My new project - 86 - 272 LS
11-09-2012, 09:14 AM
#181
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Motor update
Well, the open heart surgery has started. Starboard motor came out today, no problems there. Getting it set up on the stand and start taking a few parts off.
To recap, this is the motor that I had all the machine work done to and it was magnafluxed (block and crank). On the first run, this motor leaked water into the oil and it looked like it was along the intake manifold. So the manifold was pulled and put back on to reseal it. Oil was drained and changed and then tested on the hose, looked good. Had some residual moisture in it, but the next time we ran the boat the oil cleaned itself out and looked new. this last time we ran the boat, it again leaked and spewed the brown foam. There was not much water in the oil and it did not run long or hard, so we will see.
So we are pulling the pan to inspect bearings and replace if need be. We will pull the intake manifold again and see if we can tell where or if it leaked. I may just buy a new manifold and change it out if I suspect the sealing surface. Time will tell. But for now, the boat is back to the status of not even qualifying as a raft without the drives on it! Time to let the projects begin. Unfortunately, my job is putting a serious cramp on my boat work time.
Brian
To recap, this is the motor that I had all the machine work done to and it was magnafluxed (block and crank). On the first run, this motor leaked water into the oil and it looked like it was along the intake manifold. So the manifold was pulled and put back on to reseal it. Oil was drained and changed and then tested on the hose, looked good. Had some residual moisture in it, but the next time we ran the boat the oil cleaned itself out and looked new. this last time we ran the boat, it again leaked and spewed the brown foam. There was not much water in the oil and it did not run long or hard, so we will see.
So we are pulling the pan to inspect bearings and replace if need be. We will pull the intake manifold again and see if we can tell where or if it leaked. I may just buy a new manifold and change it out if I suspect the sealing surface. Time will tell. But for now, the boat is back to the status of not even qualifying as a raft without the drives on it! Time to let the projects begin. Unfortunately, my job is putting a serious cramp on my boat work time.
Brian
11-09-2012, 09:52 AM
#183
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But thanks for posting this as it reminded me of something I was going to do before taking it apart. I want to plug the five cooling hoses on the motor: four going to the exhaust manifolds and the one inlet hose. Then I can pressurize the cooling system with a few PSI and see if there are any obvious leaks. Hopefully this will point me in the correct direction.
Brian
11-09-2012, 10:40 AM
#184
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Brain what I did was hook a garden hose to input hose on the engine, then I blocked off the two exhaust manifold hoses. For me it was obvious when I pulled a riser and saw that I had the entire exhaust manifold full of water. When I took the heads to the shop all the guides were leaking. Some worse than others, some were so corroded that over half of the material was gone. I'm going to bet your problem is in your heads.
11-14-2012, 09:08 AM
#185
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Pressure check on cooling passage
Alright, motor is back on the stand but still all together from the pan to the carb with exhaust still on. I made up four plugs to plug the four hoses going to the exhaust manifolds and risers. I then made a plug for the cooling hose from the outdrive with a pipe tap in it so we could hook up a regulator and valve. this allowed us to hook up an air hose, set it to 6 psi and then shut the valve isolating the engine from the shop air.
The damn thing has held perfect pressure now for 1/2 an hour! I would think if it was a cracked head or bad valve guides it would leak air all the time. So now I am back to thinking it is the intake manifold gasket letting go when the engine gets up to temperature. (Note: this is also the engine without a working temp gauge. We used a thermocouple for the first run in the thermostat outlet and the motor temp seemed fine, but did want to throw this out there.)
I was hoping for some hissing sounds that we could pinpoint. Nothing is heard even with a stethoscope. Of course, holding 6 psi would not expect to hear anything. Kinda stumped on this motor now.
At the least, I will change out the intake manifold gasket and inspect the mating surfaces. Still going to pull the pan and inspect the bearings also since it is out of the boat. I think I will post this in the technical section also to see if I can get a wider audience to help with this water issue.
Brian
The damn thing has held perfect pressure now for 1/2 an hour! I would think if it was a cracked head or bad valve guides it would leak air all the time. So now I am back to thinking it is the intake manifold gasket letting go when the engine gets up to temperature. (Note: this is also the engine without a working temp gauge. We used a thermocouple for the first run in the thermostat outlet and the motor temp seemed fine, but did want to throw this out there.)
I was hoping for some hissing sounds that we could pinpoint. Nothing is heard even with a stethoscope. Of course, holding 6 psi would not expect to hear anything. Kinda stumped on this motor now.
At the least, I will change out the intake manifold gasket and inspect the mating surfaces. Still going to pull the pan and inspect the bearings also since it is out of the boat. I think I will post this in the technical section also to see if I can get a wider audience to help with this water issue.
Brian
Last edited by befu; 11-14-2012 at 09:47 AM.
11-14-2012, 02:55 PM
#187
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I have no idea what a sbc with open cooling operates at for psi, but I would think it would be low since the only pressure is from the resistance due to hoses. Although the water pump might create some inside the motor. Maybe I will try upping it tomorrow.
It is really seeming like a gasket that seals until it gets hot enough.
Brian
11-14-2012, 04:01 PM
#188
your correct, not really much pressure in the open system. But the point of bringing the pressure up would be to find a pesky leak that may only occur at operating temp. The gaskets and system should take 15+ psi no problem.
my brother is a mechanic, and when people have an antifreeze smell but can't find a leak they put 15-20 pounds to it and they always find the leak.
my brother is a mechanic, and when people have an antifreeze smell but can't find a leak they put 15-20 pounds to it and they always find the leak.
11-14-2012, 06:28 PM
#189
Registered
Thread Starter
your correct, not really much pressure in the open system. But the point of bringing the pressure up would be to find a pesky leak that may only occur at operating temp. The gaskets and system should take 15+ psi no problem.
my brother is a mechanic, and when people have an antifreeze smell but can't find a leak they put 15-20 pounds to it and they always find the leak.
my brother is a mechanic, and when people have an antifreeze smell but can't find a leak they put 15-20 pounds to it and they always find the leak.
