Can I remove the turbo from my Volvo?

[GarryP]

My Volvo 1987 TMD31 is rated at 100 hp It has been thoroughly checked out and seems to be in excellent shape with only 2100 hours on it. The fule is clean. From what I've learned these engines are smoky and you learn to live with it.

At 2000-2500 rpm the smoke is minimal and we move happily along at 6 knots. I've been told to run the engine at 3200 rpm occasionally just to keep the turbo happy. At that speed we gain maybe 1-1/2 knots and at least double or triple fuel consulption. And the smoke is terrible with soot covering the transom.

Why not eliminate the turbo? The MD31 is rated at 90 hp, still plenty. We could cruise all day long while minimizing smoke, noise and fuel consumption. How difficult would it be? Would it really gain what I hope?

 

[Steppen]

If it ain't broke, don't fix it.

I have a 1981 vintage Volvo TMD-40A in my boat.* We get an honest 7 knots at 2200 RPM and a fuel consumption of 2 gals/hr.* The turbo is working at all RPMs, not just high RPM.* It is not like your old turbo Mercedez when you could "feel" the turbo kick in going up an on ramp.

Your Volvo is designed to have a turbo.* There may be differences between the TMD31 and the MD31 non-turbo such as cooling, injectors, injector pumps etc.* That's something Volvo could tell you.* Personally, I would be resistant to screwing around with something just to prevent a little smoke and soot produced for the 5 minutes you push her to 3200 RPM.* Spend the money on an older vintage scotch.

 

[Anthonyd]

GarryP wrote:
My Volvo 1987 TMD31 is rated at 100 hp It has been thoroughly checked out and seems to be in excellent shape with only 2100 hours on it. The fule is clean. From what I've learned these engines are smoky and you learn to live with it.

At 2000-2500 rpm the smoke is minimal and we move happily along at 6 knots. I've been told to run the engine at 3200 rpm occasionally just to keep the turbo happy. At that speed we gain maybe 1-1/2 knots and at least double or triple fuel consulption. And the smoke is terrible with soot covering the transom.

Why not eliminate the turbo? The MD31 is rated at 90 hp, still plenty. We could cruise all day long while minimizing smoke, noise and fuel consumption. How difficult would it be? Would it really gain what I hope?

Hey Garry,

I'm not familiar with that engine entirely, I've worked on the 71 turbo series, but I am a diesel technician. A diesel engine is made to run with or without a turbo. If you remove it, the smoke will more than likely get worse because you decreased the amount of air getting into the cylinders for the combustion stroke. Turbos are used to boost power and efficiency. As a diesel technician, one of the first things I learned was to look at the smoke to see how the engine is doing. Black smoke indicates either too much fuel or not enough air-indicating a bad injector or a clogged air filter or something else. Bluish smoke indicates oil being burned-lots of possibilities. White smoke indicates too much air or not enough fuel-air leak in the piping, clogged injector etc. A white to gray smoke that looks like steam and dissapates quickly indicates water in the cylinders.*

Removal of the turbo may involve some custom piping. If it is a direct turbo, you may need new intake and exhaust manifolds to accomidate a natural aspiration arrangement. If it is a charge air cooler style you will need a few modifications to the engine block. These options could be costly. I would have a cylinder leak down test performed and have the fuel system tested thoroughly. It sounds like too much fuel to me. And again, not being familiar with this engine someone else may have some good ideas for you. Best of luck.

*


-- Edited by Anthonyd on Sunday 10th of April 2011 06:59:18 AM

 

[Moonstruck]

Garry,

You have some good reasons already to leave the engine as is.* As David said, over propping will cause a smoke condition.* All things on the engine are designed to work as built.* If the turbo is removed, the injecters will have to be down sized.* The current injecters are designed to work with a certain fuel/air ratio.* Without the extra air suppied by the turbo there would be incomplete combustion to a greater extent---not less.* I would leave it as is.

 

[Nomad Willy]

All good advice so far Gary.

What is your engine's rated rpm and has it been attainable in the past and is it attainable now. Have you checked your engine compartment's vents and engine air cleaner?

You say "And the smoke is terrible with soot covering the transom."

If the smoke is that bad I suspect your problem is'nt over propping. I think it would take more than a little extra pitch to cause the black smoke you're talking about. You would'nt get 3200rpm either if you were over propped 3-400rpm (enough to cause black smoke). Something else is causing the engine to run way too rich. Have you talked to Volvo?

 

[Codger2]

nomadwilly wrote:

You say "And the smoke is terrible with soot covering the transom."......

If the smoke is that bad I suspect your problem is'nt over propping..........* Something else is causing the engine to run way too rich.

******* I agree but have no suggestions.

*

 

[GarryP]

Thanks to all for the good advice and getting me back on track.

The engine achieved 3500 rpm when we ran it over the weekend so apparently the pitch is not the root of the problem.

I had the engine thoroughly serviced in February right after we bought her to minimize any trouble for the delivery. The injectors were rebuilt and the air filter was replaced. Apparently something still isn't right. This kind of soot problem is way more than acceptable.

The next step is to find a good mechanic to sort it out.

Thanks again,
Garry

 

[Baker]

DavidM wrote:
Garry:

You describe excessive smoke at high rpm. That is a symptom of an overpropped condition- too much pitch or diameter that doesn't let the engine rev to full rpm. First see how high your engine will rev in neutral. It should reach its rated rpm plus a 100 or so. If not you may have a governor/fuel injection/turbo problem.

*

*This is not entirely true. *There is a fuel cutoff point that will prevent the engine from revving any higher. *Mine happens to be 3800RPMs which is 500RPMs higher than max rated RPM. *The engine manual should have both of these figures.

 

[GarryP]

I appreciate all your suggestions. I will try to do a thorough inspection this weekend. I recall that much of the previous work by the mechanic was done with the hatches open. I can't be sure right now that the vents are fully open. I've had the grilles off and they were clear but I haven't verified the full flow paths into the engine room. Maybe not such a dumb question!

I'll try some speed tests too.

 

[sunchaser]

I cannot argue with previous poster's suggestions, but beware the Volvo hidden bank account*draining trick. A few years ago I was inspecting a twin Volvo powered Tolly 44. Both* engines smoked (black) since new with the owner having spent thousands over ten years trying to fix the same black transom issue on both engines. Props were fine and RPMs achieved OK.

One more suggestion, insure your engines are operating at right temperature and RPM with IR gun and photo tach. Older instruments can at times be in error, leading to all sorts of wrong assumptions.

 

[healhustler]

Gary: that is sure one question I hope to see on the Krogen site, cuz I'd bet you're not the only one with a sooting Volvo. I suspect a bit of an issue with the location of the exhaust also, cuz my Yanmar doesn't smoke, but I have noticed a bit of soot on the transom. Just bought some stuff to clean it today. If you come out well on the cylinder leakage test, I'd bet you could clean up that Volvo with the right mechanic. Try using the engine room blower intake fan when you have it reved up and see if it makes any difference. The standard Manatee prop for the Volvo power was a 22LH X 13 if you want to check, but you're within 100 RPM of max reccommended now, so it doesn't sound like much of an issue. At least one Manatee out there moved his exhaust to starboard about two ft. from the stern to help with this characteristic of the boat. Don't recall if it worked well, but it did make a difference.

 

[DCBD]

sunchaser wrote:

One more suggestion, insure your engines are operating at right temperature and RPM with IR gun and photo tach. Older instruments can at times be in error, leading to all sorts of wrong assumptions.

I've noticed my Volvo runs around 165° F (by the*helm gauge) while underway, never seen it hotter than that. I've always wondered if that was the reason for my sooty stern.

 

[GarryP]

I did notice that the temp gauge did not get over 170F. The mechanic checked it a few months ago and found it was within 10 degrees of his reading on the IR gun. Could the thermostat be stuck open so it doesn't get up to temperature? Would that contribute to smoking?

 

[Anthonyd]

GarryP wrote:
I did notice that the temp gauge did not get over 170F. The mechanic checked it a few months ago and found it was within 10 degrees of his reading on the IR gun. Could the thermostat be stuck open so it doesn't get up to temperature? Would that contribute to smoking?

*

*Check the engine manual to see what the normal operating temperature should be. All engines are made to operate at a certain temperature for thermal efficiency as well as other reasons. If it is running too cold it may not burn all of the fuel in the combustion chamber. A stuck open thermostat will cause the engine to run cooler and lower the thermal efficiency of the engine causing an incomplete burn of the air fuel mixture, leaving more unburned fuel to escape out of the exhaust valve thus the smoke will be blacker then normal.

 

[Avista]

I am not answering your question about removing the turbos, but I would not try that on my engines.* However, after having Cummins turbos and now Cat turbos, I have had some experience with turbo charged diesels.* My Cats run with no sooting, yea! But the Cummins engines I had before dirtied up the transom a lot.* First everyone told me I was over propped, so I repropped and that wasn't the issue, then the experts told me that I had one or more bad injectors, so I changed them out.* then I was told I wasn't getting enough air into the engine room, so we ran tests with the hatches open, then I was told the 6BTA engines just ran that way, live with it, and so forth...

When I was at the Miami boat show one year I stopped by the Cummins display to complain about the soot and the Cummins rep asked me how old were the engines?* I told him (6 or 7 years at the time) and he said 'change the turbo seals, all turbos run very hot by design and the seals get hard and let the turbo pull oil in and it burns just like diesel. You can't tell it's oil vs diesel though from the smoke because the turbos run so hot* any oil burns just like diesel'

Well I changed the turbo oil seal and the sooting stopped. End of story.* I don't know anything about Volvos, but it's something to check into maybe.

Have fun.

 

[healhustler]

Very good point, Avista. I'll remember that one. Sorry it took you so long and $$$ to get the correct response.