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88 5.7 intake manifold very hot

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Gytrdone

New member
Boat runs great for 20 min, on plane 3500 rpm's engine cuts out (loss of fuel) pull out of throttle engine will idle fine. Open engine bay and notice intake manifold very hot ( boiling water hot ). So far I have changed fuel pump added electric in-line fuel pump, new filter and water separator, new plugs, new coil, new cap and rotor, replaced fuel lines, replaced fuel, rebuilt carb, been towed more than I care to admit, and now I'm at a total loss any help or suggestions would be great

Also boat ran great this spring no problems but now it's hotter out side we are having this problem
 
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Gytrdone said:
Open engine bay and notice intake manifold very hot ( boiling water hot ).
Please explain the "boiling water" portion of this! Where are you seeing this?

FYI....... a restricted exhaust path may force excessive exhaust gasses through the intake manifold's exhaust cross-over area.


So far I have changed fuel pump added electric in-line fuel pump,
Please note that any Electric Fuel pump installed in an enclosed engine bay must have a N/O low oil pressure switch in the power loop!


new filter and water separator, new plugs, new coil, new cap and rotor, replaced fuel lines, replaced fuel, rebuilt carb, been towed more than I care to admit, and now I'm at a total loss any help or suggestions would be great
You will want to create a P of E (Process of Elimination) list for yourself. List any and all possible candidates that could be causing your problem.
Go down each item one at a time ONLY and either find or eliminate the problematic item.

When the P of E is used methodically and systematically, it will not let you down!!!!!!


Also boat ran great this spring no problems but now it's hotter out side we are having this problem
Click to expand...
 
First off thanks for the heads up on the low oil s/o.

As for the boiling water I had checked the thermostat and had one of the hose clamps leaking a little bit and it had dripped on to the intake manifold.
The most intense heat is under the carb where the choke spring is mounted, and seems to be equally hot on both sides of the manifold and a little cooler towards the rear of the engine. On the front where the thermostat housing is is a lot cooler than that under the carb.

As for restrictions in the exhaust causing this how would I go about finding that out.

Could I have an issue with my intake manifold, either a gasket issue, I read that in some applications there are block off plates to close and exhaust crossover under the intake?
 
If you ever overheated its possible that the rubber exhaust flappers melted and could be blocking the exhaust. To check you need to drain the ex manifold&riser and remove the riser and rubber exhsust hose. Then look down in the Y pipe to see if something is blocking it...
 
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