Overheat, then all 8 cylinders full of water. But wait.......

[kcsguide]

Before everyone points out the obvious, here is what happened and what I have found since. I have a 1976 Fiberform Baja 24 with a Volvo Penta AQ240A engine (Ford 351 Windsor) and a 280 outdrive. Last summer I had the engine overhauled by an overhaul shop and have put approximately 6 hours on the engine. I installed a new impeller but was not able to install a new seal kit in the pump as just about everything older from Volvo is obsolete. Yes, I did a complete winterization including pumping marine antifreeze throughout the system. First time out this year and I'm cruising along and my wife says "I smell rubber burning". I shut down the engine and open up the engine compartment and steam and or smoke is coming up from around the engine. No, older VP engines did not have an overtempt buzzer. Something I plan to correct before going out again. Got home and opened up the water pump and found just what you'd expect, impeller was toast. Started looking for external signs of damage. Checked the oil and it was still nice and clear, no water in the oil. Yes, I know it has to be changed after an engine overheat. Found very fine rust on the outside of the heads on both sides just above the head gaskets which I assumed meant blown head gaskets. Pulled out the spark plugs and looked inside with a boroscope and all 8 cylinders were clear full of water. Removed the intake manifold and no water, except for the water in the water passages and the gaskets and seals are intact with no signs of failure. Removed the valve covers and found no indication of water intrusion. Then removed the heads and as I said, the cylinders were all full of water. Then inspected the head gaskets and neither of them showed any signs of failure or water intrusion so my suspicion went to the exhaust manifolds. I did the acetone test on each of them, not for the 20 or 30 minutes that is recommended but for a full 2 hours and neither of them leaked a single drop of acetone, not so much as a wet spot inside. So I'm back to the head gaskets as I don't know where else the water could come from. I know there was steam coming out at the head gaskets but would that allow enough water to literally fill all 8 cylinders?? I don't want to put all new gaskets on it and put it back together only to find that it does it again? And yes, I replaced the water pump with a crankshaft driven Modern! New water pump. I spoke with a marine mechanic by phone and he couldn't think of anything else but the head gaskets or the exhaust manifolds that could cause that, both due to excessive heat from the failed water pump. Any new ideas out there would be much appreciated.

 

[alldodge]

Trying to make this easier to read "why" :noidea: guess I'm a glutton for punishment :face palm:

Before everyone points out the obvious, here is what happened and what I have found since. I have a 1976 Fiberform Baja 24 with a Volvo Penta AQ240A engine (Ford 351 Windsor) and a 280 outdrive.

Last summer I had the engine overhauled by an overhaul shop and have put approximately 6 hours on the engine. I installed a new impeller but was not able to install a new seal kit in the pump as just about everything older from Volvo is obsolete.

Yes, I did a complete winterization including pumping marine antifreeze throughout the system. First time out this year and I'm cruising along and my wife says "I smell rubber burning". I shut down the engine and open up the engine compartment and steam and or smoke is coming up from around the engine. (This is an older VP motor without overtemp alarm/buzzer** No, older VP engines did not have an overtempt buzzer. Something I plan to correct before going out again.

Got home and opened up the water pump and found just what you'd expect, impeller was toast. Started looking for external signs of damage. Checked the oil and it was still nice and clear, no water in the oil. ........................... Found very fine rust on the outside of the heads on both sides just above the head gaskets which I assumed meant blown head gaskets. Pulled out the spark plugs and looked inside with a boroscope and all 8 cylinders were clear full of water. Removed the intake manifold and no water, except for the water in the water passages and the gaskets and seals are intact with no signs of failure.

Removed the valve covers and found no indication of water intrusion. Then removed the heads and as I said, the cylinders were all full of water. Then inspected the head gaskets and neither of them showed any signs of failure or water intrusion so my suspicion went to the exhaust manifolds. I did the acetone test on each of them, not for the 20 or 30 minutes that is recommended but for a full 2 hours and neither of them leaked a single drop of acetone, not so much as a wet spot inside. So I'm back to the head gaskets as I don't know where else the water could come from.

I know there was steam coming out at the head gaskets but would that allow enough water to literally fill all 8 cylinders?? I don't want to put all new gaskets on it and put it back together only to find that it does it again? And yes, I replaced the water pump with a crankshaft driven Modern! New water pump. I spoke with a marine mechanic by phone and he couldn't think of anything else but the head gaskets or the exhaust manifolds that could cause that, both due to excessive heat from the failed water pump.

Any new ideas out there would be much appreciated.

Impeller was toast
Rust on both heads above head gaskets
Cylinders were full of water
Steam coming out of head gaskets

Steam coming from head gaskets, wonder how you can see this?
With cylinders full of water, how did the motor not hydro lock

Check the intake for cracks

 

[kcsguide]

Steam was rising from the engine after I shut it down but as I said, after I got home and stuck my head down around the engine I could see fresh, fine rust just above the head gasket and below the spark plug holes, etc. I know it wasn't there before as the engine had a fresh overhaul and had been freshly painted.

I can only assume that water filled the cylinders AFTER I shut it down???

 

[kcsguide]

Oh, and no visible cracks anywhere on or in the intake manifold.

 

[QBhoy]

I’m thinking that I’ve never known both head gaskets or exhaust manifolds to go bad at the exact same time. It must be something common to all 8 cylinders to do this. You’ve already ruled out the inlet manifold...so I’d be thinking the other thing that would do this is a surge of water coming up and back through the exhausts. If it was a merc I’d be almost certain of it because an overheat would likely melt the flappers that stop this. Don’t think some VP have these though. Pretty sure that might be the cause though. Did you slow down very quickly at any point or anything else happen that might allow water to come back through exhaust ? Do you have straight through exhaust?

 

[alldodge]

Unless the boat sits low in the water where the water level is above the mans, don't see how water would come in from exhaust. If this is the case, the only place left is the intake

 

[kcsguide]

The only flapper on this one is right at the exhaust outlet and it is still intack and in position (closed). If it wasn't there, the water would have to travel around a couple of pretty good curves and up 2 1/2 feet rise and then back down to the manifold. Having said that, I was actually at wakeless speed and conditions were pretty calm on the water.

 

[QBhoy]

Must be the inlet manifold then. It’s surely a million to one chance that both cylinder heads are bad. Unless you ran the boat for a good while and long enough for it to seriously overheat.

 

[kcsguide]

The only places on the intake manifold that show residue from water, (rust residue) are obviously the water ports front and back and the smaller one in the center that crosses over underneath the intake port that the carb mounts on. The rest of the intake manifold looks like new, even inside each of the intake ports and I have gone over every millimeter with a magnifying glass.

I don't know how long it was heating up before we smelled the rubber burning but it obviously was seriously overheating. The rust evidence of steam escaping from the head gaskets was on both sides. I just can't wrap my brain around how that much water could get into the cylinders, past the still complete head gaskets, AFTER the engine was shut down. I'm stumped.

 

[kcsguide]

I checked the heads for cracks as well and they also look like new.

 

[Lou C]

It would have been good if you could have done a leak down test and cooling system pressure test before taking it apart. At this point I’d take both heads and the intake to a machine shop to get them checked for cracks and to check for warpage. I don’t know the spec on Ford engines but on GM engines the max is .003”. The block deck surface should also be checked for warpage.

 

[Scott Danforth]

when you first "smelled rubber" that was the exhaust hoses burning from lack of water because your impeller died about 3-5 minutes prior to that. you could have simply hit a plastic bag in the water or the water inlet fitting wasnt changed (you need to change them every other year)

you continued to run the motor without cooling water for those 3-5 minutes and the block temperature went from 140 to well over 300 at the block and much higher at the head.

so from the time you opened the hatch to see smoke and steam, how long did you operate it to get the boat to the ramp, or did you have it towed?

FYI - new seal kit is available, its a Jabsco or Johnson pump
parts are still available for the 280 drive

 

[kenny nunez]

The flapper at the end of a 280 does not fit very tight . Sometimes when an engine gets really hot and you shut it off they will continue to run for a few seconds then stop and run backwards. Since you have not found any cracks that is the only way water can enter the engine.
Do as Scott says rechecking surfaces.

 

[kcsguide]

The minute we smelled rubber, I shut off the engine and had it towed back to the docks. Yes we could have caught a plastic bag or something. There was lots of debris in the water, mostly branches and other runoff from the river at the head of the lake. Guess I'll just have to take the parts back in to the machine shop and have them checked out. Thanks

 

[Scott Danforth]

they may have to re-assemble the motor to pressurize to check for leaks.

 

[kcsguide]

I checked the heads for cracks as well and they also look like new.

I guess it's time to update this. I used a straight edge to check the heads for warpage and there was none. I finally gave up and took the heads back to the shop that did the engine overhaul and had them re-grind the heads just to remove all doubt. They did and gave me new head gaskets and seals, etc. I put it all back together, changed the oil and sparkplugs and it once again runs perfectly. I haven't had a problem since. I did however, install a new engine overheat/low oil pressure alarm. Thanks to everyone for the advice.

 

[Scott Danforth]

change your rubber bits in the exhaust (that is what was burning)