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MAN D2848 LE403 intercooler removal

Discussion in 'Engines' started by kev cribb, Oct 4, 2022.

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  1. kev cribb

    kev cribb New Member

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    Hi all
    Just wondering if anyone has a MAN engine book with instructions for the intercooler removal on the above engine.
    I have developed an air temp alarm and have been led to believe that it could be a sensor or that my inter cooler needs cleaning. It would appear the engine is also missing so want to get the injectors looked at. To do that I need to remove the inter cooler but not sure where to start. Any help would be good thanks
  2. ChiTown

    ChiTown Member

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    The Manuals are available on boatDiesel.com
  3. BigChief

    BigChief Member

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    Been there done it... raw water comes in and out from the sides of the cooler, take some pics the raw water side plates are off set. The intake tubes from the twin turbos come from the rear. The front of the cooler is bolted to the intake manifold. I don't recall if the heat exchanger is in the way or not as we removed it at the same time. Over all its pretty simple but it's solid bronze and heavy. Use black RTV on re assembly and you should be fine.
  4. mapism

    mapism Senior Member

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    "Been there done it" specifically with a V8 LE403?
    The CAC looks similar in all MANs, but some are actually much simpler than others.

    Anyhow, everything is simple when you know what to do.
    But to put it bluntly, I wouldn't want someone who neither has a repair manual nor any previous experience to touch the CACs of my boat, which happens to be powered by the very same engines.
    They are in fact rather peculiar, divided in two sections (raw water+engine coolant), the latter regulated by a flow governor.
    As a result, the very first step for removing the CAC is draining the engine coolant, and the second is remove the whole heat exchanger.
    At that point, you've yet to start touching the CAC - go figure.

    All that said, if the OP is confident enough to take the DIY route for such job, if he sends me a PM with his mailbox address I can send him the PDF file of the repair manual, together with my very best wishes, because I think he'll need some! :)
  5. mapism

    mapism Senior Member

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    Typo: it's the former, not the latter.
  6. BigChief

    BigChief Member

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    If you're a pretty handy guy it's not that difficult of a job. I have done the after coolers (CAC) and heat exchanger bundles myself with a friend On the V10 version. However i have no knowledge about the injectors. Your era V8 V10 and V12 coling systems are very similar in design. If you are just cleaning the aftercooler its all raw water in that side of the cooling system. You should not need to worry about engine antifreeze unless you open the heat exchanger antifreeze lines to remove the core bundle. If that is your plan then drain it first. The manual of course will be helpful. I'm not here to be an expert and I'm not going to debate Others who may or may not know what they're talking about.
    I hope my past experience will help you good luck.
    Some pics will help others like yourself if you do the job.
    Last edited: Oct 5, 2022
  7. mapism

    mapism Senior Member

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    BigChief, which part of "The CAC looks similar in all MANs, but some are actually much simpler than others." was unclear, in my previous post?
    If when you say that all cooling system are very similar in design you mean that they are all painted in white, I'm not disagreeing.
    But have a look at the schematic diagram of the D2848 LE403 cooling system in the attached file.
    It isn't specifically mentioned in the legend, but if you look at the CAC (#6) you can easily see that it is internally split into two sections.
    The larger and upper one (I mean, upper looking at the diagram - in flesh, that's towards the engine front) is for raw water, and the smaller one is for the engine coolant, as you can understand by the pipes connected to each section, as well as the arrows showing the flow direction.

    Neither am I, but just in case you wonder how I know what I'm saying, aside from having read the manual, here's a hint with a photo.
    No prize for guessing which section circulates raw water (above 1100/1200 rpm only) vs. engine coolant (regardless of rpm).
    [​IMG]

    Attached Files:

    Last edited: Oct 5, 2022
    NavalArch07 likes this.
  8. mapism

    mapism Senior Member

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    I forgot to mention earlier: you can actually pull all injectors without removing the CAC.
    For some of them, it does help not to have the CAC pipes in the way (rather than the CAC itself, which doesn't interfere with the injectors at all), but it's possible to reach them anyway.
    Last edited: Oct 5, 2022
  9. BigChief

    BigChief Member

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    If you have pics you should post them as there is so little info on the AC and HE service.
    That pic explains a lot and a good reference. A skilled set of hands can easily perform the service in either engine systems.
    I hope the OP will post some pics if he does do it himself.
  10. kev cribb

    kev cribb New Member

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    Watching what I have caused with some interest. Thanks for all the positive replies. I do a lot of work on my engines and have stripped and rebuilt a few although mostly Volvo and not MAN engines. Hence looking for advice and guidance here. I have a lot of manuals but appeared to be missing the one which explained removing the inter cooler.

    I just really want the simplest way from experience to clean out my intercooler on these beasts. Can the tube stacks be removed in situ for instance or cleaned without removing them. The injectors the local mechanic will be used so he can service them as well. But great news the intercooler doesn’t need to come off to reach them all.
    As previously stated does anyone know a price or part number for the charge air sensor which I may swop first. Rather than go through all this or just get one anyway.
  11. mapism

    mapism Senior Member

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    There's a round tube bundle inside the large aluminum box in the upper part of the engine front (the one with the embossed writing "MAN marine diesel"), but that's the coolant heat exchanger.
    No such thing on the intercooler, which is a solid bronze block - as you can see in the photo I posted above.

    I just checked the MAN parts schematics, but weirdly enough the charge air temperature sensor is missing, so I'm unable to give you its part number.
    Maybe that has something to see with its somewhat hidden placement, I'm not sure.
    Anyhow, you can find it under the right side of the CAC elbow, and maybe there's some code stamped on it, if you look carefully.

    That said, in which conditions does your air temp alarm go off exactly?
    Does it happen after running for some time at or just above idle, possibly in a hot climate, but it goes away if you accelerate?
    If so, that's somewhat normal for these engines, and it has to see with the peculiar intercooler that doesn't circulate raw water at low RPM.
    OTOH, if it goes off at cruising speed (anywhere from 1600 to 2000 RPM), there's definitely a problem, but I don't think the sensor is the culprit.
    An obvious option is a clogged CAC (how long ago was it cleaned last time?), but there's another possibility.
    Sometimes, the round valve on the left side of the CAC that MAN calls "Flow Governor" gets stuck.
    And if this happens, it doesn't send any raw water inside the CAC, as it's supposed to do as soon as the turbo pressure builds up.
    You can check if this valve is stuck by releasing the screw that holds the connecting pipe in place, and push the diaphragm inside with a screwdriver.
    If it doesn't move, or it takes a somewhat relevant effort to push it, THAT is the real problem.
    In fact, even if I'm not sure of what exactly did you mean by "engine is also missing", pretty sure if the air the engine is breathing isn't as cool as it should, also its overall performance is affected.
  12. Capt Ralph

    Capt Ralph Senior Member

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    Your going to call these kids for your O rings anyway;
    https://www.performancediesel.com/
    They will need your serial number and will offer support and parts.
    They probably imported, sold, installed the package and warrantied it originally.
  13. kev cribb

    kev cribb New Member

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    No such thing on the intercooler, which is a solid bronze block - as you can see in the photo I posted above.
    Now I am confused if there are no tubes to clean inside the intercooler what is that in your picture ?
    Or is this a play on words inter cooler = CAC
  14. mapism

    mapism Senior Member

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    Intercoolers are also called charge air cooler, which is where the CAC acronym comes from - 100% synonyms.
    The brick shaped bronze thing in my previous photo is exactly that: a 2848 LE403 intercooler, removed and opened up.

    Here's a couple of other photos to better show the difference with heat exchangers.
    In this one, you can see the HE boxes with their tube bundles pulled out.
    The smaller tube bundles in between the larger ones are from the gearbox HE, and have nothing to see with the engine as such.
    [​IMG]

    Here you can see the intercooler instead: same thing as in the previous detailed photo, but visible together with its connecting pipes, both on the liquid and air sides.
    I also circled in red the air temp sensor I previously mentioned, 'cause its placement is somewhat hard to notice unless you know what to look for - though I still suspect that your problem is more likely to be triggered by a stuck flow governor, which is the round valve just on the right of the red circle.
    [​IMG]
  15. mapism

    mapism Senior Member

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    Just for further clarification: the intercooler tubes indeed are supposed to be cleaned periodically.

    When I said "no such thing" as the HE tube bundle, I was only replying to your question on the possibility to remove the tube bundle alone without removing the CAC, which doesn't make sense because the tube bundle is the CAC itself, in one single piece.

    BTW, pulling only the tube bundle without removing the rest can be impossible also with the HEs, because the tubes are rather long and they must be pulled out perfectly straight.
    This requires a space around the engines which normally just doesn't exist, on twin engines installations.
  16. kev cribb

    kev cribb New Member

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    Ah all clear now. I will start with the stuck flow governor and try that first. As you say I will notice if it moves or is indeed stuck.
  17. kev cribb

    kev cribb New Member

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    To clarify some points
    The boat hasn’t been used that much over the last 4 years due to covid and other things but has been started regularly and run for a period of time with no alarms. Last week we ran over to a boat yard some 4 miles away to be lifted out for cleaning anti foul anodes and polish. So I know the bottom is clean.
    On the way back we ran at about 1100 rpm for a while and then increased speed at about 1500 rpm the port air temp alarm sounded so we backed off and it stopped. A short time later after increasing speed again it went off again.
    We then ran on just one engine stbd and it was fine. Port felt lumpy as if it was missing. We continued back to port at low revs and no more alarms.
    The injectors and any tubes haven’t been cleaned in about 4 years and I know that not running these beasts is not the best. But it couldn’t be helped.
  18. kev cribb

    kev cribb New Member

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    If the flow governor is the culprit can it be removed and cleaned
  19. Capt Ralph

    Capt Ralph Senior Member

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    If a cylinder intake valve was stuck open, could cause these issues. A lung may be pushing compressed air back into the air intakes. Wish you would have mentioned this earlier.

    Frak, Just noticed Gibraltar.
  20. ChiTown

    ChiTown Member

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    I vaguely remember there being a service notice on the flow governor for low speed operation to ensure there was adequate flow at low speed thru the CAC? Something about a notch being properly sized on the valve gate? It was addressed by the service company when we had the entire cooling system cleaned, machined (o ring seats) and updated. Subsequently we did have an alarm once while doing some extended low speed operation, but called into the service provider (Demann) and I believe ran a bit higher rpm and then cleared the alarm,. It has never come back.