'76 evinrude 9.9 missing?

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CRAPPIE_SLAYER
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'76 evinrude 9.9 missing?

Post by CRAPPIE_SLAYER » 07 Oct 2009, 10:08

Hey guys. I've been refinishing an old mirrocraft that I bought last year. When I'm done, I would like to tear down the evinrude 9.9 I bought, but want to make sure its worth the time. Had it out 1/2 doz. times last year and it ran great till the last time. Was comming back to the dock and all of a sudden it started to miss badly. Noticed that the block was on the hot side of things when I got back as well. Figure the water pump needs replaced, but do you think that the block heating up is what caused it to miss??? Looks to me like one of the coils is new and the other is the original. Both give off spark, but thought maybe the old one was weak and causing the miss. Also, I have fired it once since for a very short run. Starts extremely hard, still misses, and will not stay running at a low idle. The thing ran like a raped ape before, and would like to tear the whole thing down and completely refurbish it to get it back to the way it was, but don't want to waste my time. Thanks in advance fellas.

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sogafishin
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'76 evinrude 9.9 missing?

Post by sogafishin » 07 Oct 2009, 11:36

Sounds like a blown head gasket to me.Might wanna take the head off and check it.Take the head to a machine shop to see if it is warped.

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CRAPPIE_SLAYER
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'76 evinrude 9.9 missing?

Post by CRAPPIE_SLAYER » 07 Oct 2009, 11:39

Thanks. Will have to check it out. Luckily I work in a machine shop, so that part should be easy :mrgreen: .

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CRAPPIE_SLAYER
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'76 evinrude 9.9 missing?

Post by CRAPPIE_SLAYER » 15 Apr 2010, 12:40

Well, finally have the boat about done so its time to get this beast of a motor running. Tested the compression the other night and found it to be 85# and 90#. From everything that I have found, this is pretty acceptable for this motor. Would the head gasket still possibly be blown if I have good compression? Really think from alot of the info that I have read on the motor that I am having an electrical problem. Planning on changing the coils and points/condenser. Any insight??

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crazymanme2
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'76 evinrude 9.9 missing?

Post by crazymanme2 » 15 Apr 2010, 13:50

85 to 90# is on the low side.I have a 1976 same motor & its compression is 120#.I agree that the low compression won't make it miss.Find out which cylinder is missing & just start swaping parts around to find out whats wrong.
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cajuncook1
Posts: 437
Joined: 24 Mar 2010, 00:02

'76 evinrude 9.9 missing?

Post by cajuncook1 » 15 Apr 2010, 14:40

CRAPPIE_SLAYER wrote:Hey guys. I've been refinishing an old mirrocraft that I bought last year. When I'm done, I would like to tear down the evinrude 9.9 I bought, but want to make sure its worth the time. Had it out 1/2 doz. times last year and it ran great till the last time. Was comming back to the dock and all of a sudden it started to miss badly. Noticed that the block was on the hot side of things when I got back as well. Figure the water pump needs replaced, but do you think that the block heating up is what caused it to miss??? Looks to me like one of the coils is new and the other is the original. Both give off spark, but thought maybe the old one was weak and causing the miss. Also, I have fired it once since for a very short run. Starts extremely hard, still misses, and will not stay running at a low idle. The thing ran like a raped ape before, and would like to tear the whole thing down and completely refurbish it to get it back to the way it was, but don't want to waste my time. Thanks in advance fellas.

Hey Crappie_Slayer,

You mentioned on the way in to the dock that is started to miss badly and the head seemed really hot. If the water pump gave out or trashed block up the intake port then the motor could have truly overheated. Yes overheating can cause it to run rough and miss.

A coil that is going bad can give out without notice and especially when the head is hot. So you make decision if it needs changing.

(Another side thought. Your fuel lines should be changed alcohol resistant lines. It is possible that ethanol in the fuel can cause the internals of the fuel line and or fuel pump to break apart or slough and clog up the carburetor. Probably a carb cleaning with a kit is needed.

Check these links out.

https://forums.iboats.com/showthread.php?t=330129 (ethanol problem and fuel system)

https://forums.iboats.com/showthread.php ... ompression (compression)

https://forums.iboats.com/showthread.php?t=309188 (water pump)

https://forums.iboats.com/showthread.php?t=365226 (determine the year of your motor)

https://forums.iboats.com/showthread.php?t=294072 (points and coils)


This a great link for your motor!!!

https://www.sschapterpsa.com/ramblings/O ... 20info.htm

Parts:

https://shop2.evinrude.com/ext/index.asp ... 317448f722

https://www.boats.net/parts/search/BRP/E ... parts.html

I have a couple of questions for you.

- Do you notice water coming out of the "pee hole" to indicate water being circulated. Depending on the year of your 9.9hp it will come out the exhaust port hole or I think 79 year or after there was a water indicator that was applied. If there is no water circulating then replace your impeller. If is unknown when the impeller(water pump) was replace then you need to replace it.

- Have you tested your temperature of your cylinder heads with laser temp thermometer (can get one for about $25 at harbor freight or auto store. Head should not be hotter than 163 degrees F.

It would be a good idea to remove the cylinder head and inspect the pistons and cylinder if think it overhead. After overheating the head gasket will leak and cause poor running. Head gasket isn't hard to do. Check the links above.

Good luck my friend,

cajuncook1

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CRAPPIE_SLAYER
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Location: Conneaut Lake, PA

'76 evinrude 9.9 missing?

Post by CRAPPIE_SLAYER » 15 Apr 2010, 21:04

Thanks for the replies and links fellas. Already had the sschapterpsa.com link, and you're right cajuncook, it is a great one. Unfortunatly, I tore the head off tonight and found some somewhat discouraging sights. The lower cylinder has quite a bit of buildup on the piston, and I think this was definitly my first clue to where the problem lies.

The piston
Image

And the inside of the head
Image

Upon further inspestion, If you look at the cylinder wall you can see a brown streak that is actually a score mark that looks to run most of the length of the cylinder wall.
Image

This score mark has to be at least a few thousandths deep just by feel. Would I be able to hone this out and re-ring it, or would I have to bore it out, and is it even worth my time? I work in a machine shop, so the resources are available to me. Thinking about it now, I didn't look at it close enough, but would it be possible that the cylinder wall is actually craked? :cry:

cajuncook1
Posts: 437
Joined: 24 Mar 2010, 00:02

'76 evinrude 9.9 missing?

Post by cajuncook1 » 16 Apr 2010, 10:56

CRAPPIE_SLAYER wrote:Thanks for the replies and links fellas. Already had the sschapterpsa.com link, and you're right cajuncook, it is a great one. Unfortunatly, I tore the head off tonight and found some somewhat discouraging sights. The lower cylinder has quite a bit of buildup on the piston, and I think this was definitly my first clue to where the problem lies.

The piston
Image

And the inside of the head
Image

Upon further inspestion, If you look at the cylinder wall you can see a brown streak that is actually a score mark that looks to run most of the length of the cylinder wall.
Image

This score mark has to be at least a few thousandths deep just by feel. Would I be able to hone this out and re-ring it, or would I have to bore it out, and is it even worth my time? I work in a machine shop, so the resources are available to me. Thinking about it now, I didn't look at it close enough, but would it be possible that the cylinder wall is actually craked? :cry:

When the head overheats, the rings expand and can cause some wear and damage, but it did not freeze/lock up on you... so there may some hope here. I'll tell you that I have rebuilt a couple of engines with help and advice, but I have never had to hone or bore out an engine, so I would not like to give advice on this matter. The silver lining to this is that your compression was not that bad and certainly within 10% of each other (good). The dark crud build up is carbon is not uncommon with 2 cycle motors. A lot of guys use Seafoam each year to decarbon their motors to prevent excessive build up and prevent the rings from sticking and causing poor performance.

What caused the overheating? If you repair/hone the cylinder and rering and replace the head gasket and don't figure out what cause your motor to over heat then you have the same issue when you go back out.
When you last went out or started your motor was water being circulated? Was water coming out of your exhaust port?

Please check your PM(privet message)

cajuncook1

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