cracked manifold

[evinrude enthusiast 93]

I have acquired a I/o with a 77 mercruiser 120 the exhaust manifold has been cracked and the previous owner for whatever strange reason he plastered it with 2 layers of jb weld. I plan on carefully grinding the jb off with small grinder wheel or dremel then polish the old coating off to get it to bare metal and then weld the small crack together grind it smooth and then prime and paint it with engine paint. does anyone on here think this would work? I have had success with car and tractor manifolds but never a mercruiser... good idea? considering I looked on here and online new ones are around 300$ before shipping i have found local whole motors without outdrive for 200 local..

 

[Scott Danforth]

buy a new manifold, it is something that does wear out after a while due to corrosion.

 

[evinrude enthusiast 93]

ill try to find a nice used one or a donor motor bc I don't have a lot of cash

 

[evinrude enthusiast 93]

just realized the web site doesn't offer a new manifold for my model just the newer ones. does anyone know the compatibility?? mine is a 76-78 21xxxxxxx model

 

[alldodge]

The Merc part number for your manifold is 63122A14, if you use this number a google it there will be some show up. Don't see you being able to use anything other

 

[Grandad]

I repaired my '72 where it appeared to be cracked only along the lower corner by cementing a piece of angle iron to it using JB Weld. That was before I realized that the manifold also has intake chambers. If you get a leak of water into the intake, there could be disastrous results. Anyway, I guess I'm lucky that I've seen no evidence of that since after many years of hard winter freezes. I made sure both surfaces were free of paint before cementing. You still wouldn't know it was patched, unless you are familiar with that manifold. - Grandad

 

[evinrude enthusiast 93]

well on my manifold the right side is the intake with the top mounted carburetor and breather and the right side is the exhaust the crack is on the right side I'm not positive of the severity but from what I can see its aprox 2-3 inchs long one crack so there shouldn't be any chamber interference as far as I can tell GD.

and thanks for the part number AD I price some I think what ill do is see about acquiring a used manifold as well as fixing mine so I have a back up in case if I cant find the same model ill purchase new but being a young adult I don't have readily available funds

 

[evinrude enthusiast 93]

this looks to be of similar severity as my current issue I attached a link the guy cast iron welded his 2 manifolds and they look great who knows how long it will last I am looking into this and might buy some sticks this looks like a great idea

 

[alldodge]

Your working with cast iron and according to muggyweld it says you need to preheat the iron to between 500 and 1200 degrees F and you need a TIG welder.

http://muggyweld.com/cast-iron-welding-rods

The vid is being done on cast aluminum and then you can use other gas such as a propane, MAPP and oxyacetylene

 

[Scott Danforth]

paying for someone to weld cast iron and guarantee their work is more expensive than a new manifold

 

[indybleck]

Also when welding cast iron it has to cool slowly, we use to have lime in a container and after welding put the cast iron in the container and cover it with lime and let it cool.

 

[evinrude enthusiast 93]

dolomite lime? or another type? bc we have a ton for the garden. I was going to weld it myself I have a torch and went to school for welding have plenty of experience but not with tig I always melted my work couldnt get the gas speed ratio quite right? even tho I do believe it can be done with an ac/dc arc welder which I have a ton of experience with and could do at my uncles shop I also have a propane torch. or my local BOCES would do the work for free to provide welding students with experience, given I provide the stick if they don't have them there. so It wouldn't cost me anything but the price of the sticks and they also have argo and propane torches there as well. thanks all for the opinions and advice.

 

[Scott Danforth]

remember, if you leak water into the engine, you can loose the engine. That $290 new manifold is looking cheap at that point.

I personally would not weld a manifold, and I especially would not have students welding on a critical part like a wet manifold.

 

[evinrude enthusiast 93]

I do agree that its not a good ideah to have a learner weld it thats why I planned to do it myself. I'm not so sure of the condition of the engine as of now it needs a complete rebuild as what iv seen from the previous owners "repair" it didn't hold up but the crack is on the exhaust side only if the previous owner had gotten water into the intake side with a rebuild of the carb and rehoned pistons and cleaned combustion chambers what other damage may have developed from the theoretical introduction of water into the intake and combustion chambers? I have found a used manifold for around 100

 

[alldodge]

If water gets in the cylinder when it's running the engine will lockup, in doing so it can brake connecting rods, pistons, cam. Turns and good running motor into a anchor/scrap. If it leaks water down the cylinder and doesn't puddle, turns the oil into milk and there goes your bearings

Think about finding a donor boat with good engine?

 

[evinrude enthusiast 93]

I found one for around 200 local the oil is clear its black from being used but not milky and lower unit oil is not fogged or milky as well I checked this first thing when getting it. the engine was set up but I got the crank broken free with break bar I assumed this was from sitting for 5-6 years I havend tome mutch other work besides that and it was missing manifold nuts as well. the only problem is the other motor I found talked to the guy and has a manifold bolt broken in it where the elbow is so this was ran last year but manifold was broken during riser maintenance so they upgraded to a newer 140. so in the end I would be buying another manifold anyways and ithers I have seen go for aroung 700-1300 but that doent mean another wont become available in the future. I can check the rods pull the valves and clean the carbon while im at it and disassemble crank case to inspect piston rods when I replace the gaskets if they chet out all good do u think it would still be worth rebuilding? the alternator is shot and the starter is rusty a little but outside looks don't always matter as I have seen with tractor and car starters in the past tho I would most likely change all accessory components a little at a time over time. its a big project but I have rebuilt a handful of 4 cyl car engines before around 5 total and this is my first time with a boat so I have experience enough to know conponents spacing and replacement methods but don't know where to get a manual for my specific model the website only offers for newer models and I found some pdf versions but u never know if u can trust the download link.

 

[Bondo]

but don't know where to get a manual for my specific model the website only offers for newer models and I found some pdf versions but u never know if u can trust the download link.

Ayuh,.... Click on the Don'S Adults Only section link, at the top of this forum, or in my signature, 'n follow the links to the factory manuals,....

Lotsa other Great info in there too,...

 

[evinrude enthusiast 93]

I did look through it and manuals but before I guess I overlooked it said 1964-91 I'm sorry so I guess they do have one for around 30$

 

[Bondo]

I did look through it and manuals but before I guess I overlooked it said 1964-91 I'm sorry so I guess they do have one for around 30$

Ayuh,... The factory manuals are Free to view,...

 

[evinrude enthusiast 93]

I will look again I'm not too keen on navigating the links yet. thank u bondo. can u tell me how to close a thread?