what caused this motor to seize?

[gazza2007au]

i have just brought a 1975 70hp johnson the person i brought it off said the motor had seized and he showed me the flywheel would not turn by hand than we laid the motor over in my trailer i drove home and all of a sudden the flywheel was turning over as normal and here is a picture of the piston in no1 cylinder look up at the top of the picture u can see a peice missing from the piston also i just pulled the thermostat out and only the frame was there with no internals and there is very little to no scoring on the cylinder walls

 

[a70eliminator]

Re: what caused this motor to seize?

looks like water ingestion from maybe a blown head gasket then motor sat for a long time without being addressed, was the piston at the top of it's stroke like it is now when you pulled it apart? Are you sure that's not just a hunk of carbon chippied off the piston? That piston looks dry compared to the other one, makes it look like water ingestion.

 

[gazza2007au]

Re: what caused this motor to seize?

the picture in my first post is of piston no 1 (very top) and it was at top dead centre at the time it blew up heres another picture u can see in the 3rd cylinder (bottom) look closely the to bottom left of the picture u can see some very fine white powder in the port the whole port was filled with this white powder when i got the pistons moving
u can also see in the bottom cylinder (no 3) i rubbed the powder off of the piston to try and smell what it was and yes you are correct after the motor blew it sat for 2 years in a shed

 

[Lion hunter]

Re: what caused this motor to seize?

Overall it just looks like a seious case of neglect. Is all the paint burnt off the motor or is it just corroded? If I had to guess from the looks of it, it may have blown a head gasket and got water in the cylinder and siezed. The PO probably didn't know what to do after pulling the cowl off they let it sit that way for years. Was this a salt water motor?

 

[gazza2007au]

Re: what caused this motor to seize?

the paint is corroded (i think) yeah the last owner didnt know what to do once it blew up he took it to a shop and the mechanic pulled the head off and said its no good the cylinder was scored and pistons blown funny he said this he couldnt get the pistons to move and the piston in question was no 1 at TDC and the side plate bolts snapped on me when trying to remove them so the mechanic had no clue obviously as he could not see the cylinders and i have and theres nothing wrong with them a hone maybe get them rebored and they will be fine
do u think the conrods and crank shaft will be rusted? im hopping there salvageable to keep cost down as im already planing a rebuilt of all bearings,pistons,rings,gaskets,thermostat and possibly a new water pump altho i was told this was replaced just before the engine blew up im not taking anyones word for it i would rather replace the parts since im doing a fresh engine

 

[crxess]

Re: what caused this motor to seize?

From piston coloration it looks like it ran hot and popped a head gasket. Rings probably stuck to the wall after making it act blown up. A hone, new rings and gaskets may put you back in business.

 

[jonesg]

Re: what caused this motor to seize?

It sat in a shed, and the shed was in the ocean.?
Tear it down and check the crankshaft.
Nothing to lose.!

 

[Lion hunter]

Re: what caused this motor to seize?

Agree with Jones, tear it apart your already that far into it. With that level of neglect I wouldn't take any chances. Trying to get something like that clean enough for reassembly w/o a complete disassembly will be tough. I'd pull everything have it hot tanked. You'll be glad when you go to put it back together

 

[gazza2007au]

Re: what caused this motor to seize?

the guy said he was out driving the boat he heard a big back fire noise and the motor shut off and wouldnt restart this is my first outboard rebuild i plan on pulling it apart tomorrow i will see how far i get but i will be happy with the carbies and power head off if i have enough day light i will split the cases aswell and take pictures of everything

 

[tx1961whaler]

Re: what caused this motor to seize?

That looks like a saltwater outboard that had zero maintenance, never flushed w/ freshwater after running, until the head gasket went. I'd seriously look at the overall condition of the motor (lower end, etc) before going too much further. It looks like every darn bolt on that would break off from the corrosion...

 

[gazza2007au]

Re: what caused this motor to seize?

can someone help me out here i have contacted the two companies on ebay about there powerhead rebuild kits a few days ago and i have been trying to call them aswell by phone no answer every time i call i even tried another company i found in the USA by doing a internet search and they specialize in powerhead rebuild kits still no answer i have checked the local time over there and what time the shops open can someone point me in the right direction of a company that sells a rebuild kit for this motor (scroll up for details) as iboats does not sell some parts for a 1975 model

 

[tx1961whaler]

Re: what caused this motor to seize?

It's a holiday weekend over here. I'd try tomorrow.

 

[ezeke]

Re: what caused this motor to seize?

Try powerheadkit.com at 1-813-673-8866. Timed zone is US eastern standard.

email at Pwrhead@tampabay.rr.com.

 

[gazza2007au]

Re: what caused this motor to seize?

ahh that will explain it and yeah i tried calling powerheadkit.com

thanks guys ill call tomorrow

 

[F_R]

Re: what caused this motor to seize?

ahh that will explain it and yeah i tried calling powerheadkit.com

thanks guys ill call tomorrow

gazza, I don't mean to be obnoxious, but save your money and effort. OK, truth hurts, but that doesn't change the truth. That motor is even beyond junk stage. If you decide to proceed anyway, eventually you will admit that I'm right.

 

[jonesg]

Re: what caused this motor to seize?

Find another 70hp and save this one for a parts engine.
Or part it out.

 

[Lone Duck]

Re: what caused this motor to seize?

Find another 70hp and save this one for a parts engine.
Or part it out.

Yep !!

 

[gazza2007au]

Re: what caused this motor to seize?

whats wrong with this engine besides being blown up? all the salt can be removed i have removed some from the cylinder walls and there is no corrosion
i split the crankcases today to find there was water getting into the cylinders my mechanic thinks it getting in thru the exhaust manifold im yet to get this part off he said it may be corroded and there rare parts to find in australia so i will be making some phone calls soon to the USA also he dismantled the crankshaft,bearings,conrods,pistons to find 2 of the pistons were corroded from water entering the cylinders the number 2 big end bearing (conrod) was corroded and welded to the conrod the conrod is of no use the main crank bearing was also rusted my mechanic is keeping my crank shaft to get me a quote on machining the journals and cleaning the surface rust if my crankshaft is ok and if my exhaust manifold is corroded and i can find another i will continue rebuilding this engine
my mechanic said the main cause of the engine blowing up was due to a blocked carby jet or someone not mixing enough oil in with the fuel because 2 pistons were dry

 

[Faztbullet]

Re: what caused this motor to seize?

You are going to need a crank and rods and OCC is out out business so the repaired crank supply is drying up, still plenty of used though. I would remove the side cover and check how much damage you have in there. I checked and powerheadkit.com only sells a kit that fits 1976 and up engines.

 

[gazza2007au]

Re: what caused this motor to seize?

so far im happy to pay for the powerhead rebuild kit that is on ebay by fasterthanmachone considering i get almost everything for under $400 minus rods and main bearing the mechanic i have been going to for the past 10 years or so stripped the crank and said it might be repairable he needs to wait for the specialist to come in tomorrow or the day after and two of the three rods are ok

Faztbullet, i didnt end up getting my uncles 60hp evinrude but im wondering do u have a used crankshaft for this motor?

also the side cover is going to be a pain in the ... as all 19 bolts snapped im in the process of using a screw extractor but there not working arggg ill work something out unless someone here has a better idea?