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+--- Thread: Coolant leaking from top cap (/showthread.php?tid=10223)
Coolant leaking from top cap - Porterave - 07-17-2025
I have coolant leaking from the top cap. Not a lot, but all the time. No coolant from side surge cap. Tried with a new surge cap, same issue.
No other symptoms.
Should I try to change the tank?
RE: Coolant leaking from top cap - Road Ranger - 07-17-2025
Maybe the cap is not the issue. Could be something else like aircompressor pushing air into the cooling system ?
RE: Coolant leaking from top cap - Rawze - 07-18-2025
(07-17-2025 )Porterave Wrote: I have coolant leaking from the top cap. Not a lot, but all the time. No coolant from side surge cap. Tried with a new surge cap, same issue.
No other symptoms.
Should I try to change the tank?
It can be the cap or tank.. or the pressure relief cap going bad at the surge tank side ... however, it can also be the coolant system building too much pressure from a couple different sources.
Like mentioned,.. the air compressor head can be going bad and pressurizing the coolant system.. but it can also be a head gasket, or EGR cooler, or injector cup starting to go bad as well.
== If it is the air compressor, there will also be excess moisture in the tanks and air dryer, and usually signs of coolant at the blow-off valve.
== If it is the EGR cooler... pressurizing the coolant system to 20 psi and letting the engine sit all night like that .. the back side of the EGR cooler will have coolant seeping out, or pooling up in it.
== If it is the cylinder head, then dropping the oil pan and stiffening plate ... pressurizing the coolant system to 20 psi and letting the engine sit all night like that .. then have someone turn engine by hand the next day while under each cylinder, you will hear gurgling sounds around the piston rings, and a few droplets of coolant mixed with oil on a compression stroke on one or more cylinders.
=================
If you keep driving it with that issue, and its one of those 3 things mentioned above, then you could destroy thee entire engine without warning .. so i would heavily suggest that you test for, and find your issues.
RE: Coolant leaking from top cap - Porterave - 07-18-2025
As far as now:
No overheating. Average 200F
No air bubbles in the coolant tank
No significant loss of coolant
Good mpg 6.9
Radiator was recently replaced after top left and top right leak at the seam.
No white smoke from exhaust
No coolant in oil that I can see or smell
No excessive moisture in air tank
No coolant smell from air dryer discharge
Does this point me in any direction?
RE: Coolant leaking from top cap - Rawze - 07-18-2025
(07-18-2025 )Porterave Wrote: As far as now:
No overheating. Average 200F
No air bubbles in the coolant tank
No significant loss of coolant
Good mpg 6.9
Radiator was recently replaced after top left and top right leak at the seam.
No white smoke from exhaust
No coolant in oil that I can see or smell
No excessive moisture in air tank
No coolant smell from air dryer discharge
Does this point me in any direction?
if your smells and visuals is all that you test things by, then I feel sorry for your engine.