Taking heads off 1987 EV 90HP. Is this going to be rocket science ?

bang4dabuck

Petty Officer 1st Class
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May 24, 2009
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I need to tap out 6 (1 + 5) cylinder head COVER bolts that won't come out. I was also encouraged from several people here to take the heads off to check the WATER DEFLECTORS. So a couple of questions.

1) The book said something about marking the pistons position with a pencil (sharp scribe). This kind of intimidates me. Do I have to worry about this for what I am going to do ? Since they are on a crankshaft don't they move in unison and therefore are in time with each other ? (Excuse my mechanical ignorance if I'm way off base, I just don't want to change this can of worms into a bucket of snakes)

2) I am trying to avoid the same situation on the cylinder head bolts that I ran into on the COVER bolts, i.e. busting. Any precursors I should perform like heat and penetrating oil (FLAMMABLE !!!) ? When should I do this (then and there or the day before) ?

3) Can I change out all these bolts with a cheaper and stronger bolt ? OEM COVER bolts $3 each (32 of them)and HEAD bolts $4 each (20 of them).

Thanks
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Taking heads off 1987 EV 90HP. Is this going to be rocket science ?

Not rocket science. You should not need to remove the heads to drill out the head cover bolts-unless you can't get drill access to the hole due to the lower cowling. If you want to check the water diverters, then pull the heads-it is really no big deal. You don't have to do anything with the pistons, like marking them. Pull the heads, drill them out, replace the cover bolts, install new cylinder head gaskets and reinstall/torque the heads. If you don't consider yourself a drill and tap expert, you may have another option. The bathtub heads for this engine are fairly common-you might be able to come up with a used set cheaply-and avoid all the machine work aggrivation.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Taking heads off 1987 EV 90HP. Is this going to be rocket science ?

replacing the heads, i have found cheaper, than the machine work. get a price on both, then decide.
 

bang4dabuck

Petty Officer 1st Class
Joined
May 24, 2009
Messages
296
Re: Taking heads off 1987 EV 90HP. Is this going to be rocket science ?

I had thought about finding some used heads but I will still take a shot at tapping them out myself or I got a friend who is a good heavy construction/auto mechanic who I would trust if he says he can do it. He is a busy guy and I have not asked him yet.

What about those HEAD bolts ? Any trick to avoiding breakage ?
 
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