Head Gasket Replacement?????

[schonn]

Hello all. I just bought a 1975 70 hp Evinrude engine and the lower spark plug has the threads striped out. I am planning on removing the head to put a heli-coil in its place but I have to remove the head to do so. Does anyone have information on how to remove the head? I have never worked on marine engines before and I really don't want to screw anything up. I have a shop manual but it does not go into detail about how to remove just the head. Is this a really big job (head removal) or can it be done without tearing the entire engine down? Can anyone help me? Thanks for your time. <br /><br /><br />Schonn

 

[ross patti]

Re: Head Gasket Replacement?????

hey schonn...welcome to iboats.I had to take the head off my 35,and was concerned like you.It was really simple. Your motor may be different.<br /> In a few hours,you will get accurate advice from experts...but I will give you the following tips: get yourself a good manual{genuine omc if possible}, listen good to the advice you get from this site..it is accurate,invaluable,and freely available.<br /> Taking the head off is not a big job,you shouldn't have to pull too much extra off.<br /> I will now leave it to the real experts....

 

[OBJ]

Re: Head Gasket Replacement?????

Hi Schonn and again, welcome!<br /><br />As rosco said, removing the head is a pretty straight forward job. On your particular model, there should be 18 head bolts to remove. If you run into one that is stuck, take your time with it, soak it in PB Blaster. Nothing is as frustrating as a busted off bolt. <br /><br />You will want to disconnect the temp sensor lead. Look for a single tan wire coming from the head...or it could be a "salmon" color. It'll have a boot you can pull back to expose the knife connector.<br /><br />Clean the surfaces real good, remove any traces of the old gasket. It's a good idea to take a known straight edge and run it over the surfaces just to make sure they are straight and not warped.<br /><br />Depending on where you get your head gasket, some will come with a heat activated sealer on it and some will not. If you get one that does not have the sealer, just apply a very thin coat of gasket sealing compound to it. The gaskets that have sealer usually have "apply no sealer" imprinted on the gasket. The BRP PN for your head gasket is 313413. Should help when getting one.<br /><br />Torque the head bolts 18 > 20 ft lb. Start with the center bolts and work your way out in a sprial around the head bolts. Torque in at least two stages.<br /><br />While the head is off, this would be a good time to take a look at the cylinders and see what shape there in.<br /><br />The job is not hard. Just take your time and make sure things are clean before you re-assemble.<br /><br />The link below will take you to the BRP site. Click on engine diagrams and follow the prompts. Take a look at your engines parts break down for the block...it'll be under "Cylinder and Crankcase". Should help you out.<br /><br /> http://www.evinrude.com/en-US/ <br /><br />Post any questions you may have....someone will help.

 

[marysboats]

Re: Head Gasket Replacement?????

When you have the head off. I would take it to a machine shop, and have them install the insert that uses locking pins to secure it in place. If you use a heli-coil, it can unscrew itself when it sticks to the plug threads. Also, if screwed into the head to deep, you have that sharp point on the end of the thread. This can cause pre-ingition just like a glow plug in a model airplane engine. I always go with the locking inserts.

 

[KYHunter2]

Re: Head Gasket Replacement?????

The only heli-coil , I ever used . Had 4 pins , that were driven in, to secure it. <br /> <br /><br /> If done properly, they work ok.<br /> <br /><br /> I dont know but , you might check ebay , etc. And find a used head , cheap.<br /> <br /><br /> The last one I bought for a V-4 crossflow. I paid $35.00 , shipping and all.<br /><br /> Just something , to think about.<br /> <br /> Good Luck,<br /> KYHunter

 

[ross patti]

Re: Head Gasket Replacement?????

I told you they would help,didn't I schonn !!<br /> Further to the advice so far....as OBJ said,clean off the head and check for trueness.If your head is alloy,you can lay some fine wet and dry sandpaper on a thick sheet of glass and lightly rub it in a fig.8 pattern.This will soon show you any high spots in your head surface.<br /> If these are not too bad,continue rubbing till you get 'em out.Or get the head machined at a shop.<br /> If the inside of the head is carbon coated,give it a blast with the sea foam and clean it up.<br /> And coat your bolts with anti-seize grease before putting them back in.<br /> that's about all from me. The only reason I know even this much is 'coz I got iboats advice on the same issue.<br /> Once you have done the head,you will be able to say to your mates how you " pulled the head on the 70 "....mates get impressed by knowledge such as that !!

 

[ezeke]

Re: Head Gasket Replacement?????

Marysboats (RJohnson) of course is correct. HeliCoil is a brand name and does not come with locking pins.<br /><br />If you clean the head and take it to a shop it probably won't cost you any more than the insertion tools will.

 

[jim_in_day]

Re: Head Gasket Replacement?????

While you are in there, replace the thermostats, It will save you the hassle of having to take it appart later to replace them. I did on my 76 70hp RUDE, which had a leaky head gasket when I got it.

 

[schonn]

Re: Head Gasket Replacement?????

Thanks all for the advice. I just got the head gasket in the other day made all the necessary repairs. I will be putting it in the water this weekend. (If the weather holds out) Thanks again for the advice. Talk to you soon!!!!!<br /><br /><br />Schonn