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Thread: TD5 Cracked Block - Looking for Donor

  1. #1
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    TD5 Cracked Block - Looking for Donor

    Hi Everyone,

    A year or so after replacing the head gasket on my TD5 it started pressurising the crank case with enough pressure to pop off the PCV hose to the provent filter. The engine was still running fine with plenty of power. I checked the compression and was getting 430PSI on every cylinder (which is quite good for 250K). Chemically tested the vapor from the oil filler cap for exhaust fumes, which was negative. It didn't seem to be blow-by, it appeared to be coolant vapor. Thinking the block was OK with good compression, I pulled the head of and put it in to the cylinder shop for crack testing. They called me to inform they did find a couple of small cracks and recommended replacing the head with a new head. When I looked at the cracks in the head I had a hard time trying to see how they would cause coolant to enter the crankcase, however there could be cracks on the inside of the water galleries inside the head that we couldn't see. At that point I was fairly confident it was the head causing the issue.

    I finally got around to ordering a new head from Turner Engineering, new harmonic balancer, new water pump and new oil cooler. I checked the top of the block with a dial gauge and everything was in spec. Put everything back together expecting it to be sorted, only to find I had the same excessive crankcase pressure problem . Quite disappointing, although not totally unexpected as it was always a possibility there was a crack in one of the water galleries inside the block.

    Would anyone have a donor block, or a short engine that is known to be good ?

    Also happy for you guys to post any advice and/or tips where I could get hold of a block/short/long or complete engine. Obviously I have already spent a lot of money so looking for a way to resolve this economically.

    As always help from this forum is much appreciated. Thanks,

    TAHAIC

  2. #2
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    https://www.aulro.com/afvb/complete-engines-for-sale/
    https://www.aulro.com/afvb/wrecking-notices/

    Please don't start negotiations here. Should anybody be in a position to provide what is asked for, do so by PM.
    Thanks.
    If you don't like trucks, stop buying stuff.
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  3. #3
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    Thanks V8Ian.

    Hopefully someone can post a message and PM me to help.

    Also hoping people can suggest ideas to help prove me wrong!! The engine is back together and running in the Disco at the moment so I am able to run more diagnostic testing in an effort to try an confirm if it is a cracked block or if its something else. I would be over the moon to find out its NOT a cracked block as I am sure you can all appreciate. For the life of me I can't think of anything else that it could possibly be other than a cracked water galley in the block somewhere.

  4. #4
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    Have you done a pressure test on the cooling system?
    If you don't like trucks, stop buying stuff.
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  5. #5
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    Is the car using coolant?
    If you don't like trucks, stop buying stuff.
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  6. #6
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    I am just trying to think this through.
    The most likely culprit of pressurised water into the crankcase would have to be if there is a crack in a cylinder maybe near the bottom that has the ring push any water into the crankcase.
    Did you look carefully at all the cylinders when you had the head off?
    If the crack were near the top A la RV8 then the water would disappear out the exhaust.
    To have high crankcase pressure I would think that the crack would have to be in a cylinder. I guess there could be a crack between the cooling system and crankcase itself but this should not cause high crankcase pressure just goopy oil and an increase in oil/water level.
    If the temp stayed under 100C then the water should stay as water and the oil should be caramel..

    in my 8 years or so interest in TD5s I have never heard of this problem before.

    The oil cooler problem on the other hand is well known but AFAIK this causes a mix of both oil in the cooling system and water in the oil.
    Maybe a borescope through the injector holes will see which cylinder is the culprit and maybe where the water is coming from.
    Regards PhilipA

  7. #7
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    Quote Originally Posted by TAHAIC View Post
    ... it appeared to be coolant vapor ...
    It would be good to prove that the vapour is in fact coolant based. I am not aware of any labs that test crankcase vapour for coolant contamination but there appears to be tests available that detect coolant in oil (e.g. Atomic Emission Spectroscopy). Perhaps one of these tests could be adapted for your application. Maybe a phone call to a lab that tests oil and discuss.

    As for sample collection, I imagine that the crankcase vapour could be bubbled through a clean and rinsed glass container of distilled water which would dissolve and concentrate any coolant products present. The longer you bubble through the more coolant products would concentrate if present. This is thinking outside of the box and novel as far as I am aware so not sure if this is worth a try. A negative result would not rule out but a positive would confirm.

    Another thought, I assume you have confirmed that there are no blockages down stream of the camshaft cover outlet e.g. blocked Provent filter or PCV (if still used). I believe newer Provents no longer bypass to atmosphere with a closed system.

    Good luck with it.
    Martin

    The secret to happiness is to truly want what you already have
    Oil leak?...Nah, sophisticated anti corrosion system!


    ‘04 D2a TD5 Manual “Snowy” – My toy
    ‘16.5 D4 TDV6 Auto “No Name” – Wife's toy
    ‘03 Def 90 TD5 – Son's toy
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  8. #8
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    irontite sealer

    If it's coolant to anywhere bad or compression to coolant irontite sealer
    will fix it. I have used it about 20 times and i'm always amazed. Oil to
    water is it's downfall. Don't worry about blocking the radiator the passages
    are too big.
    Last edited by Injec; 24th September 2022 at 08:52 PM. Reason: spelling

  9. #9
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    Sorry for the delayed response and thank you for the input - everyone's comments are good suggestions and much appreciated!

    The car has some history with symptoms that I need to explain which hopefully helps in the diagnosis. I bought the car and sorted everything out as normal issues D2's have (see my other posts about it if your interested) however it had a problem that persisted being it did use excessive fuel around 12.7L/100km instead of the expected 9L/100km and it did have touchy egts over 750C when I put my foot on the pedal up hills etc which resulted in coolant temps rising quickly in direct proportion to the high egts. equipped with a Madman I found I had to back off on the gas alot more than I would consider normal. Coolant would leak from the fuel cooler and I eventually fixed that and replaced the head gasket and steel dowels only to get another small leak from a heater hose at back of engine. Drove the car for less than a year after that before the crank case pressure became an issue popping off the silicon hose from the rocker/cam cover to the provent filter at the provent filter connection. I posted some videos of the steam coming from the rocker/cam cover at that time.

    I have tested the vapor coming from the rocker/cam cover vent and oil filler cap chemically (just one of those kits where the blue liquid turn green with CO2 gas) and have verified there is no exhaust gas in this vapor which should theoretically prove that there is no crack in the cylinder bores or the head (head is now a new AMC). This means that that the only other possibility, that I can think of, for the source of vapor and pressure from the crank case is coolant/water. I don't actually have any antifreeze in it at the moment only distilled water (not paying the money for coolant when I most likely will be dumping it again soon).

    I have always (mostly always) maintained lab test results for oil analysis from every oil change. When this problem first happened I changed the oil and sent a sample for analysis and the results showed a spike that the lab informed me about saying it was indicative of typical gasket failure of some kind (see attached oil analysis). This was kind of weird but I came to the conclusion that the guy I bought the car from had used Chem-i-weld with a spike of sodium silicate in the oil sample I looked at products available to solve cracks in coolant systems and found exactly that composition as the active ingredient in chem-i-weld! (see attached photo) I really hope I am wrong! Please prove me wrong Guys!

    Lab results guy said I didn't have any coolant in the oil and it is definitely not milky or anything however the test results show some evidence of coolant in oil with a high sodium content. I agree that is strange as I would also expect coolant/water to be in the oil if it is in fact coolant leaking through a crack in the block. What ever it is its coming straight up into the top of the head area where the cam is and venting straight out the port in the cam cover. I don't have anything connected to the PCV port on the cam cover at the moment and it literally looks like steam coming out of the port and also the oil filler cap if I remove it. I thought this problem would have been resolved by replacing the head but it has not.

    I haven't driven the car to see how it is with fuel consumption or egts now that I have replaced the head either. This is mainly because it still has positive crank case pressure and I don't know why and I don't want to drive it when it has the fault. I stopped driving the car when this problem first happened and haven't driven it since so as not to cause any further damage.

    I purchased a coolant pressure tester kit and had a quick effort in checking it - system had a slow leak with pressure dropping slowly but no sign of coolant/water on the ground. I didn't have much time last weekend to do this properly so I will have another go this coming weekend and try to check it more thoroughly.
    Attached Images Attached Images

  10. #10
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    Finally got a chance to do a proper pressure check on the coolant system. I found the small leak which was just a hose clamp not done up completely on the hose to the thermostat body to the head. After tightening that its holding quite well, pressure tested to 12 PSI and it 40 min to drop 1 PSI.

    I started the engine after testing and checked the PCV from the open head port (don't have anything connected to it at the moment) - at first there is no pressure then after a minute or two it starts to build with vapour coming out of PCV port on head. I only let it run for 5 minutes or so at which point it had visible vapour coming out at a pressure that you can feel the force of with ones hand and building stronger. I only have distilled water in the coolant system at the moment with traces of diluted coolant still present, however the vapour colour did look a little on the greyish side, almost like blow by. When I loosen the oil filler cap it dances around and the pressure is enough to force the cap to tilt over to one side. As previously stated I have tested this before for CO2 with a negative result so I ruled out blow by because of this.

    I'm starting to think that maybe its not coolant/water vapour coming from the head on the basis that if it did have a crack in a water gallery in the block then it must be a hairline crack in order for it to hold pressure for 40 min and in that case it would possibly open up as the engine heated up but the fact that the crank case pressure built up so quickly ie. started getting vapour coming out in less than 2 minutes tends to rule this theory out. The issue I have with this is that if it is blow by then 1. I would have lower compression than 430PSI on each cylinder and 2. I would have a positive CO2 reading on the vapour from the PCV.

    Perhaps it is a cracked cylinder liner or possibly a crack in a piston top but again I would expect a positive CO2 reading.

    Is it possible to have some pressurisation coming back into the sump from the turbo ? - but again I would expect positive CO2 reading.

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