5.7 omc carb leak

[Nick_1987 5.7 OMC]

Hey all back again, sadly…. So I have a 5.7 omc from 1987-89. Just did a carb clean on the motor and everything is fine in the mechanical side of things but I think I may have a electrical issue. While running a few days ago, the motor was stubbling out of the blue and then back to normal after 10 sec of stumbling. I Would try and rev out of it but it would just die completely. Decided to see motor running with the hatch up. While the motor had is “seizure” I ask my father to wiggle the harness around along with the rest of the electrics back there and it seemed to stop something from interrupting the motor. After he would set down the harness the motor would stumble again. Once he wiggled it around and help it in his hand the motor ran fine. Another thing today while running into port boat was running fine then while de acceleration. The boat stumble again mid way through at around 2000 rpm and then died. After I went to check under the hatch there was a leak on the starboard side of the carb, right by the lever. I will attach a photo for this. About the electronic kicking in and interrupting the motor I have no idea, I’d guess a loss connection somewhere but that’s why I’m here. Now the carb leak maybe I didn’t tighten down the carb enough and after a few hours of running things came lose. Or maybe the vibrations from motor stumbles made a crack somewhere. I’m not sure, that’s why I’m here. Any help is much appreciated!

 

[Lou C]

You might have 2 problems there you have intermittent connections in the 9 pin cannon connector and your carb needle valve may be leaking or the float has absorbed fuel and is causing the engine to flood. In any case take the connector apart clean the terminals and put it back together use a hose clamp to keep it from loosening. The carb should come apart & get rebuilt,

 

[Nick_1987 5.7 OMC]

You might have 2 problems there you have intermittent connections in the 9 pin cannon connector and your carb needle valve may be leaking or the float has absorbed fuel and is causing the engine to flood. In any case take the connector apart clean the terminals and put it back together use a hose clamp to keep it from loosening. The carb should come apart & get rebuilt,

Will be going back tmr. I’ll give this a try

 

[Nick_1987 5.7 OMC]

You might have 2 problems there you have intermittent connections in the 9 pin cannon connector and your carb needle valve may be leaking or the float has absorbed fuel and is causing the engine to flood. In any case take the connector apart clean the terminals and put it back together use a hose clamp to keep it from loosening. The carb should come apart & get rebuilt,

My fuel line is alittle messed up so I want to change it while boat is in water. If I drain the block of the water will it suck up water through the exhaust manifolds and into the chamber?

 

[Lou C]

My fuel line is alittle messed up so I want to change it while boat is in water. If I drain the block of the water will it suck up water through the exhaust manifolds and into the chamber?

I'm not really sure what you're asking here, you can replace a fuel line without it having anything to do with the cooling system, but do not overtighten the mounting bolts for the Quadrajet, or else you will warp the air horn (top cover of the carb) and it won't seal. Unless you have to disconnect a water hose (raw water intake from the transom mount) to get at the fuel line. In that case you can get a big wooden plug and put it in the hose, elevate it above the water line and it won't leak. No need to drain block in that case.
What you need to do is probably get the boat out of the water and go through the carb again. They do not leak if they were done properly. I've had mine apart a couple of times, it is a little tricky because you have to drive out the roll pin that holds the lever for the accel pump lever , and disconnect one of the links on the other side for the auto choke, to get the air horn off . Then when re-installing the air horn, you have to carefully line up the air bleed tubes and not bend them or knock them loose.

 

[kenny nunez]

The fuel leak may be caused by the 2 plugs that are pressed into the bosom of the float chamber. The fix is easy. Remove the carburetor and flip it over. Remove the throttle body and you will see the 2 plugs. Clean the area and roughen up the area around them and the plugs. With some JB Weld, cover them and let the material cure for 24 hours. Most times the gasket is reusable or obtain the correct rebuild kit just to be safe. If the fuel line is in question you may be able to obtain one from Crowley Marine for an OEM replacement. If not, then if there is a hydraulics shop in your area then take the fuel line to them and have a flexible one made up with new fittings. If there is NAPA store near by you can buy a straight 3/8” steel line with the flare nuts and bend it to fit. Bending the line is not easy but if you are careful it can be done.

 

[Nick_1987 5.7 OMC]

I'm not really sure what you're asking here, you can replace a fuel line without it having anything to do with the cooling system, but do not overtighten the mounting bolts for the Quadrajet, or else you will warp the air horn (top cover of the carb) and it won't seal. Unless you have to disconnect a water hose (raw water intake from the transom mount) to get at the fuel line. In that case you can get a big wooden plug and put it in the hose, elevate it above the water line and it won't leak. No need to drain block in that case.
What you need to do is probably get the boat out of the water and go through the carb again. They do not leak if they were done properly. I've had mine apart a couple of times, it is a little tricky because you have to drive out the roll pin that holds the lever for the accel pump lever , and disconnect one of the links on the other side for the auto choke, to get the air horn off . Then when re-installing the air horn, you have to carefully line up the air bleed tubes and not bend them or knock them loose.

Ok carb issue is fixed for now, but I discoved That the y pipe from exhaust is lose. It bolts from inside the boat through the transom and I’m guessing it screws into the gimbal on the outside. I have water trickling in. How the **** do I tighten those bolts, they are very loose. And it’s super tight in there.

 

[Lou C]

Well hate to say this but pulling the engine is the only way. And those bolts normally don’t just get loose there probably is corrosion in the joint between the transom mount & Y pipe. Might have to replace both. A big job overall. How much do you want to keep that boat?

 

[Nick_1987 5.7 OMC]

Well hate to say this but pulling the engine is the only way. And those bolts normally don’t just get loose there probably is corrosion in the joint between the transom mount & Y pipe. Might have to replace both. A big job overall. How much do you want to keep that boat?

What do you mean by corrosion? Transom rot? I had the boat surveyed this year. The boat is rot free. Is there no other way to fasten those bolts, not even with a flexible bit driver? I really don’t want to have to pull the motor.

 

[Scott Danforth]

this thread is longer then the time it takes to pull the drive and the motor

the bolts corrode

 

[Nick_1987 5.7 OMC]

Well hate to say this but pulling the engine is the only way. And those bolts normally don’t just get loose there probably is corrosion in the joint between the transom mount & Y pipe. Might have to replace both. A big job overall. How much do you want to keep that boat?

I have a video of leak

this thread is longer then the time it takes to pull the drive and the motor

the bolts corrode

how long will it take me, can it be done it a weekend? What are the steps I need to take and anything I should order?

 

[Scott Danforth]

how long will it take me, can it be done it a weekend? What are the steps I need to take and anything I should order?

duration of time depends on how handy you are, your experience, your tools and if you have been up on your maintenance

pull the drive. if you have been doing this every year for the annual maintenance, then it should only take 20 minutes.
disconnect exhaust, fuel, cables and wiring
unbolt rear mounts and remove lag bolts from stringer mounts
pull motor. this should take less than 40 minutes

now with motor out, clean bilge and access the bolts

then buy what you need.

 

[Nick_1987 5.7 OMC]

duration of time depends on how handy you are, your experience, your tools and if you have been up on your maintenance

pull the drive. if you have been doing this every year for the annual maintenance, then it should only take 20 minutes.
disconnect exhaust, fuel, cables and wiring
unbolt rear mounts and remove lag bolts from stringer mounts
pull motor. this should take less than 40 minutes

now with motor out, clean bilge and access the bolts

then buy what you need

duration of time depends on how handy you are, your experience, your tools and if you have been up on your maintenance

pull the drive. if you have been doing this every year for the annual maintenance, then it should only take 20 minutes.
disconnect exhaust, fuel, cables and wiring
unbolt rear mounts and remove lag bolts from stringer mounts
pull motor. this should take less than 40 minutes

now with motor out, clean bilge and access the bolts

then buy what you need.

I’m a handy guy, been wrenching for over 30 years. What should I buy before hand ?

 

[Scott Danforth]

I’m a handy guy, been wrenching for over 30 years. What should I buy before hand ?

a 6-pack of beer.

open one and drink it.
then cut the top off. put the outdrive bolts in that one

when the drive is off, open another and drink it
when done, cut the top off that one, then put the motor bolts

when the motor is out, you drink one to celebrate

until you get eyeballs on the problem, you dont buy anything hardware related

 

[kenny nunez]

All you need are basic tools that you already have. Of course a engine hoist. Once the engine is out run water through the exhaust outlets to narrow down where the leak is. Hopefully it just the exhaust and not the transom.

 

[Nick_1987 5.7 OMC]

a 6-pack of beer.

open one and drink it.
then cut the top off. put the outdrive bolts in that one

when the drive is off, open another and drink it
when done, cut the top off that one, then put the motor bolts

when the motor is out, you drink one to celebrate

until you get eyeballs on the problem, you dont buy anything hardware relate

a 6-pack of beer.

open one and drink it.
then cut the top off. put the outdrive bolts in that one

when the drive is off, open another and drink it
when done, cut the top off that one, then put the motor bolts

when the motor is out, you drink one to celebrate

until you get eyeballs on the problem, you dont buy anything hardware related

I have a video of the leak I will try and attach it, one clip shows the leak and the other you can see the the bolts including there thread. No corrosion visible on bolts. When I pull on y pipe the leak increases. When I push it against the transom. The leak stops.

 

[Nick_1987 5.7 OMC]

Well hate to say this but pulling the engine is the only way. And those bolts normally don’t just get loose there probably is corrosion in the joint between the transom mount & Y pipe. Might have to replace both. A big job overall. How much do you want to keep that boat?

Here is video of leak ^^^

 

[Lou C]

well I'll be damned, the bolt is out just like you said.
I'd start taking off the exhaust manifolds/hoses so you can get in there and tighten them, might need a chiropractor after ward though.
I was able to change the steering actuator with the engine in place maybe you can do this...

 

[Nick_1987 5.7 OMC]

well I'll be damned, the bolt is out just like you said.
I'd start taking off the exhaust manifolds/hoses so you can get in there and tighten them, might need a chiropractor after ward though.
I was able to change the steering actuator with the engine in place maybe you can do this...

I was stunned to when I noticed it. My father and i starred at each other for a few good seconds I have no explanation how it could have happened. Has to be from vibration. I can’t think of anything else. Both of the top screws are like that. The bottom ones might need a bit of tightening to. Did you see the mint water fall?

 

[Lou C]

Yep quite impressive water fall. I'd give the threads a light coat of Evinrude gasket sealer or Permatex Aviation, both help prevent corrosion and also may keep them from getting loose.