Ok, I haven't had time to r/r the aux water pump yet, but a conversation with an MB tech has me thinking.

First, he said that one problem (reduced heat at idle) could rather be a vacuum issue, as noticing a reduction in heat from a non-pumping aux pump would take a few minutes. Any comment on that?

Second, the gurgling is indeed getting worse, or more pronounced. I never notice it at speed -- only at idle, as just as I slow to a stop or accelerate. Whether I have a vacuum issue or not I don't know, but regardless, I think for sure that my aux pump is faulty.

Third -- the pump or heater core question. I did notice some leaking last week. Could that be from the core OR the pump, or is it more likely to be one or the other? Also, if the core was leaking -- would ANY of the leaking be to the inside of the car, or would it only drip under the car?

Basically, I'm trying to determine how many problems I have involving the pump, the core, and a vacuum issue.

I never, ever have any problem at speed. I don't notice any appreciable coolant loss. The coolant smell is very infrequent and mild whenever I do smell it.

All thoughts or constructive comments would be appreciated.

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1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
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1989 Mustang GT Cobra Convertible
43k miles