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  1. #1
    Seaman Apprentice GSB Cruiser's Avatar
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    Default How do you know if the turbo on diesel is working full force?

    I have been noticing a reduction in performance with my diesel and i suspect a few causes. I think i may have a too high of pitch wheel and im sure there is some growth on the bottom. Also the diesel fuel in my tank is from last season. However, I have also noticed that I dont hear as high as a whine from my turbo as I used to. It is an '89 motor and i think it may be the original turbo. Is there anything I can do to see if the turbo is working right? I get a lot of blow-by and a lot of oil goes into the turbo. I took the air cleaner assembly off and looked at the rotor and it was very oily but it spun freely.

    Basically i have a lot of problem getting outa the hole but once up to speed it cruises ok, but sometimes I even have trouble getting the motor to run up to the 3800 rpm it's supposed to top out at.
    If I'd never seen the sunshine I would not curse the rain.

  2. #2
    Moderator QC's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by GSB Cruiser View Post
    I have been noticing a reduction in performance with my diesel . . . I have also noticed that I dont hear as high as a whine from my turbo as I used to. . . I get a lot of blow-by and a lot of oil goes into the turbo . . . looked at the rotor and it was very oily but it spun freely.
    1) Turbos are basically passive devices. They spin as fast as the exhaust you shove through them. When a turbo ain't "whining" the engine is probably not getting as much fuel as it needs or the load is too high (your bottom condition) to get the thing (engine) spinning hard enough to get the turbo spinning.

    2) Oil in the "rotor" (compressor wheel aka cold side) is really baaaaaaaaad. If you get enough flowing they can suck themselves dry and even run away Really baaaaaaaaaaad!!!!!

    3) I think you need to clean the bottom, reseal the turbo, check for cause of high blow by, and stop running her NOW!! She is trying to tell you she is sick and it is not because of a lack of boost pressure, although a fresh turbo could give you more air, I suspect a lot more issues . . . Sorry to be so emphatic, but a leaky oil seal on the cold side can pack an aftercooler full of oil and when the aftercooler gets full they go sky high before you can even get out of the wheel house. The key means absolutely nothing in this situation and the ONLY fix is a big block off plate stuck over the air intake. Oh, oh, and do not approach one like this from the side, that's where they chuck stuff

  3. #3
    Supreme Mariner Silvertip's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    And add boost pressure and exhaust gas temperature gauges.

  4. #4
    Seaman Apprentice GSB Cruiser's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Thanks for the info guys,

    QC....The reason there is so much oil in the cold side is because the way my motor is set up (like this when i got it) is the hose that the blow by shoots out of is aimed right into the air cleaner. When I first got the boat i was going through air cleaners fast so I made a catch can in line with that hose, but some oil still makes its way into the air supply. I have talked to mechanics and they said that is the way it is supposed to be set up, but they didnt know why there was so much blow by and pressure. If I take off the oil cap right after a long run there is so much pressure!

    I understand your warnings about the run away, but I'm pretty sure that is where the oil is from in the cold side. Do you think I can just run the motor for the season as is and get the turbo reconditioned over the winter? If I do that now, I will lose weeks out of the summer.
    If I'd never seen the sunshine I would not curse the rain.

  5. #5
    Moderator QC's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    What engine is this? Sounds like a 3208. Yes, blow by oil is different than the runaway concern. You are still thinking turbo and I think the turbo is indicating other issues, e.g. low fuel flow.

    Silvertip is right about a boost gauge, but the fact is we watch boost gauges to indirectly indicate fuel flow. Fuel burns, makes exhaust, turns turbo, packs air, burns more fuel, makes exhaust, turns turbo faster, more boost, more fuel . . . etc. etc. etc.

    It is very common for people to think turbo for more performance, but
    basically they either spin or they don't or they have pieces missing, the last one will turn into the second one real fast . . . I think you need to be thinking a diesel tune up along with the hull work. If it's got decent oil pressure and temps are right, you're probably not hurting it . . .

  6. #6
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    He's got a Volvo AD41-A. It's not going to run away, but it will start leaking oil out onto the starter out of the intercooler.
    You need to get the turbo rebuilt or replaced. It really kills performance when the bearings slow it down.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  7. #7
    Seaman Apprentice GSB Cruiser's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Thanks for the replies guys. I'm going to see if I can get the exhaust elbow off on the other side of the turbo and inspect the blades on that side. I'm also gonna get some fresh fuel in the tank and see if that helps. The filters are brand new, that's why I didnt suspect them.

    P.S. I don't have a blower installed in my engine compt. I was told that I needed one to get more much needed air to my diesel. Alls I have now are those in and out vents on the deck. Should I consider getting one?
    If I'd never seen the sunshine I would not curse the rain.

  8. #8
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    Default Re: How do you know if the turbo on diesel is working full force?

    EGT gauge is the best thing you could ever do to a turbo engine. it will tell you weather you are running lean or rich. you overheat that turbo a couple times from running it too lean and you're going to be sorry. A boost gauge is good, but not nessesary unless you are just curious to see what the boost is. The waste gate will regulate the boost unless you put a boost controller on it and you don't want to do that unless it's running up to par... Hope all of my mid 90's turbo ricer knowledge helps out with your boat. LOL!!

  9. #9
    Senior Chief Petty Officer
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    Default Re: How do you know if the turbo on diesel is working full force?

    If you have a turbo and are interested in performance, educate yourself in the ways of turbos. There are many automotive turbo sites on the web, and turbos are turbos the world around. The guys that know turbos have all kinds of tweaks and mods to enhance performance;most, if not all, can be done by a STM. My turbo 4 banger Rampage eats stock Mustangs all day long.

  10. #10
    Moderator QC's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by fourwinnsdook View Post
    EGT gauge is the best thing you could ever do to a turbo engine. it will tell you weather you are running lean or rich. you overheat that turbo a couple times from running it too lean and you're going to be sorry. A boost gauge is good, but not nessesary unless you are just curious to see what the boost is. The waste gate will regulate the boost unless you put a boost controller on it and you don't want to do that unless it's running up to par... Hope all of my mid 90's turbo ricer knowledge helps out with your boat. LOL!!
    It will not help because this is a diesel, waaaaay different. Diesels run lean most of the time, and run cooler EGTs when doing so . . . they are supposed to . . . That's one of the super duper things about them. The only time that a diesel is too rich is when they are blowing a column of black smoke, which will also probably not hurt it although EGT will be up . . . Actually with diesels we are getting away from Pyrometers and still recommending boost gauges . . .

    Don,

    I am surprised you have determined his turbo is dragging without more info. and how did you know his engine model? Seems you are recommending part swapping without data, one of your cardinal rules, no? Also, what about air intake piping leaks, aftercooler housing leak, exhaust leaks, low fuel rates, timing and yes, also a dragging turbo will cause low boost. In my experience dragging bearings fail, but you definitely have more experience with Volvos. No disrespect intended, but your response seems out of character . . .

    Edit: Ahhh, I see the engine model in previous threads now.

  11. #11
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    Default Re: How do you know if the turbo on diesel is working full force?

    Yea, i don't know much about diesels, and as far as turbo performance goes it is endless on the possabillities of horsepower that a well tunned turbo can provide. I used to have 95 eagle talon turbo that ran 11's in the 1/4 mile. Not impressed...? it's a 2.0L engine.

  12. #12
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by GSB Cruiser View Post
    Thanks for the info guys,

    QC....The reason there is so much oil in the cold side is because the way my motor is set up (like this when i got it) is the hose that the blow by shoots out of is aimed right into the air cleaner. When I first got the boat i was going through air cleaners fast so I made a catch can in line with that hose, but some oil still makes its way into the air supply. I have talked to mechanics and they said that is the way it is supposed to be set up, but they didnt know why there was so much blow by and pressure. If I take off the oil cap right after a long run there is so much pressure!

    I understand your warnings about the run away, but I'm pretty sure that is where the oil is from in the cold side. Do you think I can just run the motor for the season as is and get the turbo reconditioned over the winter? If I do that now, I will lose weeks out of the summer.
    If you think the oil is coming off your blow by return, why don't you install a oil catch can or an oil cyclone.

    All My SC'ed and Turboed motors have an oil catch installed on the blow by return to prevent oil entering the air system.

    My NA BMW M5 has oil cyclones that are gravity powered to pull the oil out of the blow by system.

    As far as the turbos health, is there any side to side play in the main shaft? If so the bearings are getting worn. There should be no play in the shaft and it should spin freely by hand. Just pull the front hose off and check.

    Just my .02

    -Ryan

  13. #13
    Moderator QC's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by rdm190 View Post
    If you think the oil is coming off your blow by return, why don't you install a oil catch can or an oil cyclone . . . As far as the turbos health, is there any side to side play in the main shaft? If so the bearings are getting worn. There should be no play in the shaft and it should spin freely by hand.
    Totally agree on both points.

  14. #14
    Seaman Apprentice GSB Cruiser's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by rdm190 View Post
    If you think the oil is coming off your blow by return, why don't you install a oil catch can or an oil cyclone.

    All My SC'ed and Turboed motors have an oil catch installed on the blow by return to prevent oil entering the air system.

    My NA BMW M5 has oil cyclones that are gravity powered to pull the oil out of the blow by system.

    As far as the turbos health, is there any side to side play in the main shaft? If so the bearings are getting worn. There should be no play in the shaft and it should spin freely by hand. Just pull the front hose off and check.

    Just my .02

    -Ryan

    I have already installed a catch can. I'm not sure it is done correctly though. I have the hose going into a gallon size plastic bottle with a smaller 1/4" hose coming out of it that goes back up and aimed at the air cleaner.

    I am going to check for play in the shaft today. I guess I'll just pull of the air cleaner and reach in and pull on the rotor?
    If I'd never seen the sunshine I would not curse the rain.

  15. #15
    Moderator QC's Avatar
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    Default Re: How do you know if the turbo on diesel is working full force?

    Quote Originally Posted by GSB Cruiser View Post
    I am going to check for play in the shaft today. I guess I'll just pull of the air cleaner and reach in and pull on the rotor?
    The shaft is actually part of the turbine wheel (hot side). The turbine and shaft are one piece and the compressor wheel is attached by a nut to the threaded turbine wheel/shaft . . . Remove the piping as close to the compressor housing as possible. You should be able to easily spin the shaft and feel any end play.

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