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    trolling motor wiring

    I'm installing a 24 volt trolling motor and was more or less doing it exactly as in the diagram at the thread linked below without the onboard chargers. I thought the 24v system was completely isolated from the 12v engine system. At least that's how I was going to do it. In this diagram it...
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    OMC cooling

    This is a general question out to the OMC experts. My engine is running great, but I'm always looking to be ahead of problems and keep a close eye on things. I had the exchanger off when replacing my alt belt and water pump belt. Even replaced the circ pump (probably didn't need to) and...
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    1979 OMC 800 Tilt system

    Well it's been kinda a tough year. Did a bunch of general maintenance and tuning and thought I had this boat perfect for another fun season and it did the following: please follow my long winded story if you care. Last four trips the same thing happened: start great, putt around and also on...
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    OMC 260 spark plugs for reading

    I'm tuning up my 1979 OMC 260 and would like to share some pictures for the pros. I've run 2 full seasons on these plugs (maybe too long?) after they were installed with a new mallory breakerless and CDI ESA. The boat has run flawless since then, shifts smooth and idle is very predictable...
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    Water Pump assembly

    I have a little problem with my manuals. The Seloc manual says that there should be sealer applied to the impeller plate between the water pump housing and the impeller plate. It warns that if it's not done this way that an ovrheating condition might result. It says this in the water pump...
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    OMC Ball Gears

    I have read in other posts that the ball gears should be replaced as a set. On my 1979 800, I am replacing the upper with a unit that is assembled and has a new ball gear. I wasn't going to work on the intermediate and its current ball gear. I would say that the amount of wear is...
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    Lower unit oil seal

    Been using this boat for 4 seasons now. 1979 OMC 800 drive with a 5.7 GM. I've always struggled keeping water out of the upper but the lower with its quart of oil was always clean and clear when I changed it. Not anymore, the lower is getting quite a bit of water in it. I was changing it and...
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    Shipwrecked

    I've been boating with my 79 Formula for three years now. It's going to hurt to post this story of me screwing up but maybe it will help someone else. It's an old boat and an OMC so each season has required some rework or repairs. Got through all that and this season had to replace the...
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    SAE 30 oil

    I really hate to start an oil thread, but anyway, is Penzoil SAE HD-30 the same as any other SAE 30 weight oil? My OMC 260 is supposed have SAE 30 oil per the manual. I know any old oil would probably work, but I like to stick to the book if possible. My guess is it's just a marketing thing...
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    New parts for my old OMC

    I fought what I thought was a fuel/carb problem for a while and I think I have found my problem elsewhere. What it would do is run great for about half an hour and then start running like crap or not all. 1979 OMC 260/800 mallory distibutor. Was going through the distributor and found that...
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    OMC ESA and overstroke switches

    After rebuilding my carb because of what I thought was an idle circuit problem. And also after going through other fixes and general tuning of my engine I am convinced my problems are not in the Carb. I am also convinced that my problems are not fuel related. I could go through all that but...
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    Rochester Carb rebuild

    This is a 4MV, 17059286. About done but I have a question. The new pump assembly is different than the one that came out of the carb. In the picture the old one is on the left it is 2.375 long and the one on the right is 2.625 long. Just not sure if the kit was wrong or what. It seems like I...
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    OMC water pump belt

    1979 OMC 260 with the select trim. Call me crazy, but all I wanted to do was a little preventive maintenance so I was going to change the water pump belt. Are you kidding me I have to remove the engine mounts to do this? I looked at this 3 ways to sunday and that belt is looped through the...
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    Used 1978 OMC outdrive question

    I have a 1979 OMC hooked to a GM 260 hp in a 20 ft Formula/Tbird. It's been an adventure the last 2 seasons but I've had some fun times in this girl. I really don't have a problem with being an OMC owner. That being said I'm trying to prepare for keeping it going the next few years. I...
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    OMC Impeller replacement

    I'm changing the impeller in the 1979 OMC sterndrive. I'm doing it chief's way and so far so good. Maybe someone can add the link to chief's process. I'm not sure how to do that. Now the swivel housing is stuck. Can't get it loose to get to the pump. I've tapped on it as hard as I like to...
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    OMC manifolds

    I need to fix the cooling system on my 79 OMC 260. The manifolds are original I believe, I could be wrong. The boat has about 650 hours. No matter what else related to the cooling system that needs fixing these manifolds are done, they need to be replaced if I'm going to get some years out of...
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    OMC 260 fuel filter issues

    I have a 1979 OMC (could be a 78) with the 800 drive. It's a 5.7 GM. It ran pretty good 4 times out this summer. Before the last trip I decided to check the fuel filter because I was having trouble at very low speeds and idling. I realize it could be a lot of things but anyway I was just going...
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    My Omc 800 Works!

    I've read all the horror stories. I'm prepared for the worst. I've learned a lot from all you folks. Thanks. This is a great resource. Maybe this will be a hot topic, maybe not, but since my OMC outdrive is still working what are the three most important things that I can do to keep it...
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    1979 OMC 800 gear lube

    At the risk of repeating a question I'll ask anyway. I have read many threads on this and still feel as though I don't have an answer. For use in the upper and lower drive units, is Mobil-1 75-90w SYN an acceptable or maybe even better gear oil than the OMC HI-VIS oil suggested in the manual?
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    Omc 260/800

    I've been reading this forum for months and I think it's excellent. Many experts here and it's very much appreciated. Helped me a lot. Didn't stop me from buying a 1979 OMC though. I'm thick. First trip in the 1979 Thunderbird F20CL with the OMC 260 and the 800 outdrive I had a little...
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