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Intake manifold hot

kevin_z

Regular Contributor
1995 Crusader 454XL with full closed cooling. 100 hrs since rebuild. Using a IR gun, these are my readings...

Top of risers: 86 degrees
Manifolds: 143 degrees
Intake manifold
#1 154
#3 156
#5 154
#7 144

#2 160
#4 145
#6 183
#8 167

Gauge on helm is reaching 180 degrees plus. This all start after I did my yearly maintainance that include cap,rotor,plug,wires,impeller,oil,filter,thermostat
 
you change your t-stats every year...???? is it one or both engines? did you purge the closed side of the cooling system? check the raw water seacock to make sure it is fully opened?? ensure strainer is not leaking air?
 
Just the rebuilt engine is running hot. Don't do T/S every year. did it this time because of overheating issue. seacock is open fully. strainer is showing no bubbles. Fresh water side was purged after new T/S was installed. NOW I don't know if the baffles were installed or not. where are they located? The engine ran fine all last summer
 
I'd be inclined to measure the output of the raw water pump first...fairly easy...how old are the elbows?
 
elbows were replaced when rebuild was done. 100hrs. year and half in salt water. will recheck raw water pump. just ordered new wear plate for pump.
 
I'm confused with your data. "manifolds" are 143. Exhaust manifolds? This is low for EM, since they use engine output coolant to cool, so they will be higher than 180 at cruise. You say your Intake manifolds are too hot. Well, they are not really cooled by coolant. there is an exhaust crossover in the center that is designed to make the IM hot under the carb. If the stainless baffles are not installed at the ends of the IM exhaust ports, they will let in more exhaust, more heat.

http://www.overtons.com/modperl/pro...IWf-_OqHXVpwzoOz5NIfafva9tQSKrMw4yhoCptfw_wcB
 
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If by "top of the risers" you mean the elbows, then 86 degrees at cruise is a very good temperature. These are cooled by raw water so it would seem that you have adequate flow of water. But +1 to Dave's comment that the data does not make sense if your exhaust manifolds are at 143. Your temperature sender is located somewhere (likely in the intake manifold water passage) where it can read coolant exiting the engine/block. This coolant then enters the bottom ports on the exhaust manifold, exits the top ports and then goes to the heat exchanger to be cooled. So the exhaust manifold should run hotter than the temperature at the temp sender for the gauge.

You should use your IR gun to follow the coolant path and write down observed temperatures at every point. The temperature on the gauge (180) should be the same (within a few degrees) as the temperature your IR gun shows at the metal right next to the sender. Maybe your problem is a bad gauge or sender. You should see the temp rise as it goes though the block/heads, rise more though the exhaust manifolds and drop going though the heat exchanger. Something does not add up.
 
FIXED!!! I did a couple of things. First I bought a new IR gun. the old one was over 15yrs and the lens were banged up a little from the tool sack. I replaced the RW wear plate and then got the diver to check out the thru-hull. Clean. Then the strainer basket. Clean. Then the U-cooler. Clogged!!! Removed it. Flushed with muratic acid. Replaced. all temps are now in line with the Port engine and temp gauge is steady at 165-170. I took the end plates of the heat exchanger to inspect and it was clean.

NEXT question: Can I take the hose off the strainer and put it in a bucket of muratic acid and run a few gallons of acid thru the system?
 
Glad you found it....since you ran acid thru the oil cooler, the only thing left is the HX....I'd be inclined NOT to run acid thru the raw water pump...pressurized acid isn't high on the low risk approaches in my book...

that said, it wouldn't hurt to fill the raw side of the HX with acid..same for the oil cooler & HX on the other engine...and change the u cooler zincs more often will help prevent future clogs...
 
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