Water in cylinder

C

Comogene

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Motor is 454 Gen 4, Mercruiser, full closed cooling system. When cranked over, it started backfiring through carburetor and finally started but clearly running rough. Pulled wires from distributor one at a time and found two dead cylinders, 2 and 4, middle cylinders on right side. Removed spark plugs and both were soaked with water. Smelled and tasted and clearly it was salt water and not anti-freeze. Oil in crankcase was clean with no evidence of water or anti-freeze. Started motor to blow out water and it kept spraying out.

Removed and plugged raw water hose to exhaust manifold eliminating raw water feed and removed exhaust elbow. Could see water sitting in the manifold just above cylinder #2. Used a rag to dry out standing water and fired up again. Water was still spitting out. With both water in and out disconnected, could not figure out how the salt water was entering the exhaust manifold.

Removed belt from raw water pump, closed sea cock totally eliminating the influx of raw water and wallah! no more water! It boggles my mind how water can get from the left side of the motor to the right when there is no external crossover. Any ideas?

By the way, I've removed both elbows and risers and in the process of replacing gaskets. There was no obvious signs of porous risers and water passages in all are clear (3 years old). No rust streaks in exhaust passageway of risers or elbows. Once done, will check the other plugs and replace all before restarting.

Almost as if a stuck valve is allowing compression and resonance to pump water leaking on the left side through the intake manifold to the right side.

Anyone ever experienced such a situation?

Gene
 
You probably have a pin hole in the riser.

95% of the time that is the culprit for saltwater ingestion in a gas block.
 
In all cases where water was spitting out the spark plug hole. did you check that it was raw water every time?

Need more info on your cooling system but the thermostat housing may have rusted out. The raw water going to the riser...does it come from the heat exchanger or one of the thermostat housing nipples?

There's no raw water cross-over in FWC, but there's antifreeze that crosses from each head thru the rear of the intake manifold.
 
If you have dripless shaft seals, is there any way their RW supply setup on your engine(s?) could back into the manifolds? Are they T'd between the 2 engines in case one engine has to be shut down and free-wheeled, so closing one seacock might not prevent that supply to the other engine? I can't quite picture the effect but thought I'd throw that out.
 
To respond to all:

Sandy: No dripless shaft seals and no connection between the two engines except for electrical (battery cables and charger)and fuel lines.

Charlie: It was raw (salt) water - no antifreeze. Raw water flows from sea cock to transmission cooler, oil cooler to heat exchanger and then "T's" with one hose to left riser and one hose to right riser. From risers up into elbow and out. There is a steel plate with gaskets above and below between exhaust manifold and one riser to seal off anti-freeze in manifold from raw water in riser. Raw water enters that riser, flow-through gasket to second stacked riser and then flow-through gasket to elbow. Needed to stack risers to get elbow high enough above water line.

No raw water in block at all so thermostat housing only has anti-freeze. No compromise or contamination of crankcase oil or of anti-freeze.

Because there is no raw water crossover, we were baffled when the raw water apparently leaking on the left side showed up on the right side in the middle two cylinders right under the center rise exhaust manifold. Shut off flow of raw water to left side and no more appearing on right.

I remember reading about harmonic inversion (I think that is what they called it) some years back of sucking raw water back up the exhaust, but this appears to be using the intake manifold to cross over.

Can't find any holes, wear spots, thin metal, etc. and presume is was a leak in one or more gaskets.
I'll figure out the cause for the water intrusion on the left side, but it is the effect of that water appearing on the right side that is mind blowing.

Gene
 
OK, Gotcha on the raw water flow. Same as mine. The 'crossover' is happening at the 'T'. Any restriction of flow on one side will just increase flow to the other side. May be as simple as hose on one side is longer than the other, or a slightly sharper bend in the hose.

What's causing the raw water getting in the cylinders is probably a poor seal in one of your stacked spacers. What you refer to as an elbo is what merc calls a riser.

Exactly how many spacers and what length are they? They have 3" and 6" spacers.
 
I bet it is the spacer. I have the same engine and had water in #1. Finally found that the spacer was worn paper thin on the side that meets the manafold. This compromised the gasket.......D......
 
The manifolds are OSCO generic for the 454 with a center rise (CW-994). Spacers are 3" and have two stacked on each side. Risers are 3" hose with 30 degree down angle (2018). I always called the part with the angle an "elbow" since that is what it looks like and how it is referred to in the plumbing field. Now I see Osco calls it a "riser". I also see that the part to gain the height for the riser is actually called a "spacer" not extension. Makes sense. The original engines were Chrysler 440s with a 3" exhaust hose and I had no desire to change over the exhaust collector which then feeds a 5-inch exhaust tube and muffler.

Charlie: we disconnected the raw water hose from the "T" to the manifold and plugged it. Yes, this diverted all of the raw water from the heat exchanger to the left spacer.

As with all of you, I suspect the problem is a compromissed gasket on the left side and all will be replaced this weekend. Still having a hard time wrapping my mind around the raw water crossing over through the intake manifold to the right side. But them, valve timing overlap and harmonic resonance are concepts that engineers love to debate.

Gene
 
Raw water can't cross over thru the intake manifold. It's a closed cooling system. Like I said, it can cross over from the 'T' coming from the heat exchanger. Restricted raw water flow down stream may be clogged up water passages in the riser. They get pretty skinny and can(and do) clog from rust.

Took me a while to figure out why the design of the raw water out flow from the risers were so small. Turns out, if the raw water drains out too fast from the riser, it allows an air pocket to form at the high point of the water jacket within the riser. It can get very hot there.
 
I burned out my exhaust flaps on my 8.1 motor. I had water on both sides middle cylinders.
Replaced the flaps and no problem.
 
Doug: I suupose it is possible but it is a eight-foot run of hose and mufflers to a collector and then uphill to the riser which has a 30-degree down angle. Would have to be heading down hill with no exhaust flow for that to happen.

Charlie: Your conclusion that "raw water can't cross over thru the intake manifold" is what I thought. However, with the right exhaust riser off so no water could be returning from the common exhaust collector to the right side and the hose from the heat exchanger to the extention removed and plugged, the only flow of raw water was to the left side. I then dried the standing water in the right manifold, started the motor and water again pooled in the manifold at the #2 cylinder. Dried it again, started and more water. Removed belt from raw water pump so that no water flowed to the left side (right side already disconnected) and started motor. No water! Somehow that water migrated from the leak on the left side into the right exhaust manifold whose only connection was to the exhaust head and the closed circulation system. The water was clearly salt and no antifreeze.

I examined and cleaned the extensions. Will check the risers on Saturday and if clear, will install the left side with new gaskets, new spark plugs and open raw water to that side only and start. If no water appears in right manifold, I've cured the cause of the leak and will reinstall the right side. I can live without a concrete explanation of how it crossed over and chock it up to the extraterrestrials.

Thanks,

Gene
 
I'm a little confused about how you think raw water is crossing over thru the intake manifold. It can't. The only way raw water can cross over is thru the exhaust system. I think you're saying there's a common riser? If so, raw water and exhaust isn't mixing 'til after that riser. The exhaust system up to the riser would have to be water jacketed to prevent a fire. Either that or the raw water mixes with the exhaust right after thr riser, which is normal. Also, a water restriction within a common collector could increase the exhaust water pressure and force it up the exhaust system and out any weaken seal like in the stacked spacers.

You got pix of the exhaust system? I only have a vague picture of what your fix is. Understanding what you did and locating the cause will help others that run into this problem. Your explanations of how you go about finding the cause is the other major contribution to discovering the cause. Most people would take it to a shop and end up replacing the whole exhaust system and maybe even the whole cooling system.

I mostly worked on I/O's which have a slightly different exhaust system, so I'm learning as we go.
 
Went and re-read your original post. That backfire would have sucked a lot of raw water right up the exhaust. Had that happen to me. Hydrolocked the engine. Pulled the plugs and blew out all the water. Still wouldn't start cuz water was still getting on the plugs...just like you. That means raw water must have been forced out the intake valves and up into the intake manifold. Didn't realize it until just now. The cure for that particular incident would have been to manually choke the carb while full throttle which would have sucked lots of raw gas into the cylinders and out the exhaust and cleared any water within the intake system.

DANG!! That happened over 10 years ago and it took until now to figure it out. Had to get towed in...much to my chagrin. Could have gotten the engine running by purging the water that got into the carb. You learn something new every day. Thanks for forcing me to think about it and learn.
 
Charlie:

It is those mind boggling experiences that keep life interesting. I think you nailed it. I suspect that the backfiring was caused by an intake valve that was hung up when I started the motor for the first time since winterizing last Fall. That combination may well have sucked the raw water back down the exhaust and wound up getting into the intake manifold and cylinders and it may well have been compounded by a leak in the raw water gaskets. And your comments made me think about that starting episode and there did seem to be an unusual amount of water vapor from the hoses connecting the valve covers to the flame arrester. I though it was just condensation from sitting over the winter.

Having played (amateurishly) with internal combustion engines since my first car (1948 Anglia -flathead 4-banger English Ford)I was just stymied how raw water could get from one side to the other when, after disconnecting the exhaust manifold from any probable source of water, the only common area was the intake manifold.

Now that we have solved the major problems of the world, I have to get back to the root of the issue and see about freeing up that sticking valve.

Thanks again.

Gene
 
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