Logo
FULL SITE MENU

Search results

  1. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Thanks Jimn, No, there was definitely no gasket sealer used. Genuine Mercury gaskets each time. Always doing compression testing with the throttle open and fuel pump disconnected. I actually unplug the cable that powers the fuel pump as that is very easy to get to.
  2. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Thanks Iouc, The initial blown head gasket cause was unexplained but it appeared to happen slowly over time. Fuel pressure has been checked and found to be within spec. I'm not sure how else we can check if it is running lean? I'm unsure whether the props are correct, but ths has never been...
  3. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Finally got around to fixing the motor and replying to this and let you know that you were correct. We had valve that was stuck open (only by a few mm) and likely a small crack in that head. Highly possible they were linked. The stuck valve appeared to have evidence of rust on the stem. We're...
  4. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Still unresolved I'm afraid. Yes the reading was zero. Couldn't say for sure if it was the same cylinder but last time it was definitely caused by a failed gasket between two of the middle cylinders (either 3 & 5 or 4 & 6). It was a very obvious failure. Will do a leak down test first then...
  5. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Great thanks for that.
  6. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Thanks again AllDodge, sorry, I meant the head gasket gone in the cylinder that is now showing 0 PSI. What could be causing the high pressure readings in the other cylinders?
  7. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    I'm not sure if it was shaved, it's a good question to ask them. Are you implying it's possibly a head gasket gone? This was what led to the rebuild, head gasket blown between the two central cylinders.
  8. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    I would think so but they dont seem too interested in helping TBH.
  9. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Thanks heaps Alldodge, appreciate the response. The timing was checked during the repair and I checked it the last time it ran and it was 8 degrees as it should be. The other plugs all looked good aside from a very slight carbon build up. I was thinking that may have been due to the last few...
  10. G

    Not Again! 0 PSI in Cylinder After Recent Repair to Merc V8 TBI

    Recently had the top end (cylinder head, valves, new plugs etc.) on our Merc 5.7L TBI redone by an authorised reputable Mercruiser mechanic. The manifolds and risers were inspected and retained as they were still in good condition with no signs of holes etc. Genuine Merc parts, gaskets etc were...
  11. G

    1998 Mercruiser 5.7 TBI Backfiring Under Load & Loss of Power

    Just been through a similar repair, very important to get the heads checked and possibly resurfaced by a reputable engine/head repair place otherwise you'll be back to square one very quickly. It's not going to cost too much but could save you a large headache.
  12. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    Thanks very much for your time Jimn, all great points. In regards to the footage, the boat is in a wet pen where it is often unsteady on the water. Did my best to keep it stable. I posted a video instead of snapshots because the still photos wouldn't tell the story of how the numbers are...
  13. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    Okay so we are now getting good numbers on the voltage, up to 14.1v under load and low's 13's at idle. We also re-checked the timing after this. There is a slight improvement in performance but the problem still persists albeit slightly less. Anyone have any another ideas on what could be...
  14. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    I'm not sure how ScannerPro reports the codes but I think it's just 'flags'. Will look into that further. It gives a few - Yes, we have been referring to the Mercury service manual #24 to diagnose and check specs.
  15. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    Thanks Makomark, will try and do that today (y)
  16. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    Thanks very much mate, this is great information. Really appreciate it. It is a quite big difference between the two motors, especially when they are practically identical. I looked at the data recordings on the problem motor when it was under load and it sits around 12.0 - 12.1v which is even...
  17. G

    Unsolved Mystery MerCruiser 1999 TBI 5.7L V8

    Hi everyone. I'm posting this out of complete dispair after days of serious head scratching. We've been struggling to diagnose a problem despite many hours of work by several mechanics. We have two MerCruiser 5.7L V8 TBI's in our 1999 34 foot sportscruiser attached to Bravo legs. The current...
Back
Top