Dear Fellow Brickboarders,

May this find you well. I suggest a minor upgrade. Some 940 radiators have a plastic plug, press fit into a rubber grommet, just above the top transmission cooler pipe, on the right side of the radiator (passenger-side, North American models).

To secure this "radiator plug", I've wrapped a single strand of stainless steel wire around the base of the brass fiting (to which the transmission fluid line connects), through the gap in top of the radiator plug, and around the radiator's top corner fin, closest to the plug. I twisted the ends of the wire, to snug them. I did not make the wire super-tight, only snug. This safety wire will keep the plug from backing out.

Here's why. Early Tuesday evening, I parked at a library. I thought I heard running, the electric auxiliary cooling fan. That should not have been: the ambient temperature was 45-50˚(9-10˚C). There was much background noise. I was pressed for time. The car sat for about an hour. I then drove home (2.1 miles).

When I pulled into the garage and shut down, the electric fan was indeed running after I shut down. I at once opened the hood and was horrified to see en empty coolant overflow tank and coolant "puddles" on the right side of the engine bay. I thought a hose had failed, even though I'd just replaced the rad hoses with Volvo brand items.

I quickly found that the radiator plug was missing. I at once checked the temperature gauge and found it to be right in the middle, where it usually is. This suggested that the engine had not overheated.

I added two quarts of coolant and water, bringing the water level up to the opening of the radiator plug. Today, I replaced the plug and grommet with Volvo-supplied items, topped-up the system, and ran it until the temp gauge needle was in the center. There is no sign of coolant in the oil (the oil is clear, not milky/frothy).

I think no harm was done to the engine because:
(a) the drive was brief;
(b) outside temperature was just below 50˚F (10˚C); and
(c) the electric cooling fan worked.

Moral of the story: secure the plastic radiator plug. It is a weak point. I think it simply worked loose. The stainless wire will hold it in place.

I also connected the low coolant indicator wiring: I had put the wiring into place, but had not taken the time to complete the job. Lesson learned!!!

I hope this is useful.

Yours faithfully,

Spook