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Exhaust Manifold Question

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foreverfishing

Member
I have a Yamaha stern drive with a GM 3.0 L4 engine, I am getting water in the oil and on the plugs. I replaced the head gasket and manifolg gasket this weekend and still have t he problem. Pulled the plugs out, cranked the engine and water shot out of all four cylinders. I am thinking the manifold is cracked but as everyone knows Yamaha does not make the manifold anymore. I think I found a match with a Mercruiser, my question is will the Mercruiser manifold work?
Any help will be greatly appreciated, I have been wworking on this for over a year and think this will be the final fix.

Thanks​
 
You asked one question and i have to ask a few question.

Whats compression on this motor right now ?

Second post a pic of the motor i don;t think it was the same 3.0 motor as was used in mercs and omc's

and finally that is such a rare drive i have never seen one in person but have heard of them.

There is only one guy in Fl who even has a used part for it.

Why would you sink a dime into it this motor and drive combo ?

After you get the compression, post the pic. in the same post back
 
Thanks for the reply. I don't know what the compression is, didnt put a gauge on it but when the water shot out it went about 8 feet do I am assuming it is OK. ( propably not a good idea to assume though) Who is the guy in Florida?
 
Dude,
read his post before asking stupid questions..........


foreverfishing said:
i have a yamaha stern drive with a gm 3.0 l4 engine, i am getting water in the oil and on the plugs. I replaced the head gasket and manifolg gasket this weekend and still have t he problem. Pulled the plugs out, cranked the engine and water shot out of all four cylinders. I am thinking the manifold is cracked but as everyone knows yamaha does not make the manifold anymore. I think i found a match with a mercruiser, my question is will the mercruiser manifold work?
Any help will be greatly appreciated, i have been wworking on this for over a year and think this will be the final fix.

Thanks​
Click to expand...
 
To answer your questions.... A merc manifold can work as long as the carb fits and the exhaust elbow connects with the rubber exhaust boot and the water supply hoses are made to fit..

If you suspect a cracked manifold you should have it pressure checked to confirm a internal crack. If you do not confirm and just replace you may not correct the problem.

If the block was not winterized properly typically it cracks on the out side of the block below the manifold. It is not impossible it could have cracked inside also, or possible a cracked head... a lot of unknowns.....each has to be confirmed good or bad.
 
KGhost, thanks for the advise. The thing is I was out last month and it ran great for about two hours. After I shut it off for a while it would not start, checked the oil and it was milky and pulled the plugs and they were wet. if it was the block I would think I would have seen it right away. The engine is a 93 and the guy I got it from ( a so called frien) never maintained it or ran it for that matter. it stayed at the dock and he would start it oonce a week, thats it.He would never go out alone and never could find anyone to go with.
 
chiefalen said:
You asked one question and i have to ask a few question.

Whats compression on this motor right now ?

Second post a pic of the motor i don;t think it was the same 3.0 motor as was used in mercs and omc's

and finally that is such a rare drive i have never seen one in person but have heard of them.

There is only one guy in Fl who even has a used part for it.

Why would you sink a dime into it this motor and drive combo ?

After you get the compression, post the pic. in the same post back
Click to expand...

Here are a few Pics of the manifold, hopefully they will help.

Thanks
 

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I did read his post he replaced the head gasket who's to say it didn't go again.

I know your trying to push me into a fight, you just might get it.

So i will ask here for you to keep your post to the point and not directed at me please !

Original poster, personal family activity's are consuming my time for a few day's now so i couldn't look for the guy in Fl i got a call in to a friend in Fl, yes he has a personal life also and will let me know if the guy in Fl with the yammy drives is still alive.

I don't see anyone else going out of their way to help you, in that regard.

Ok Your problem might not be related to the mani but the head.

See if you remove the t-stat housing off the head , and look into the neck with a flashlight, and probe the opposite wall with a screwdriver gently see if that wall is solid or a hole opened into the hole for the pushrod allowing water into the oil.

If you take the valve cover off you will see how close the first pushrod hole is to the neck it is a thin wall. Want to try that before you start spending 300 dollars for a new mani you might not need.

Also i think the omc mani might be closer to what you need for a 85 i think motor . I will look it up and post back to this thread within the hour.

And by the way what is the compression right now on the motor today ? All the plugs out and the throttle down ? Use a screw in type compression tester.
 
http://www.marineengine.com/parts/mercruiser-stern-drive/mercruiser-engine-parts.php?modelId=2830&model=3.0L%2FLX+GM+181+I%2FL4+1990-1995&serialId=2831&serial=0C856559+THRU+0F603999&componentId=2

Here is a merc one piece. I knew i saw one in person a very long time ago. But i can't see the mount for the cable.

Another thing i don't know if your carb will mount up. You got one adjustment screw. The rochester 2 cg has 2.

It's a problem.

Don't buy anything yet.

Check out the head and the compression and get back to us.

I got to ask someone else a few questions and will post back.
 
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chiefalen said:
I did read his post he replaced the head gasket who's to say it didn't go again.

I know your trying to push me into a fight, you just might get it.

So i will ask here for you to keep your post to the point and not directed at me please !

Original poster, personal family activity's are consuming my time for a few day's now so i couldn't look for the guy in Fl i got a call in to a friend in Fl, yes he has a personal life also and will let me know if the guy in Fl with the yammy drives is still alive.

I don't see anyone else going out of their way to help you, in that regard.

Ok Your problem might not be related to the mani but the head.

See if you remove the t-stat housing off the head , and look into the neck with a flashlight, and probe the opposite wall with a screwdriver gently see if that wall is solid or a hole opened into the hole for the pushrod allowing water into the oil.

If you take the valve cover off you will see how close the first pushrod hole is to the neck it is a thin wall. Want to try that before you start spending 300 dollars for a new mani you might not need.

Also i think the omc mani might be closer to what you need for a 85 i think motor . I will look it up and post back to this thread within the hour.

And by the way what is the compression right now on the motor today ? All the plugs out and the throttle down ? Use a screw in type compression tester.
Click to expand...

Thank you for your help, I never looked into an OMC match. Everything thing else on the engine seems to be crossed to a MErcruiser. I found the giy in Fl, Capt Ken and got in contact with him yesterday, he is very knowledgeable and helpful. thanks for all of your help, I will post the results of how everything works out for anyone else eho has this issue.
 
Last reply in this forum for a while, i will be posting in the omc forum.

I wish you well in all your endeavors, especially the hobby you have chosen boating.
 
chiefalen said:
http://www.marineengine.com/parts/m...1&serial=0C856559+THRU+0F603999&componentId=2

Here is a merc one piece. I knew i saw one in person a very long time ago. But i can't see the mount for the cable.

Another thing i don't know if your carb will mount up. You got one adjustment screw. The rochester 2 cg has 2.

It's a problem.

Don't buy anything yet.

Check out the head and the compression and get back to us.

I got to ask someone else a few questions and will post back.
Click to expand...


The manifold in the link looks identical to what I have the only difference that I can see is it says its for a 181, my engine is a 140, will that make a differebce or is ir the same?

Thanks for your help
 
foreverfishing said:
The manifold in the link looks identical to what I have the only difference that I can see is it says its for a 181, my engine is a 140, will that make a differebce or is ir the same?

Thanks for your help
Click to expand...

Ayuh,... a 140 hp is a 3.0l which is a 181 cid....
 
OK.... I picked up a new manifold and riser, installed it yesterday and stilll will not start. I am using thee old carb off the Yamaha manifold, not the mercarb that came with the manifold. The reason I used the old carb is the cables, I didnt want to have to try and adapt them to the mercarb. Would using the old carb make a difference or should I try and use the Mercarb? Trying to figure this out and its driving me crazy, any help will be appreciated.

Thanks
 
The water in the cylinders sounds familiar, heres a quick test to try.
Remove the spark plugs, remove the hose going to the manifold.Remove the large hose from the therm housing.
Using a garden hose fill the block with water thru the big hose.If it comes out a spark plug hole, suspect a cracked block or a hole rotted thru the head .Most likely #1 exaust port. If no water comes out, fill the manifold .If water comes out a spark plug hole, manifold is cracked.
 
You want to start it correct.

You got good fuel to the carb ?

You got spark at the plugs ?

You got compression ?

The old carb don't work ?

Thow on the merc carb.

Put water to the drive.

Place the key in run position.

Dribble some gas into the carb

With the cable off the merc carb, jump the starter.

The choke should be closed.

Work the linkage by hand.

You can mess with the cable latter.
 
I got spark on the plugs, compression seems good (160 on all cylinders) and no water on the plugs. It cranks and I get a pop like it trying. Can it be in the timing? I also put a new distributer cap, rotor and pick up coil
 
I got spark on the plugs, compression seems good (160 on all cylinders) and no water on the plugs. It cranks and I get a pop like it trying. Can it be in thetiming? I also put a new distributer cap, rotor and pick up coil. I tryed somee ether in the carb and got a flame out of the carb
 
Bt Doctur said:
The water in the cylinders sounds familiar, heres a quick test to try.
Remove the spark plugs, remove the hose going to the manifold.Remove the large hose from the therm housing.
Using a garden hose fill the block with water thru the big hose.If it comes out a spark plug hole, suspect a cracked block or a hole rotted thru the head .Most likely #1 exaust port. If no water comes out, fill the manifold .If water comes out a spark plug hole, manifold is cracked.
Click to expand...

No water coming out spark plug hole.
 
r u sure the block isent cracked?if so drill 1 hole on each side and jb weld.there is no pressure in block.but ya manifold will enterchange just b sure and see spects
 
I've reread your posts and did some contemplating about your issues.

...I am using thee old carb off the Yamaha manifold...
Click to expand...

How sure are you that the carb is working? Is there a big vacuum leak whereby the engine is sucking more air than fuel? The old Mercarb required a thick base gasket for proper fuel atomization.

...I got spark on the plugs, compression seems good (160 on all cylinders)....
Click to expand...

The spark plugs may not be firing even though you see some spark at the wire end. The spark may be weaker than you think. The spark needs to be strong and bright w/a slight blue tinge. Orange tinged spark is weak. Pull a plug and check how strong the spark jumps the gap; if it does at all.

...I also put a new distributer cap, rotor and pick up coil....
Click to expand...

Check the spark coming out of the coil HV wire using a spark tester or plug. Is it the same as at the plug wires?

...I tryed somee ether in the carb and got a flame out of the carb...
Click to expand...

That should not happen if the ignition is correct w/good compression as you stated. Pickup coil may be defective or timing is off. Are you using good marine grade plug wires?
 
Last edited:
guyjg said:
I've reread your posts and did some contemplating about your issues.



How sure are you that the carb is working? Is there a big vacuum leak whereby the engine is sucking more air than fuel? The old Mercarb required a thick base gasket for proper fuel atomization.



The spark plugs may not be firing even though you see some spark at the wire end. The spark may be weaker than you think. The spark needs to be strong and bright w/a slight blue tinge. Orange tinged spark is weak. Pull a plug and check how strong the spark jumps the gap; if it does at all.



Check the spark coming out of the coil HV wire using a spark tester or plug. Is it the same as at the plug wires?



That should not happen if the ignition is correct w/good compression as you stated. Pickup coil may be defective or timing is off. Are you using good marine grade plug wires?
Click to expand...

I am getting a clan blue spark on all cylinder and the coil wire.
The cap and rotor are mercruiser, I am thinking I am off on my timing. I am going tomorrow to put the mercarb on. I would'nt think it would have made a difference though.


Thanks
 
tjohnson1129 said:
r u sure the block isent cracked?if so drill 1 hole on each side and jb weld.there is no pressure in block.but ya manifold will enterchange just b sure and see spects
Click to expand...

If the block is cracked would'nt I have water coming out if the spark plug holes? I know the old manifold was cracked thats why I replaced it last week.

Thanks
 
...I am going tomorrow to put the mercarb on...
Click to expand...

A thin base gasket won't allow the mixture screw to adjust worth a crap. The correct gasket is available from a Merc. dealer or you can cut one out of heavy sheet gasket material. Are you sure the fuel pump is working? Isn't there a filter inside a mechanical pump? Have you tried to check the timing?
 
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Hi,I know this thread is almost a year old but I have the same problem.Could anyone tell me which manifold and riser will work to replace the yamaha manifold and riser that is no longer available.I have the 3.0 same set up that is shown in the pics.Also when you put the manifold on did you have to make any mods with the throttle cable or alternator bracket.And did the elbow boots and every thing line right up any help would be greatly apreciated.
 
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