1974 15 hp rude/johnson gasket sealant

[Jon123]

Hey guys...Ive got a few questions N hope ya can help me out if any I really appreciat it. Im planning to remove the head on the motor to get the upper motor mounts replace. I was told to use 3m 847 sealant for gasket sealant but have any of you use cheaper sealant from a auto parts store to reseal that will do the job just as good as 3m?


thanks for looking

 

[boobie]

Re: 1974 15 hp rude/johnson gasket sealant

If it's the power head gasket, I've always used OMC gasket sealing compond or Permatex # 3. Unless the new gasket says "use no sealer" on it.

 

[OptsyEagle]

Re: 1974 15 hp rude/johnson gasket sealant

Definitely do not use 3M #847 on a head gasket. OMC gasket sealing compound or put it on dry. Torque it to spec and in sequence.

 

[Jon123]

Re: 1974 15 hp rude/johnson gasket sealant

thanks for the heads up Opsty Eagle... Im glad I came on here first and ask ya professionals =) before handling this project or eles I would've had to redo it twice....

Do you recommend using the Permatex # 3 like Boobie or is there other sealant out there I should use thats cheaper. Im planning to redo my rings also can I use the same sealant on the crank case halves or is there specific sealant for each.
As I recall I dont think the power head comes with a gasket but please let me know if im wrong. Since the head is off im planning to do a overhaul on the engine so any advise on type of sealant should be use would be greatly appreciated.

is this the right
squence

4 6

1 2

5 3

thanks again

 

[Jon123]

Re: 1974 15 hp rude/johnson gasket sealant

thanks Boobie but all i can find is this Permatex 80019 Aviation Form-A-Gasket No. 3 Sealant is this the one yr talking about please let me know thanks.

 

[boobie]

Re: 1974 15 hp rude/johnson gasket sealant

If it comes in a can in a liquid form with a brush in it, that's it.

 

[OptsyEagle]

Re: 1974 15 hp rude/johnson gasket sealant

I would go:

5 6

1 2

4 3

On the head bolts. Do 1/3 of the torque, then another 1/3, then the last 1/3, all around.

I cannot say what to use on the crankcase halves. I have never done them but it is possible the 3M #847 might work well there. Others could tell you better. That stuff works better when you are trying to form a gasket where one does not exist. With the cylinder head you have a very precisely machined gasket and all you would want in addition is some light sticky stuff to help form a better seal. You will need a new head gasket, since they are single use gaskets. You should never reuse a head gasket if it can be avoided.

Any BRP dealer would have the OMC gasket sealer. As boobie says, it is in liquid form and will have a brush connected to the lid. I do believe permatex makes a version of it, but I do not know the name. Google Permatex and they probably will have a product list for you.

Here is a picture of the OMC Gasket sealer stuff. I think the permatex stuff comes in a similar can with a brush.

 

[nwcove]

Re: 1974 15 hp rude/johnson gasket sealant

not sure if the op is referring to the cyl head or the power head, but if its the power head, i have had no problems using an aerosol gasket sealant there, ( uap/napa). its wonderful stuff to spray on a gasket ,as it gets tacky enough to hold a base gasket in place, and isnt messy. ( not as good as permatex if the mating surfaces are pitted or gouged tho) jmo.

 

[OptsyEagle]

Re: 1974 15 hp rude/johnson gasket sealant

Yes. Perhaps I was mistaken. I was assuming the cylinder head gasket. For the powerhead to the midsection, I still just used the OMC gasket sealer and I wouldn't worry too much about torque and sequences there. Just get the bolts very, very snug.

 

[Jon123]

Re: 1974 15 hp rude/johnson gasket sealant

Thanks for all the help guys. I went ahead and call my local boat shop today and the guy there told me I can make my own head base gasket with the gasket materials from my local auto parts store and put it on dry cause they didnt carry none and it would take days for the order. Now that Im reading through this post I think i should go back and redo it and put some kind of sealant on it. =( I shouldve of came and check this post sooner. Oh well, back to get my hands dirty.....thanks for the pics and the bolt sequence Optsyeagle.

 

[OptsyEagle]

Re: 1974 15 hp rude/johnson gasket sealant

The boat shop guy told you that you could make your own "head gasket" with your own gasket materials. The head gasket for that motor utilizes both both fibre material and metal and is precision cut for your motor. I would highly recommend buying one.

If the gasket was for the powerhead to mid-section then if I recall there is not one there currently and I wouldn't recommend putting one in there. 0.020" to 0.030" may not seem like a lot of thickness but it can make some big differences on some other parts of the design so if this is the area you are talking about I would go with the OMC gasket sealer ... or go dry.

 

[boobie]

Re: 1974 15 hp rude/johnson gasket sealant

Power head base gasket is part # 318988.

 

[OptsyEagle]

Re: 1974 15 hp rude/johnson gasket sealant

I guess there is a gasket there. That one could be made at home with gasket material, if needed.

 

[Jon123]

Re: 1974 15 hp rude/johnson gasket sealant

Thks again to both you two. U guys been great help. I call another boat shop 45 minutes away n got the gasket I needed. I couldn't go boating with this motor thinking I did a sloppy job with my homemade gasket so I tore down the motor n redid it.

Thks again