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Any tips for removing exhaust manifolds on 242ss
Trying to replace risers and manifolds on my 90 242ss. The manifold bolts are tough to get to because there isn’t much side clearance. Some of the bolts I can’t get a socket on because they are crusty but there isn’t any room to tap a socket onto the bolts. Looking to see if anyone has any tips. Really don’t want to pull the motor. I’ve gotten 5 bolts out so far but those were the ones with clean heads on them. Thanks in advance |
Let the games begin. What are you planning going with for exhaust?
Good Luck, Really Good Luck. These are a Bitc? to work on. |
Just doing stock replacements. Didn’t know when they were done last and I’m hoping I got to it in the nick of time saw some rust in both and some moisture in the heads so want to get it back together flush the oil and get it winterized |
You may need to lift the motor up a few inches which isnt the time consuming if done correctly.
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I was thinking about if I had to I’d possibly do that but hoping to figure it out in the boat. Hopefully can work on it this weekend and put it away until spring |
You did remove the batteries and the "cabinetry", correct.
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In some cases I have been forced to grind the bolt head off with a burr, then remove the bolt after the exhaust is off. Try heat and penetrating oil first and if possible, beat a socket that is too small ( may need to be metric) on the head. There isn’t much room to work so go slow and use a mirror. I went through all of this after I bought my boat, it’s a real good time. Best of luck. |
What ever you do try not to shear bolt. Mine sheared and removal of head was required.
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I didn’t remove the batteries as all the rear bolts came out easy. I haven’t removed the “cabinetry” as it was starting to get dark out but that may definitely help being able to lay down. Basically all the bolts that have come out came out pretty easy and all had never seize on them. Biggest issue is the crustiness on the heads of the bolts and not having room to tap a socket onto them. I will let you know how I make out after getting a chance to work on it again. Hopefully get some decent weather to work on it too |
When you remove the cabinetry also remove the bar that holds the sliding doors and the front of the seat rests on. Now you can get to a lot more places than you thought. On the port side you mast likely will want to remove or loosen the power steering pump. When you get the manifolds off now would be an excellent time to replace all of the raw water hoses as you cannot do it with the exhaust on and I bet they are original to the boat
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All of the above^^^ and pull the spark plugs so you don’t break one when that heavy manifold slips down without your permission. |
If you are looking for a like new set of manifolds/risers I have a buddy that just replaced his with IMCO. His Mercs are like new in/out all fresh water.
I helped him remove so I have personally seen them. Let me know. |
I did remove the plugs and will definitely replace the raw water hoses. All great ideas. I already bought the manifolds and risers but thank you for the offer. I may replace the starter too if that’s easier with the manifolds off which I imagine it would be. Trying to stay ahead of problems done the line but it is a boat. Lol |
While you are there I would also replace the block drain petcocks. I prefer this type as it is almost impossible to get to them but with a 9/16" wrench you can reach them be assured of being able to tighten and loosen. You will need 2 ea. of them.
https://www.ebay.com/itm/Genuine-Mer...-/153107583902 |
I just ordered some for my engine. They are much nicer than a regular steel plug.
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Ok I'm not a mechanic by any stretch of the imagination - I have replaced a manifold on our 7.4 mpi which went very well but that doesn't make me an expert. Just a question - if you are replacing the manifold - the ones that are coming off will be scrap- right? why not just take a saw and cut off as much as you can of the old manifold so that you can get a socket at the bolts that are hard to reach. in other words make room for everything - after all you are throwing the old ones out. Then when it gets time to put the new ones on - start with the bolts that you can get your hand to first and tighten them up. Again I'm not a mechanic and please don't shoot the messenger.
3pointstar |
My 2000 260ss 454 mpi manifolds were mounted with studs & nuts so I used a dremel to cut off the nuts, slide manifold off, back out studs with pliers/vise grips (all came out easy) and replaced all.
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How goes the battle?
How bad are your manifolds/risers? If they have much rot/rust you really need to look at the iron intake manifold. Mine was almost ready to break through just below the thermostat housing, I caught it just in time. Keep us posted and good luck. |
Unfortunately I didn’t have anytime this weekend. Got rained out Saturday and I had too many other house projects today. Hopefully next weekend. Got to get it done before it gets too cold out |
Where are you located?
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Cape cod , Ma |
So I have another update. I had a friend of mine pull the engine from the boat because I didn’t have any time. Too many projects at the moment. Manifolds are off. Looks like the heads have to come off. They are looking pretty ugly due to the water. Going to inspect lower end while it’s apart. Hopefully that’s ok. Didn’t find any water in the oil. So now that the engine is out I’m going to clean up the bilge and do a lot of preventative maintenance while it’s out. Wasn’t planning on it but just makes sense. I guess this is boating after all. Lol. I couldn’t believe how heavy the hatch was. The foam in the cushions must be waterlogged so I’m going to look at getting the vinyl and foam redone on that too. All in all hopefully all this work will make for a good boating season next year |
Hatch about 250-300 lb and very awkward. If you are going to redo the gasket I have the spec/supplier around here somewhere, let me know if you need it.
Be sure to check your intake manifold under the t-stat for rot. Good luck and thanks for the update. |
Been here and done this Skirby. Sorry it worked out this way for you too. On the bright side, you will know what you have and what you don’t by the end of it all. Best of luck to you. And if I can give any advise, it’s to do things right this time and avoid the next time. |
Skirby, Just ran across this. If you are looking for stock replacement this looks real clean. Looks like a good deal on stock 454/330
https://www.riverdavesplace.com/foru...engine.193102/ |
Thanks Glenamy. I think mine is a mag I'll know more once I take the heads off. I'd like to save the mag if possible to get the little bit of extra horsepower but I appreciate the heads up on that engine it does look very clean
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So I got the engine home and pulled the valve covers and intake. Looks like a 330. Oval port heads. Had 2 bent pushrods. Still working on getting heads off. Still have 3 head bolts that are being difficult. Any thoughts on rebuilding the 330? Was rebuilt in 2008. Or should I try to find something else to drop in? Don’t want to spend $10-12k on a brand new Mercruiser. Looking for options and opinions. I’d like to use the boat for one more season I think then upgrade to a 272 or 292 |
https://cimg8.ibsrv.net/gimg/www.off...656c7986f.jpeg [img]blob:https://www.offshoreonly.com/7043eb51-7313-42b5-8acf-034561159f5a |
I don't think you can get a brand new Mercruiser for $10-12k !
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You can order a new block from 1800 runs new and save a lot of hassle, or buying something unknown but atlas you have time to look around.
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Where can you buy a new block for $1800 or am I misunderstanding? Just trying to figure out all my options |
Might try contacting ph1971 here on OSO, not too long ago he removed a perfectly good 502 and was thinking of selling. He went with a built 540. His stuff is top quality. Just an option.
By the way, that motor you have looks like **** or worse. Good luck. |
Thanks Glenamy. I just sent him a message |
The web site is 1-800 runs new , its in mass a remanded 454 is 3k just an option.
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Good info here, thanks everyone
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Great info on this forum and great people. I am finally getting my engine back in tomorrow. Weather here has been horrible but hoping to be in the water for the 4th much needed therapy |
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