Help! Bought a 1993 Four Winns W/ 5.0 OMC Cobra Motor and Drive - Losing power after crusing

[cameron92]

Not bad ideally you want a warmed up engine & throttle wide open, I think they’d be higher then. Next leak down test and what did the air pressure test show? If all is good test your manifolds & try running it again. See if you still get water in the oil. Air pressure test is really the most important

The air pressure test is losing psi somewhere. I cant hear anything, smoke test didn't reveal anything. Thought maybe I could hear something in the valve cover but hard to say. I think it might be my setup, it is just a rubber ball that inflates and if I pump more then 12 psi it shoots out of the hose

 

[Lou C]

You have to get a better seal for a valid test

 

[Scott Danforth]

It just occurred to me that the previous owner installed a new distributor cap. He mentioned something about timing being out but he had a mechanic look at it. Wondering if that relates to my original issue.

Probably wired it to the wrong firing order

 

[cameron92]

So I tested my manifolds for leaks. Didn't have acetone but just filled the hose with water. The exhaust ports filled up with water as well after about 5 mins. Guessing that's my issue..

 

[Lou C]

I guess in freshwater you don't see the rust like we do here!
PS was the manifold sitting level when you tested it, because it could have run out the outlet of the elbow and then ran back in the center exhaust port and filled the exhaust ports if you tested it with it lying down like the pic! The only way to test a manifold with any liquid is with them standing straight up as installed on the engine!

 

[cameron92]

I guess in freshwater you don't see the rust like we do here!
PS was the manifold sitting level when you tested it, because it could have run out the outlet of the elbow and then ran back in the center exhaust port and filled the exhaust ports if you tested it with it lying down like the pic! The only way to test a manifold with any liquid is with them standing straight up as installed on the engine!

Oh! I was laying them down yes.

 

[Lou C]

Dry em out and try again!
You have water passages and exhaust passages inside those castings, the water must stay separate from the exhaust passage. I would be surprised if yours leak because there was no sign of rust in the exhaust ports in the cyl head or the exhaust ports on the manifold. Usually if they are leaking it's obvious from the amount of rust. The water passages are to keep the manifold at a resonable temp given that it's on an engine in a closed compartment. The exhaust gas flows up and out the elbow and the water does as well, but separately and they mix together when the water and exhaust exit the elbow inside the rubber hose. So if it's lying down like that, the water can flow backwards and wind up right in the exhaust ports.
Get in closer to the engine and see if you can get pix of the inside of the exhaust port on each cyl head and see what the exhaust valves look like. You should be easily able to see them.

 

[cameron92]

I guess in freshwater you don't see the rust like we do here!
PS was the manifold sitting level when you tested it, because it could have run out the outlet of the elbow and then ran back in the center exhaust port and filled the exhaust ports if you tested it with it lying down like the pic! The only way to test a manifold with any liquid is with them standing straight up as installed on the engine!

No relatively rust free!

Dry em out and try again!
You have water passages and exhaust passages inside those castings, the water must stay separate from the exhaust passage. I would be surprised if yours leak because there was no sign of rust in the exhaust ports in the cyl head or the exhaust ports on the manifold. Usually if they are leaking it's obvious from the amount of rust. The water passages are to keep the manifold at a resonable temp given that it's on an engine in a closed compartment. The exhaust gas flows up and out the elbow and the water does as well, but separately and they mix together when the water and exhaust exit the elbow inside the rubber hose. So if it's lying down like that, the water can flow backwards and wind up right in the exhaust ports.
Get in closer to the engine and see if you can get pix of the inside of the exhaust port on each cyl head and see what the exhaust valves look like. You should be easily able to see them.

Here's a video of all 8

 

[cameron92]

Dry em out and try again!
You have water passages and exhaust passages inside those castings, the water must stay separate from the exhaust passage. I would be surprised if yours leak because there was no sign of rust in the exhaust ports in the cyl head or the exhaust ports on the manifold. Usually if they are leaking it's obvious from the amount of rust. The water passages are to keep the manifold at a resonable temp given that it's on an engine in a closed compartment. The exhaust gas flows up and out the elbow and the water does as well, but separately and they mix together when the water and exhaust exit the elbow inside the rubber hose. So if it's lying down like that, the water can flow backwards and wind up right in the exhaust ports.
Get in closer to the engine and see if you can get pix of the inside of the exhaust port on each cyl head and see what the exhaust valves look like. You should be easily able to see them.

No water leakage. Obviously not the same as acetone but I figured it's better then nothing for now.

 

[cameron92]

If I reinstall my manifolds do I need fresh gaskets? Can I get away with automotive gaskets temporarily?

 

[Lou C]

You just need the cyl head to exhaust manifold ones, I think automotive would be ok…

 

[Lou C]

The exhaust valves look ok from what I can see. Make sure to go back & re do your air pressure test.

 

[cameron92]

The exhaust valves look ok from what I can see. Make sure to go back & re do your air pressure test.

Ok I will try to rig a better test setup for the pressure test. Going to grab a stethoscope tomorrow too. The smoke test didn't reveal anything either, only leak was where it was connected.

 

[cameron92]

The exhaust valves look ok from what I can see. Make sure to go back & re do your air pressure test.

I was just thinking this morning. Should I be pulling the thermostat out, wouldn't it be closed and be blocking airflow into the engine?

 

[Scott Danforth]

The thermostat is set up as a mixing valve in raw water cooled setups

No need to pull it for pressure testing

 

[Lou C]

Leave the manifolds off till you complete the air pressure test, in case the leak if there is through an exhaust port...also leave the oil fill cap off, for the same reason, (cracked head or block may put air out there).
Also if you can get the smoke machine properly hooked up, it may make it easier to see where there are leaks if any. I found many leaks on my 19 year old OEM exhaust on my 2007 Grand Cherokee 5.7 with it (which led to the installation of a 3" Gibson stainless cat back) and also fixed 2 evap codes on both my 2007 and 1998 Jeep with it. Very useful tool if hooked up right.

 

[cameron92]

Drained the oil and no water in the oil! I think it was in the dipstick tube.

 

[Scott Danforth]

You're just draining now?

 

[cameron92]

You're just draining now?

Lol ya

 

[cameron92]

You're just draining now?

Fried my impeller with all the compression testing I guess. She's a mess.