Removing Head on Evinrude 50hp 50573B

[JerEazy]

Ok - so today i'm removing the head to replace the head gasket, pressure relief valve and support parts and also the thermostat.

I know the big worry here is that the head bolts sheer off or snap - so i've been hitting them with PB blaster for the last 3 days to hopefully help out. Is there ANYTHING else you can toss my direction as potential traps or pitfalls?

Would i be better using a battery impact on the bolts as opposed to traditional socket wrench or spanner? last thing i want to do is drill and tap these. But on the bright-side i have a replacement cyl head. So if i do sheer a bolt head off (as long as it's not broken flush to the power head) i should be able to grab it with some vice grips and work it out after head removal.

 

[F_R]

Best way to avoid broken bolts is---don't break them. If they don't move with a reasonable amount of torque, use some heat.

 

[JerEazy]

really hoping for no breakage. of all the things i'm doing to the boat and engine, this is the only part that has be a bit worried.

the LU is the most annoying (getting that damn shift rod up the shaft correctly is a PITA!) but this is the most worrying.

 

[racerone]

Shift rod assembly is done by folks every day.-----Nothing to it and easy.---Just take the starter off.

 

[M.A.CCruiser]

Shift rod assembly is done by folks every day.-----Nothing to it and easy.---Just take the starter off.

I really hate that i didn't think of this.... Thank you. i kept getting it up under the power head but it would be turned left or right our whatever and wouldn't line up to the linkage.

Anyway, i'm I'm waiting on a new linkage (old one broken) and need to fix the control box (stuck in reverse) - so it'll be a minute until i'm there again.

but thanks again.

 

[racerone]

Hopefully the shift rod has not been turned carelessly.-----That can and will affect the shifting.------Also the control box should not be shifted without either turning the prop or the motor is running !

 

[M.A.CCruiser]

lets assume it's been turned - because i'm assuming worst case on everything in this engine. What should i watch for? With the LU dropped i can lift and push down on the shift rod and get FWD, N, and REV.

I completely agree the control box shouldn't be shifted while the engine isn't running - but the engine didn't run during my inspection and i wanted to make sure it wasn't frozen up. So i shifted it a few times before purchase. But i had to take it one step too far while walking my wife through it and i shifted a few times in the garage. Clean shift 2 or 3 times then got locked in reverse. But its locked even with the shift cables unhooked and the LU was dropped at the time. Google/YouTube showed the dogs will jump sometimes and come off and may need replaced. I'm opening up over the next few days and will check it out. Hopefully an easy fix.

 

[racerone]

Of course you can shift it with the lower unit off.----You need to look up the subject of " shift rod height "------The shift rod is SET to a certain dimension before installing it on the motor !

 

[M.A.CCruiser]

Of course you can shift it with the lower unit off.----You need to look up the subject of " shift rod height "------The shift rod is SET to a certain dimension before installing it on the motor !

Thank you. I'll search that now.

 

[JerEazy]

I’m no mechanic - but I’m thinking maybe the head gasket was blown.... and probably overheated to some degree in the past....

 

[JerEazy]

Luckily I have an extra head and water jacket cover that’s in very good condition. It’s spending the night in the bath to get it ready for install.

But there was a casualty. Middle bolt on the port side snapped. I mean very easily snapped. I was using my 1/4” driver to make sure I didn’t over torque.

Now i I had to drill it (sloppily no doubt) to get it down enough so I could remove the head. I’m guessing I have to cut it down flat and drill/tap?

never actually done that - so may call a mobile mechanic out to knock that out. Anyone in Sarasota wanna make a few bucks? Haha

brightside of the evening is that I do have 2 freshly rebuilt carbs ready to install and a brand new water pump installed as well.

 

[racerone]

Simple words----That motor needs rebuilding.-----Or was rebuilt and old head used.-----Post pictures of top of the pistons.

 

[JerEazy]

Top of the pistons don’t look too bad - I hit them with some PB and a rag and this is what’s left

they are already 30 over
top

bottom (where head damage was)

 

[JerEazy]

Broken bolt is out! Awkward combination of vice grips locked down on a flat head screwdriver, some wiggles and then the old steroid push. Pop!

 

[JerEazy]

Am I good just replacing the one bolt? Or should I order a whole set?

 

[kbait]

I’d probably replace ‘em all since you had one go bad.. likely not essential.

 

[M.A.CCruiser]

rgr that - thanks.

 

[JerEazy]

New head and jacket cover ready for install - waiting on bolts to be delivered.

 

[JerEazy]

She lives! Compression went from 120 to 140ish on both.

https://youtu.be/uSy8xQzBp08

wish it had a tell tale - but the overheat alarm didn’t go off and water was coming out of a small hole in the back (or front depending on how you look at it) of the engine and there was Smokey water out of the through prop exhaust.

hope to splash the boat Thursday after I install a tach tomorrow.