84 Mercury 2 stoke 150 rebuild

**paradak** · 07-10-2022, 12:20 PM

Originally Posted by Baker343

Are you sure it's an 84 block? Looks more like a 78-81 with the older heads that mount to the cylinders not the block.
It's not a 175hp 2L because the exhaust dumps aren't rectangle shaped.
Those cylinders look to be chromed maybe the .040 piston got steel sleeved.
You've got an oiler crank with non-oiler front half.
Engine has been opened up and stuff replaced. All normal for a 40yo fishing motor

Check each cylinder with a magnet to determine if steel vs chrome. It won't attach to chrome. Record results as rings are different for steel vs chrome cylinders in my understanding.

**rgsauger** · 07-10-2022, 03:00 PM

Originally Posted by paradak

Check each cylinder with a magnet to determine if steel vs chrome. It won't attach to chrome. Record results as rings are different for steel vs chrome cylinders in my understanding.

very true. You will need to order different rings for the steel cylinders versus the chrome cylinders. That’s a great point

**thesignguy** · 07-10-2022, 03:07 PM

Originally Posted by Baker343

Are you sure it's an 84 block? Looks more like a 78-81 with the older heads that mount to the cylinders not the block.
It's not a 175hp 2L because the exhaust dumps aren't rectangle shaped.
Those cylinders look to be chromed maybe the .040 piston got steel sleeved.
You've got an oiler crank with non-oiler front half.
Engine has been opened up and stuff replaced. All normal for a 40yo fishing motor

See, this is where the rookie starts to shine... The 84 was the tag on the mid section (6568987), the casting on the block is 8587788. I just assumed it was all an 84 and did not know any better, and now I know why the head I bought is not the same and the ones I took off. I tried to look up the 8587788 serial number on Merc's site but no luck, what am I missing there?

I put a magnet on all of the cylinder walls and it stuck to all of them. I have to get a bigger dial caliper (the one I have only goes up to 3.03) But #1 does seem to be a tad bigger then the rest of the other 5.

Thank you for the help and the Ah Ha moment between the block and the mid.

**Baker343** · 07-10-2022, 06:41 PM

Originally Posted by thesignguy

See, this is where the rookie starts to shine... The 84 was the tag on the mid section (6568987), the casting on the block is 8587788. I just assumed it was all an 84 and did not know any better, and now I know why the head I bought is not the same and the ones I took off. I tried to look up the 8587788 serial number on Merc's site but no luck, what am I missing there?

I put a magnet on all of the cylinder walls and it stuck to all of them. I have to get a bigger dial caliper (the one I have only goes up to 3.03) But #1 does seem to be a tad bigger then the rest of the other 5.

Thank you for the help and the Ah Ha moment between the block and the mid.

Most of us are still being educated by the members that built this site. I've broke my far share of stuff to learn the hard way.
Buy some HF cheap calipers to give you a quick idea of what you've got.
From 76-81 (I think) was the 1st gen mercury V6's and I believe they only built steel sleeve 175hp 2L's and chrome cylinder 2.4 200's.
And you definitely dont have a 175 based on your exhaust chest and dumps.
I don't have a chrome bore block to check and it might grab a magnet?

**thesignguy** · 07-10-2022, 08:03 PM

Not sure where the 175 came in but I assumed it was just a 150 Black Max, that would have been nice if it was through.

So piston #1 that was stamped @ .040 was the worst at 55psi when I did the compression test. I know the head gasket was burnt and shot, I can assume that's where the low compression came from. I also expected the rings to be missing from #1 when I took it apart because when I removed the head it was pitted bad just on #1. This would also explain why #1 had no damage to the top of the piston but the head did. The piston did have some slop in it but again not sure how much it should have. Could it just have been the head gasket and the block was fine?

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**tlwjkw** · 07-11-2022, 02:30 AM

tha reason ya had head damage and none in tha cylinder is because that hole/piston (40 over) has been fixed and tha head reused without being resurfaced........... this would also lean toward tha cause of tha gasket failure.... jmo.

**lbhsbz** · 07-11-2022, 09:30 AM

I have one (good) early 2.0L cylinder head if you'd like to replace that one.

**thesignguy** · 07-11-2022, 10:04 AM

Originally Posted by tlwjkw

tha reason ya had head damage and none in tha cylinder is because that hole/piston (40 over) has been fixed and tha head reused without being resurfaced........... this would also lean toward tha cause of tha gasket failure.... jmo.

I would agree with this, now it makes more sense to me.

**thesignguy** · 07-11-2022, 10:07 AM

Originally Posted by lbhsbz

I have one (good) early 2.0L cylinder head if you'd like to replace that one.

Yes, thank you. No point in putting the bad one back on. Send me a pm with what you need for it and I'm also looking for the exhaust divider for the 2.0 if you have one.

**thesignguy** · 07-11-2022, 10:47 AM

These are the only numbers I've found off the Black. I've tried the search (on www.perfprotech.com) but still don't know what I have here:

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**paradak** · 07-11-2022, 11:17 AM

Originally Posted by thesignguy

These are the only numbers I've found off the Black. I've tried the search (on www.perfprotech.com) but still don't know what I have here:

Look for a freeze plug like thing about the size of a quarter on the top of the block between the banks (closer to port I believe). Should have the original engine serial number stamped in it.

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Then go to this page and request info on that serial number. They usually reply within a day and it will tell you the original configuration of the motor.

https://www.mercurymarine.com/en/us/...mer-assistance

**paradak** · 07-11-2022, 11:20 AM

You can also enter the serial number at:

https://www.marineengine.com/parts/m...oard/index.php

and that should get you a near complete list of all parts.

**thesignguy** · 07-11-2022, 11:24 AM

Originally Posted by paradak

Look for a freeze plug like thing about the size of a quarter on the top of the block between the banks (closer to port I believe). Should have the original engine serial number stamped in it.

Then go to this page and request info on that serial number. They usually reply within a day and it will tell you the original configuration of the motor.

https://www.mercurymarine.com/en/us/...mer-assistance

Thank you, It just has a 4 stamped on it.

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**tlwjkw** · 07-11-2022, 01:07 PM

you can use tha one below and be pretty safe with parts for it.. one thing for sure its a pre '83 first gen 2.0 150 motor.. tha one number ya show "7 1481" could possibly tha build date (july 14 '81).. they didn't take a lotta pain with tha stamping (depth and/or spacin') of it on any of 'em

1980 Outboard 150 [ELPT] [1150620] - Parts Lookup | Crowley Marine

**Darkcloud** · 08-20-2022, 04:05 AM

1985 150 black max
Hi All I am brand new to this forum and enjoying what I’m reading. Can anyone please tell me how to tune and sync all three carbs. Also want to check timing ensuring it set correctly and advances correctly. Or point me where I could find good info. I can’t seem to find any vids on utube.
thanks