Does anyone have a good link or diagram for the path coolant travels in a 300tdi? I'm trying to understand how the system works.
I have a coolant leak that only shows itself after the engine has warmed up. I get a puddle under the truck in the AM. I just had the entire hose/radiator system out for the P gasket so I am thinking it is related to that.
My theory is that the top radiator hose isn't sealing well where it goes into the motor and it is causing a drip down the side of the alternator and then the power steering box to the ground. I think there would only be coolant in that hose after the engine warmed up and the thermostat opened.
You have probably already checked, but take a look at the expansion tank. Mine had leak in it that only showed once it was warmed up. Can't help with the diagram.
There should be coolant everywhere all of the time. It needs to warm up to be pressurized, though.
The P-gasket is where the coolant is pumped into the engine block and it comes out of the head into the thermostat housing. If the thermostat is closed, the flow goes through the bypass hose to the pump. As it opens, it directs flow through the radiator.
Build this and put it inline on the small hose from the radiator to the expansion tank.
Put 15psi in it. Spray Windex on all the hose joints, the ones that foam-up are leaking.
Be sure to check your freeze lugs too, there's on on the back of the head too.
The system should be able to hold the pressure for at least 1/2 an hour with only 1 or 2 psi loss.
I had 2 freeze plugs start leaking.
The one in front of and behind the turbo.
I put a block heater in the front hole and a new plug in the back one.
I'm sure at some point the middle one will go...I'm selling the truck when the rear ones let loose.
Have you checked your hose clamps and made sure they are tight?
I second Carl's suggestion of a pressure tester.
Another method that's even cheaper and simpler than putting a pressure tester inline with the expansion tank is to connect a quick-connect air fitting with a hose barb to the expansion tank overflow hose.
The coolant tank cap can be defective and allow pressures way beyond the rated blow off point of 15psi and blow something else apart. That's why I built mine with the gauge and it also allows me to see if there is any "leak down" of pressure of time.
I found 7 hose clamps that were leaking & the seal on my block heater was leaking too.
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