1992 3.0L I hear air leak in #4 cylinder

[octoberfarm10]

Hi All, Brand new here so please bear with me.
So engine has water in oil. I isolated the block by capping off the thermostat where the manifold hose attaches and made a tee fitting out of hose. I put a tire valve in one part of the tee, a guage in another part of the tee, and attached the third part of the tee to the lower 3/4" heater hose sized fitting on the thermostat housing. I believe it goes to the outdrive. When I pressurized the block and could hear air bubbling in the #4 cylinder. Obviously this is the cylinder where my problem is. My question to the forum is; I your expert opinion do you think its block cracked, manifold cracked, head cracked, or a bad gasket somewhere? Do these engines have a common problem with #4 cylinder getting water? Any further diagnostics?
Thanks for the help!!

 

[Scott06]

How was it winterized?
Without disassembly it could be head gasket or cracked block. Did you isolate the manifold water jacket for the pressure test?

if your sure its leaking into number four pull the head and see if the gasket is roached.

 

[octoberfarm10]

How was it winterized?
Without disassembly it could be head gasket or cracked block. Did you isolate the manifold water jacket for the pressure test?

if your sure its leaking into number four pull the head and see if the gasket is roached.

I just got the boat and little info on it. Alls they know is that it has oil in the oil pan. That was reflected in the price. I did not isolate the Intake but i pulled the riser elbow and checked the gasket which looked fine. I pulled the plug out of the manifold and got a steady drip when pressure was introduced to the engine. I then tried turning the engine so the piston in #4 was in a different spot. the bubbling stopped. I can see water on the piston.
I think its a cracked cylinder because when the water hits the crack it would bubble again. Not looking good! I guess I will pull the head to confirm unless you have a suggestion before I tear it apart. How do I test the manifold. doesnt the air full it when I pressurize the block?

 

[blando]

As i just recently found out one thing you can add to the list of possible issues is that the intake valve for that cylinder has tuliped.

 

[octoberfarm10]

As i just recently found out one thing you can add to the list of possible issues is that the intake valve for that cylinder has tuliped.

Thanks for that. What do you mean tuliped?

 

[Rick Stephens]

Need to cap off the water line going into the manifold. Then you are just pressure testing the block. You cannot pressure test the manifold as the water jacket is open to the exhaust.

Valves aren't the problem. Water jacket in the motor is the problem. Could be cracked block, could be cracked head. No way to tell without disassembly. So might as well go to it.

 

[blando]

You're probably correct but Why do you say valves arent the problem. Is it bec the pressure test he did indicates the block or head water jackets? I n my case Machinist said the tuliped valve could create a vacuum and draw water into motor.

 

[blando]

Thanks for that. What do you mean tuliped?

My basic understanding is when a valve warps inward and can no longer seal properly. It appears to be sucked into the valve seat. Usually from advanced timing situation with overheating. I'm sure others can chime in with better description. Besides RICK STEPHENS who has vast more experience in these things says its not the valves.

 

[blando]

As i just recently found out one thing you can add to the list of possible issues is that the intake valve for that cylinder has tuliped.

As advised by Rick. This isnt the issue for this situation. Sorry for any confusion.

 

[Eric 3.7LX Alpha 1]

As advised by Rick. This isnt the issue for this situation. Sorry for any confusion.

Yes, he pressure tested the cooling system with air, which lost pressure he believes in cyl 4. A bend valve would not cause the cooling system to leak. If you did a compression test through the spark plug hole, that would indicate a valve issue. Don't be too hard on yourself, no big deal.

 

[Scott06]

Need to cap off the water line going into the manifold. Then you are just pressure testing the block. You cannot pressure test the manifold as the water jacket is open to the exhaust.

Valves aren't the problem. Water jacket in the motor is the problem. Could be cracked block, could be cracked head. No way to tell without disassembly. So might as well go to it.

Like rick said if you dont block off the manifold the air in the cooling jacket on the manifold will leak out the riser into the exhuast. if a exhaust valve is open you will get airflow back in the cylinder. either block off the manifold to riser joint or take the manifold out of the test circut.

You can test the manifold for cracks with acetone as well as it will wick into cracks that water cannot

 

[octoberfarm10]

Update: I found that the #4 cylinder was cracked. Good news is that I found a GREAT source for a new engine block. Its called ATP Engine. They shipped me a new engine block all ready to assemble with freeze plugs and cam bearings already installed for $1214.00 including freight from Florida to my door. I suggest calling them and speaking with Wendy directly instead of going thru EBAY. She was excellent and even got me a camshaft when Engine Parts Center informed me that they were out of stock. ATP only charged me $138.00.