Pressure testing exhaust manifolds |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Posted: June-18-2015 at 10:33pm |
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Why would Bruce have to change to the "crummy cast iron"? Repair is certainly and option. The Commander's are worth it!! |
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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Gary, we cleared that area and made the driveway bigger so we could park more stuff. And we bought an engine hoist as I was afraid that eventually someone might get hurt. If you ever come visit me you'll be disappointed to see that set up gone. My kids are happy as they were a little self conscious about it when their friends from the city came to visit.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Is the old engine hoist up for one more pull Bruce? If you knew then what you know now you would have cpes'd it
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shierh
Gold Member Joined: April-29-2015 Location: Florida Status: Offline Points: 605 |
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block off all hoses on engine and put air in the block. i drain the block on both sides and then put the rubber tip air gun in it and put some lbs in the block. Listen for hiss.
u can use pcv pipe plugs and hose clamps . remember to block off raw water pump. Hope all turns out ok for you. Im in process of restoring 83. Engine was new 12 years ago and put away 10 years ago, got ruined by leaving it full of water. at some point the manifolds cracked from being frozen and water in a few cylinders, rusted but no frozen. Boring it out 30 over, found heads cracked from being overheated as well. also prior owner kept it covered from time to time using blue plastic tarp, turned it into a greenhouse inside and just played havoc on the thing. |
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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I see what you are saying about the gasket between the manifold and riser. We'll be pulling everything apart at this point so I can testing them again in water. We were hoping to test run this boat, but I think it probably needs a tear down at this point. We changed the oil. I don't know why there's so much gas in it as it only ran about 5-10 minutes. .
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shierh
Gold Member Joined: April-29-2015 Location: Florida Status: Offline Points: 605 |
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Port Manifold has aluminum oxide between the manifold and the discharge which is an indication of a leak.
Hope they are not cracked because then you have to change to these crummy cast iron center riser manifolds. My First Nautique in 1978 had Commander in it and i preferred this type of manifold over the heavy cast iron type, at least for this type of application. My Hatteras had Crusader 454's that were heat exchange cooled and the only thing that got sea water was the Risers and Elbows along with the oil/trans cooler and Heat Exchanger. Weight wasnt an issue with that boat as the extra few hundred pounds would make no difference in its performance. |
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shierh
Gold Member Joined: April-29-2015 Location: Florida Status: Offline Points: 605 |
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Isnt there a block off plate and 2 gaskets between them? if so then it needs to be taken apart and re sealed to rule out leaks there if you want to get a good test. Can not imagine a casting with no openings in the water jacket. have to get the casting form material out somehow.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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Steve, It sounds like you aren't familiar with Commander exhausts. Look at the picture Bruce posted. There isn't water porting between the manifold and elbow. You'll see the hose connection on the elbow. It's a great method to eliminate potential air pockets in the manifold.
Bruce, They should hold all the air. Put them in a tub of water and look for bubbles. Make sure you aren't leaking air on your temporary air connection. If the engine froze, the manifolds typically go first. The pressure test is always recommended but the only downside is it's done cold. Cracks can open up when the manifold gets hot. |
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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Water comes in and out of the front of the manifold, so I put the T between the 2 hoses and pressurized it. The engine has issues. I checked it tonight and it's leaked about 1..5 quarts of gas and oil out of the rear main during the past 10 days.
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shierh
Gold Member Joined: April-29-2015 Location: Florida Status: Offline Points: 605 |
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how did you block off the rear discharge or elbow.?
i would take that apart and install flat rubber and seal it off. then re pressurize it. Would think you should not hear any leaks, should not drop pressure. you can use soap water around all joints and schrader valve to test for leaks. You can pressurize the block the same way. Plug everything up. and put some air in it. i did this before by taking intake off and making block off plates for the head water jackets and pumping it full of air. found crack pretty fast that way. |
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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We are tying to resurrect this Commander engine that suffered a freeze up. I've pressure tested the exhaust manifolds with this device I made up. I put 40 lbs into them and after 20 minutes, 1 has 10lbs left and the other 30lbs. Would that indicate that they are not cracked? I would think that they wouldn't hold air at all if they are.
This engine is a bit of a mystery and we will probably have to take it apart to know the extent of any damage, but the cylinders have compression and the exhaust manifolds hold pressure, but there is still water getting into 2 cylinders. The engine runs, but runs rough. Any ideas on the manifold or where the water could be coming from? |
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