7.4 MPI Milky oil now a noise, listen

Thanks. The motor that puts out less water also runs about 180 degrees vs. the other motor that puts out a lot of water is 170. My boat was sitting for maybe 10 weeks so its also a possibility that the intake under the boat is barnacled up...
 
This has to be a failed head gasket. Also could be a cracked head or warped but unlikely if it is new or reconditioned. When the engine is cold, run the exhaust manifold dry for a few minutes and see if you get the milky oil. Remove the rubber exhaust bellow also so you dont burn it up and you will be able to see if water is coming out. If water is and you don't have any water running thru it, then the water is coming from the cylinders via a bad gasket. My 2 cents..... good luck
 
NJMatt50 said:
Thanks. The motor that puts out less water also runs about 180 degrees vs. the other motor that puts out a lot of water is 170. My boat was sitting for maybe 10 weeks so its also a possibility that the intake under the boat is barnacled up...
Click to expand...

Both of mine run just a bit above 160 consistently
 
Ok, I tested a bit more. I removed the hoses under the exhaust manifolds and ran the boat a couple times. No water present in the oil. I am unsure if removing the piece of stuck riser from the muffler and flushing it a couple of times with new oil had something to do with this so I must run it again with water through the exhaust. I did notice that a bit of exhaust comes out of the water fitting on the bottom of the manifold. Not sure if this is normal? Also the 1,3,5,7 side of the water hose to exhaust manifold has low pressure almost like peeing compared to the other side. If i pinch the good side a bit I get more flow from the bad side , not sure if this is normal. I did remove the end cap and there was nothing obivious...
 
"I did notice that a bit of exhaust comes out of the water fitting on the bottom of the manifold" Not good
 
Ok. Here is the latest update... Hooked all raw water up as should be. Compression is 160 all cylinders, leak down is ok.No water in oil, now water exits the side of the boat properly. I do have a ticking noise like a time bomb or clock. I found 3 bent exhaust push rods. Hopefully changing them takes care of the noise. All of this I believe goes back to the piece of riser stuck in the muffler...
 
Matt, Sounds like you almost there... No you just have to clean your props and you should be ready to start using your boat...
 
Well here is another update on this in case you are following. Pushrods did nothing. So I pulled the engine and found that #7 piston was .025 smaller than the others, rattling in the bore. Rest of the motor was in great shape, bearings were all good. So the water washed that cylinder down and ate up the piston. Its at the shop now being repaired. Upon removal of the motor I also found sea water in the #4 and 6 exhaust manifold as if it were coming back into the engine through the riser. I really don't understand how this can be happening as I did not even drive the boat just ran it for a few minutes. I know that the log style muffler is not good but to get this water in the exhaust ports just running it in the slip seems over the top. My exhaust angle was sloping downwards too. I will be updating to the lift mufflers when I put the motor back, but what else can be causing the water ingestion like so. I have brand new manifolds and risers.
 
It's possible the manifolds and risers were not installed properly and continued to leak even after they were replaced. Did the instructions specify a sealant on the surfaces or were the gaskets supposed to go on dry?

Doug
 
I used mercruiser gaskets. They go on dry. From the looks of the exhaust outlet it seems that there is a rust trail leading from the 4" tubing into the engine... I am going to redo the riser gaskets anyways..
 
I sure sounds like a bad exhaust/riser assy.
Also I keep looking back at the videos you posted and keep thinking there should be more oil pumping up top!!!! A bad oil pump could account for the hydraulic lifters not pumping up and create the tapping too.
It's not impossible that you may have 2 separate problems brought on by a bad riser/exhaust manifold.

What a nightmare :wow: keep the faith.
 
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