# Can you run a Yanmar w/ turbo out?



## bennyd10 (Mar 26, 2008)

I am looking at a boat that has a Yanmar JH4-TE Turbo 55HP engine in it. I was told that the turbo has been bypassed? This is because it is blown. They replaced the turbocharger once, but the oil cooler was not replaced and the turbo blew again... So then they bypassed the turbo and brought the boat from the Bahamas all the way up to N. Carolina. Should I be concerned???
Is the fact that the oil cooler is the problem cause the oil to burn and overheat? Would the turbo going out cause metal to enter crankcase oil? Sounds like it is not a good move, I am just wondering what damage could occur and how I can tell what all is wrong!!!


----------



## sailingdog (Mar 19, 2006)

Why would someone be stupid enough to put a turbo diesel on a sailboat? It isn't like a sailboat is really the proper use environment for a turbo diesel. You really need to talk to a good diesel mechanic. If you're not going to use the turbo, you need to convert the engine back to a non-turbo setup IMHO.


----------



## SteveInMD (May 11, 2007)

I believe you will continue to see turbos on smaller and smaller diesels for quite a while now. The really do wonderful things for efficiency and emissions. The down side is obviously there is on more system that can fail. However, despite this post, turbo failure rates have been greatly reduced in the last few years by improved technology.

If you've had two turbos die you most likely have an oil system problem (but it sounds like you already know this). You can run without a turbo, but I wouldn't expect the motor to preform well at all unless you make a whole number of changes including replacing injectors, and possibly the entire high pressure pump, and obviously the intake system, and the prop.

If it were my boat I would find and fix the oil system problem, replace the turbo, and then keep up with oil the changes.


----------



## timebandit (Sep 18, 2002)

To start with your 55hp motor is only making about 35hp without the turbo.

I'm betting the boat came out of a rental fleet and the renters were not instructed to let the engine idle for awhile to cool the turbo down and prevent coking of the oil in the turbo.

Most turbos can be rebuilt for under 500 dollars.

I hope that the bypass was done in such a way that the parts are still there to reverse the procedure.

Let me know if you need the name of my rebuilder.

Rick


----------



## Kage2021 (Sep 28, 2008)

Before I comment I would like to offer this disclaimer: I have never worked on a marine engine, I have only recently gleened an interest in watercraft but I am an avid automobile enthusiast. At the very least have someone verify the following. I am only offering this to help because I do know quite a bit about turbos and all engines operate in the same basic manner.

That being said here's what I would assume/deduce in your situation.
Any engine built from the factory with a turbo is engineered with certain chateristics to deal with the turbo's additional psi. Physically this usually means higher quality parts to deal with the added pressure the turbo creates, as far as that goes it's a plus for you.

On the other hand, the engine is designed to run with the turbos added PSI. The engine will be running rich now that the turbo is gone. If you don't care about the loss of fuel economy I would think you would be alright on such a small engine. Another consideration is that most diesel engines simply compress air untill it's hot, then add fuel so it burns. Once agian, your engine will be designed to compress the air from the "intake" plus the additional air that the turbo would have compressed to reach firing temperature. If you feel that it is running fine, roll with it.

The only notes of caution I would offer you are the following.
1. Be sure who ever disabled the turbo did it correctly. Turbos are generally powered by exhaust fumes, if some jackass unhooked the turbo incorrectly you run the risk of building up exhaust fumes where they shouldn't be which is a fire risk.(especially considering the fact that your engine is running rich, your exhaust fumes are extra volatile)
2. It is possible (and probable) that the timing of the valves is slightly more aggressive than an engine w/o the turbo to maximize the efficency of the turbo, if this is the case at least you will have further decreased efficency, at worst you could ruin the engine. It's unlikely it's that bad, but if it is, you would deffinately be able to tell. It would run bad.
3. Turbos DO BLOW, BREAK UP, AND GET SUCKED BACK INTO THE ENGINE. You need to know if this happened. Drain the oil, get a magnet or something and see if you have metal particles in your oil. Take off the turbo, look at the blades, or make the person who disabled it instead of fixing it do it.
If it were me? I'd use this as a point to knock cash off the boat, change the oil twice over a short period, and ride it until I could fix the turbo. Chances are if the boat has ridden that far without any crazy problems, then all you need is to change the oil just in case.
Anyone want to add or adjust that feel free. I am only offering what I know in an attempt to help


----------



## Omatako (Sep 14, 2003)

Here's my take on this:

The prime reason causing turbos to blow is that the rotor spins at a very high speed (as much as 30,000rpm) when under power. The spindle is supported by a film of oil pressure, not bearings. When the engine is turned off too soon after running at a significant RPM, the oil pressure disappears and the spindle, still spinning at a high speed, has no support causing it to seize.
It is possible that the poil cooler only serves to cool the turbo oil supply (which gets significantly hotter than the crankcase oil because the turbo body thru which the oil passes gets really hot) before returning it to the crankcase. It is also possible that the cooler is clogged with oil sludge (poor maint) and this is possibly why the second turbo blew as well.
When the spindle siezes the rotor touches the housing and the blades snap off. The exhaust blades are probably stuck in the exhaust mixer or water lift. The intake impeller will end up either sticking in the intake manifold or will go thru to the engine. If this had happened, there would some unwelcome noises coming from the engine.
Converting the engine to non-turbo has one expensive problem if it is to be done right. Turbo engines are designed with lower compression ratios than naturally aspirated engines with the turbo boost lifting the compression ratio to same-as or better with "charged" air. So without a turbo the compression ratio will be such that any tiredness in the engine over time will eventually make it imposible to start. You will also get sedentary performance at best - lazy, smokey and thirsty. The only way to overcome this is probably to replace the pistons and there may even be cylinder head variations so it could get really expensive.
The pump and injectors will probably have a slightly different spec but that's not a huge expense can be re-tipped and calibrated.
But I agree with SteveInMD, the efficiencies and benefits of small turbo diesels are considerable and if the old parts are still around, I would restore it to original. Even if they aren't it may still be the more affordable choice.


----------



## oldchief (Jul 27, 2006)

Turbo's on diesel engines are generally extremely reliable. While they can fail, it is rare. Outside of some foreign object flying down the intake, the most common turbo killer is lack of oil or dirty oil. 

Basically, you don't know what happened, and you can't rely on anyone else, so I would recommend that you find the best diesel mechanic you can afford and pay him about three hours labor to look it over. It is obvious that the previous owners took the cheep way out on the fix, and they probably took the cheep way out on everything else. 

If you end up with this motor it will probably be cheaper to leave it as a turbo. Change the oil at least twice as often as the manufacturer’s recommendation. Everyone wants to extend the service intervals on engines, but it is a bad idea and the people that are recommending it do not own your engine or have to repair it.

Concerning an earlier post, the engine is not currently running rich due to lack of turbo pressure. Turbo boost comes on and off continually as the throttle position and RPM and load change. The fuel injection compensates for manifold pressure to keep the fuel to air ratio correct at all times, even when there is no additional boost provided by the turbo. 

Good luck with this engine. Be very suspicious. It gives me the willies.

Rod Sorenson


----------



## Gryzio (Dec 13, 2007)

*Talk to a mechanic*



sailingdog said:


> You really need to talk to a good diesel mechanic. If you're not going to use the turbo, you need to convert the engine back to a non-turbo setup IMHO.


I will agree with SD on this. Ask around local to you. I am cautious of things when I not know the facts behind why it not work. Now, if the boat is priced like the engine not work, I not have a problem buying, if, it what I want. I not pay for a 1/2 running engine.
I did put a Turbo Charger on my 1966 Mustang back in the 70's and it worked and I assume it would work without the Turbo or disconnected. But, if the Turbo is blown and junk like that, then I would check the oil and filter for debris.
Also, I never buy something I can not fix. That not mean I will not pay for labor, but, I want to know what going on, then I know if I pay someone, I know what I paying them to do, not what they tell me. I can tell some stories about this; real mechanic rips if I were not educated.
This may help get you started.
HowStuffWorks "How Turbochargers Work"


----------



## BarryL (Aug 21, 2003)

Hello Benny,

Good luck with this engine. There is a lot of information listed above, most is not correct. I am not going to review the info above, just note that there is a huge difference between a gas turbo and a gas diesel, and an automotive engine and a marine engine.

If you are serious about this boat, the best advice has already been given to you: Hire a good diesel mechanic and have him perform a thorough analysis of the engine. The engine may be fine, it also may have serious and expensive problems.

If anyone is interested in some of the mis-information listed above, let me know and I will try and provide an accurate list.

Barry


----------



## Omatako (Sep 14, 2003)

BarryL said:


> just note that there is a huge difference between a gas turbo and a gas diesel, and an automotive engine and a marine engine.


1st question: What is a gas diesel?
2nd question: What is the difference between an automotive engine and a marine engine (other than the obvious marinisation)?



BarryL said:


> If anyone is interested in some of the mis-information listed above, let me know and I will try and provide an accurate list.


3rd question: Why not provide the list here?


----------



## BarryL (Aug 21, 2003)

*Additional Info*



Omatako said:


> 1st question: What is a gas diesel?
> 2nd question: What is the difference between an automotive engine and a marine engine (other than the obvious marinisation)?
> 
> 3rd question: Why not provide the list here?


Sloppy writing on my part. I meant to write gasoline turbo and diesel turbo.

Gasoline engines are quite different than diesel engines. A gas engine runs at a much lower compression than a diesel engine. A turbocharged diesel engine has a LOT more pressure than a normally aspirated diesel engine. Generally, the higher the compression, the more important it is to accurate control timing, both spark (for gasoline) and valve (both diesel and gas).

Four stroke internal combustion engines, whether gasoline, diesel, alcohol, turbocharged or normally aspirated, all operate pretty much the same. The difference is in the typical use.

For an automotive engine, the typical use is various RPM and load, very rarely running at high load conditions for extended periods of time. A turbocharged automotive engine uses the turbocharger for short periods of high power output. For most of the engine use, such as highway driving, or around town driving, the turbocharger is not producing any power, or putting any load on the engine. When the engine is subject to high load conditions, such as hard acceleration, power to pull a heavy load, or climb a hill, the turbocharger will spin up, provide the extra power, then spin down for more typical highway type cruising.

The typical use of a marine engine is much different. For a boat that is heading from point A to point B, the engine is started in the morning, the transmission placed in forward, the throttle moved to cruising speed, and the engine will then operate at mostly a constant RPM and load. A boat has no hills to climb, stop lights to wait at, or other cars to pass. The turbocharger in a marine engine will be under load the entire time. The turbocharger puts a significant load on the engine, which requires additional maintenance.

Other significant differences between automotive engines and typical marine diesel engines is in engine management. All modern automotive engines are computer controlled. There are sensors for throttle position, engine temperature, exhaust, RPM, ignition, etc. The computer runs the engine in closed loop, constantly adjusting the amount of fuel injected to ensure the engine is running properly, not too rich or to lean. Turbocharged engines, when the turbo is producing power, are intentionally set to run rich. The extra fuel helps to cool the combustion chamber. As soon as the extra load is removed, the engine reverts to running lean for economy.

Marine engines (at least the ones that I am familiar with, which are small auxiliary engines for sail boats) are quite primitive. The fuel injection is mechanical, and there are no sensors to monitor engine performance. Since the marine engine operates in a relatively narrow range, it is easy for the manufacturer to dial in the fuel injection curve so you get adequate performance over the RPM range. A turbocharger requires a different fuel injection map. If you just remove the turbo, without changing anything else, the fuel map is going to be off.

That's about all I have time for now.

Let me know if there are any additional questions.

Barry


----------



## SteveInMD (May 11, 2007)

If you're going to trash out everyone's advice, it would be helpful to say more than to have a mechanic fix it. I agree the fuel map will be out, hence the need to replace the injection pump and injectors, since there's no computer control unit to adjust the map. The power produced by the motor will not be the same, hence the need for a new prop (or pitch adjustment). Other changes that may need to be made are cams, intakes, and exhaust systems.


----------



## tweitz (Apr 5, 2007)

By the way, I would not rely too much on the fact that he brought it from the Bahamas to North Carolina unless you know more about the trip. It is a sailboat. He may have barely used the engine.


----------



## cardiacpaul (Jun 20, 2006)

*hmmmm*

Given the OP's question, it is rather obvious that the background isn't in engine repair. 
This isn't a bad thing, may just not be the OP's cup of tea...
The responder that responded "have a mechanic fix it", was probably more spot on that trying to de-cipher system internals of a turbo vs. non-turbo.

I'm suprised that it ran at all.
If it did, I'll bet it was smokin' like a chimney, and had the power of a one armed kayaker.

Many items are different. this ain't a 5.0 mustang, where you can buy a "kit" for 1500.00 outta the back of a jcwhitney catalog.

*IF* there is a non turbo version of the same engine, pistons, rods, head, valves, cam, fuel system, and exhaust system will be different. Cooling too. Lube systems too. Possibly main and rod bearings... the list goes on. It might not even have the same block. (wet vs dry sleeves, oil passages, yadda, yadda, yadda)

Just saying "have a mechanic look at it" ... period....
is probably the best advise that I've seen on this thread.

the old man used to say... "If i have to take the time to explain it to ya, you can't afford to fix it."



SteveInMD said:


> If you're going to trash out everyone's advice, it would be helpful to say more than to have a mechanic fix it. I agree the fuel map will be out, hence the need to replace the injection pump and injectors, since there's no computer control unit to adjust the map. The power produced by the motor will not be the same, hence the need for a new prop (or pitch adjustment). Other changes that may need to be made are cams, intakes, and exhaust systems.


----------



## SteveInMD (May 11, 2007)

I agree in this is a job for a good mechanic. I take issue with the statement that everything everyone else has posted is rubbish. The goal here is to help the OP understand why a mechanic is required in this case.


----------



## Omatako (Sep 14, 2003)

You know, I had written a long dissertation picking some of what BarryL said to bits but then I thought the better of turning this into a bun-fight. If you have an opinion that is different, Barry, then express it but (and once again  ) I agree with Steve. . . . . .

Make a sweeping statement that "a lot of what has been said above is incorrect" and then providing the magnanimous offer of "If anyone is interested in some of the mis-information listed above, let me know and I will try and provide an accurate list", you're going to elicit a response from me, for sure.

And for the record Barry, a few points on your last so-called "accurate list" are questionable so try to avoid having people put you on their "ignore" list - have some respect.

Sometimes it's good to listen to what others have to say - it allows you to understand the true depth of your own knowledge (or lack thereof!).

And the response "go find a decent mechanic" would actually be correct for *every mechanical thread* posted here so we could all save a huge amount of superfluous chatter by issuing one-line responses. But geez, would it make this forum boring.


----------



## harryrezz (Dec 10, 2003)

If thye boat itself is what you want and is in good shape check it's fair market value IF IN GOOD CONDITION. Then offer that price LESS the cost of a new engine. That way you'll be covered and can afford to simply pull out that Yanmar and replace it. 
Turbo diesels are great if properly maintained ... which this one clearly wasn't. If the maintenance was bad enough to blow two turbos it was probably bad enough to have caused some other damage as well.
If they don't take the deal, walk away and find another boat.


----------



## bennyd10 (Mar 26, 2008)

*Thanks*

Thanks for the crash course in turbo diesels! I have talked to three or four mechanics and hired the one most recommended who owns the yanmar distributer in town. Sounds like this is the best course of action.
The crazy thing is, I went down to the boat with a mechanic today and got to fire the boat up and run it with him. It ran great! No blue smoke, no black smoke... ran it for a while, then ran it in gear at 2000 RPM... ran great. revved up to 2400, no black smoke. 
The mechanic that I have hired for Thursday said that if the engine was run below the 2800 to 3500 range where the turbo "kicks in" then the fuel levels wouldn't be very much different, turbo or not. Another mechanic at the same shop just got finished telling me that the cylinders would be polished and wasted from carbon deposits after 10 to 15 hours of running without the turbo functioning. I guess it goes to show that there will be differing opinions on this... I am having the owner/mechanic at the yard come over and take a look in person and give me his opinion... 
I also got to talk to a third party guy who was on the boat when they brought it back and he told me they were running 2200-2500 RPM's which has me hopeful that no major damage was done... I intend to replace the blown turbo unit if the engine seems sound. The mechanic said it would be cheaper/better to do this than to change out the engine to non-turbo. The main cost with this is the injection pump. I am not a mechanic and am passing this info on as accurately as I remember...
Sounds like the boat sails great in any case!!! We get to take it out on Wednesday! This is a Bayfield 36... I don't think I mentioned that. 
Thanks again!
Ben


----------

