Chrysler M440 - water in oil

Ok folks. I ended up buying Adam's (pcjeeper) 73 SN with the Chrysler M440 this last weekend. Adam was looking for a boat that he could use right away and when this boat gave him some engine troubles, he decided to sell. With the 67 project still underway, I definitely didn't need another boat, but I have always loved that color combo on a 2nd gen, and with the rare big-block power, I just couldn't pass it up.

I need some help with the engine however. Adam successfully ran it on the hose but when he ran it at the boat ramp, it ended up hydrolocking on him 2 times. The 2nd of which broke an exhaust valve and bent a pushrod. The oil was also milky. I am definitely not a motorhead, so I need some guidance. What are the first steps to diagnosing this thing.

What we know:
-It ran on the hose (don't know if it started getting milky oil at this point)
-It started at the lake but locked up and died
-Pulled plugs and cranked over to remove water
-Refired engine but locked up again
-Locked up a 2nd time
-#8 exh. valve is broken, and associated pushrod is bent
-Oil was milky

So I figure the possibilities are:
-Bad exhaust manifold
-Bad ex. manifold/riser gasket
-Bad head gasket
-Cracked head
-Cracked block

The engine is still in the boat, but the Stb. head is removed.

Any thoughts?

I'll just keep talking to myself here . Maybe some pictures will get some interest.



I took a few pictures last night of the intake and heads. I noticed that the intake had visible rust on the #8 runner (and its corresponding #5 on the other side). Naturally there was also signs of rust inside the head intake port as well. I don't know if this is the cause or the affect of hydolocking the cylinder.

Picture of #8 intake runner



Picture of #5 intake runner



Picture of #8 intake port on head

Believe Joe mentioned the odd manifold config "could" be to keep water from backing up via exh, any chance that could be why no issue on hose but issue in water??

The swivel/risers on this should only help ingesting water from the exhaust, assuming it's coming from the pipes up to the engine. Now if it were leaking inside the riser itself, then the second you shut off the engine it would pool up in that rear cylinder. I would think that would just hydrolock it during cranking and you'd never get it started. Apparently this locks up while running for a minute or so.

It will make me cry knowing such a beautiful boat won't be on my lake anymore. Never got to see it in person even .

Beautiful boat and with such a unique engine.

Steve Workman will near wet his pants when that blasts past his under powered chev. version

Not what you wish to hear but anytime an engine hydro locks there is a very real possibility of a bent connecting rod.   I have seen it many times and had one myself. With the heads off you can put a dial indicator on the pistons and check the deck height on all 8 pistons.
For each piston you would need to check in 4 spots. 12:00, 3:00, 6:00 and 9:00.
If you find one side low and the opposite high compared to the other pistons you have a rod issue.   You would check each one at Top Dead Center.   I hope yours are OK.
Good looking Nautique and I never knew they came with a 440, what a torque monster those engines are. Must be very fun to drive.

Tim, this is what was posted when he had the boat, "Pulled the exhaust manifold today and didn't really find any cracks, going to do a compression test Saturday next...".

"And the Verdict is....

Compression Test (Bow to Stern)
Port side
120-120-90-120
Starboard side
110-115-110-0 :(

Going to pull the starboard head as soon as I get a chance..."

Here is the picture:

All I got right now is the picture above and a slighter wider view here. Can get more pics when I get home. But what you see is pretty much it. There are the 4 intake ports and 1 water port.

I've seen on some replacement valley pans, that the water port is blocked off. What would the purpose of that be then?

I'll definitely check the #8 TDC vs. the other cylinders tonight. If the rod is bent, the whole thing has to come apart and pretty much makes troubleshooting this inside the boat pointless.

I'll get some pictures of the exhaust manifold runners tonight as well, but I do know the previous owner did leak check the manifold and it checked OK. I suppose it could still be coming from the elbow/swivel water jackets if they were cracked, but wouldn't the exhaust pressure just push water out by that point?

Side question: How does water in the cylinder go backwards through the intake valve into the intake? Obviously a leaking intake valve would allow this, but after I replaced the broken exhaust valve and lapped in the new one, I filled the #8 chamber to make sure the new valve wasn't leaking into the runner, and neither valve did. Obviously this wasn't under the pressure of the compression stroke but still.

The rod bend might be relatively ok, or it might be side loading the bearings or piston to the bore. If you could see it from the bottom you would know.   I think you are holding back your leak checking by not pulling the engine out . If you know for sure it is leaking into number 8 and your connecting rod is bad on 8 I would have that bad boy on an engine stand in front of me looking for cracks in the cylinder wall of number 8. If you don’t see any get the rod straight and put your short block back together. Have the heads checked for cracks and then put them back together with good gaskets….   Don’t trust that the other guy checking the manifold ruled anything out. As for how things get in the intake, you don’t know that the intake valve was open or close or water tight when that cylinder was running full of water just because after cooling and removing it seems watertite.   Bottom line is there is no water in that intake casting so it didn’t come from the intake, unless it was sprayed in the carb it came out of cylinder, or through a crack in the intake runner of the heads.

When a rod bends it will tweak to one side or another. That will leave one side of the piston high and one side low. I have never seen one stay flat when a rod bends.
Hydro lock does not normally bend valves I suspect your water leak rusted a valve and it stuck prior to being hit by a piston later and bending it.
I don't know the 440 to comment on where your water came from. Good Luck

It depends how bad it is bent Craig. Normal performance rebuilding the rods are checked for straightness in a fixture and straightened if needed. If yours is noticeably bent check with a engine shop. If it needs to be checked for cracks and or stress releved it might be better just to get another. The new one can be balanced using the old one for reference,they can match the total weight and end to end balance from the old to the new.

Craig,
Get the cans of dye out and check that #8 bore. You may not be able to see a crack especially when the block is cold.