Overflow pressure
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Overflow pressure
My 1984 F-250 diesel has developed the problem of pressuring up the radiator and overflowing the overflow bottle. This leads to overheating eventually. No water is showing up in the oil and no oil is showing in the radiator. A mechanic told me that is probably the intake manifold gasket due to the lack of oil or water being in the wrong place. Is this even a possibily?
More Turbo
Joined: Aug 2006
Posts: 581
Likes: 72
From: Double Oak, TX
the only reason cooling systems (on any vehicle) should overflow beyond a certain point is either a bad radiator cap (cheap, easy, replaced it anyway, make sure you get right #'s) or the engine is overheating. (period).
now, overheating can be caused by several items. bad thermostat, bad water pump, bad fan clutch, clogged radiator, etc,etc,etc
now, overheating can be caused by several items. bad thermostat, bad water pump, bad fan clutch, clogged radiator, etc,etc,etc
Posting Guru
Joined: Aug 2006
Posts: 2,175
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From: Kent WA
Originally Posted by 2jhanna
the only reason cooling systems (on any vehicle) should overflow beyond a certain point is either a bad radiator cap (cheap, easy, replaced it anyway, make sure you get right #'s) or the engine is overheating. (period).
now, overheating can be caused by several items. bad thermostat, bad water pump, bad fan clutch, clogged radiator, etc,etc,etc
now, overheating can be caused by several items. bad thermostat, bad water pump, bad fan clutch, clogged radiator, etc,etc,etc
Cargo Master
Joined: Nov 2003
Posts: 2,585
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From: Duluth, Mn.
Prolly not. There's not enough pressure on the intake to force that much coolant.
Replace the rediator cap, first. If that doesn't solve the problem. More than likely, your in for a head gasket change.
Replace the rediator cap, first. If that doesn't solve the problem. More than likely, your in for a head gasket change.
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
On a turbo engine the intake manifold gasket can allow turbo boost into the cooling system.
The IDI engine has no coolant in the intake manifold.
But the valley pan gasket does block off several coolant passages in the heads.
On an 84 6.9 I would suspect one of three things.
The head gaskets are leaking compression into the coolant passages.
Or you have a very small leak in the cooling system somewhere.
The coolant leaking out may be so small that it evaporates before it drips, but when the engine cools the leak lets air into the cooling system equalizing the pressure before all the coolant is returned to the engine.
After several cycles of this, the engine overheats.
You have a bad radiator cap outer gasket or a crack in the overflow tube letting the radiator suck air instead of coolant out of the recovery tank.
If you have your problem over several days of driving, check for the second two things first.
If you have your problem a hundred miles down the road after you just refilled everything before you started, I would point at the head gaskets.
The IDI engine has no coolant in the intake manifold.
But the valley pan gasket does block off several coolant passages in the heads.
On an 84 6.9 I would suspect one of three things.
The head gaskets are leaking compression into the coolant passages.
Or you have a very small leak in the cooling system somewhere.
The coolant leaking out may be so small that it evaporates before it drips, but when the engine cools the leak lets air into the cooling system equalizing the pressure before all the coolant is returned to the engine.
After several cycles of this, the engine overheats.
You have a bad radiator cap outer gasket or a crack in the overflow tube letting the radiator suck air instead of coolant out of the recovery tank.
If you have your problem over several days of driving, check for the second two things first.
If you have your problem a hundred miles down the road after you just refilled everything before you started, I would point at the head gaskets.
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Thanks to evryone for the information. I had changed out the radiator cap already, but need to double check to make sure the parts guy gave me the right pressure rating. The bubbles do not appear in the overflow tank until the engine has been running for awhile.
Thanks again.
Thanks again.
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Cracked head can also cause this, I just finished repairing a 93 7.3 IDI on our lot that was doing the same thing, crack at #2 cyl near the exhaust valve, No water in oil, no oil in water. Check compression, that will lead you to the correct bank, and cyl, the cyl with the crack had considerably lower compression than the rest.
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