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  1. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Well, we did check the compression on cold engine and all was good, also no major visible burns, however it was always flooded when heads came off... I will let you know, if I am that happy in September :)
  2. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    It was checked as well - and was OK. Consensus here seems to be linked to dead valve springs - during 3000 rpm excaust valve stayed mostly open and overheated that one spot, when cooling down with sea water, it made it crack All manifolds were faulty in the same spot. I do hope that it will...
  3. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    So! 3 trips made and it seems to be fine now. What was done and what fixed it - I have no F***ing clue:) New valve springs, heads done, all new gaskets, left and right side heads were swapped, new manifold. Engine is running better and not so big difference between port and stb engine anymore on...
  4. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Sorry to disappoint you - Searay Sundancer has a muffler in the middle so there can not be hydrolock from water getting in from exhaust. Exhaust pipes are on the side of the boat hence sudden stop will not get the water in. I am not sure how other boats are done, but this IS NOT the issue here...
  5. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Went to the boat today and made a short clip of the heads, here you go: https://www.dropbox.com/scl/fi/18ofm7g8en376nqgy5t6s/2025-03-24-14.32.05.mp4?rlkey=0s45svoylnnjqhn6mm3nuwwxq&st=ng9jmgmx&dl=0 Should not be the issue that they are so bad. Will replace the springs. And all the contact...
  6. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Heads are good and tested - will try to make better pictures with proper light. Those were done in the dark below the boat. Water part was pressure tested and each valve separately tested for leaks. IRL they are good and nice. On Friday will try to go to the boat and unwrap them and make better...
  7. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    After not finding anything else, one (last) idea came: valve springs :) Will swap those for new ones. Doctor AI gave this out: Reduced Power & Overworking the Engine – If the engine struggles to produce power due to valve issues, you might push it harder to maintain performance, leading to...
  8. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    I do have 2 (two) engines and during my time all 4 of the manifolds are changed - all of them are from RecMar and are working fine (minus the always broking one). Whole last summer I had issues with one side of the one engine, did swap the manufacturers, but I did not put the used working one to...
  9. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Yes, always the same side Yes - this was straight, we will check once more as it is easy to do now That we have not done, but all bolts go tightly and they feel like they are fine, but worth to check, as I do not have any other ideas... thank you! Märt
  10. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Like you mentioned earlier, 8 pages and hard to read and understand:) However - previous post stated that different brands are used, means one was done by Recmar and another one was done by Sierra. Both different castings forms.
  11. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    I have two engines with 4 manifolds - only one of them is cracking. Last one did two trips and is broken again. Two different manufactures. We used the thermal gun to measure temps on the run and on idle, no major differences between manifolds or engines. Also added see thru pipes to see if the...
  12. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Anyone selling a good engine in Estonia? Even Europe would be a good spot :) Shipping from US is not too cheap:(
  13. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Sorry - what is reversion?
  14. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    There have been different manufactures already - problem remains
  15. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Three point connector with ball was replaced to brand new one, no difference :( Ball is working nicely, you can close it by blowing inside. We will go thru the pipes just to avoid that there is part of impeller or anything funny blocking the water on higher flow. out of ideas. I did order brand...
  16. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    and no leaks! Head and block does not leak air on 5 atm pressure test.
  17. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Was too pissed to start the work last year and yesterday started the investigations again - there was a bit water in the manifold again :( Will do now again the the test to find any cracks, blinds produced to close the holes and will pressurize the block and head to see if there are any leaks...
  18. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Sad to state that nothing has been done with the boat - will start dismantling process next month... Sadly standing alone in the winterspot and waiting for a better summer...
  19. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    All cracked manifolds are aftermarket ones and from two different brands - hard to get other in Estonia. We checked the surface and it was straight. We will go first for water flow -pipe by pipe... and hope to find something there. If nothing at all, then for next cracked one in 2025 I will...
  20. M

    2002 5,7 Mercruiser exhaust manifold keeps cracking - 5 times this summer

    Issue is, that NO ALARMS, NO BEEPS - nothing. Just cracks on the bloody manifold. Temps are fine, water and oil pressure is fine. Old gauges are not too reliable, they have been showing funny numbers all the time I owned the boat. One engine has been from the day one slower to speed up.. After...
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