![]() Testing/replacing the cap is a good place to start, as a cap that fails to open can result in high pressure, and leaks.ĭiesel engines do not always show obvious bubbles in the coolant reservoir with a HG leak. Obviously there could be other sources of coolant loss, but the presence of positive pressure after the engine has cooled is not normally present in these cases. There are fluid/tools which let you do this cheaply/easy. The definitive test is to test the coolant for combustion gas traces. This will tell you if the coolant is being pushed out.Ī bad cap can sometimes cause coolant loss this way, but usually only if the coolant level is nearly full to begin with, or if the coolant is boiling (incorrect water mixture). Small leaks tend to cause aeration in the coolant, and result in some being pushed out the overflow when running.Ī diagnostic test is to route the radiator overflow hose into a catch bottle. It depends on where the leak is, and how bad it is. Since it won't fit in my shop ( too tall) any major repairs will need to wait till spring. So, I'm open to ideas on how to further diagnose the problem.I'd like to take the van on a Thanksgiving trip camping to Utah and Arizona. I washed down the engine compartment yesterday to facilitate looking for minor leaks, and i'll do that more. I actually looked for a 2L coke bottle to use as an overflow tank at 2 truck stops but they were too well cleaned up to have a loose one! I'm considering ordering an OEM radiator cap from europarts SD to see if it better than the wagner. The fact that the system retains pressure well, and that the new cap greatly reduced coolant consumption makes me think that the radiator and expansion tank are probably OK. Don't need to add any between oil changes. No problems with overheating, no off-color exhaust smoke or whiteness in the oil. ![]() Coolant level never gets more than a little below the cross bar in the lower part of the expansion tank. It is always present, but does not seem excessive. This vehicle has always had some pressure in the expansion tank, even after sitting overnight, when you remove the cap to check level. I did read the forum postings about similar problems. The coolant seems to be coming from either the rubber overflow hose, or the upper portion of the expansion tank. Made it home to Idaho fine, with only minor coolant loss. The new cap seems to have greatly reduced the rate of coolant use.Īfter lunch in Wells, I got the light again, and added another cup of coolant. I added another cup of coolant, and successfully drove to Wells,NV, everything running well, at 70 or so. In Winnemucca, I found an O'Reilley's and purchased a wagner 20# cap, $6- the light went on as I was shutting down on the parking lot. The base gasket on the radiator cap seems thin. I added another cup of coolant, and made it to Reno fine, but it was too late to find a parts store open. I stopped and aded another cup of coolant or so, and made it up the main summit fine, then got the light again going down the far side. ( outdoor temp about 55 degrees) Going down the far side, I got the low coolant light again. It was fine for local driving, and returning over donner pass, I made the first summit no problems, no overheating, barely got up to 180. The expansion tank level was down a little, so I added more coolant. The following day, I got a low coolant light after AM start up at the campground. On a recent trip to Ca, including driving over Donner Pass, it all went fine. You will get a better idea how it works.I have a 2003 T1N with 162 K miles. The square peg that the bail mounts on is up, hard against the top of the unit without the bail up. Look at the valve when your engine is hot. That is why you should start with a cold engine, bail up, when you are using the start it, rev it to various RPMs, method of bleeding the system. On a cold start,with the bail up, as the coolant warms up it pushes out air pockets. When the valve is open the system can vent to the atmosphere allowing air bubbles to escape. When you have the bail up it holds the diaphragm up as the engine cools this forces the valve to open. The black unit with the bail is a spring loaded diaphragm 'vacuum break' valve, not pressure relief. The blue cap, 996 106 447 04= latest rev #, has the pressure relief built in to it. I see a green liquid which to me says coolant and not steam pressure which would dissipate on hitting the atmosphere. Does one open under water pressure and the other under steam pressure? I am baffled. To have two pressure relief valves on the same system standing next to each other, makes no logical sense to me what so ever. So you are saying that the lift up relief valve only opens at a higher pressure than the blue cap? Or ONLY opens under high water pressure? Can you tell us the exact pressure when each component opens? That's if there is a relief at all on the actual blue cap. ![]()
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