79' I-6 powerhead removal with pics

[nathanhooper]

Well, after conversing with guys on here about the issue of water in my lower cylinder, I removed the powerhead.

I was not going to at first, not right now at least, I had planned on using a few more times before I was going to tear into the motor again. I had only seen a little, and I wanted to run it at least one more time to verify that it was water getting into the cylinder. I got home friday and went to start it up before I took my boy fishing on the lake, I could not get the thing to fire for anything. It finally did, and ran pretty rough for a few mins.

I shut it down to run and get a tool to mess with the carbs, and when I went back to start it up it would not for the life of me. So I started pulling the plugs and quite a bit of substance was on the bottom plug this time, and what seemed like some on the one above it. I am still not positive on that one, but I think there may be. Does that still lend itself to water coming up through the lower crank seals?

So needless to say I had run the battery down trying to start it so I just decided to pull the powerhead. I am still not sure just how water can get "sucked" up through the lower crank seal, it seems like that area is separated from the water intake area. But, I can see if that gasket was leaking it would. Here are some pictures, feel free to draw on them and let us unwise in the world of outboards get a feel of what we are looking at.

Throw in a little advice on the water being in the next cylinder up if you would. I have another post I will make concerning corrosion, I have a bad feeling that it is going to be the culprit of something even worse. In the third photo you can see a small crack. That is now a large hole thanks to my picking at it. Probably not the best thing to do, but it was extremely brittle and more or less just flaked off when I touched it. Many thanks.

 

[Chris1956]

Re: 79' I-6 powerhead removal with pics

That crack is just below the perimeter of the exhaust outlet? Any idea what is behind it? If it is not a blind hole, you will need to fix the block. You will need to get rid of the corroded metal, and clean it up and fill it with Marine-Tex or equivalent.

Interestingly, I thought the midesction looked very clean, in comparison to the block, in the same area. I still think that motor must have seen some salt water.

 

[Chris1956]

Re: 79' I-6 powerhead removal with pics

You could also embed some fiberglass cloth in the marine-tex, to give it more strength.

 

[nathanhooper]

Re: 79' I-6 powerhead removal with pics

the crack, now hole, leads to the water jacket surrounding the cylinders. The midsection does look a lot cleaner than the powerhead. I too am now thinking saltwater, because I cannot see how just plain freshwater alone would cause this kind of corrosion with everything else on the powerhead looking as pristine as it does.

 

[Chris1956]

Re: 79' I-6 powerhead removal with pics

Maybe someone installed a saltwater powerhead on a freshwater midsection?

If that hole goes to the cooling passage, will it mess up the original path of the water? Maybe some water got trapped in there and froze and cracked the casting?

 

[arsenalpsu]

Re: 79' I-6 powerhead removal with pics

maybe try some high heat epoxy on that weak section. http://cgi.ebay.com/ws/eBayISAPI.dl...f7651d3&itemid=180521514212&ff4=263602_263622 or some JB weld. For the water in your cylinder, it could come from 2 seals where the LU plugs into your block or from a bad seal in the exhaust area of the powerhead(leaks through from the water jacket) If you are getting water in a cylinder your piston crown will be steam cleaned. Get a light and look in.

 

[nathanhooper]

Re: 79' I-6 powerhead removal with pics

Thanks for the replies! Yea, not sure on swap outs or anything, anyones guess on that. Messing up the original path of water is a big curiosity for me now. The actual water flow would be great to know/understand. Based on thermal dynamics alone, the hotter water will always find its way to the top while the cooler water settles down. With a pump continuously pumping cooler than engine temp water up, then I would say that the water is SOME what self circulating. I know that there is a lot more to that, so someone, with a diagram or a good understanding on what the intentions of how water should flow, would speak up on this matter it would be cool.

Thanks for the advice on the epoxy. I am feeling a tiny bit better than I did when I pulled the exhaust covers, after pulling the head cover last night. I understand a little more of what has happened. You can see from the pics that the major corrosion is toward the bottom half of the power head. That is normal I would think, if someone had indeed run it in salt water and then not flushed it out. The area that bothers me the most is beneath the bottom cylinder. I am not sure how a hole like this would effect water travel, but I think that someone could very easily slide a curved piece of aluminum/stainless inside, epoxy, and re-institute the normal water flow.

That would take care of the major damage, the other "weak" areas could be fixed with epoxy. The cylinder heads are corroded, but not to the point of being "unsafe". I went ahead and tested compression, same as when I got the motor, so I am going to say that cylinders are still good. I can see the pistons and cylinder walls somewhat through the exhaust ports and they indeed look good also. Good call on water steam cleaning the piston, I wish I would have thought of that last night, but I will check tonight to see what it does look like. I cant say that I remember seeing anything out of the ordinary when looking at the pistons and cylinders through the ports, so I am going to bet that it has not been steamed cleaned. Which would make some sense because the thing has literary only been run less than an hour since coming alive after sitting for all these years.

I think I am going to go ahead with the process of replacing the two lower crank seals and then cleaning/epoxying the covers and corroded parts on the casting. It was a more or less free motor to start with, I have put a lot of time and energy into getting it set up on my boat, and I loved the way it ran the one time I did have it on the lake, so I am going to spend a little bit more time on it.

Anyone with knowledge on the water flow of these motors would be sure appreciated to speak up. Any other opinions on my circumstance would also be appreciated. And while I have this thing where it is if there is anyone that can think of a picture they would like taken let me know.

The first picture is the over all look of it after I pulled the cover off the heads. I wish, looking back now, that I would have pulled off all the gasket material for a better overall picture. The second picture is of the bottom cylinder. You can see the hole that I picked at on the bottom of the power head, where the water enters the block from the L.U. This is where I think a piece of additional metal could be placed to repair this problem. The other three pictures are from top down. Just a look at how much "cleaner" the top of the block is than the bottom.

 

[Chris1956]

Re: 79' I-6 powerhead removal with pics

OK, It appears that the normal flow of water is from the top of the head to the bottom. That hole is likely not an issue, however, I would clean it up and lay some marinetex on the block near the cylinder liners(not on the bottom of the powerhead). I would also stick a piece of cloth in the marinetex, and put more putty over the cloth. That should reinforce the whole area.

It looks like some salt water layed in there and ate the metal away...

 

[nathanhooper]

Re: 79' I-6 powerhead removal with pics

yea, never thought in a million years that I would be handling a motor that had been in salt water up here in N.W. Arkansas. From just looking at the different passage ways and such, it seems to me that water comes up through the inlet tube, goes into that large area where the power head meets up to the leg, then proceeds through a passage way into the exhaust cover, then through some smaller passage ways to the cylinder heads. From there it confuses me because it seems that the only way in/out is there at the top of the cylinder heads where the hole is for the tell tale stream. With that hole in the bottom it just seems like it would flood the whole thing all at once. But I agree, I think that getting it back as close as possible to normal flow is best.

That marinetex looks like some interesting stuff. The good thing is that this is not a 'high' pressure area. Oh what troubles could have been avoided if someone would have just flushed the motor out after use. Boggles my mind why people don't do that. The crazy thing is that I only snapped off one bolt head in all the bolts I took off. And that was me just getting in a hurry. Most of them were not too hard to get out, and I did not use any heat whatsoever. I did tap a few with a brass punch to try to break loose the corrosion. That symptom right there lends itself to a quick corrosion problem verses a long time corrosion problem, which points yet again to salt water.

I will pull the cover off that lower crank seal tonight hopefully and see what seals I have to replace in there. I assume, someone correct me if I am wrong, but replacing those two seals along with new gaskets on the exhaust covers, should end all water intrusion into the cylinder(s?)? I guess what I am asking is if there is anywhere else I would need to look at to see if something needs replaced/repaired?

 

[Chris1956]

Re: 79' I-6 powerhead removal with pics

You have correctly identified all the areas that allow water to leak into the motor. I would put three seals in the lower endcap, plus a new Oring. Check the exhaust baffle for trueness, and install new gaskets with some hi-temp silicone on them. Use a new powerhead base gasket, with some permetex #2 sealer on it. I would also repair the block with the marinetex. It should work pretty well, as long as there is some good metal to adhere to. Use a putty knife to get it smooth. Cleanup is with Acetone.