2001 Mercury 90hp Sunken

mav6759

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2001 Murcury 90hp Was Seized

I have 2001 Mercury 90hp it was given to me with the pistons seized... It took 4 week but I got it unseized...I have a couple of issues... one I spun the nut that holds the flywheel down...I believe the threads on the crank is gone as well... when trying to get the motor upsized, I started with a 600 pound impact and ended with a1200 pound impact which in turn spun the nut on the crank. ok first question, can I try a different size nut on the crank, to try to cut new threads on the crank itself, or well I have to tap the threads on the crank... Second question, I got the motor to run on muff's, it runs very well with no issues so far... can I use anything to protect the walls of the pistons, such as some type of oil or piston saver... lol...

Any Help would be appreciated... thanks Mav
 

racerone

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You must be joking ----600 lb and 1200 lb impacts.---------Have you thought of inspecting internal parts and bearings for rust / corrosion damage ??
 

mav6759

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Nope just started it and let it run for about 2mins it was oil locked with all the oil I put into it.... but a spayed some crab cleaner in the spark plug holes and it ran great.... the 600lbs, did not move it at all... but when I put the 1200lbs it freed it up after a couple of hits... The instructions I got with the stuff I used said to use an impact to shake up things.... and it did... now it runs a little to good... I want to do everything I can to save this motor....
 

Scott Danforth

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who ever told you to use an impact on the motor simply made you a pile of junk parts

to free up and save a siezed motor, you must carefully take it apart, inspect everything and repair appropriately

putting a 1200 lb impact on it is basically beating it with a sledge hammer and breaking internal parts, and in your case, external as you damaged the crank

your crank is junk. no, going to a smaller nut wont help, the smallest nut available for the task was already in place.
your pistons and bores are now junk. anything that was stuck and galled is now broken and galled

"oil locked" as you put it is actually galling, when two surfaces do not have lubrication, they weld themselves together. simply breaking them apart doesnt repair them.
 

Chinewalker

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A teardown is in order. Period. Yes, it may run now, but it's expected service life will likely be measured in minutes. Steel bearings, cranks and rods do not like being put back into service after rust builds up enough to seize things. Steel rings and bore sleeves to not like being put back into service after being unstuck. I would not trust this motor if you try bandaging it back together without a teardown. As noted above, the crank needs to be replaced anyway. Maybe you'll get lucky and that's all it'll need.
 

mav6759

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I listened to everyone, and got scared and call In a mechanic... He is suppose to be the best with almost 40 years of working on Mercury outboards and 3 shops. I asked him to go through the motor... he took the head off and he said he found no damage to any of the pistons or piston walls... he said he spent over 5hours on it and can't find anything that was damage except for the threads on the top of the crank. He said he ran the motor 10 times for 2mins each times. Each time he increased the power until he reached full throttle. He warned me that the motor could have some internal damage as you guys spoke about. But he said it ran just fine, no problems (other then the crab's needed to be cleaned) and that he could not find any damage what so ever... He just said I lucked out, he said he never seen a motor that was seized that didn't have some form of damage. He did say he would have to tap the threads on the crank, but that's it as far as he can see... he did mention that he didn't believe the motor was seized at all, he believes that the rings were just stuck with some rust and not seized. He did say people use the word seized out of context, when the motor was just stuck.. He ran a compression check and found 110p per cylinder..(which he said he looked up the compression for that motor when it was first made, and the compression was 110p out of the factory.. He found some rust on the top of the pistons, and he ran some Quicksilver Quickleen (whatever that is) through the fuel to clean everything up, Other then that, he said to continue to use the Quicksilver Quickleen and see what happens.
 

racerone

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Perhaps you meant that he took the exhaust cover off !------Because there is no " head " to take off to inspect cylinders and pistons !!
 

flyingscott

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Did anyone check the Lower unit? More than one motor has been diagnosed as seized when In reality the Lower unit is the problem. You may have finished off the gears.
 

mav6759

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You are so right, I never thought about the lower unit... come to think of it, it may have been stuck in the lower unit...I may a call to him today to have him checkmate lower unit....I just want this motor to run right... but I would rather deal with a putting another lower unit on the motor then buying another motor.....
 
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mav6759

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So far everything looks and sounds good....But here is a picture of the threads on the crank....My question is can I use a nut and try to cut new threads on the crank bolt or would I have to tap new threads....
 

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mav6759

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My question is can I use a nut and try to cut new threads on the crank bolt or would I have to tap new threads....
 

Bondo

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So far everything looks and sounds good....But here is a picture of the threads on the crank....My question is can I use a nut and try to cut new threads on the crank bolt or would I have to tap new threads....

Well, you can try, but I doubt it'll work,....
It would be better to chase the threads why the right die, then with a new nut, it Might hold torque,...
 

lmuss53

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Bondo offers the best way to possibly salvage the existing thread, but it will likely strip off again as you tighten the new nut. Put some red thread locker on the CLEAN nut and crank and crank it down good and snug. I would shoot for about 80% of the recommended torque. If you get there and it holds, stop and pray that the loc-tite keeps it on.

Sometimes there is good thread surviving above or below the stripped off portion, you can sometimes get to use those good threads by adding or leaving out washers. In this case I would stack a few washers and try to get out on the undamaged threads at the end of the crank.I would actually try that before I tried to do anything with the damaged thread. Stack enough washers on it to get the nut out just about flush with the end of the crankshaft, where there is undamaged thread, tighten it to 80% with the loc-tite and leave it alone. If it strips, you can try the fix below.

I hate to offer this up, but in my days of patching printing presses back together, for a company that did not believe in new parts, I would have drilled the end of the crank out about an inch deep, and tapped it with about a 3/8 thread. Make a little cap or stack washers, so that goes down far enough to just contact the nut. Get a socket head cap screw that uses most of the tapped thread (no less than about 5/8 inch) put some red loc-tite on the threads and tighten it down.

Since this motor seems to be on borrowed time anyway, that is as good of a fix for the stripped nut as any.

If the crank is hard there you will know it as soon as you start to drill. If it doesn't drill freely right away you will probably not be able to drill and tap it. If you break a tap off in it you are likely done. Don't drill the hole any bigger than 30% of the crank diameter out there at the threads,

I know these are "jury rigged" methods and I don't recommend them or use them often myself. I am just making some suggestions based on things I learned years ago, working in the maintenance shop for a company that thought "jury rigging" was good business.

BTW, you tap internal threads, you chase or trace external threads. Putting new external threads on the end of that crank would be a major undertaking, especially in the engine with hand held tools. Drilling and tapping a hole straight is difficult but certainly possible.
 
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lmuss53

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Looking at you picture there I would clean all that crap out of the hole and off the thread and put a couple extra washers on that with a new nut, lock washer and red loc-tite, tighten it to about 80% of the recommended torque and hope for the best.

And one more thing, if your mechanic spent 5 hours with this motor he should know if the lower unit is working or not.
 
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mav6759

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Ok, I have been dealing with this 2001 Mercury 90hp that was first sunken in 8ft of water and frozen.. So I got it unfrozen, and got the motor running with a little starting fluid...Just want to see if it would run...now I had it look at by a marine mechanic and he say everything looked good to him...I did not want him to start it, because there was water in everything..Water in the oil, and I imagine carb's...My question is, besides the lower unit, carb's and the oil tank, should I look any other place for water...and what can I use to clean all the lines...

Thank, Mav
 

mav6759

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The starter was the first thing I did...solenoids, never thought of that, should the carb's be rebuilt or just cleaned...
 

Chris1956

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Fresh water or salt water? If salt water, a tear down is advised.

Either case check all electricals. i.e. If a coil has a crack, water can get in. You can bake starter and solenoids/relays in oven on low temp to dry them out.

Carbs should be cleaned, and new gaskets installed. Replace floats and inlet needle if in doubt about condition..

Run her soonest for 45 minutes to dry out crankcase. Gearcase is probably OK, but check condition of gear oil.
 

jbcurt00

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Merged

A lot of the sunk/seized stuff has already been covered
 
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