.

Step 8: Tighten the bolts

Next, you need to tighten the four bolts that secure the crankcase separator to the block. You can use the same 16 mm socket and a ratchet or an impact wrench to do this. However, you need to be careful not to over-tighten them. You should use a torque wrench to torque them to the proper specification, which is 25 Nm or 18 ft-lbs.

Step 9: Install the vent tube

After the bolts are tight, you can install the new vent tube that came with the crankcase separator kit. It should snap into place easily. Just push the top and bottom tabs in and push the tube into the crankcase separator and the intake manifold. Make sure it is secure and does not leak.

Step 10: Install the sensor

The last step is to install the sensor back onto the top of the crankcase separator. You just need to plug it in and push the gray tab to lock it. Then, you can zip tie the harness to the nearby bracket or hose to keep it out of the way.

That’s it! You have successfully replaced your crankcase separator. You can now start your engine and check for any leaks or codes. You should notice improved performance and reduced emissions from your diesel engine. Congratulations on completing this easy and rewarding repair!

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