Turbo Questions, Yanmar 4JH2-TE

[CrispyCringle]

My 4JH2-TE motor has me suspecting a turbo issue. Ive had the boat 2 years now. I used to be able to hear the turbo whine at high revs, and this summer I cant say Ive heard it. The engine had about 360 hours since a pretty extensive rebuild when I bought the boat, but I dont know what, if anything was done to the turbo unit during that rebuild.

I typically cruise about 28-2900 rpm, but bump it up to 3600 for short periods every now and then. Maybe not long enough or frequently enough. But I am getting a very light white smoke while cruising and sometimes a puff of white on startup. Engine otherwise runs great and no obvious oil consumption or leaks.

Air screen is clear and I can see the intake turbine blades and they look clean. When I spin the turbo by hand (by sticking my finger into the unit) it spins freely, but doesnt coast. It turns and stops in probably less than one revolution. But I know the shaft floats on an oil bearing, but I dont know what normal feels like, as far as freely spinning.

Ive been reading up on "turbo washes".

Am I being paranoid or would the experts dive a little deeper into the health of the turbo unit? Not sure where to go from here.

[skipperpete]

Here are a few things to do that might help you to decide if you have a turbo problem. Check the boost, your TE has a port into the intake manifold, you should read around 15-17psi at full load.
Check the exhaust back pressure maybe.... but
Check the mixer elbow definitely
Check the crankcase pressure... just pop the oil filler cap off, you’ll quickly see if you have excessive blow by.
Have the valve clearances been adjusted since the rebuild?
It can be helpful to take off the boost hose between the turbo and the intake manifold, if there’s a lot of oil in the bottom of that loop, you might have a problem.
If you do decide to wash the turbo take care with the compressor blade tips. I occasionally wash turbo compressors but prefer to remove the scroll and manually wash the blades with degreaser and a very very soft brush ( no wire, brass or bristle brushes), I’ve seen a few turbo compressor wheels that have been damaged by indelicate cleaning.... both static and dynamic.

[CrispyCringle]

Thanks for the tips. That gives me some good starting points.

I think I see the port on the intake you referred to for a pressure tap. Now to get a gauge.

For the mixer elbow, I assume Im looking for excessive soot buildup.

I doubt the valves have been adjusted. I can check that.

For the turbo wash, the Yanmar manual says to run at 3/4 to 4/4 load. Im very experienced with gas engines, but this is my first diesel. With no throttle plate it seems like, as far as air flowing through the intake side, that the only thing that would matter would be RPM. Is the intake airflow really different in neutral at a given RPM than with the prop engaged? Obviously fuel is different, but I dont see how the air would be affected with no throttle plate. The reason I ask is doing this procedure at the slip is a little different in neutral than in gear.

[rslifkin]

Yes, engine load affects airflow on a turbodiesel. As you add load, more fuel is added to maintain the same RPM. The increased fuel being burned means a larger volume of exhaust gas, which spins up the turbo faster and produces more boost and therefore more air being shoved through the engine (which allows you to burn more fuel and make more power).

So you'll see more boost and more airflow at a given RPM with more load applied. Exhaust temps will be higher as well.

[CrispyCringle]

Excellent! I didn't consider the additional exhaust gas and all that follows. Thank you.

[sealife2]

re turbo questions
skipper pete had excellent suggestions. further to those suggestions boost is measured at full load full rpm, a lightly loaded turbo has much less boost pressure and on these engines a light load builds up carbon on the hot side of the turbo. Carbon buildup can be seen after the exhaust elbow is removed. the sticky turbo fan suggest carbon build up . Carbon can be removed carefully by hand with the turbo in place, it is possible if not ideal. the turbo hot side studs break off easily so be careful removing the nuts that hold the exhaust elbow on. alternatively use a turbo wash, on some yanmar engines they recommended a turbo wash be introduced into the engine while running to remove carbon build up. that will be in your manual. For ongoing maintenance running the engine hard for a few minutes per hour is the usual method of removing the carbon from the turbo on these engines, that also is in the manual
re the white smoke i would more expect a dirty or worn injector rather than the turbo if you are getting full rpm under full load with expected boost reading. in that case have the injectors pop tested. injectors do wear over time and can cause white smoke.
sometimes white smoke is caused by high exhaust temp, id check that with a hand held thermometer gun at the exhaust elbow on the turbo and exhaust hose attached to the exhaust elbow. btw the 4jhte type yanmar ss exhaust elbows have a limited life span and do crack sometimes, with catastrophic results. hdi makes some reliable less expensive replacements
best of luck
jake

[skipperpete]

Originally Posted by CrispyCringle

Thanks for the tips. That gives me some good starting points.

I think I see the port on the intake you referred to for a pressure tap. Now to get a gauge.

For the mixer elbow, I assume Im looking for excessive soot buildup.

I doubt the valves have been adjusted. I can check that.

For the turbo wash, the Yanmar manual says to run at 3/4 to 4/4 load. Im very experienced with gas engines, but this is my first diesel. With no throttle plate it seems like, as far as air flowing through the intake side, that the only thing that would matter would be RPM. Is the intake airflow really different in neutral at a given RPM than with the prop engaged? Obviously fuel is different, but I dont see how the air would be affected with no throttle plate. The reason I ask is doing this procedure at the slip is a little different in neutral than in gear.

I know the “dynamic” turbo wash sounds like a good idea but it can really cause a lot of damage if done inexpertly. On the rare occasions that I do dynamic washes, I never leave the boost hose connected to the intake manifold and usually redirect it to a bucket and spray degreaser or turbo cleaner into the compressor intake at idle..... this is probably not how YouTube or Yanmar tells you to do it but I’m damned sure I DON’T want anything other than clean air going into my customers engine..... no degreaser, no turbowash and sure as hell no dislodged debris caused by the procedure. (I still think EGR is one of the dumbest and most damaging things EPA has pushed us to adopt.)
So for me the safest way to wash a turbo compressor is the old fashioned brush and spray, easy to do on your turbo Yanmar, just 4 bolts, 2 hose clamp and you’re in, no mess, no spinning turbo and actually.... a better result. On your engine the mixer elbow is supposed to be removed inspected and cleaned from memory every 250 hours.

[CrispyCringle]

I appreciate all the great advice.

Originally Posted by skipperpete

So for me the safest way to wash a turbo compressor is the old fashioned brush and spray, easy to do on your turbo Yanmar, just 4 bolts, 2 hose clamp and you’re in, no mess, no spinning turbo and actually.... a better result. On your engine the mixer elbow is supposed to be removed inspected and cleaned from memory every 250 hours.

I need to go down to the boat and look at the turbo. But are you saying to clean it while still mounted to the engine? I really want to take the elbow off now and get a peak. Ive got pretty good access. A plastic brush and what cleaner?

[skipperpete]

Originally Posted by CrispyCringle

I appreciate all the great advice.







I need to go down to the boat and look at the turbo. But are you saying to clean it while still mounted to the engine? I really want to take the elbow off now and get a peak. Ive got pretty good access. A plastic brush and what cleaner?

Yes, on your engine it’s not too difficult with just the boost hose but more difficult on the HTE, DTE and UTE with the intercooler pipes, nothing aggressive for washing, usually it’s just an oily residue so I use spray pack engine degreaser and a spray bottle with water in it to wash the degreaser off. Also wash out the boost hose, it usually has a bit of oil sitting in the low point and a film over the inside of the hose. When you get the mixer elbow off use a bright flashlight to inspect the turbine wheel and the housing, too much carbon buildup or corrosion is what you’re on the lookout for (and anything at all unusual about the turbine itself).

[Toccata]

I too had this issue, many investigations later, it turned out to be the fuel pump affected by water in the fuel causing the rack to not open fully. (Old thread somewhere in the archives here)
Along the way I overhauled the turbo, (was worth doing as it was clagged) and redesigned the exhaust to improve (reduce) backpressure.
I would check the exhaust back pressure, while it may not be the primary cause I reckon it could be the underlying issue for you.
Make up a board about 1.5m long and fasten a clear plastic hose to it in a "U" shape
Fill the clear hose about 2/3rd with water
One end of the loop open, the other connected to a hose tail fitting, screwed into a threaded outlet closed by a stud, that you will find on the exhaust elbow
Start the engine, run under load (similar to your normal cruise).
The water in the loop will move in response to the exhaust pressure. Measure the difference between the height of the column of water in each arm of the loop.
1 foot of water equates to .433 psi or 1 Bar equals 10193.68mm of water, lots of help on the net for this calculation.
David Gerr has a great section in his book "Boat Mechanical Systems Handbook" on proper exhaust design.
Please let us all know what you find as that makes this a really useful thread for others later on.

[CrispyCringle]

I started digging today to get a look at the turbo condition. I dont think I like it so far. Tried taking the flange bolts off for the Y-Pipe. Tight. So they have some PB Blaster soaking overnight. On the high pressure side, I got the pipe off between the turbo high pressure air and the intake manifold. See pics. There was no puddled oil in the pipe, but it was oily and the intake manifold looked oily and like it needed a good cleaning. Not pleased. So, it seems pretty oily to me, but I have no experience with a turbo unit. And note that the pics of the turbine intake blades may look disorienting, but its a pic using a mirror.

Looking for opinions, based on pics so far. I wish I could put captions on the pics, but they start from the intake of the turbo, through the pipe to the intake manifold. All pics on the intake side.

Oh, and just to make it a normal boat task, I dropped a flange bolt into my 6' deep full keel/bilge. Another couple of grams of ballast never to be seen again.

[CrispyCringle]

Went to the boat to continue messing around with this turbo and I think I have found the source of that intake oil shown in the pics. When I got back today the air intake screen had about a spoon full of oil that had drained out in a puddle the way I had it laying down. The intake screen has a breather tube going to it from the valve cover and that is where the oil had come from.

So that makes me want to check the blow by. Which means putting it back together to run the engine. I’ll degrease the parts first.

[skipperpete]

Those photo’s show more or less a healthy compressor, the presence of an oil film can be explained by the turbo breathing the crankcase fumes via the hose from the rocker cover to the intake and the lack of a bit of liquid oil in the boost hose is an encouraging sign.

[GreenWave]

Interesting findings. This prompts me to ask - what would cause oil to be in the breather tube where it enters the air intake screen? Is that possible from over filling the oil sump or ir it a failure of something, if so what?

[skipperpete]

No engine has zero leakage past the piston rings, I do cylinder leakage tests and never see a zero leakage result, the ring gaps are always there and provide a path for the combustion gases into the crankcase, if this wasn’t the case, there’d be almost no need to change the lube oil. Your turbo compressor gets to breathe that mist of oily fumes so you don’t have to as with the ancient traditional automotive breather pipe to the pavement hence the oil in that hose on your engine. Some folks put a speed shop catch can in the line if the blowby is substantial. If your engine isn’t using lube oil, don’t panic about a bit of oil in the compressor pipework.