Why Do Diesels Leak So Much? Why Do Diesel Engines Leak So Much Oil?

If you have a Diesel Engine or have worked on them, odds are it has a little oil leak or weep somewhere. This seems to be normal on these engines, but why is that? This video describes the main reason for it and what can be done about it.

[MultiPowerlin]

It's like the old Detroit diesel saying if there are no oil leaks it's out of oil

[guy]

Diesel’s don’t leak they just mark their territory.

[DowntownDeuce]

As many engines as I have rebuilt through the years, this never occurred to me! This guy is a true mechanic/ engineer in a world of a bunch of parts changers. Great diagnostic and analytic skills

[laurencemarkmallak]

Hi, I think you are very good at explaining thinks especially to truckers that are not their own mechanics. I had a 1999 Pete with 3406E and had 1, 1800, 000 when I sold it. I was lucky with very seldom having breakdowns, I always caught things during services and was able to repair thinks on the road and never needed a tow. One time I was losing coolant and it wasn't leaking. I was looking under the radiator and noticed very little puffs coming out of the radiators little rubber over flow hose, they were so slight that the only way you could even tell, was by my face being an inch away from the hose. I used 4 gallons of coolant to make it back 400 miles to my shop. I checked it out further and decided it must be the head gasket. I pulled the head checked all the cylinder liners and had the head pressor tested and decked. I put it back together and had the same problem, woops, took it apart again and had my 35-year-old son with better eye then mine check the cylinder liners again and there it was no. 1 cylinder liner had a micro crack in it. Needless to say, I will have my son do the looking from now on. Just wanted to share that with you, thanks.

[JD-hyyc]

When it is no longer leaking, it is out of oil/fluid

[JohnMayer]

Brilliant. 50 years ago I got an excellent Caterpillar apprenticeship and ended up running an engine shop. Your explanation was excellent. It was erudite and simple, the best kind of tutorial. Bravo!

[speedmph]

Adept ape, big fan of your channel, greetings from alberta Canada.

Since today's topic is PCV I thought that I'd share another method that we use. Bit of background. I work for one if the large railways here in canada as a locomotive mechanic. Our engines are upwards of 11, 000 cubic inch, 4500 hp, giants that move a lot of air and a lot of boost (up to 70 PSI on the new units)

To keep our crankcase from suffering an over pressure (which actually trips the engine shut down on our engines) we use what's called an eductor tube system. An eductor tube is a tube that goes into the exhaust stack of our engine. A hose comes from the crackcase, through an oil strainer, and to the eductor tube. The eductor tube is a venture tube that uses the venture effect of the passing exhaust gases to form a vacuum that draws blow by gases out. It is very effective. I did a load test (essentially an extended dyno pull on the engine using the generator) on a unit. At full throttle, the system was able to hold the crankcase pressure at -3psi.

I know this would be impossible today with how oil poisons the DOC, DPF and SCR filters but it shows another method that overlooked on road.

Looking forward to the next video. Cheers!

[bucketsamson]

Huh, I always just figured it was because they vibrate more than a gasoline engine. I never thought about it this way. Thanks!

[onlylikenerd]

Yes, girls leak a lot too, but I still love em

[paulmaxwell]

This is a great series of videos. I've been working on engines all my life but I'm always interested in learning new things. Thanks!

[julianzovluck]

It took me a while to grasp the concept of crankcase breathers and why you get more oil in the air inlet and turbo during idle rather than load thanks for your videos. I work on MTU marine engines; they use a crankcase breather filter system that leads right to the air inlet horns.

[UQRXD]

Nice explanation. I have worked on industrial equipment that has oil under pressure up to 6000 pounds and no leaks. The simple truth the gaskets are not as good as can be. If you can keep the compression in the cylinder the for sure the oil can be kept in the engine. The diesel engine is a big polluter. I have worked on large marine diesels and many don't leak a drop.

[peanut]

Best customer to have is one that can't stand oil leaks on their equipment 😁. Great video Josh, great information and well-spoken.

[scdevon]

Capt. Ron: "Diesels love their oil".
"Why is that"?
Capt. Ron: "Nobody

[josephsfields]

Hi Josh, I really enjoy your channel content. My 17 years old Powerstroke has never piddled on the driveway. I hope watching this video doesn't jinx it.

[romanshevy]

Glad you did this video. I’ve been trying to fix every leak with another springing out not long after lol.

[jimshireman]

Admit up front that I'm not even close to being a diesel mechanic or technician but did appreciate that you dumbed it down some so that I understood it. I have a 2003 Motorhome Diesel Pusher with a CAT7 engine in it. Had one oil leak last year that was fixed by changing the oil cooler and just came back from a trip where we noticed oil leaking again. First long trip and was obviously concerned that we had another oil leak. Going to have a diesel mechanic give it a look just to make sure we don't have something stupid going on but was interested to know that diesel engines like the CAT7 would probably leak or seep now matter what. I read a lot of the previous responses from other folks and at least felt I learned a little bit about what might be going on. Thanks to all of you.

[superglider]

The DD60 in my truck doesn't leak, and neither do any of the other trucks in our fleet... because we maintain them. One of the fastest ways to get put out of service at a DOT inspection is to be bleeding oil.

[guvsgarage]

Plus, the last thing you'd want to do is blow oil laden crankcase air onto the intake side of a turbo. If something fails its a sure fire way to feed a turbo lots of lovely engine oil. Run away anyone?

[overnighter]

Cheers mate! 🙏🏻 I have 300 Tdi engine (by International) on my LR Defender and your video perfectly describes the situation 👍