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  1. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Backfires could be lean fuel mix (clogged injectors) or an intake valve sticking open. Did you check your thermostat? It should start to open @ 160* and be fully open @ 180*
  2. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Did you replace the impeller? Your temp @ idle should be 160-170 with a 160 stat. You put in new spark plugs right? 30-40 psi is ok for oil pressure at idle. Mine idles @ 40 cold idle to 30/25 hot idle. At high rpm it hits 55-60 on the gauge. The missing could be dirty fuel injectors but I’m not...
  3. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Consider yourself lucky Freshwater HOWEVER there is one thing many people do not know fresh water doesn't have barnacles, etc growing in it nor does it corrode steel/cast iron BUT it rots wood faster than salt water by a lot transoms actually last longer in salt water because the organisms that...
  4. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    That's not gonna work, if you remove the impeller housing it looks like this: (ignore the bolts, that's for pulling the water pump plate to replace the seal) so the 2 large holes at the bottom, are the ones where water comes up from the lower unit and then gets pulled into the impeller and sent...
  5. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    good to know and I kind of suspected that. there are options for the alternator and starter (ARCO) and the distributor (DUI).
  6. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    next time when you have to do the compression test just hook up the water hose and leave it on not full blast but like half open. I don't know about the EFI engines but on the carbed engines with the old style distributor, I always grounded the coil lead, you don't want spark sent to the spark...
  7. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Yeah, its very easy, just use some silicone grease to hold the o ring gasket for the cover in the groove.
  8. Lou C

    What spark plugs to buy for 93 5.0 EFI

    I think that chart is for GM engines, remember the one in the OMC boat is a Ford 5.0/302 cu in (although OMC/Volvo used both for a while). Might want to double check. My '88 OMC shop manual only has info for the Ford 460 so I don't know for sure.
  9. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Leave the manifolds off till you complete the air pressure test, in case the leak if there is through an exhaust port...also leave the oil fill cap off, for the same reason, (cracked head or block may put air out there). Also if you can get the smoke machine properly hooked up, it may make it...
  10. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    The exhaust valves look ok from what I can see. Make sure to go back & re do your air pressure test.
  11. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    You just need the cyl head to exhaust manifold ones, I think automotive would be ok…
  12. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Dry em out and try again! You have water passages and exhaust passages inside those castings, the water must stay separate from the exhaust passage. I would be surprised if yours leak because there was no sign of rust in the exhaust ports in the cyl head or the exhaust ports on the manifold...
  13. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    I guess in freshwater you don't see the rust like we do here! PS was the manifold sitting level when you tested it, because it could have run out the outlet of the elbow and then ran back in the center exhaust port and filled the exhaust ports if you tested it with it lying down like the pic...
  14. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    You have to get a better seal for a valid test
  15. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Not bad ideally you want a warmed up engine & throttle wide open, I think they’d be higher then. Next leak down test and what did the air pressure test show? If all is good test your manifolds & try running it again. See if you still get water in the oil. Air pressure test is really the most...
  16. Lou C

    Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

    Not sure; these models are very different than the older ones like mine in that you have a ECM that runs the EFI, not sure if it also controls spark advance or not. This is why I’m not a fan of old EFI boat engines; when trouble starts you don’t have a starting point for diagnosis unless a...
  17. Lou C

    Can I buy a used 302 and use parts from my bad motor to convert it to marine?

    Like Scott said, everything aft of the flywheel is different, if you want to check the only way to know, is to head over to marineengine.com and look at the OMC parts catalog for your year and model, and then compare parts #s and the reality is, most of those parts are NLA, even if you wanted to...
  18. Lou C

    Can I buy a used 302 and use parts from my bad motor to convert it to marine?

    You’d have to get the OMC bellhousing for the GM engine. I agree at that point I’d look for a complete Merc drop in power package.
  19. Lou C

    I/O (Sterndrive) Conversion to Outboards

    I bet those guys will be impressed when they find out you built that extension yourself!
  20. Lou C

    Knocking sound from my Alpha One Gen 2

    Just make sure it doesn't fall out. Or, you could run the hose up to the thermostat housing if you can make up an adapter to make it fit. I had a knock like that that drove me nuts for a while after my top end overhaul. It took me a while to figure it out. The cause? I changed the exhaust...
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