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Port side Engine stalls left side exhaust manifold verrrry hot right side manifold same engine cool

J

jclays

Regular Contributor
Twin 350 GM 1966 boat totally raw water cooled not closed system. Engines have been running great. Today heading out idled the engines for about 20min waiting for my passengers. Port engine stalls. Restart stalls acts like carburetor issues. Out of gear she revs fine. Put in gear will idle rough then stall. Got her idling messed with the carb. Accidentally put my hand on the left exhaust manifold burned my hand. Right side exhaust manifold still nice and cool. Blocked water intake to that exhaust manifold???
 
Ok let engine cool off for a few hours. Checked still clear/dark honey amber. No sign of water. No burnt smell. Just smells like used motor oil. Pulling spark plugs on the left side of the motor to check for water. Got 3 out of the 4 plugs off no water however the 2nd plug is frozen. Broke the porcelain. Got a better fitting socket still very hard dont want to strip it. Any ideas? Will order a new manifold and elbow. I dont want to go thru the trouble of removing the exhaust manifold and putting the same old one one. I replaced all 4 ( both engines) about 4 years ago.
 
Ayuh,.... Both sides of the motor will rarely to never be the same temps,...

Hot by feel of the hand, ain't really hot, when measured with a temp gun,...
Normal runnin' temps of the motor, will burn yer hand,...

My only guess is, the impeller is worn, the riser might be restricted/ pluggin' up,...
Or,...
It is what it is,....
 
My exhaust manifolds run cool. Raw water cooled not a closed system. Just manifold, elbow. Right side of the same engine running cool as usual. Left side so hot hot that I spit on it and it just hissed and boiled off. Impeller is good or both sides would be hot. Still had water coming out of the exhaust. Most likely from the good exhaust side. With heat gun normal temps when both engines are running all day is about 119 degrees at the elbow. Im thinking clogged elbow maybe manifold also. Replaced both engines manifold and elbows 4 years ago. Now I also have one very stuck spark plug on that side.
 
Put in a new impeller. As they age they become less compliant and the vanes don't rebound as quickly after going over the cam in the pump housing. This results in lower pressure and flow. There is not a lot of restriction in the system (other than the thermostat) and at low pressure and flow the water will take the easiest path, in your case the right side of the engine. I had the same problem and actually took pressure readings on the water exiting to the manifold. New impeller solved the problem.
 
Had the same problem with a 5.7L years ago. Turned out to be a delaminated hose. Might try and run fresh water from a hose to the exhaust manifold hose (engine cold) to see if it flows. Rust is also a real possibility.
 
Have a new elbow and manifold ordered. I however have the #2 spark plug stuck. Cant budge it. Have been spraying in penetrant everyday and letting it soak since Sunday. Will let it soak till Saturday. Couldnt budge it today when I tried. Might try a small impact wrench and feather the trigger and try bumping it.
 
jclays said:
Have a new elbow and manifold ordered. I however have the #2 spark plug stuck. Cant budge it. Have been spraying in penetrant everyday and letting it soak since Sunday. Will let it soak till Saturday. Couldnt budge it today when I tried. Might try a small impact wrench and feather the trigger and try bumping it.
Click to expand...

Also try bumping the impact wrench is the clockwise direction then counter-clockwise. Sometimes a tighten first helps to loosen a stuck nut or bolt.
 
If it still has the original T-stat outlet, I'd bet on the elbow being plugged on the hot side - manifold is likely to be just fine. If it has been changed to a merc style, I'd bet on the poppet valve in the housing on the hot side...

On the stuck spark plug, I'd suggest a good socket, an extension, and a breaker bar - you can control the force applied much better than with a trigger....
 
makomark said:
If it still has the original T-stat outlet, I'd bet on the elbow being plugged on the hot side - manifold is likely to be just fine. If it has been changed to a merc style, I'd bet on the poppet valve in the housing on the hot side...

On the stuck spark plug, I'd suggest a good socket, an extension, and a breaker bar - you can control the force applied much better than with a trigger....
Click to expand...

I had a fairly recent experience with a very stubborn pipe thread that went into another aluminum fitting on a poly fuel tank. I tried and tried with manual wrenches; maybe got 50 to 100 ft-lbs on it with zero result. In desperation, I tried an impact, fearing the worst with the plastic tank. But, the fitting came right off. Sometimes, the hammering effect does the trick. The other issue with a spark plug (tapered thread, right?), is that a thin wall socket may split before the plug moves. Still worth trying, though.
 
Going to remove the manifold and elbow on the left side of my port engine. I ordered new units and this will also give me clear access to the spark plug. Have been spraying it down with PB Power blaster all week. Took a strain on the plug with a six point socket and ratchet and it didn't budge. Going to try the impact wrench.
 
Bad news. Used a brand new spark plug socket and my long handle ratchet for leverage. The spark plug disinigrated. The guts and nut came out leaving the threads in the head.
 
If only the threads of the plug are in the hole then I would go for an " Easy-Out", probably a #5 soak with some Blaster first and if/when you get the plug out, use a shop vac to clean anything out that may have dropped in the cylinder.

If for some reason the plug was in cross threaded you may have to re-thread the hole ar perhaps a helicoil//not sure. Good Luck
 
Feel your pain !! Safe route is to pull the head and have the plug remains professionally removed. May be a good time to consider a valve job and pull both heads if necessary. Since the manifold and elbow will be replaced, almost half the job is already done. Good Luck.
Florida Panhandle
 
Will have to go the ez out route. Three of the head bolts have lots of corrosion on them(52 year old boat). I will destroy the bolt heads trying to remove them. If the plug does not come out. I'll hire the local mechanic to give it a go. Then time to pull the engine. Will replace it with new if I go thru that trouble.
 
Success.....had to reset and drive in the square drift/ez out until it held firm on the fourth attempt with a half inch drive large ratchet and fair amount of force it popped and started to move then unscrewed. Wow relief. Got my new manifold and elbow delivered yesterday. Time to put it all back together. The manifold looked good however the elbow was very restricted. Just going to change out both. Thanks for the ideas.
Jim
 
Got everything put together and fired it up this afternoon. Idled smooth good water flow coming out of exhaust. Quick rev to take the engine out of cold idle and the engine stalled. Had to maintain the fast idle to keep from stalling. Fair amount of smoke in the exhaust dont think it was steam. The new elbow was running about 10 degrees hotter than the old one on the opposite side of the same engine. Going to swap carburetors with the starboard engine and see if I also had a carburetor issue going on when I had the original problem. Any thoughts??
 
Check the bottoms of the carbs for flatness and install new gaskets when you mount the carbs. Pull them down slow to nice and snug (technicle term). A common mistake is tightening carbs too tight it bends the ears and creates vacuum leaks. Allways install a new gasket when you pull a carb I just get a roll of material and make my own.
 
Pulled the carb on the Port engine. The gasket was wet on the left side. Swapped with the carb from the Starboard engine. Fired right up and runs good. Time to rebuild the Port side carburetor.
 
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