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  #31 (permalink)  
Old 6 Days Ago
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Quote:
Originally Posted by cleddau1 View Post
Prior to fitting head checked with straight edge and there does appear to be some warping so will have to get this skimmed. Is there some way of knowing the maximum the head can be skimmed?
The block seems to be OK.

Also on the diagram here:

1998 T9.9MLHW Yamaha Outboard CYLINDER CRANKCASE Diagram and Parts

There is an O ring part number 38. Where does this go?

Although the new gasket has built in sealant is it worth using some extra and if so what?

Any advice would be appreciated.....

Well do you know how much the head is warped? Service manual gives .004" limit, and then procedure to flatten it if not to badly warped.

Also what are you using for a straight edge? Are you sure it is dead straight and it is not warped itself?

Item #38 is a grommet...not an O ring. Is there a threaded hole that it might sit on as show in diagram and something bolts to that cover. The grommet serving as a damper maybe....I am not sure.

Put head gasket on as is.
Attached Images
File Type: jpg head 9.9.JPG (81.8 KB, 5 views)
File Type: jpg head 2.JPG (84.7 KB, 4 views)
File Type: jpg head 3.JPG (84.0 KB, 3 views)

Last edited by panasonic; 6 Days Ago at 01:17 PM.
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  #32 (permalink)  
Old 6 Days Ago
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This pic from earlier:

http://www.yamahaoutboardparts.com/a...7621-block.jpg

Looks like possible a white o-ring/grommet and it's BELOW the lower cylinder(as in the parts diagram)..

In the block, close to where the power-head meets the mid section...(about 2/3's over in the pic)

It's about the only place it can go.



.



.

Last edited by TownsendsFJR1300; 6 Days Ago at 04:04 PM.
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  #33 (permalink)  
Old 5 Days Ago
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Location: Pembrokeshire Wales
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Thanks for replies. It is part 34 not 38; senior moment for me; I think it goes over one of the oil pump orifices.
German made precision pristine straight edge.
Have noted the sandpaper method and seen the videos but not sure about this technique. Eyeballing warpage is way over tolerance in several places but will measure.
Thread is getting long so will start new one if further queries.

Diolch yn fawr
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  #34 (permalink)  
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PLEASE KEEP IT ON THIS THREAD.. It's easier for us...

Part #34 is what I was talking about, I refer back to my last post re the location....

I would think it'd be partially machined inward...

Re the warpage, that certainly helped with the head gasket / leakage failure...



.
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  #35 (permalink)  
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Location: middle Texas coast
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Quote:
Originally Posted by cleddau1 View Post
Thanks for replies. It is part 34 not 38; senior moment for me; I think it goes over one of the oil pump orifices.
German made precision pristine straight edge.
Have noted the sandpaper method and seen the videos but not sure about this technique. Eyeballing warpage is way over tolerance in several places but will measure.
Thread is getting long so will start new one if further queries.

Diolch yn fawr
I have used this method for cleaning and resurfacing heads on 2 strokes many times before.
main thing is to keep even pressure and turn often to keep from taking too much off on one area.
I kept a small amount of running water on the paper to help wash the cuttings off,So the paper would not plug up on any certain spots.
If the part is too big for the sheet of sand paper it will be difficult so may want to have it done a a machine shop

Last edited by 99yam40; 5 Days Ago at 08:37 AM.
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