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Evinrude 70 head stuck

N

Nick0151

Regular Contributor
Hi iv tried to take my head off to inspect gasket and the interior 4 bolts have snapped. I can’t get the head off iv tried with a lot of force still won’t budge.

Any ideas?


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Where did the bolts break, level with base of head, part way into the head? If part way, heat may help. JB40 too.
 
The bolt hole is jammed on the bolts with corrosion products , the white powder.---AKA aluminum oxide.-----Soaking with some penetrating oil for a few days.----Jarring it with a rubber mallet may break it loose.
 
Guys let me know if this is bad idea but was thinking of starting the motor and letting the combustion push it off with the other head bolts in but not all the way? I am thinking bad idea but just wanted to know for sure
 
That is a normal thing that happens when motors are not maintained.----Head bolts checked for torque..------Sorry , many folks just think that if a motor barks and roars then everything must be OK.----Sounds like a bit of moisture leaked into the hole around the bolts.-----All easy for me to say as I would simply cut the head off and install another one.
 
I agree with you on that, why I was little apprehensive about taking it off iv only owned it for just coming up to a year was little bit of a project to get it running well. Head had never come off still had the original paint on it.
 
Well took water jacket off the head to try and get some more room and heat to it.. no bloody thermostat at all guy before said it’s been done…
 
Ha! Yup, nothing new to me, either. Those 2 busted bolts right at head indicate what Racer said.. it would be nice to work that head off those bolts and then you can vise grip or weld a nut on them to remove them. If welding be careful with electronics and disconnect anything that could be harmed. A little heat goes a long way because aluminum expands more than steel and will relieve some of the pressure on the threads from the oxidation. Heat and tap heat and tap. You can also heat and quench with cold water.
 
Note:
Racer, thank you so very much for your commitment to the forum. You have helped so many over the decades. You are a true "beast" of a man. Never ever will take you for granted. You have been a great mentor.
 
That was a battle!

Got the head off and definitely to me looked like need replacing. Tell me what you think please.
Pistons all seem ok little bit of side to side for #2 but nothing to bad.

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The head is warped ( they all are ) and needs refinishing before mew head gasket is installed.-----Move piston #2 down and post pictures of intake and exhaust sides of the cylinder walls.
 
Thanks will have to find a shop may need a replacement as two bolts can’t get out of the head not even started on 4 head bolts yet

This is all #2

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Heat the block near the broken bolts with a torch.----Aluminum expands more than steel.----Often the stud can be turned out with a vice grip.----Or make a drill jig from 1" plate .----That will keep the drill centered.----Pictures need to be at a better angle to show condition of cylinder walls.
 
Thanks racerone! On video looked like little bit of scoring on #3 and that one was the one giving highest competition reading.

When you say torch like a blow torch I have mapp Pluss one or a oxy one?

Thanks again for the advice
 
It looks like it has a lot of hrs on it.----Fix up those bolts.-----Refinish the head.---Install a new gasket.----New water pump impeller.----Test run.
 
will do, was running really well before took head off well ran well enough with the 19p and two adults and 3 kids would rev to 5200 ish and do good 38mph.

But glad started the head replacement as know not the best it could be.

Going to try clean out the water passages as don’t look great.

You think run better than before?

Thanks again
 
I don’t think going to get the bolts off the block without a battle just tried and they snapped again got enough to weld a nut on and try failing that may be drill and tap or a heli coil. Anyone know the bolt size and thread for the head bolts please?
 
I would replace all the bolts when you get to that point.----Now they are expensive from the factory.----Visit your local bolt supplier and get them for a fraction of the cost.
 
Thanks again Racerone! Yes Jesus your right there they want crazy money if OMC packed them like £15 ish per bolt going to go regional fasteners company about £2 per bolt would a A4 bolt do that’s 316 ss? Can get higher grade not sure what are on it G8 maybe?
 
If I drill inside the bolts and tap them think that would be ok? If get a 5/16 -18 unc blind tap? Just trying to figure next step.
 
One more question racerone, do you know bolt size and thread for the water jacket that goes onto the head too iv got two bolts stuck there too can’t get them out but ones ready to be taped il take photo now..
 
racerone said:
Read post #16 --carefully.
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Yes will definitely make a jig to do it and clamp it over each bolt! I tried heat and the bolts snapped closer so before I go to far think I’ll make the jig and go down that route rather than welding a nut onto the broken bolts as I think that they are one with the block now 😂
 
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