QuestionJohn, I don't expect you to remember, but I have previously asked about my '99 Discovery losing water with no visible leaks. I should mention another oddity in hopes that it helps you suggest a cause. I commute roughly 15 miles each way, and in the afternoons, on my freeway trip, routinely run 80-90 MPH with no overheating issues. When I reach my exit, there are times when I can brake smoothly with no issue, but there are times when I must slow to a stop very quickly from 70-80 MPH, and I notice a burst of something emerge from the exhaust behind me, a cloud, a smoke screen of sorts; that clears before I reach the bottom of the exit ramp. (I know we shouldn't drive like this, but anyway...) Could this be coolant blowing out? I put a dye in the coolant tank last weekend, but have not been able to replicate the condition exactly, except for one mild instance, and did not see the dye color I expected. This has happened maybe 10 times in 3-4 months of daily commutes in this hot Tennessee summer, but like I said, no overheating, ever. I have to top off my coolant tank at least three times a week, but have no other symptoms or problems relating to coolant. The water pump was replaced due to leakage in June, the upper hose and thermostat in July, and a leaky intake manifold way back in March. I perform all the work myself, I just can't get my head around this one.
Thanks for taking the time to read, and think about this!
Michael
AnswerOften small coolant leaks just evaporate off without a trace. You could certainly degrease the motor so everything is clean and look carefully for evidence of leaks around the heads, timing cover, water pump, intake, etc. That might be the answer. If not, there is probably an internal failure in the motor. If you search my robisonservice car blog there is an article from May where I cut a failed block apart to show what can happen. It's got to be one of those two things, right? An external leak you are failing to see, or something inside.
