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  1. #1
    Join Date
    Dec 2011
    Location
    San Jose del Cabo, MX, Osprey, FL
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    363

    Default Getting closer on the coolant leak

    Boat has been sitting dry for several months. I came down to find the ongoing coolant leak, which, as discussed in previous posts, I thought for sure would be the heat exchanger. Pressure tested the system, very slowly lost pressure but nothing seemed to be happening in the heat exchanger. Pulled the plugs and found #2 plug very wet with antifreeze. Compression checked and found #2 and #4 way higher than in the past. Stuck a rolled up paper towel in #4 and found antifreeze there as well. I suppose it could have dripped down from a failing gasket between the exhaust manifold and the elbow but I would expect to find it in #4 and #6, not way foward in #2.

    Or it could be a cracked head or blown head gasket. I will pull it apart tomorrow and see if I can see anything. Any guesses or advice? Maybe I should start a pool.

  2. #2
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    Sep 2008
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    Default Re: Getting closer on the coolant leak

    sorry to hear that....

    the normal installation angle usually fills the manifold from flywheel to balancer so it sounds painful....

  3. #3
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    363

    Default Re: Getting closer on the coolant leak

    Hi Mark,

    It looks like only you and I have any interest in this thread so I thought I would bring you up to date on the latest, and on my confusion. I pulled the elbow and found plenty of evidence of DexCool inside the exhaust manifold (red crystals), although most were in the passageways to #8, #6 and some #4. The one to #2, which was the cylinder with the most coolant in it when I took out the plugs was carboned up nicely and had little coolant evidence. ??? First mystery.
    At this point I was tempted to put in some new gaskets under the elbow and put it back together as the evidence seemed to indicate that the leak must be coming from above. Since the system leaks I doubt it builds pressure. I put air pressure on it when I tested it and that could have squirted coolant down to #2 where as in normal operation it dribbles down the other way. Anyway that could be the story. But I was concerned that while the gasket on the coolant side of the divider did split upon removal (as these new graphite gaskets do) there was no evidence of coolant anywhere on the gasket. So was that the source of the leak? And later I saw that the valve stems looked perfect, which means I was not getting salt from the same gasket complex.
    But I had a rebuilt head that has been in the garage for several years and a new gasket set, so I decided to press on and look inside. When I got the head pulled the gasket looked as perfect as I have ever seen. No evidence of leaking around the cylinders or water passages. #2 piston looked pretty good, some carbon and what seemed to be some cleaner areas on the bottom side, like maybe water washing. Ditto for #4 and #6, although there was some general crud that would indicate (perhaps) oil burning and my consumption has gone up the last 200 hours. #8 was fully carbon coated and no sign of coolant stain (even though that was the exhaust passageway that had most of the crystals.
    Head story was a little different. Lots of red stain in #2. Ditto for #4 and #6, although also considerable crud that indicate oil burn. #8 looked very normal with carbon and a very small area of red.
    I've gone on too long as most of this stuff is contradictory. Maybe it will light a bulb for you.
    So my plan is this. I put the new head on and will send the old one to the head shop. They will check for cracks and do a rebuild so my garage spare will be back if it is OK. I will pressure test the exhaust manifold (once I figure out just how to do that) to insure that the very unlikely case of leaking coolant though a hole or crack in that thing is not the issue. I will clean up the surfaces between the manifold and the elbow and reinstall. I have the same gasket set I used last time (the graphite ones) and I know they go on dry. But if that was really the failure I am tempted to try a half torque with hi temp RTV and then a full torque the next day. Bad idea? I hate to do the same thing as last time knowing I was losing a gallon a trip of coolant.
    Any other suggestions from you (or anyone else that might chime in) would be welcome. I will probably put the intake manifold/fuel system on tomorrow, along with a new raw water pump. Test the exhaust manifold over the weekend and if good install on Monday. Refill with coolant, change the oil and splash on Tuesday. I hate putting it back together without knowing for sure I fixed it, but I don't have any better ideas.

  4. #4
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    Sep 2008
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    Default Re: Getting closer on the coolant leak

    Tough one John.....usually when coolant gets in the cylinders, it cleans them out pretty well.

    I'd suspect the manifold/elbow gasket as most likely with maybe a crack in the cooling jacket on the manifold next...as far as testing the manifold, caps on the fittings and a plate on the outlet is the usual approach I use....you need a fitting to pressurize the water jacket in one of the block off points....

    I don't think the RTV will stick to the graphite gaskets....

    Any idea what the red stain was from....I've seen some things that fit that description and as best I could tell, it was from some fuel additive..

  5. #5
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    363

    Default Re: Getting closer on the coolant leak

    Hi Mark,
    Doesn't look like I can find what I need to presurize the manifold, but I should be able to seal it up and fill with water to check for leaks overnight. I am making my blocking plate now and have rubber gasket material I bought for heat exchanger ends (back when I thought that was the problem).
    I assumed the red stains were DexCool related but it could be some additive the Mexicans put in because it looks good or whatever. Or it could be rust. Doesn't really matter at this point.
    I am cleaning up the threads on the bolts and holes to insure I get good torque readings (trying to think of what could have gone wrong) I believe I have been told that I should not use anti-seize as the bolts could back out with temp swings. (And I did retorque them after the first temp cycle) The long bolts do go into the manifold water jacket and have had sealant on them in the past. Is that a bad idea? I don't remember what torque I used last time other than it seemed low (maybe 30 lbs). But whatever the source of information I can't swear it was correct for the new graphite gaskets. Do you know what torque is best for them?
    Thanks for any advice. Tomorrow is the big day. Hope the whole thing holds pressure.

  6. #6
    Join Date
    Mar 2009
    Location
    Dresden, Maine, United States
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    365

    Default Re: Getting closer on the coolant leak

    John,
    Its not a lack of interest just a case of nothing to add that would be usefull. That said, when you go to bolt on your exhaust manifold use new bolts. I tried reusing the old ones once and with very little torque one snapped. Don't know if its a case of them losing strenth with age and all the heat but it sure was a pain in the butt. Good luck on the chase.

  7. #7
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    Default Re: Getting closer on the coolant leak

    Good advice. I tried Saturday but no grade 5 in correct size availabe. I suppose I could have gone a little longer with a washer stack but it looks so bad...
    I will measure carefully and bring them down from the States next trip or just buy from Crusader if available.

  8. #8
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    Sep 2008
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    Maryland - USA
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    Default Re: Getting closer on the coolant leak

    25 ft * lbs rings a bell but I don't have access to my service literature today.....

    I've always used PST on bolts that enter a 'jacket' and get wet....

    On the leak test...I supposed you could do a limited test by blocking the manifold so its stable, with the outlet at the top, and just using a hose to connect the barbs....then fill with water/coolant and see it the level recedes...???

  9. #9
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    Default Re: Getting closer on the coolant leak

    I had to put it together today. No more time available. I got to thinking that when I have used the graphite gaskets dry, when they went on clean shiny metal they pretty much "welded" themselves on. Where on an old surface (like my manifold) that had been razer blade scraped but was dark in color, that did not happen as much. So I took the parts to my local auto mechanic (that sends my heads out for rebuild) to get them milled flat and shiny. He inspected and pronounced the manifold surfaces were high all around the outside but particularly at the corners. This of course means that most of the crush load was on the edge that did not seal my fluids from going in the engine. But also, unfortunately, he said the local head shop needed pieces that would lay flat on their milling machine table and could be bolted down, and mine did not qualify.
    So I bought a brand new large file and a helper/holder and I started filing. Lots of magic marker put on and filed off and many straight edge checks. It took 2 1/2 hours but the manifold and elbow were finally as flat as I could measure. Followed with a little sanding and put on dry at 30 lbs.
    I don't know if this will work but at least it wasn't a case of doing the exact same thing again and hoping for a better outcome.
    Will splash the boat and run some tests tomorrow.

  10. #10
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    Default Re: Getting closer on the coolant leak

    Update. After all of the above I tested the reassembled boat. It ran rough and upon checking, #2 had coolant in it again. I gave up at that point and went back to the States.

    Only possiblility left was the exhaust manifold (which "never" fails). I came down in November, took off the exhaust manifold and rigged a test where I could plug the holes feeding the water jacket and installed a schraeder valve in one. Laid the manifold down on it's side so I could fill exhaust passages with soapy water. Pressurized the water jacket with air and easily found the leak (halfway up above #2 and #4). I now have a new manifold and will have installed in a few days. Meanwhile I went out with a friend and picked up a 60 lb. yellowfin last week. Darn near wore this guy out but it ate well.

  11. #11
    Join Date
    Sep 2008
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    Maryland - USA
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    Default Re: Getting closer on the coolant leak

    So the inner wall of the manifold was cracked ~ 1/2 (vertically)?

    Good work on the ahi!!

  12. #12
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    Default Re: Getting closer on the coolant leak

    I am back in Florida after getting chased out of Mexico because of the virus. We are staying home and doing well (so far). I thought I would finish the story. After some delay I managed to import a new Crusader exhaust manifold. That fixed the leak and we did some nice boating for several months. Then, the engine again started losing antifreeze. I chased it down to the other side of the engine and found that the exhaust manifold on that side had also developed a pin hole leak. So that is proof positive that if something goes wrong on one engine (or side of an engine), fix them both since the problem will occur again. So I found a new importer and brought down the parts to do the three remaining exhaust manifolds, and while I was at it I also will change out the elbows (they are just ending year 3, but I am sick of fixing stuff and they will have to be pulled and replaced in a year or so anyway). And for good measure, I am replacing my 17 year old wet exhaust hoses that are starting to crack and drip. Also my rusted pulleys (why stop now?). New raw water pumps as well.


    Unfortunately, I only had one engine done before we had to leave or risk getting stuck down there. And as a final note, my Rinda TechMate gave up the ghost. I brought it back and they said send it in. It needed a new face screen (a switch had gone bad) and a new plug. Charged me $80 and had a one week turnaround. Seems fair.


    Stay safe everyone!

  13. #13
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
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    11,880

    Default Re: Getting closer on the coolant leak

    John, I'm with missnancy in that its not a lack of interest, just a case of nothing to add that would be useful.

    Although, I will add:

    ..... you should be able to find a better assortment of exhaust manifold bolts if you look at grade #8.
    ..... also, I would suggest using the Automotive Never-Seez on the threads. This is one application where this can be safely used in a marine environment.



    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  14. #14
    Join Date
    Mar 2009
    Location
    Dresden, Maine, United States
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    365

    Default Re: Getting closer on the coolant leak

    Arnt boats grand? several grand at a time.
    What is a rinda techmate? Have a Happy Easter

  15. #15
    Join Date
    Nov 2008
    Location
    Trenton, Ontario, Canada
    Posts
    430

    Default Re: Getting closer on the coolant leak

    Quote Originally Posted by missnancy View Post
    Arnt boats grand? several grand at a time.
    What is a rinda techmate? Have a Happy Easter
    Click image for larger version. 

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    Don Keye
    From 600 kts to 6 kts
    Dun-Fly'N

  16. #16
    Join Date
    Dec 2011
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    San Jose del Cabo, MX, Osprey, FL
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    363

    Default Re: Getting closer on the coolant leak

    When GM went to fuel injection they developed a controller specific to marine applications, the MEFI series. It's main purpose is to look at manifold air pressure, air temp, engine temp, rpm and throttle changes to determine the correct "on time" for the injectors. Over the years additional functions were added including spark control. These engines are best serviced with a scanner to read the outputs of all the sensors. To my knowledge, typical automotive scanners will not work and as of several years ago only Rinda made scanners that would do the job. Their Techmate is one of them. They also private label the scanner for Mercruiser but it is the same device. Also on some engines (including mine) there is an adjustment needed to correctly align the position of the distributer cap with the rotor. (For some reason they call this the "cam retard" setting). There is no work around way to do this. You must have a Rinda scanner to get it correct.

    And yes, boating is grand!

  17. #17
    Join Date
    Mar 2009
    Location
    Dresden, Maine, United States
    Posts
    365

    Default Re: Getting closer on the coolant leak

    Thanks, Never had heard of that gadget. I'm lucky that Miss Nancy is old school. (I think)

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