VW diesel marine conversions

Discussion in 'DIY Marinizing' started by moTthediesel, Apr 6, 2006.

  1. AShley5031
    Joined: Aug 2010
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    Location: Brazil

    AShley5031 Junior Member

    VW Marinized diesel

    Ok people, thanks for helpful suggestions from CDK, Baeckmo, Jonr, Petros and Thudpucker

    Here is what I did today in light of your suggestions. I tested the thermostatic valve in a pan of water and tested the temperature with a laser thermometer. It opened at 85 degrees. I did this a couple of times and then fitted it back into the freshwater pump housing. I then filled up the system with water again, tried to get the air bubbles out by squeezing the hoses, and started her up.

    So far so good, the thermostatic valve opened up at 85 degrees and the water circulated correctly in the cooling system on both the fresh as well as salt water side. There was a temperature differential between both sides of the heat exchanger, 70 going in and around 55 going out, so difference of 15 degrees or so (Retipar said it should be 16) so that seems OK.

    BUT, and here is the problem, I pointed the laser thermometer at all four fuel injectors. The one nearest the front of the block, where the timing belt flywheel is, was the coolest at 45 degrees, and I shall call this number 1. Number 2 was hotter at 55 degrees, Number 3 was around 60 BUT number 4 was wopping 100.5 degrees. This being closest to the heat sensor, it set of the overheating alarm. So I turned off the engine.

    From Petros’ comments, it seems highly likely that there is an air bubble somewhere inside the block or the head, so I suppose the answer would be to take off one of the connections that feed the fresh water into the head. There is one almost in the middle, and there is another one right at the end, which also houses the heat sensor.

    I suppose that I should bleed it cold, to avoid getting scalded, but I really wonder whether this is the problem. The mechanic who helped me today, Brazilian, said that he thought it highly unlikely that the air bubble would stay in the system once the engine had been running for a while. This time the engine ran for ten minutes before the heat alarm went off. He is of the opinion that there is a crack in the block, but then I had this tested, and the company said that it was OK. But then in Brazil, it is difficult to trust anyone.

    I should add that there was some diesel oil leaking out of number 4 injector, which eased somewhat after tightening. Perhaps I should put some sealant compound on the injector thread, I have a silcone compound which says that it is good up to 315 degrees. Anyway, could this leaking fuel have been the cause of the overheating in number 4? I think it unlikely but I thought I would mention it anyway.

    Any thoughts anyone? Should I try and bleed the head cold by removing one of the cooling connections?

    Any other suggestions…I seem to be making some progress at least.
     
  2. AShley5031
    Joined: Aug 2010
    Posts: 29
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: Brazil

    AShley5031 Junior Member

    Ok people, thanks for helpful suggestions from CDK, Baeckmo, Jonr and Petros.

    Here is what I did today in light of your suggestions. I tested the thermostatic valve in a pan of water and tested the tempertaure with a laser thermometer. It opened at 85 degrees. I did this a couple of times and then fitted it back into the freshwater pump housing. I then filled up the system with water again, tired to get the air bubbles out by squeezing the hoses, and started her up.

    So far so good, the thermostatic valve opened up at 85 degrees and the water circulated correctly in the cooling system on both the fresh as well as salt water side. There was a temperature differential between both sides of the heat exchanger, 70 going in and around 55 going out, so difference of 15 degrees or so (Retipar said it should be 16) so that seems OK.

    BUT, and here is the problem, I pointed the laser thermometer at all four fuel injectors. The one nearest the front of the block, where the timing belt flywheel is, was the coolest at 45 degrees, and I shall call this number 1. Number 2 was hotter at 55 degrees, Number 3 was around 60 BUT number 4 was wopping 100.5 degrees. This being closest to the heat sensor, thus set of the overheating alarm. So I turned off the engine.

    From Petros’ comments, it seems highly likely that there is an air bubble somewhere inside the block or the head, so I suppose the answer would be to take off one of the connections that feed the fresh water into the head. There is one almost in the middle, and there is another one right at the end, which also houses the heat sensor.

    I suppose that I should bleed it cold, to avoid getting scalded, but I really wonder whether this is the problem. The mechanic who helped me today, Brazilian, said that he thought it highly unlikely that the air bubble would stay in the system once the engine had been running for a while. This time the engine ran for ten minutes before the heat alarm went off. He is of the opinion that there is a crack in the block, but then I had this tested, and the company said that it was OK. But then in Brazil, it is difficult to trust anyone.

    I should add that there was some diesel oil leaking out of number 4 injector, which eased somewhat after tightening. Perhaps I should put some sealant compound on the injector thread, I have a silcon compound which says that it is good up to 315 degrees. Anyway, could this leaking fuel have been the cause of the overheating in number 4? I think it unlikely but I thought I would mention it anyway.

    Any thoughts anyone? Should I try and bleed the head cold by removing one of the cooling connections?

    Any other suggestions…I seem to be making some progress at least.
     
  3. AShley5031
    Joined: Aug 2010
    Posts: 29
    Likes: 1, Points: 0, Legacy Rep: 18
    Location: Brazil

    AShley5031 Junior Member

    Additional info on VW diesel

    Just an added thought, which I had forgotten, a propos Baeckmo, there are no coolers for any of the oil, either in the engine or the gear transmission. Just fresh and salt water cooling systems for the engine as described. Really quite crude, which I why I find it so hard to see why the problems are persisting in such a simple system. By the way, apart from the overheating around Number 4 injector, everything elso was fine, and the temperature gauge remained steady at under 80...around 76. But the alarm sensor went off all the same. Really weird.
     
  4. Petros
    Joined: Oct 2007
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    Location: Arlington, WA-USA

    Petros Senior Member

    The fact that the back of the head is running hotter means only one thing; there is no coolant circulating there for whatever reason. Most engines have the cooled water from the bottom of the radiator, get sucked through the pump and enter the engine low on the block around the cylinders. From there it pushes up past the head gasket into the head, and than flows around the combustion chambers, ports and valves to the outlet near the top of the head (usually at the front of the head in the older engines, can be anywhere on the head of the newer engines), and than back to the top of the radiator.

    So either you have a large air bubble trapped in the head at the number 4 cyl location, or something is blocking the water from circulating there. The wrong type of head gasket can cause this, but it appears to me it is an air bubble. This is exactly what happened to my old Mercedes, the circulating coolant did not force the air out. I had to bleed that part of the head.

    One thing you can do is see if you can tilt the engine to allow the air bubble to go out the inlet (or weigh front of the boat enough to get the water jacket in the head level). The other might be to feed a small tube in from the outlet to the area where air might be trapped and allow it to vent out, or even fill it through the tube.

    It likely is the way the engine is installed so the back of the head is higher than the outlet, trapping the air. In the car install it was level and did not trap the air. It would not be difficult to drill a hole in the high point of the water jacket on the head and install a bolt to allow it to bleed when you fill it. I would not do that unless you have a sample to head to examine exactly where to drill it. You also might find a factory plug or fitting nearby that will allow you to bleed out the air.

    once cylinder running lean because of a fuel leak should not affect temp on a diesel (this is not true in a gasoline engine, lean means runs hot). It will mean that that cylinder will produce less power than the other three, so it might run rough, but I do not think it will affect anything.

    Just so you know, a lifetime ago I designed the water jacket and cooling system that went on a 900 hp race car (a factory sponsored team). Getting the coolant to circulate evenly to all parts of the engine, especially the head around the combustion chambers, is critical to preventing overheating. We actally improved the cooling of the head over the factory Nissan engine. The car was undefeated in the IMSA race circuit back in the 1980's
     
  5. AShley5031
    Joined: Aug 2010
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    Location: Brazil

    AShley5031 Junior Member

    VW marinized diesel

    Thank you Petros. Actually the engine is at an angle so that the part of the block that is hottest is lower. The slope is around 15 degrees. The end of the engine connected to the propeller transmission is lower than the end connected to the water pump and timing belt. So you would have thought that the bubble would come out by itself. I think my best bet will be to take off the connection at the back of the block and fill the block up with water from there with a siphon tube. This is not the highest point on the block though. One would have thought that the air bubble, if that is what it is, would be at the highest point, which is precisely the coolest end.....weird.
     
  6. AShley5031
    Joined: Aug 2010
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    Location: Brazil

    AShley5031 Junior Member

    VW marinized engine

    One thing further Petros, the gasket simply can't be wrong, it is an original VW part with the correct part number proscribed in the manual. By the way, sounds like you had fun in the racing world. I am ex-British army, former Lt in the Blues and Royals, a lifetime ago. I moved to Brazil about 15 years ago.

    But one has time to breath in Brazil, quality time, and that means time for sailing, learning the piano...etc. I never had that luxury in England. Here I am a freelance translator in the financial markets, working wherever I have my laptop, be it on the boat or up in my cabin in the mountains!
     
    Last edited by a moderator: Aug 27, 2010
    1 person likes this.
  7. dskira

    dskira Previous Member

    Ho yes, their marine engine came in the US. With a extremely high price tag. I don't know if they continue the distribution, they seams to have fade away.


    Daniel
     
  8. baeckmo
    Joined: Jun 2009
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    Location: Sweden

    baeckmo Hydrodynamics

    Ashley, good job with the IR thermometer! The water is distributed in the cylinder block through calibrated openings from a manifold channel. It seems that the openings for the no 4 cylinder are blocked. You say this is the lower end of the engine ok? Then I suggest that the problem is debris collected in the cooling area around this cylinder. I understand you are in Brazil, and never worried about freezing; could it be that you have no additive in the fresh water, such as glycol with a rust inhibitor? If yes, then there are corrosion products in your fresh water cirquit.

    Off with the head again and clean out the block, watch out for forgotten rags and dead frogs! Good luck!
     
  9. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Make a slender stainless tubing out of an old brake line.
    Connect that to an air hose, and to some water.
    Poke it way down the holes into the block and run the Air/water hose down that same hole .
    It will crackle and Pop loudly, but the flakes of rust etc will break up and come flowing out.

    Use a small (Ultrabrite LED) lite to make sure you got it all.
     
  10. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    No chance that will work, Thudpucker.
    The coolant entry point is a flange between cyl. 2 and 3 in the head; the brake line cannot follow the 90 degree angles.
    Besides, debris drop in the block and end up in the water pump where a plastic impeller is waiting.

    I'm afraid Baeckmo's solution is the only correct one.
     
  11. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    I'd take the head off and then pressurize the cooling water passages and make sure that the flows out of the block are all symmetrical. Then do something similar with the head.
     
  12. AShley5031
    Joined: Aug 2010
    Posts: 29
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    Location: Brazil

    AShley5031 Junior Member

    VW Marinized diesel

    Hi Baeckmo,

    Well I have pretty much ruled out the air bubble idea, because the freshwater intake is fitted with a bleed line which goes back to the cooling reservoir thus maintaining pressure, precisely to bleed out any air trapped in the block. But just to be sure, I tookoff the hose and, yes, it is full of water, and no air. As the block has just been cleaned and reconditioned, the water passages in it should not be blocked. So that means that it really has to be some kind of blockage within the block, according to your reasoning, which makes perfect sense. So off with her head, again, to misquote Henry VIII!
     
  13. AShley5031
    Joined: Aug 2010
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    Location: Brazil

    AShley5031 Junior Member

    Just a last desperate thought...what about putting in some radflush to see if that loosens up anything?
     
  14. AShley5031
    Joined: Aug 2010
    Posts: 29
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    Location: Brazil

    AShley5031 Junior Member

    VW marinized diesel

    One last observation worth mentioning Baeckmo, the hotspot of 100.5 degrees is ONLY ON THE INJECTOR. The areas around No. 4 cylinder and the end of the block are relatively cool. So I am wondering why the heat should be concentrated JUST IN THE VERY SMALL AREA and not around the cylinder jacket as a whole
     

  15. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    I forgot to mention that kind of work has to be done with the head off. Sorry!
    You'd almost have to tip the block so the debris would run out by itself too.

    I had two VW Rabbits. The Diesel didn't give much trouble at all, but had no power. The Gas was a pile of problems but it would scoot right down the road.
     
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