Stuck Power Head Merc V-150

[Tinkerer]

Re: Stuck Power Head Merc V-150

I expect you've tried impact wrench.<br /><br />Another method of freeing bolts is to put cheater bar on normal wrench and give it a sudden real hard pull. Gives a lot more shock/breaking force to corrosion than standard steady pressure on wrench, even with cheater bar. Also 50/50 chance of breaking head off even big bolts, just like I did on half inch diameter bolt on my boat trailer a couple of days ago. But at least then it's easy to centre drill for stud extractor, which usually breaks off flush with top of bolt even if you actually manage to get it started in hole and is harder than any drill bit you can find, so you spend ages and break countless bits drilling little holes beside extractor to get it out so you can drill the bolt out and retap the hole, which it would have been a lot simpler and quicker to do in the first place. <br /><br />Let us know how you go, because removing corroded bolts has to be one of the worst jobs in home workshops.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Your rite Tinkerer corroded bolts and studs are the scourge of the shade tree mechanic. Let me apologize for not using the right terms and clarify my situation. There are 10 stainless steel studs holding the power head to the aluminum exhaust housing, 6 of them go through about ¾” of the housing, 2 of them go through about 3” of the housing, and 2 of them go through about 5” of housing. I have all 10 nuts off of the studs. I don’t think the 6 short studs are the major hang up. The 4 longer studs how ever have 15 years of aluminum oxide from running in salt water and are the bear. One of my buddies had another possible solution which is to double nut the long studs and try to back them out of the block while tapping with a hammer, heating with a torch or what ever else I can think of. Any way I have a bunch of good ideas to try this weekend and I’m sure they’ll all come in handy. Thank you everyone for your input and I’ll let you know what happens.

 

[AndyL]

Re: Stuck Power Head Merc V-150

Not wishing to dampen the fire but I tried double nutting, and attempted to work the studs loose. Wound up stripping the threads on the nuts. They are about $5 a go in UK and I wrecked all of them. I am following this thread closely as I was stumped. There is an acid which is used for cleaning cement off bricks that reacts violently with the "salts" formed by aluminium. That is the way I would go if I ever really need to get in. Fortunately I was only trying to renew the bottom crank seal that isn't actually busted. As someone said " if it isn't busted, don't fix it".

 

[jim dozier]

Re: Stuck Power Head Merc V-150

Andy I'm not surprised. The double nut idea is worth a try, but I think if there is enough corrosion on the shaft of the stud to hold the bracket tight its probably gotten into the threads also. It is truly amazing the deathgrip that aluminum corrosion can get on stainless steel bolts/studs in the marine environment.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Thanks for the tip Andy. I’m going to try the least invasive things first, solder flux, muriatic acid, then move on to drilling reservoirs and things like that. In any case the power head has to come off so I can replace a piston.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Update. I pulled the lower unit to insure it was not the sticking point. It came off with ease. I tried sweating solder flux into the stud shafts with a propane torch. It got bubbling pretty good so I kept feeding it in while moving the torch up to the power head but the farther I got from the end of the stud the cooler the end got until the flux would no longer flow, unfortunately that was only half way up the housing. May be with acetylene I could heat a larger area. I tried a small hammer drill (no bit, just chuck) and a block of wood to vibrate things loose but still no go. The muriatic acid took the paint off the aluminum and smoothed the edges but not much more. It looks like the gasket is about the same thickness as a hack saw blade so I’m thinking I can weasel a hack saw blade in between the power head and the exhaust housing, cut the four studs and be done with it. Any opinions or other comments welcome.

 

[AndyL]

Re: Stuck Power Head Merc V-150

I share in your pain. I am not sure if you will have much luck sawing through with a hack saw blade, and if you damage the faces at all you may be amazed at the cost of an exhaust plate. If you could invert the motor, build a plasticine/ plastic padding "moat" around the studs and leave them in a pool of penetrating oil or acid for some time it may gradually work its way down the studs, especially if you can double nut them and just give it a working from time to time. Whichever way you go you do not want to inflict more costs. Talking to someone in the trade they say that the only way is extreme heat in the form of acetylene torch but that seems awfully brutal. Good luck.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Thanks Andy. I thought about taking it to a mechanic just to pull the power head but no one around here wants to say how much it will cost because they don’t know how long it will take, and at $75.00/hr I can’t afford for it to take too long. Plus every shop in the area is busy dewinterizing.

 

[jim dozier]

Re: Stuck Power Head Merc V-150

How far out of the housing does the stud stick. Your problem is virtually identical to what I went through. I used a drift (basically an old stainless shaft of the same diameter as the stud) and kept banging on the end of the stud while the motor was hanging from a lift. Because I had no other options I kept banging. After a while I noticed that the stud had mushroomed so I cut it off even with the housing and continued banging. I did this for eons and eventually I noticed very small movement. I was afraid it was mushrooming inside the housing so I drilled it out about 1/4" to relieve it. Eventually I got the powerhead off about a 1/4" and used a dremel tool with a rotary blade and cut the stud like you suggested. Then I had to drill out the stub and put in a helicoil. You can use acetylene but I would keep it on the stud not the aluminum. I would heat that stud as hot as I could and then bang on it when it cools down. Patience. Think geologic time.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Ya Jimd I read that in your earlier post. The acetylene torch is wishful thinking, as I don’t have access to one. I was just giving in and accepting the fact that what ever I do I’m going to have to damage those studs to get the power head off so I might as will make quick work of it. I’d like to be in the water for Memorial Day week end, but this weekend a bunch of us are driving down to Hatteras NC for an off shore charter, next weekend is my wife’s birthday, the following weekend is a friends wedding, there’s also a 15’ Glastron with an Evenrude 50 I’m suppose to get running for Memorial Day week end and somewhere in there I’d like to get the garden planted. I think it’ll be more like 4th of July before I’m in the water.

 

[jim dozier]

Re: Stuck Power Head Merc V-150

Its a bummer when life gets in the way of your boating. You can rent an acetylene torch, or for small jobs (this may or may not qualify as small, how many stuck studs do you have anyway?) you can buy an inexpensive oxygen/map gas torch at Home Depot. The problem with those is that the oxygen tanks don't last long and if you have to buy a bunch the cost goes up and it begins to be cheaper to rent the real thing.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

There’s 4 stuck studs, 2 of them go thru about 3” of the exhaust housing and 2 of them go thru about 5” of the exhaust housing. Big job or small?? I just looked on Lowe’s web site the oxygen/map torches there go for $50.00. Could be worth the investment. I also have a small spot on the trailer I’d like to cut out and repair.

 

[jim dozier]

Re: Stuck Power Head Merc V-150

The torch I have (don't know if it is the same as the one you have) uses oxygen in a bottle similar to the map or propane cylinders commonly found in hardware store. But since oxygen doesn't liquify easily like propane they can't put much gas in one. I don't think the one I have would cut much more than sheet steel but its good for heating up the occaisional bolt.

 

[Tinkerer]

Re: Stuck Power Head Merc V-150

Spoke with a very experienced outboard mechanic who says that the only way is oxy-acetelyne heat on the stud, but beware overheating the alloy or you'll end up with a big blob of molten alloy on the ground, just like some of his apprentices have done. He couldn't give any real guide to when it's overheated - just experience. I guess you know the alloy is overheated when it melts.<br /><br />Just to cheer you up, I have an interest in an obscure British V8 car which is notorious for corroding the heads onto the block. I've heard of one case where the front wheels were lifted off the ground by a hoist on the head and then it was belted with an air hammer for ages. Only effect was a tired mechanic. The last resort for this problem is some kind of fine power saw that slides between the head and block, but then you're up for the cost of resurfacing both if they're not damaged beyond repair.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

Jimd I think I'll go ahead and buy that oxy/propane/map torch and try it. Anyway as I said in an earlier post I can fall back on wiggling a hack saw blade through the gasket and cut the studs.<br /><br />Tinkerer I know what you mean about over heating the alloy. I worked at an Evenrude dealer for 2 years in the early 80’s and did just such a thing on a 1960 something V 4 lower unit trying to replace the water pump.

 

[jim dozier]

Re: Stuck Power Head Merc V-150

I believe if you only apply heat to the stud, even if you get the stud red hot it is not going to melt the aluminum, because the aluminum conducts heat away so fast. That's part of the reason why you have to heat the end of the stud so hot, just to get the other end of the stud to warm up some.

 

[Tinkerer]

Re: Stuck Power Head Merc V-150

What jimd is right. Problem with short studs etc is heating stud without flame blowing past onto alloy and heating it as well. If you can come at it from the side rather than dead ahead it would be OK. I couldn't used heat on my tilt shafts because they were sawn off flush with alloy and I'd have flame direct on alloy.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

That's good information thanks guys. My next go round won't be until next weekend. I'll keep checking and adding to this post, if no new ideas come in I'll bump it up to the top just to make it easy to find.

 

[Tinkerer]

Re: Stuck Power Head Merc V-150

Maybe a dumb suggestion, but could work in theory.<br /><br />I assume oxy heat works by expanding the stud or whatever against the thread and forcing the corrosion to break, because the corrosion is the weakest substance.<br /><br />Would the reverse work, i.e. applying super cold to the stud so it contracts away from the thread and breaks the corrosion, without fracturing the alloy if it's cold too? If so, is there some sort of freeze pack or aerosol that's readily available? I remember when I worked for the Aussie Navy back in the dark ages there was a continual problem with empty fire extinguishers (maybe CO2?) in the dockyard because the workers used to give their drinks a squirt to cool them down pronto.

 

[Outrage-19]

Re: Stuck Power Head Merc V-150

In theory you’re right the different expansion and contraction rates of the different metals causes a shift between them and brakes up the corrosion so cooling should work too. I wonder if canned air would do it, or if something like 134a would be needed. Does anybody know or has anyone tried this? Maybe heating and then cooling would do the trick.