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Stuck piston rings

M

markkingscraft

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"Last year I installed two reb

"Last year I installed two rebuilt 318s.

They had been rebuilt about 10 years ago and although the cylinders etc were clean - no rust - had been oiled and turned regularly - the rings appeared stuck to the pistons.

Compression test on all cylinders in both engines was between 95 and 115.

After about 10 hours of running, the starboard engine is improving. I have 155 in one cylinder and 115 to 125 in the rest.

When I do a wet test I get 150 to 155.

This engine has a water pump problem and has been running fairly warm. The side where the one cylinder has come back was steaming hot on a few runs.

Port engine is another story. It barely comes up to temp ( I run in the St. Lawrence River where the water temp is chilly all the time) and compression is still 95 to 100 in all cyclinders.

I have dropped some MMO in the cylinders for a few days, added some to the oil as well and am now using it in the fuel.

I am going to run this engine without the water pump to heat it up to try and heat / cool the rings free.

With no water in the engine how will I know when it is getting too hot? Can I use a spray bottle and squirt water anywhere for an indication?

Anyone have any ideas?

Thanks

Mark"
 
"If the motor won't warm u

"If the motor won't warm up, then the thermostat is stuck open. Don't mess with the pump or you might fry the block. Fix the t-stat!

Mercury outboard sells a ring freeing oil additive that works great. You put it in a small (outboard tank) and run it through the motor.

Jeff"
 
"Thanks Jeff.

I tested the

"Thanks Jeff.

I tested the T stat on the stove two days ago.

It opens and closes when it should.

I re-installed it today but left the hoses off. I will test it tomorrow and hook up the hoses when / as / if, it works on the boat.

I've never heard of the Mercury marine stuff but I'll check my dealers. Do you know the name of it at all.

I take it you add it to a tank of gas and run it through.

I have used MMO in the past with good success but I have also found the key is to run the engine hot and hard to help free up the rings. Something about the slightly unequal expansion and contraction of the rings and the pistons. Once the MMO gets into the rings it helps them slip loose.

I just can't get this one hot. After four hours I can still place my hand on the block with only slight discomfort and the exhaust manifolds are cold. cold. cold.

The other engine, that was actually missing almost half the vanes on the raw water intake impeller, (it is the double pump variety) got hot and things started to happen with the rings.

I just don't want to haul these things out and tear them down just for rings when everything else is shiny and new.

Mark"
 
"Mark:

On my raw water cool

"Mark:

On my raw water cooled 360s, the place where the t-stat fits is so rusted that water sneaks around it (and slows the heating up period). To counter this I made a plate with the t-stat epoxied to it that doesn't allow leak past. IF you have RWC engines, this might be your problem as well.

On the magic cleaner, any good Merc outboards dealer should have it. Not sure what it's called, but a description of it sure tell the man-behind-the-counter what you need. The trick is to concentrate it--that's why the smaller outboard gas tank.

Jeff"
 
"Jeff,

Here's an update

"Jeff,

Here's an update.

On this engine I have never seen the temperature gauge read. It starts at 120.

I have replaced the gauge, replaced the sender, and tested the wire. All but the wire were brand new anyway.

Today when I fired up the engine I watched the thermostat housing before I put the hoses back on.

The cold water side had excellent flow, and as you suggested the side that exits when the engine is hot, leaked a bit.

So I plugged that side and ran the engine hoping to just keep recirculating the water.

An hour later the temp gauge still had not moved and the engine was cool.

So I disconnected the water pump.

Within five minutes the temperature gauge moved for the first time ever and within another couple it was up to 220.

I shut it down. Let it cool and when the gauge read below 160, fired it up again and ran it to 220.

So the real problem is, my engine runs way too cold. With the pump in the system it isn't even reaching 120.

Let's tackle this problem and then maybe the rings will start to release.

Any suggestions about why this would be running so cold?

Thanks"
 
Water is bypassing the t-stat

Water is bypassing the t-stat somehow. That's the only way it will stay cold.

Jeff
 
"Jeff,

Could something be s

"Jeff,

Could something be screwed up in the exhaust manifolds?

That seems to be the only place where "water coming in" and "water already in" could mix.

The engines have vee drives so they are installed backwards. I followed the plumbing diagrams and both engines are plumbed the same.

The only thing I can't really see is inside the exhaust manifolds, and of course in the engines.

But water seems to flow proeprly through the whole system with the manifolds as the only variable.

Mark"
 
"Mark:

Your motor's odd

"Mark:

Your motor's oddball behavior is assbackwards from the usual trouble (overheating). Virtually anything that normally causes overheating--like plugged water outlets in risers--would IMPROVE your situation, not harm it. Weird. Putting it in the most basic terms, more water is going through the block than should be. Period. You need to find out why and stop it.

Jeff"
 
"Jeff,

Replaced both the th

"Jeff,

Replaced both the thermostat and the housing this weekend and also swapped for the one on the other engine.

No luck.

So I plugged the bypass hose.

This brought the temp up to about 130 and the entire block and intake manifold and valve covers actually got warm just idling at the dock for 20 minutes. Not hot, but warm. Could still touch everything with my palm.

The T stat had "140" stamped on it so I suspect my gauge is off a bit and the temp was actually at about 140.

Do these gauges come in greater increments like say 160?

Even with the bypass plugged I still had a fair bit of water exiting the exhausts as well.

I notice in the plumbing diagram for the 318 with the dual pump that there always seems to be water flow from the exhaust manifolds through the risers.

How great a flow is this supposed to be? Is it possible I am losing too much water overboard so there is always a large amount of fresh water floating around in the exhaust manifolds and mingling with the bypass water and cooling it down too much?

If that is so, how is this fixed?

Any thoughts?

Thanks

Mark"
 
"..."How great a flow is t

"..."How great a flow is this supposed to be? Is it possible I am losing too much water overboard so there is always a large amount of fresh water floating around in the exhaust manifolds and mingling with the bypass water and cooling it down too much? "

Not sure, but that weird dual pocket setup is famous for goofy things like what you're experiencing.

I'd install a valve in the bypass hose and dialing in the restriction you need to get the temperature up.

Jeff"
 
"Jeff,

That is what I was t

"Jeff,

That is what I was thinking.

And I realized after I sent my last post that the t stat should be 160.

I'll install that and it should bring it up to temp.

Thanks again.

Mark"
 
A 160 stat would be TOO hot. Y

A 160 stat would be TOO hot. You need to get the motor running about 140 to 150. Raw water engines should not be run hotter than that or steam will form in the block when you throttle down--and that can wreck the motor from localized overheating. FWC motors have a pressure system that allows running at higher temps.

Jeff
 
Do you have a water heater or cabin heater that is not plumbed properly? Maybe clamp a heater hose with a vice grip and see if the engine heats up properly?
 
Mr. Sea Ray Select...... while it is fun and interesting to search the forums ........ it is best to let old threads die a peaceful death.... especially if from 2009! :D
 
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