cig1988

Recently did a leak down test as follows:
#1 10% comp 140 psi
#3 8% " 140
#5 40% " 110
#7 5% " 140

#2 12% " 120
#4 20% " 120
#6 8% " 140
#8 12% " 140

This is a 330 bbc in a friends Sea Ray. Has a milky oil problem. I pressure tested the block full of water blocking off the exhaust. Pinned the pressure tester (stant) and leaked 1/3 way down overnight. Noticed a very small leak at one of the hose connections that may have caused this. I re-tested #5 compression again after several squirts of oil & only went up 5 psi. Inserted the remote viewer through the spark plug hole and noticed a little rust and possible a valve hanging up.

Need advice, could this be a riser and or exhaust manifold?

Cord

A riser or exhaust manifold wouldn't cause a increase in leakage. I'm guessing that he has a head gasket that is starting to go bad.

cig1988

Thanks Cord. I was going to tell him to pull the heads. When the shop air was hooked up it was clearly heard through the exhaust. As far as the mily oil I'm sure it may be just what you said or a bad riser/manifold. Stan.

cig1988

Sutphen30, we ran the engine 20 minutes to warm the oil to change it. And yes, after sitting all winter. After a new set of plugs it sounds OK witout a miss but still concerned. Today, he said he ran it for an hour with new oil. Compression went up to 120 #5 with the same leak down result (40%).

offthefront

Pull the heads and have them checked ...If its been a while and they check ok I would do the valves ...New Headgasket ... and should be good to go ...I would recheck the manifolds while the heads are out ...

cig1988

OTF, Thats exactly whay I had told him. "but it runs good" he says. In return I said its either now or later once the boats in the water. Thanks for the advice.

racinbird

My engine ran fine last year but no8 was low at 80psi, ended up being burnt valve and poor valve seat, got too hot.

Cord

Which could be the reason why the air could be heard escaping from the exhaust.

cig1988

Cord,
On the leak down test the piston is at TDC with both valves closed. I have a Snap On leak down tester which has a manifold with 2 gauges (hi psi in/%leak out).
Once air pressure is introduced into the cylinder, PSI will find the source of least resistance. In my case the exhaust valve.
I peaked in the cylinder through the spark plug hole with one of them fancy camera's and noticed a little rust on the face of the valve. Seems as if the rust is holding the vavle open a bit. Tried PB blaster and ran the motor for a few and the leakage dropped down to 20% but took that reading hot after shutting the engine. Waiting till it cools off and will try again. Stan.

blue thunder

That is an interesting problem. Possible that just running it will fix the milkshake problem, at least I am hoping so in my case. I don't have a milkshake, just creamed cheese under the valve covers of one engine. Heard a little popping out the odd bank when initially started and I am hoping that caused enough reversion to give the creamed cheese look. No more popping and the engine is strong and the cream cheese seems to be subsiding. I have the benefit of closed cooling and am not loosing any antifreeze, so I know it is not a head gasket. Keep us posted and good luck.

BT