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  1. Kola16

    Overheating issue.

    I would not advise that. I would think that that could overheat the manifolds causing them to crack, which would make replacing them mandatory.
  2. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Scott was correct I had only tested the one. Tested the other tonight and it was good, but still going to replace both. I also tested the block with the heads still on. There was a leak somewhere. I could here something in cylinder 1. I could not get my ears close enough to hear the starboard...
  3. Kola16

    Overheating issue.

    Have you pressure tested these manifolds? You mentioned there was water in the exhaust part of the manifolds so that is something to suspect. Leaky manifolds can cause overheating. If they sat for that many years, there is a very good chance the water jacket is rusted through. Go to Autozone and...
  4. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Oooh thats a great idea i wouldn't have thought of that thanks!
  5. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Another update. I pressure tested the port side exhaust manifold. It leaks. They are about 4-5 years old so it was time to change them anyway. Another thing to check when you boil all the water out of your engine. I'm still going to test the block and heads.
  6. Kola16

    Mercruiser 260 Backfire Through Exhaust

    I did not. I will have to look up how to do that. I have feeler gauges, but I am not sure that I have a compatible straight edge.
  7. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Oooh I looked up "block blockoff plates" and that is exactly what I need. I think I can make my own out of all the aluminum plates I have. So my plan is to take the heads into a machine shop to get tested, and then make blockoff plates for the block, so I can test the block. Seems like a big...
  8. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Update. You are all correct. There was water getting in. I removed all the plugs and did a water pressure test through the heat exchanger. Water was clearly leaking into cylinder number 1. Also, plugs 6 and 8 were wet. Additionally, I had switched plug wires 2 and 4, which is probably the reason...
  9. Kola16

    Why Did My Thread Get Nuked?

    https://forums.iboats.com/threads/mercruiser-260-backfire-through-exhaust.760715/ Hello. I am wondering why my thread got nuked. What rule did I break? I am just trying to find out why my boat is not running. The link above is the aforementioned thread. Thanks!
  10. Kola16

    Mercruiser 260 Backfire Through Exhaust

    Hello all (again). I have a 5.7L Mercruiser 260 with electronic ignition and a Holley Sniper throttle body EFI. The engine recently overheated due to throwing the water pump belt and it blew the head gasket. I have now replaced both head gaskets and all spark plugs, wires, cap, and rotor...
  11. Kola16

    86 mercruiser alpha one 140 does not go under load

    If its high pitch like a belt squeal, then that is most likely the rubber of the engine coupler giving way.
  12. Kola16

    Mercruiser, which engine model do I have (no serial number)

    What pitch prop do you have and what is the performance of your boat? Eg. Speed vs. RPMs. Also what is the weight of your boat? And is it carbed or MPI? The 5.7 and 6.2's can use all the same external parts, many times its the internals that are the only difference. The performance can usually...
  13. Kola16

    86 mercruiser alpha one 140 does not go under load

    Do you smell burnt rubber when you throttle up? If you do, look at your engine coupler. That is the part at the back of your engine that connects the engine to the outdrive. It will spin like your hub on the prop and if it spins it needs replaced.
  14. Kola16

    Is My Impeller Bad? Mercruiser 228

    It was antifreeze in the cylinders. Fully closed system. I'll have to put it all back together to test it then. I have the manifolds, heads, and heat exchanger taken apart now.
  15. Kola16

    Is My Impeller Bad? Mercruiser 228

    Weeeeell, I took the spark plugs out, and sure enough, there was plenty of water in the port side cylinders. I still haven't seemed to find water in the oil though. I am going to pressure test my heat exchanger while I have it out (why not). Should I also pressure test the block where the...
  16. Kola16

    Is My Impeller Bad? Mercruiser 228

    I have run this cooling system for about 200 hours and never have had an overheating issue. So 200 hours ago would be the last time it was cleaned. The FWC was installed by a boat mechanic when I did the engine swap. The only raw water I have coming in is the impeller in the outdrive. No other...
  17. Kola16

    Is My Impeller Bad? Mercruiser 228

    It's in the title and my bio sorry haha. Bits and pieces. My brain scatters. Mercruiser 228 is a 1979 system that was originally a carbed 305. Now it is a 350 with throttle-body injection, but still the MC-1 outdrive. Fresh-water cooled.
  18. Kola16

    Is My Impeller Bad? Mercruiser 228

    Update: I just put 3 quarts of antifreeze in the system. Now it is running back at 170 F (digital gauge) at 1500 RPMs on the hose. And my IR temp gun at the thermostat housing says 170 F on my gauge is actually 155 F. That is the outside of the thermostat housing and manifold of course, but that...
  19. Kola16

    Is My Impeller Bad? Mercruiser 228

    Okay long story. It is still running hot. The overheating was not because of the impeller, although it was good to replace it thanks all. The engine threw the belt that runs the water pump and the alternator. That is why it overheated. I did replace the impeller and housing though...
  20. Kola16

    Is My Impeller Bad? Mercruiser 228

    Good to know. I have run it on the hose at high RPMs many times over its life. Will not do that any more I guess haha. Just ordered an entire new pump kit. Thanks!
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