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  1. K

    Replacing Risers/Elbows and Exhaust Manifolds on a Ford/OMC Cobra 5.8 Ltr

    I think that you mean cleaning the block, right? You had earlier said that the exhaust manifolds must be replaced. What would you suggest for cleaning the engine block and the mounting surface?
  2. K

    Replacing Risers/Elbows and Exhaust Manifolds on a Ford/OMC Cobra 5.8 Ltr

    Here are pictures of the starboard side. Any comments or observations?
  3. K

    Replacing Risers/Elbows and Exhaust Manifolds on a Ford/OMC Cobra 5.8 Ltr

    I'm replacing the risers/elbows and exhaust manifolds on a Ford/OMC Cobra 5.8 Ltr I started this with the post: "Overheating Possibly Caused by Restricted Thermostat Housing Port". Now I know that the thermostat housing may have been contributing to the overheating but I will change the risers...
  4. K

    Can I do a Compression Check with the Risers Off and no Hose Connected?

    I'm planning on changing the impeller anyway, so if spinning it dry for a few turns hurt it, no big deal
  5. K

    Can I do a Compression Check with the Risers Off and no Hose Connected?

    Update: I did the compression check: All spark plugs Removed, the lead to the coil disconnected (and protected with electrical tape). No water connected. Throttle wide open, and carb held open with a screwdriver. I left the fuel pump connected. Around 6 cranks of the engine to get a steady...
  6. K

    What are the symptoms of cracks in an Exhaust Manifold?

    I'm in saltwater, Southern California. This boat was in a lake for the first 21 years, then in a saltwater marina for 4 years. I've had it for 9 years. I keep it on a trailer and always flush it out after use. I have also been using Salt-Away for the last 5 years. The risers were pretty rusted...
  7. K

    What are the symptoms of cracks in an Exhaust Manifold?

    5.8 Ltr Ford, OMC OD. 1991 I'm changing the risers/elbows. I already have those. I am considering replacing the exhaust manifolds as well. The motor has been running fine. It starts easily, has plenty of power, and doesn't burn oil. Just to be sure, if there were cracks in an Exhaust Manifold...
  8. K

    Can I do a Compression Check with the Risers Off and no Hose Connected?

    Can I do a Compression Check with the Risers Off? 5.8 Ltr Ford. I removed the risers (Elbows) because I will replace them. (See other post "Overheating Possibly Caused by Restricted Thermostat Housing Port") I'd like to do a compression check before I spend a lot of money. The boat has been...
  9. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    I don't know what you mean by "2XS with bondo". Why would the manifolds cost me a new engine? I am planning on changing the Elbows/Risers. If I file the manifolds flat why wouldn't they seal? I will look for a metered bypass hole for the thermostat, but how sure are you that there is one...
  10. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    Here are pictures: The first one shows the green material. The next 2 show the manifolds after cleaning them up as best I could.
  11. K

    Hard Lime Green sealer/Filler (?) on Exhaust Manifold

    91 5,8 Ltr OMC/Penta V8. I'm changing the Elbows/Risers. I was overheating only on the port side. See other post I'm cleaning the mounting surface on the top of the exhaust manifold where the gasket will be, and on the port side there is a very hard sealant or something. BTW, that is the side...
  12. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    I'm cleaning the mounting surface on the top of the exhaust manifold where the gasket will be, and on the port side there is a very hard sealant or something. BTW, that is the side that was overheating. The sealer (?) is lime green and comes off with a lot of scraping. Could it be a filler used...
  13. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    One of the suppliers says his fits a 5.7 but 19192 and on. My boat is a 92 but with a 91 motor: Ford 351 Cu In Model 584APLRGD Serial No. T01224704 Did something change in 92?
  14. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    Lou, thanks, you have been a great resource for years. I have not been on since the gimbal bearing/ housing/ bellows repair a while ago. She has been running well. The exhaust manifolds look better than the elbows but I will try to clean them out. I can prevent large pieces of rust from falling...
  15. K

    How Do I remove the Thermostat from the Housing, Ford 5.8

    The thermostat seems to be working fine. With the housing off the engine. the spring is holding it closed. The engine warms up and then stays right near the middle of the range on the gage. The port elbow getting hot is a different issue. There is a separate post on that. Should I just leave it...
  16. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    Some of the gaskets between the exhaust manifold and the elbow have 4 wide open passageways for water. On some of the gaskets, 2 of the sides only have a hole for water flow and not the full area. Why is that? Did OMC make a revision? Which gasket should I use? BTW, I am using new elbows...
  17. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    Update 7/29 I was able to separate the round pipes from the elbow. A few hits with a rubber mallet was all it took After looking at the elbows more closely and checking prices, I have decided to replace both elbows. I can get both with the gaskets for under $250 I will clean and repaint the...
  18. K

    How Do I remove the Thermostat from the Housing, Ford 5.8

    Thank you. I found a video on YouTube that shows the O-ring being removed with a sharp pick. I should be able to get it out.
  19. K

    How Do I remove the Thermostat from the Housing, Ford 5.8

    How do I remove the thermostat from the housing on a 91 Ford 5.8? The shop manual only says, "The Thermostat is held in place with an O-Ring. Pry the O-ring out of its groove, then lift the thermostat out of its housing." The inside of the housing is a bit rusted, and it is hard to see the...
  20. K

    Overheating Possibly Caused by Restricted Thermostat Housing Port

    1991 Four Winns 200 with 5.8 L Ford V8 and OMC OD. I was cruising the harbor on Sunday with friends and noticed overheating at the port exhaust elbow. The engine temp gauge was only slightly above the midpoint, so it was approximately 172 Deg F. The starboard elbow did not seem as hot. I was...
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