powerhead base gasket question

[adot1111]

Hi, all.

I have a yamaha 75hp 2 stoke outboard motor. I want to replace the powerhead base gasket.

However, after I took off the head, I found few questions.
How to resurfacing the head and block surface?

Also, should I use any sealer for the new base gasket? I read some threads, some people say 'yes' and say'no' I start confusing now.

Thanks advance

[cpostis]

If the metal surfaces themselves are corroded/damaged, you may have to have a machine shop fill, dress the damaged areas. If not too bad, you can use JB Weld to fill the area and then file them to the existing surfaces. I had my block done this way while having it dipped and cleaned for $75.

If you talking about removing gasket material and adhesive, here's what I did.

I recently pulled and did a lot of work on my power head. I cleaned all gasket surfaces in the following manner.

1. Dissolved and softened any adhesive (from the gasket itself) with mineral spirits.
2. Scraped as much old gasket material off with plastic scraper (available from auto parts stores).
3. Used Scotch pad on sanding block to remove remaining material. (use figure 8 pattern as much as possible).
4. Cleaned all passages, including small orifices within block/exhaust plate.
5. Cleaned all exhaust passages within intermediate housing (I fabricated a long handle brush of appropriate size to do this, with mineral spirits as well).
6. Vacuumed any debris from all passages and blew out any small passages with compressed air.
7. Cleaned gasket surfaces with acetone and installed gasket WITHOUT any sealer.
8. Torqued all bolts to specs

Here are some pics... Last pic nice clean block without all the components on it, huh?

[TownsendsFJR1300]

Hi, all.

I have a yamaha 75hp 2 stoke outboard motor. I want to replace the powerhead base gasket.

However, after I took off the head, I found few questions.
How to resurfacing the head and block surface?

Also, should I use any sealer for the new base gasket? I read some threads, some people say 'yes' and say'no' I start confusing now.

Thanks advance

Per my Yamaha F150 shop manual, NO sealer is used.

[adot1111]

If the metal surfaces themselves are corroded/damaged, you may have to have a machine shop fill, dress the damaged areas. If not too bad, you can use JB Weld to fill the area and then file them to the existing surfaces. I had my block done this way while having it dipped and cleaned for $75.

If you talking about removing gasket material and adhesive, here's what I did.

I recently pulled and did a lot of work on my power head. I cleaned all gasket surfaces in the following manner.

1. Dissolved and softened any adhesive (from the gasket itself) with mineral spirits.
2. Scraped as much old gasket material off with plastic scraper (available from auto parts stores).
3. Used Scotch pad on sanding block to remove remaining material. (use figure 8 pattern as much as possible).
4. Cleaned all passages, including small orifices within block/exhaust plate.
5. Cleaned all exhaust passages within intermediate housing (I fabricated a long handle brush of appropriate size to do this, with mineral spirits as well).
6. Vacuumed any debris from all passages and blew out any small passages with compressed air.
7. Cleaned gasket surfaces with acetone and installed gasket WITHOUT any sealer.
8. Torqued all bolts to specs

Here are some pics... Last pic nice clean block without all the components on it, huh?

Per my Yamaha F150 shop manual, NO sealer is used.

Thank you guys for the reply

So, no sealer for the base gasket.

Here are some pics about my base gasket. Some marks left on the block and head surface, but it feels smooth. I think it's ready for the new gasket.

[TownsendsFJR1300]

Looks good!

Make sure you lube those splines with the correct grease.