jct
Senior Member
an over heating issue, due to it running lean from the leak. water pump, radiator, thermostat all has good flow, i'm currently doing a chemical flush for the cooling system just so i can clean out the heater core which is clogged
Does a leaky intake manifold cause
- Thread starter jct
- Start date
An intake leak will not usually cause an overheating problem on a mopar big block. Odds are if the heater core is plugged up, some of the radiator tubes are probably also plugged. If this is the 383-2BBL car, it probably has the 22" radiator which is on the small side to start with. If the car has an intake leak, that is something that should be repaired. If you put a few drops of fuel next to the various intake ports, the engine will speed up briefly as the extra fuel is sucked into the leaking area. If you try this test and nothing happens, the intake gasket is probably not leaking. Be sure to remove the thermostat prior to doing the chemical flush.
Dave
Dave
jct
Senior Member
26 inch radiator, and it is noticably louder like an exhaust leak sound but it's not an exhaust issue and there is splatters of oily soot on the valve cover
twostick
Senior Member
If it is a big leak at the heat riser passage, exhaust is flowing thru the head to the point of least resistance, ie the leak. This brings a bunch of heat with it. you should change the gasket for the intake. Be sure to clean up the area around the heat riser ports well as they are probably carboned up where the leak is. Might also want to check the heat riser to be sure it is not stuck shut as that might have overheated the heat riser passage under the carb and toasted the gasket at the ports.
Dave
Dave
For general principles, do check the torque on the rear exhaust manifold bolt/nuts, on both sides. Sometimes, they'll get a bit loose and cause a minor exhaust sound on acceleration. Just 1/4 turn loose might be all it takes to make things quiet again. Not sure why just the rear ones tend tro get loose, over time.
For a little better seal, when done, you might also consider using the FelPro paper gaskets that go with the metal valley pan gasket. I believe they were 440 3x2bbl items? Using them with some high-heat silicone in the bead of the metal gasket (smoothed out with a gasket scraper), will ensure an excellent seal of the intake to the cyl heads. Might be over-kill, but it made enough difference on my '67 383 that I could hear it. Didn't seem to run any better or affect the existing idle mixture adjustments, but knowing it is as good as it can be means something to me. Just my experience.
DO clean all of the gasket surfaces well, but you'll probably do that anyway.
Just some thoughts,
CBODY67
For a little better seal, when done, you might also consider using the FelPro paper gaskets that go with the metal valley pan gasket. I believe they were 440 3x2bbl items? Using them with some high-heat silicone in the bead of the metal gasket (smoothed out with a gasket scraper), will ensure an excellent seal of the intake to the cyl heads. Might be over-kill, but it made enough difference on my '67 383 that I could hear it. Didn't seem to run any better or affect the existing idle mixture adjustments, but knowing it is as good as it can be means something to me. Just my experience.
DO clean all of the gasket surfaces well, but you'll probably do that anyway.
Just some thoughts,
CBODY67
jct
Senior Member
The heat riser is stuck open
jct
Senior Member
Should i CLR my heater core?
One thing to consider with any older vehicle and cooling system "deposits", that corrosion/accumulation can possibly be degrading the surface it's attached to. When the "chemicals" dissolve those deposits, the thinness of the metal they were attached to is exposed to the coolant liquids. If the base metal's integrity has been compromised enough, seeps and leaks can occur when the deposits are removed. A gamble, at best. Whether it's a radiator core/tank flange (which are easy to see and service) or a more-hidden heater core.
Flush what you can with clear water, but do NOT "reverse flush" as if there happens to be something left in there, putting the water in "the wrong direction" can break it loose and clog things up. Been there, done that, unfortunately.
Just some thoughts,
CBODY67
Flush what you can with clear water, but do NOT "reverse flush" as if there happens to be something left in there, putting the water in "the wrong direction" can break it loose and clog things up. Been there, done that, unfortunately.
Just some thoughts,
CBODY67
jct
Senior Member
Had to do a reverse flow, i wasn't getting any heat from the heater core ಠ_ಠ
jct
Senior Member
Don't mind my wiring mess and zip ties, here is the sooty mess of something going wrong
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