Yanmar 4JH3-DTE needs to quit smoking

[jt11791]

The first thing to be removed was the intercooler. The intercooler uses raw water to cool the compressed air coming from the turbocharger. It's remarkable how effective it is, my engine is rated at 125HP, while the 4JH3-HTE (exact same engine, turbocharged but without the intercooler) is rated at 100HP.


Removing the intercooler was easy, I just undid some hose clamps and removed three bolts.


Once the intercooler was off, the first thing I noticed was a film of engine oil in the air passageways. Oil should not be there and the only place it could come from is the turbocharger.

[Yellowjacket]

Originally Posted by jt11791

My Hylas 54 is equipped with a Yanmar 4JH3-DTE turbo-diesel which makes an embarrassing amount of smoke on start-up.

I'm going to assume that your eninge, like mine (4jh2-DTE) has a max rpm of about 3400.

What rpm do you run your engine?

Many owners (including previous owner of my boat) run them at 1700 or 1800 to conserve fuel. These engines don't like that as a steady diet. In my experience, the engine has a "sweet spot" between 2700 and 2800, which happens to be maximum horspower per gallon of fuel burn.

Every time I bring her into port after a few hours of running, I take the rpms up to close to max, or as high as I can stand it, for five minutes or so. At first there can be some darker smoke, then that lightens up as carbon is blown out.

The engine appreciates this, and runs far better now than when I first ran it with far less smoke at start up and during operation.

[Oceansailor]

I have the 4JH4-TE. It does the same thing if I have been charging batteries on anchor or been running them at low RPM 1700-1800 for extended periods. Go out and run the engine on high RPM for an hour. (high rpm maximum rpm minus 300) would not be surprised if that fixes the smoke problem. In the future try to run the engine on (max rpm
Minus 300) for 20 minutes of every 5 hours of economical motoring.

[jt11791]

I run between 2000 and 3000 rpm, depending.


I have tried the "Italian tune up" running at max revs for a bit to clear things out. I always cool it down and then rev once before shutdown.



All of these are good practice, but don't change my issue with excessive smoke.

[Oceansailor]

How much is a bit? It is important that you run hard for a longer period in order to create a high temperature that burn carbon deposits. If I remember I did run the the engine hard 2-3 hours to get rid of the smoke the first time. It was everything between 2700 to 3200.
Today it is normally enough with 20 minutes every 5 hours.

[jt11791]

Once I ran hard from Cape May to New York Harbor, maybe 15 hours. That enough? Didn't fix it.

[Oceansailor]

15 hours should be enough! But your engine is designed to do 3800 RPM. That means italian tuning should be done in the 3000-3500 range. Can you do 3800 RPM or are you overpropped?

[jt11791]

Yes, it will reach max rpm. Did you read my post above about the oil leak in the turbocharger? Is running at max rpm for any amount of time going to fix that?

[Oceansailor]

Sorry I missed that part. I do not think Italian tuning will fix an oil leak in the turbocharger.

[Paul L]

Originally Posted by jt11791

Yes, it will reach max rpm. Did you read my post above about the oil leak in the turbocharger? Is running at max rpm for any amount of time going to fix that?

Are you sure its a leak and not just the oil that naturally comes out of the breather tube?

[bstreep]

I also have the 4JH-DTE. But ours is only turbo charged, not intercooled. You should not be getting oil leaking into or out of your turbocharger. When was the last time it was rebuilt? The bearings inside of the turbo spin at 70-85,000 RPMs, and they float on a supply of engine oil. It seems possible to me that you are getting some oil leaking into your exhaust stream. If it's been a while, you might want to pull the turbo and rebuild it or have it rebuilt. They are staggeringly expensive for what is essentially the same turbo charger VW uses and sells for around $250.



I have had so much practice removing my turbo that I can take it off or install it in about an hour. If you want some pointers, I have 'em! Just PM me. I had ours totally rebuilt about 2 years ago.



Oh, we we still get some smoke/steam when we start, especially in cooler weather... And it's kinda cold up there now, isn't it? Nice boat, by the way. Our boat almost got totaled in Hurricane Harvey, and Hylas was the direction we were looking if we had to replace.

[jt11791]

Originally Posted by Paul L

Are you sure its a leak and not just the oil that naturally comes out of the breather tube?

My breather tube is routed to a catch can, rather than back to the air intake.

[jt11791]

Originally Posted by bstreep

I also have the 4JH-DTE. But ours is only turbo charged, not intercooled. You should not be getting oil leaking into or out of your turbocharger. When was the last time it was rebuilt? The bearings inside of the turbo spin at 70-85,000 RPMs, and they float on a supply of engine oil. It seems possible to me that you are getting some oil leaking into your exhaust stream. If it's been a while, you might want to pull the turbo and rebuild it or have it rebuilt. They are staggeringly expensive for what is essentially the same turbo charger VW uses and sells for around $250.



I have had so much practice removing my turbo that I can take it off or install it in about an hour. If you want some pointers, I have 'em! Just PM me. I had ours totally rebuilt about 2 years ago.



Oh, we we still get some smoke/steam when we start, especially in cooler weather... And it's kinda cold up there now, isn't it? Nice boat, by the way. Our boat almost got totaled in Hurricane Harvey, and Hylas was the direction we were looking if we had to replace.

Yep! The turbo is next off after the intercooler, pics to follow.

[Paul L]

Originally Posted by jt11791

My breather tube is routed to a catch can, rather than back to the air intake.

For the life of the engine?

[jt11791]

Originally Posted by Paul L

For the life of the engine?

Yes, that's how the shipyard set it up when they built the boat. I've heard that the idea is to keep the turbo clean. I thought it was strange too, when I first saw it. On this engine, there's really no blow-by so the catch-can doesn't catch anything, and it probably doesn't make much difference.