Overheated 84 140 2 stroke

[Hennysemitara]

Aloha everyone i had a question about my outboard. We went to the sandbar and my impeller was acting up. When we came home it stopped peeing halfway in the bay so i just cruised it in very slowly. The port side cylinders are discolored. Motor starts up, and idles fine. I changed the impeller and it pees now. I didnt take it out on the water because im afraid it will die out on the water. Gaskets have a liquid coming off of them. What do you guys think? Is my motor toast or am i lucky?

 

[interalian]

Might be lucky. You need to re-torque the exhaust cover and cylinder heads, and check compression. Anytime you overheat, gaskets can loosen/bolts slacken.

 

[BrettNC]

Yeah. It sounds like the internal parts are probably ok, but it is important that the gaskets are still sealing up properly. Do what interalian suggests then run the motor for a few minutes. Remove the spark plugs and check for water in the cylinders.

 

[Hennysemitara]

Thanks guys for the help that what i figured it should be okay, hopefully it is cause i dont have money for another motor. How can u tell if a motor completly overheated??

 

[interalian]

The real problem is overheating repeatedly, and especially if you 'lock up' the powerhead due to massively expanded pistons. Overheating will cause some damage to the cylinder walls and possibly weaken and break rings too. If you got it hot enough to discolour the block, that's pretty hot - surprised it didn't lock up.

10 years ago, my brother repeately had the overheat horn go off on our '82 90 while running in the 'no wake' zones on the west coast. The problem was sticking thermostats then. When I tore it down this year for rebuild/upgrade found the bores and pistons were pretty much perfect - rings too. Did your overheat horn go off?

 

[interalian]

You running it in Hawaii? Lucky you.

 

[Hennysemitara]

The real problem is overheating repeatedly, and especially if you 'lock up' the powerhead due to massively expanded pistons. Overheating will cause some damage to the cylinder walls and possibly weaken and break rings too. If you got it hot enough to discolour the block, that's pretty hot - surprised it didn't lock up.

10 years ago, my brother repeately had the overheat horn go off on our '82 90 while running in the 'no wake' zones on the west coast. The problem was sticking thermostats then. When I tore it down this year for rebuild/upgrade found the bores and pistons were pretty much perfect - rings too. Did your overheat horn go off?

I did doscolor the block and warped some hoses. I dont think i have an overheat horn.

 

[Faztbullet]

Replace the t-stats/poppets as likely melted if that hot.....

 

[emdsapmgr]

When you get into the stat housing, make sure the two small holes in the valve body are clear of debris. If they are not, you will get an automatic overheat on one side/both.

 

[interalian]

I did doscolor the block and warped some hoses. I dont think i have an overheat horn.

Do you have the OMC remote? There's a buzzer inside for overheat - you need to test it as part of your repair now. Iginition on, remove the neoprene cover from a knife connector from one of the tan wires coming out of the cylinder head cover and ground it. Should beep. Repeat for other side. If you do get a beep, your sensors may be shot. Replacement can be a pain due to them being held in place by the dozens of bolts holding the cylinder head covers on.

 

[Hennysemitara]

thanks guys for all the help i been kinda busy with work but i did do a compression test today, 120 across the board so i may have really gotten lucky, gaskets definitly need to be changed. i will fix the buzzer and probly put some temp gauges. any suggestions on putting a temp gauge on a 84 johnson 140?

 

[Hennysemitara]

also i always ran my outboard rich i guess it cant hurt right? 32:1 is my premix ratio

 

[interalian]

If you're going to replace head gaskets and exhaust chest gaskets, watch out for breaking bolts. I'm assuming it's a salt motor, no? If you're doing head gaskets at a minimum, check and maybe replace the water deflectors in the block.

Oh, and running extra oil might not hurt anything, but it's a waste. These run great at 50:1.

 

[emdsapmgr]

These older crossflows don't have a place to accomodate a temp sender. If you get the typical marine sender, you'll have to make a "Z" bracket to hold the tip of the sender flush with the head face. Use one of the head cover bolts to secure it. It will read temps just fine, but just on that one head. There are two temp zones on that powerhead. So your sender will read only one.

 

[interalian]

These older crossflows don't have a place to accomodate a temp sender. If you get the typical marine sender, you'll have to make a "Z" bracket to hold the tip of the sender flush with the head face. Use one of the head cover bolts to secure it. It will read temps just fine, but just on that one head. There are two temp zones on that powerhead. So your sender will read only one.

Or you could be a nut like me and drill and tap for a sender in the cylinder head cover. Or both and put in a switch.

 

[Hennysemitara]

nice job interalian, the thing is, since there is 4 cylinders should i need 4 senders 1 for each cylinders or just that one for each bank.

 

[interalian]

One on each bank, up at the top where they're hottest. Looking at the coolant flow, the cylinder head covers are pretty much the hottest part of the motor. Maybe the bottom would be warmest. I have one gauge and leave it on the STBD side normally, flicking to PORT just to check once in a while.

I also went 'overboard' so to speak and put dual pissers tapped into the top of each cylinder head, but let's not go there...

 

[Silvertip]

Thanks guys for the help that what i figured it should be okay, hopefully it is cause i dont have money for another motor. How can u tell if a motor completly overheated??

There is no partial overheat. It either overheated or it didn't. If your overheat alarm is not working then that little device could have alerted you to the overheat. And just like your car or truck, when an overheat occurs the alarm and indicator means it is HOT right now. Shut down and call for a tow if you can't figure out why or fix the problem on the spot.. Continued operation gets expensive. If it got hot enough to discolor the head it got VERY hot and compression will very likely be low because the rings have lost their tension and can no longer seal properly.

 

[Hennysemitara]

There is no partial overheat. It either overheated or it didn't. If your overheat alarm is not working then that little device could have alerted you to the overheat. And just like your car or truck, when an overheat occurs the alarm and indicator means it is HOT right now. Shut down and call for a tow if you can't figure out why or fix the problem on the spot.. Continued operation gets expensive. If it got hot enough to discolor the head it got VERY hot and compression will very likely be low because the rings have lost their tension and can no longer seal properly.

i did compression test its at 118 across the board, gonna change gaskets hopefully soon..ill keep you guys updated.