The water pump/alternator V-belt failed on my 1991 Vanagon (2.1L engine). I
drove 4.8 miles home. When I parked steam was coming from the engine
compartment. I discovered that the A/C compressor belt also broke. I
believe the A/C belt broke first and then that broken belt got caught
between the water pump/alternator belt and a pulley which caused it to
break. The steam was caused by coolant spraying on the engine from a hole
smaller than a BB in the white plastic coolant bleed ring. I believe that
hole was caused by either excessive heat or impact from one of the broken
belts. I have assessed the damage and begun repairs.

I have replaced the leaking coolant bleed ring with this kit from GoWesty:

https://www.gowesty.com/product/bundles-and-kits/24210/coolant-bleed-ring-replacement-kit

I did not follow their instructions entirely. They supply self-tapping
screws they propose I fasten to painted sheet metal in the engine
compartment. My assumption is that will cause rust. Instead, I purchased
two 3/8-inch oak dowel rods and cut them to length. They fit perfectly in
the white plastic clips that held the original coolant bleed ring. Then I
used zip ties to attach the rubber hose to the dowel rods. I like the final
result.

I blew on the 16-PSI blue coolant cap and it would not make the trumpet
sound so I replaced it with a new one. I put a washing machine flood tray
under the engine and found a coolant leak. It was at the Temp II sensor. I
removed the sensor and found the O-ring was dry. I replaced it with a new
one. I also polished the sensor with Brasso and coated the O-ring with a
thin layer of dielectric grease. I installed new belts. I made a "Libby
bong" and followed the fill procedure. There were no external coolant
leaks. I then started the engine and drove five laps around the block. I
have oil temperature and pressure gauges. I noticed on my drive that the
coolant and oil temperatures began to rise and the oil pressure, which
started high, began to fall. Everything seemed good, but I still needed to
look for coolant and oil mixing. I extracted about 8 ounces (250 mL) of
coolant from the pressurized coolant tank with the blue cap. I let the
coolant sit in my house for a week and eventually noticed a tiny film on
top of the coolant which I assume is oil. I can provide photos if anyone is
curious. Two days ago I leveled the Vanagon and let it set overnight. Then
yesterday morning I let about 1-2 ounces of oil drain from the drain plug
into a glass beaker. I found no coolant in the oil.

I searched the mailing list archives and found a thread about oil being
found in coolant. It looks like Dennis Haynes wrote in 1996 that 95% of
"oil in coolant" problems are caused by a bad oil cooler. If the Gerry
website were up I would provide a link to his post. I bought a new oil
cooler but have not replaced it yet. I drained the oil yesterday. My next
step is to drain the coolant. I will then remove the oil filter and then
the oil cooler. My plan is to install the new oil cooler and then add fresh
oil and coolant. Should I test the oil cooler I plan to remove from the
engine? If I find oil in the coolant after replacing the oil cooler and
fluids where should I look next?

Many thanks,
Ryan