228 Mercruiser (1982 YR) - Overheating on Port side only - burning up exhaust baffles

[johnspruill]

Over Heating problem with 228 Mercruiser, 1982 year, 305 GM V-8, serial no. 6045972. I first noticed I had a problem when I blew a hole in the Port baffle that comes out of the elbow riser that is attached to the log style manifold. I had my repair guy, who normally works on the boat, replace the baffle. He had a used baffle, but it appeared to be in good shape. Everything worked fine as far as I could tell until after maybe 10 hrs use, it blew another hole in that replaced baffle.

I questioned maybe the used baffle was bad, but that didn't seem likely, so we started to look for heat related problems. I've got a laser temp gun and started to check the temp at different locations. The starboard side of the engine including the manifold, elbow, baffle, hoses never gets above about 120-140 degrees. But the port side temps are all over the place. Some times it will start out acting normal and run for 10 minutes fine, then start to heat up to over 200+ degrees. Other times it will start heating right away, and then may start to cool back down to the 120-140 range after running a few more minutes.

At first we thought I had a plugged manifold, elbow, or even a bad shutter value, but now I'm thinking it could be something like a bad thermostat or something that is opening and closing the PORT SIDE ONLY. Have NOT replaced the thermostat yet, but wouldn't think it would be selective (port or starboard)? I have also heard that some cooling systems that use a check ball and spring setup that controls the water flow. Not sure if that would apply in my case? But this sounds like it could be more selective and might be my problem??

We have replaced the impeller in the out drive recently, and the system appears to be getting water or both sides would overheat I would think. The starboard side log manifold was replaced 4 years ago because it was cracked. The engine itself does NOT appear to be over heating, just the exhaust manifold, elbow and baffle at times. Engine appears to be running okay also.

Any ideas whats going on, and how to trouble shoot? And how about the check ball & spring question? Where would that be located? Thanks much. john

 

[alldodge]

Howdy John

Should have this posted in the Mercruiser section instead of the outboards. One of the mods will be around to move it for you. Bondo

In the mean time is the pic below look like your cooling system?

 

[johnspruill]

No, my elbow riser is mounted on the end of the log manifold, not the middle. thanks.

 

[alldodge]

OK then my guess would be water is not passing by the housing, and over the top of the thermostat enough to keep the port cool.The housing your working with has an issue with passing sufficient water, note the port on the left of the top of the pick. The other problem can be the elbow which is clogged

 

[alldodge]

Lets try some more mods to see if one of them can move this to the merc section
Fun Times GA_Boater

 

[Fun Times]

Lets try some more mods to see if one of them can move this to the merc section
Fun Times GA_Boater

On it. thanks.

 

[johnspruill]

Sorry about the posting location (my first time here), looks like I'm in ?Engine Repair > Mercruiser Sterdrives & Engines? currently, that sounds correct to me. Please advise if that?s not the best place to be.

Anyway, the second diagram posted marked page 28 looks like my system. However, I'm having trouble understanding how it relates to my problem of only the PORT side heating up. It appears when the thermostat is closed, cold water goes to both exhaust elbows, and when it warms and the thermostat opens water should still flow to both sides. If it was plugged in that housing I would think it would be solid condition, not intermittent? Is there anything moving there other than the thermostat? Are there any check balls or valves in this system?

I guess that's why you think it could be a plugged PORT exhaust elbow, but seems strange that it is intermittent there also and that the manifold heats up also? Perhaps the manifold is bad also. Any ideas how to test these parts rather than swapping out??

Thanks again, appreciate any thoughts at this point.

 

[Bondo]

I guess that's why you think it could be a plugged PORT exhaust elbow, but seems strange that it is intermittent there also and that the manifold heats up also? Perhaps the manifold is bad also. Any ideas how to test these parts rather than swapping out??

Ayuh,..... If there's rust, 'n crud bounin' 'round in the manifold/ riser, the water flow could come, 'n go,....

Pull the manifold/ riser, tear it apart, 'n inspect it for blockage, 'n rust loss,...

 

[johnspruill]

Okay thanks I hear you. We've got to pull the elbow to put the new baffle on anyways. However, what do you think about the thermostat and/or its housing?? Really hate to pull the mainifold if not necessary, but since the parts are 33 years old, should probably bite the bullet and go with new manifold/elbow if thats the problem? Just hate to waste $500++

Thanks, john

 

[Bondo]

Ayuh,.... The manifold can't be over 40 or 50 lbs,.... probably considerably less,...

I wouldn't go buyin' new parts, til I cleaned up, 'n Inspected what's there,....

Btw, I forgot,..... Welcome Aboard,.....

 

[johnspruill]

Thank you.

 

[johnspruill]

Can't post pics, says they are corrupt, never had that problem before.

 

[Bondo]

Ayuh,.... I post 'em on photobucket, 'n link 'em back here to the forum,.....

 

[alldodge]

The point I'm trying to make is the water comes thru the thermostat and thru the one hole in red. Item 2 also circled in red is the fitting which sends to water to your elbows. Since the elbow is the only item which sends water out the exhaust, the thermostat housing, tee fitting, hoses and elbows must all be clear. I'm betting there is a restriction somewhere

 

[johnspruill]

The part that confounds me is that:

1. The starboard side works fine and stays cool and no blown baffle. Starboard manifold has been replaced previously.
2. The hole you noted in red supplies both sides
3. When the thermostat opens it allows water flow to both sides
4. Sometimes the Port side works fine and stays normal for several minutes, then heats and cools
5. When the Port side does heated up, everything seems to heat up including the manifold, elbow, and baffle. It has read up to 200+ degrees before shutting it down.

Question:

1. Does the water going into the upper part of the elbows designed to cool the exhaust?
2. Are you saying before the thermostat opens there is no water leaving the system?
3. How much heat is the system designed to take? And does that make sense it would burn up the baffle?

I'm actually thinking to order a new port elbow, manifold, thermostat, baffle, plus gaskets. I think I can return any parts not opened. My problem is my repair guy has to drive about an hour and a half, and I would like to make this a one trip fix.

Thanks again,

john s.

 

[johnspruill]

Also looking at the diagram, does the water going through the manifold cool the exhaust? Looks like the "end caps" receive the hoses, so I guess they could be bad or plugged also? Geez, thats another $125.00+ bucks!

 

[alldodge]

The manifolds may have a small hole in the gasket but most the cooling water goes thru the hose to the elbow, not thru the manifold gasket.

Another possibility is the engine circulating pump. It wouldn't be the first time the vanes in the pump are coming loose from the shaft

 

[Bondo]

Are you saying before the thermostat opens there is no water leaving the system?

Ayuh,.... When the t-stat is closed, excess water from the impeller pump cools the exhaust,.....

That water spray is supposed to keep the rubber parts from burnin' up,.....

The impeller pump moves more water than the motor normally needs,....

 

[jimbo_jwc]

No Title

Pull it all apart and look ,this is what I found in mine .Will still probably have to go thru log style exhaust manifolds .

 

[johnspruill]

WOW, interesting. Externally mine doesn't look quite that bad, but its 33 years old so the inside could be in bad shape also. The outlet tubes on mine look pretty good, not broken. What is that part called? You how difficult is it to replace?

I thought about the engine water pump also, mine looks like it has been replaced once. But I have had the boat 25 years and never touched it. Wierd it would cause just one side to heat up however?