Why turbo wash the intake when exhaust side is dirty?

[Jeanneau 45.2]

Recall many past threads about Yanmar turbo washing, but I can't seem to locate one that answers my question, which is ... why is turbo wash is added via the combustion air intake which, except for a small amount of crankcase breather gas is an entirely clean air feed? The exhaust side of the turbo is the dirty air stream, and it would seem that there is no cleaning benefit to this area since I assume all the blower wash "disappears" in the combustion process. Could someone enlighten me?

[a64pilot]

I don’t know about Yanmar, but in turbine engines you wash the suck side, and if you have even a tiny oil leak, you have a mess cause oil of course will have any dust particles stick to it.
I have never washed the turbo on any other motor I own, but in truth none of them connected the crankcase breather to the suck side of the turbo either.
I think that is maybe not the best thing to do.
If had a turbo Yanmar, I think I might just disconnect that and fit a catch can.
I’m not telling you to do that, but I think I would.

Washing the hot end isn’t effective, it just doesn’t clean anything.

[shakey doug]

Turbo water washing is a must with larger diesels to keep charge air at optimal output, smaller High speed engines also benefit from this practice. Washing the Compressor side removes Carbon, oil mist condensate or any other muck that may affect turbine balance & efficiency. The best way with a small turbo is to fill a spray type detergent bottle with washing up detergent & warm water, bring engine up to temp then reduce rpm to around 1200 wait 3-minutes then spray directly on to compressor blades as required. Run motor for a further 15 minutes to dry out before boxing up. Naturally the wash procedure is carried out with Air Cleaner removed.

[Dockhead]

Originally Posted by shakey doug

Turbo water washing is a must with larger diesels to keep charge air at optimal output, smaller High speed engines also benefit from this practice. Washing the Compressor side removes Carbon, oil mist condensate or any other muck that may affect turbine balance & efficiency. The best way with a small turbo is to fill a spray type detergent bottle with washing up detergent & warm water, bring engine up to temp then reduce rpm to around 1200 wait 3-minutes then spray directly on to compressor blades as required. Run motor for a further 15 minutes to dry out before boxing up. Naturally the wash procedure is carried out with Air Cleaner removed.

Yanmar are very particular about it, and they insist on a special turbo wash liquid which you buy from them.

I haven't done mine in a few years, and the impeller blades look clean and the turbo runs smooth and sweet, but I'll do it this spring anyway.

As to why you wash the intake side and not the exhaust side -- I have no idea, but that's what you do.

[shakey doug]

Larger diesels have provision to Dry Wash the exhaust side Carbon granules or similar.

[Pete7]

Military helicopters often have the air intake side washed to remove salt if used near the sea. Normal practice is to run the engine and use a fire hose to squirt water in at full pressure, quite spectacular.

I wonder if Yanmar are thinking along similar lines for engines used in boats.

Pete

[SailRedemption]

I thought it was the steam from the water spray exiting the exhaust helped break loose and remove the carbon build-up on the exhaust side. I know at work on our OSV the two diesel generator engines that aren't running, when it rains and the wster/dampness get in the stacks, they blow all kinds of carbon flakes on startup.

Nothing scientific but that's my hypothesis on why you spray the intake side. Though I'm sure you get a cleaning of the blower blades as well.

[Sailmonkey]

Originally Posted by SailRedemption

I thought it was the steam from the water spray exiting the exhaust helped break loose and remove the carbon build-up on the exhaust side. I know at work on our OSV the two diesel generator engines that aren't running, when it rains and the wster/dampness get in the stacks, they blow all kinds of carbon flakes on startup.

Nothing scientific but that's my hypothesis on why you spray the intake side. Though I'm sure you get a cleaning of the blower blades as well.

On the relatively small engines on an OSV there is no need to clean the turbine side of the turbo. The light fuel oil and combustion temps alone are enough.

On a ship with a slow speed two stroke and heavy fuel oil, it’s a regular practice to blast the turbine side with walnut shells to clean off the carbon/sulphur deposits.

“Turbo wash” is simply to remove oil and grime from the compressor wheel to increase efficiency and keep the little spinning thing balanced (25,000 rpm likes balance).

[Surfnski]

I use the Yanmar turbo wash every 300 hours or so. I have a 4JH2-UTE in my boat which I tend to run at low RPM. I know this is bad to do for long periods but I am a bit over-powered and need to conserve fuel.

Does anyone recommend removing the turbo charger periodically and cleaning it on the bench? I spoke to one skipper that does this every year. There is nothing in the Yanmar PM manual that recommends this practice.

Thanks for your thoughts.

[a64pilot]

Originally Posted by Sailmonkey

“Turbo wash” is simply to remove oil and grime from the compressor wheel to increase efficiency and keep the little spinning thing balanced (25,000 rpm likes balance).

This is the answer.
However if you don’t feed the thing oil mist and have an air filter, then there is nothing to wash.

Dockhead, ever wash the turbo on a Porsche?
Of course not, it’s not allowed to get dirty

[Dockhead]

Originally Posted by a64pilot

. . . Dockhead, ever wash the turbo on a Porsche?

Of course not, it’s not allowed to get dirty

Ha, ha.

I did have a Porsche Turbo for a while but never washed the turbo and don't recall it was part of the maintenance schedule. That was a sweet beast, but I liked the 2.2 liter 911S even better.

[a64pilot]

If I had a Yanmar turbo, I think I’d fit a K&N filter and route the blow by hose to a catch can. Letting it eat oil mist and then let some belt dust or just plain dust in seems stupid.
However washing the turbo ought not be that big a deal, I believe it’s just spray soapy water into the suck side of the turbo with the engine running? If so do you rinse with fresh water?

A turbine engine is compressor washed on schedule or when there is a performance drop, first you pump soapy water into it a couple of times motoring over with the starter, let it sit 5 min or so, then fresh water flush until water runs clear, all on the starter. Some of the soap is pretty aggressive, a lot like engine “gunk” cleaner.