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Do I have a riser gasket problem in 43 L Mercruiser

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rylleeryllee

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"I started up my boat in the s

"I started up my boat in the spring and it started up fine. I have a 2005 4.3L Mercruiser. I put it in the water and boated for about 5-10 minutes and then it stalled. I opened up the hood and saw that there was milky oil coming out of the valve cover vents. I took the boat out of the water, drained the milky oil, ran new oil through it twice and then replaced the oil and the oil filter. I took the boat into a boat shop and they removed the intake manifold, saw a crack underneath and replaced it. They could not see any cracks in the block or heads. The boat shop indicated that there is a pocket in the manifold that water can remain in if the boat is sitting at a certain level. I started the boat and that's when I noticed it running rough and steam coming out of the one valve cover vent. The boat ran perfectly before it stalled in the water. When I take the plugs out, the engine turns over perfectly with no sounds or hydrolock. If I connect the ear-muffs and turn on the water with the plugs out, it still turns over perfectly. When I put the plugs back in and turn it over with the coil wire disconnected, after it turns over 2-3 times, it seems to experience hydrolock (sounds like it's sporadically undergoing load). I’ve taken out the plugs three times and turned over the engine to check for water, and no water comes out and the plugs are not wet. I’ve tested the compression and it’s 120 psi in all six cylinders. Your suggestions would be appreciated."
 
""When I take the plugs ou

""When I take the plugs out, the engine turns over perfectly with no sounds or hydrolock."

No water to the OD? You fried the impeller.

"When I put the plugs back in and turn it over with the coil wire disconnected, after it turns over 2-3 times, it seems to experience hydrolock (sounds like it's sporadically undergoing load)."

Battery getting weak; you said plugs aren't wet? Or a defective exhaust manifold, riser or elbow. You don't say that they tested them."
 
I was thinking that there was

I was thinking that there was no hydrolock before the intake manifold was replaced but there is now. Do you think it could have been installed incorrectly and the intake manifold gasket is leaking?
 
Now I don't know what to t

Now I don't know what to think. The hydrolock is gone completely now. Guy I think you were right. I noticed a spark by the battery when I was turning it over. One of the battery cables was slightly loose. I guess there was no hydrolock. The engine fires right up but there is still something wrong. There is still a little bit of steam rising from the valve cover vents and it's still not running quite right. There is still no water in the oil or the cylinders.
 
I put my boat in the water yes

I put my boat in the water yesterday and had it in the water for about an hour. It ran fine at trawling speed but when I opened it up it seemed like it was being held back. There wasn't enough power to get it going. I checked the oil and it was fine. The level didn't change and no water in it. Could something electrical be causing the lack of power? I bought the boat in 2005 brand new and the condensor went on the boat after one year.
 
"Can anyone tell me where this

"Can anyone tell me where this wire with a ring terminal goes on my 4.3L Merc. I think they forgot to attach it when they replaced my intake manifold.
292425.jpg
wiring harness
 
I just looked again and there

I just looked again and there are two wires with ring terminals coming out of that same wiring harness that aren't connected
 
The big black wire is a main g

The big black wire is a main ground. What is the color of the other wire? Post a picture of it. There should be a ground stud nearby.
 
"both are black wires. They co

"both are black wires. They come out of the black plastic wiring harness sheathing. They are about 18 ga wire.
292445.jpg
wiring harness
 
"I think the one on top of the

"I think the one on top of the photo goes onto the ground stud under the dissy, not sure if on later models but its on mine, you cant see it, its hanging down from under the dissy housing, have a feel around.. the other one im not sure, either shift plate or carby. looks like you dont have cut out switch on your shift plate so it may not be needed. Is there any electrical thingys on your carby that need grounding?"
 
Thanks for the response Mark.

Thanks for the response Mark. I will have a look. not sure if I have anything under the carb needing grounding but I'll look
 
Look closely at the connectors

Look closely at the connectors to see if there are any marks on them that shows they have been previously connected.

The blown up first picture made me think it was 10 ga. wire.
 
Thanks Guy. It's hard to s

Thanks Guy. It's hard to say. The engine is like new. There are a few scratches on the terminals but I'm not sure if that was from being previously connected or not. Maybe I should try grounding them and see if it makes any difference? I had another question: is there a way to test the electric choke to see if it's working properly?
 
The electric choke should have

The electric choke should have a ground wire attached to one of the screws. To test it just turn the ignition to the run position. The choke should have 12 vdc and start to get warm as the heater warms the choke coil. Feel it w/your hand and watch the choke open.
 
There is no ele choke on a TKS

There is no ele choke on a TKS (turn key start)carb. that is what those extra grounds are for. you need to have that motor timed in base timing.
 
"I need to revise my previous

"I need to revise my previous post, you do indeed have a shift cut out switch. (Every merc does i think) I can see the it in your first photo, it looks white, has a philips screw and two black wires comin out of it. those two black wires go to a plug, which plugs into the engine harness, engine harness wires are white/green and BLACK. IT MAY BE ONE OF YOUR LOOSE WIRES? If The black wire from the switch is not grounded, your ignition will not cut out during gear selection. As for the other black wire, I still think its from under the dissy. Mark."
 
Do you think it's possible

Do you think it's possible that they put the distributor back in incorrectly when they replaced the intake manifold or can it only fit back in one way?
 
"I took the boat back today an

"I took the boat back today and had the timing set properly. It still has a knock in it at higher rpms. The spark plugs are all still normal, compression is still 120 psi in each cylinder and there is still no water in the oil. It has steam coming out of the valve cover vent on starboard side only. Does anyone know what could cause that?"
 
If the steam stops when the en

If the steam stops when the engine reaches operating temp it is a normal part of combustion. Water vapor can collect in the oil from combustion if the boat is used on short trips like an automobile. The oil has to get hot to boil off this moisture contamination.
 
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