YM 1700 head gasket

[puresol]

The two picture I sent before are from the night I removed the head, these two I just ran outside and took-Still makes me wonder how good that gasket was sealed if there was alot of carbon under it. If I had the proper instruments it could have been measured in some places- probably 1/32 minimum in places, but to one degree or the next it covered the block.

 

[Car Doc]

Thanks for posting the pics we like pics! :thumbsup:

I agree with you that gasket is in pretty bad shape alright it looks like several places it had leaked besides the cracked fire ring and that was definitely a leak. I didn't see much of the carbon or where it was though but scrape it all off the deck and piston tops you should be good to go.

fwtw I use a rubber sanding block and 80 grit air file sand paper and spray oil as a cutting fluid to finish clean engine surfaces works the best for me.
good luck

 

[puresol]

Thanks Car Doc. I had already done a quick clean on the block the night I pulled the head or I would have sent you picture of the build up. Cleaning is next just waiting to hear back on the block. Hopefully I will get the go ahead today. I didnt like some of what I saw when I pulled the head. Will post more picture tonight if you dont mind taking a look.

 

[Car Doc]

Sure be glad to anytime its what we are here for. :thumbsup:

Did I see some crosshatch in that back cyl? The pics were focused on something else I couldn't see real detail no biggy just would mean the cyls are still in super good shape is all.

 

[puresol]

I didnt feel or see any crosshatch. Cylinders were pretty smooth. I do however have access to a hone. I am going to pull the pistons out and put new rings, I was getting a little blow back before head gasket issue. I plan on having this old girl a while so I want to put some money in the engine while im in there. I will post top of block piston shots tonight. There is some damage to the top edge of the pistons maybe its nothing. I will be interested in getting a second opinion.

 

[Car Doc]

Ok sounds like a good plan doing it right now is the way to go for sure. :thumbsup:

I will just throw this out as something I do...fwtw not saying its the only way etc but on a re-ring (if I do any honing at all) I like using a 180-220 grit dingleball hone. my .002

 

[puresol]

I know nothing about hones, except my friend is a fork lift mechanic, and he said if I put in new rings come by his shop and I can borrow his hone. I had no idea why, just know he knows his stuff. Now I know- Thanks. I have learned a ton from this forum. Ok here are the over head shots I promised. Tonight I also pulled the #2 piston (closest to radiator). Not 100% sure but I think I will be buying pistons and rings.
I was able to feel the lobes on the cam- they felt good-no noticeable wear. Also felt the crank shaft- felt good to me.

 

[Car Doc]

Well the short answer on hones is a traditional glaze breaker/hone has 3 stones on it that are about 2" long and rings are 1/8-1/4" wide and will create an uneven surface on the walls in service they all do. Taking a 2" stone over this unevenness will only hit the high spots and really doesn't work well on a worn in cyl. The flex hone what most call a dingleball once you look at one the name is obvious anyway they hit all of the surface and rings will seat as good as they possibly can and they are very quick a few passes is all that's necessary that means less grindings around the main bearings. fwtw

Ok on to the parts I agree on replacing the pistons yikes I hope the cyls are ok! The one piston shows a valve has been hitting it slightly that bothers me. I can think of a few ways that could happen like a weak/broken valve spring or bad rod bearing (you said the crank was ok so this probably not it) or what is more likely excessive carbon build up on the valve and/or piston but w/o putting hands on all I can do is guess sorry.

Id sure have your buddy check it over and see if I am seeing what I think I am seeing to be on the safe side it may not be anything but to see something that is different like that is a red flag to me! hth

 

[puresol]

If I am looking at the drawing right that is an exhaust valve. Could it just be out of adjustment? The shop working on the head will let me know if I have a worn out or broken spring. The cylinder is smooth- I wonder if that damage isnt a past artifact and maybe there has been some partial work done at some point.

 

[Car Doc]

I agree it is an exhaust valve they typically are the valves that hit just because they are open as the piston is going up. As far as being that far out wow imo it would have had to be held open all the time since it only requires .006" clearance but that is just me thinking logically its not an indictment of that idea.

A more reasonable or feasible idea may be worn cam and crank gear set which your buddy could help you with all you need to do is use a bar and socket on the crank and move it back and forth watching the cam.