I appreciate everyone's replies. Dennis, you gave me a lot to think about.
Thank you. I know it's been quite a while since I've provided an engine
update. So here goes. I checked the compression following the instructions
in the Bentley service manual and the results are disappointing.

Cylinder #1 = 141 PSI
Cylinder #2 = 126 PSI
Cylinder #3 = 96 PSI
Cylinder #4 = 136 PSI

I have noticed that each year since 2017 when I have the emissions tested
in Tucson that the CO% increases. I have read that oil burned in the
combustion chamber due to worn piston rings and/or cylinders can cause
excessive CO% in emissions. I doubt the Vanagon will pass the emissions
test in August when it is due so I'm considering my options. What is the
most likely cause of low compression in cylinder #3? I feel confident the
overheating event is a factor.

Thanks as always,
Ryan

On Sun, Jan 3, 2021 at 8:27 PM Dennis Haynes <d23haynes57@hotmail.com>
wrote:

> So a few things. The reason that low coolant generates a red light in the
> center of the gauge and loos of water pump/alternator drive turns on that
> tred light is that both are critical failures which require an immediate
> shut down as soon as it is safe to do so. As the temp gauge sensor is
> mounted on a plastic housing and not as part of the head it relies on
> coolant flowing in order for it to work. Even still it’s response is damped
> both for speed and temp change indication. Simply put, once the water pump
> stops turning the gauge will not rise until after you make steam and engine
> damage is occurring. Driving 5 miles you have pulled studs, possibly
> cracked or warped the heads and damaged the seal at the top of the
> cylinders.
>
>
>
> In this condition the relief at the pressure cap just doesn’t have enough
> capacity to vent all the pressure. The pin holes in the coolant loop are
> due to excessive temperature and pressure. Consider that every hose and
> plastic junction along with the radiator and heater cores have been exposed
> to this trauma. My rule of thumb is continued operation after a cooling or
> lubrication system failure cost $1K per mile until you need the tow truck
> anyway.
>
>
>
> It is also likely that this event damaged the oil cooler so you may have
> it passing oil into the coolant.  If you don’t have the means to actually
> test both sides under pressure just replace it. Also replace the thermostat
> and if still plastic housing remove and inspect it for damage/cracking.
>
>
>
> For the belt failure most likely it was the water pump/alternator belt
> that went first. The belts available just suck for this application and few
> properly tension them. This belt drive is very poorly designed and it
> frequently fails.
>
>
>
> Regarding the GoWesty kit I don’t recommend this as it still uses plastic
> fittings. I use all brass tess and threaded fittings/hose barbs for the
> connection to the tank. Silicone coolant hose makes this a near lifetime
> repair. For mounting I use the tie wraps with the Christmas tree or pin
> mounting using the existing holes maybe adding a couple more. As part of
> upgrading the system get rid of that plastic coolant pressure tank and
> replace with the Van Café or GoWesty aluminum tank. Besides the tank itself
> getting a pressure cap that is common, can be visually inspected, along
> with a design where both a cpa and system pressure tester can be easily
> used is worth the cost of admission.
>
>
>
> After you think you have it all sorted after 500 miles or so have the oil
> tested. Coolant getting into the oil become destructive to the bearings
> long before it become visible. After an overheat coolant can get into the
> oil due to the cylinder becoming loose and coolant seeping under them and
> also under the head nuts. The top studs/nuts will leak externally but the
> lower ones under the rocker shafts will go into the oil.
>
>
>
> Hope this helps.
>
>
>
> Dennis
>
>
>
>
>
> *From:* Ryan Cresawn <jrcresawn@gmail.com>
> *Sent:* Sunday, January 3, 2021 1:13 PM
> *To:* Dennis Haynes <d23haynes57@hotmail.com>
> *Subject:* Fwd: oil in coolant
>
>
>
> Hi Dennis,
>
>
>
> I sent this message to the Vanagon mailing list yesterday, but I think it
> might not be working. If you have time to reply I sure would appreciate it.
>
>
>
> With sincere gratitude,
>
> Ryan
>
>
>
> ---------- Forwarded message ---------
> From: *Ryan Cresawn* <jrcresawn@gmail.com>
> Date: Sat, Jan 2, 2021, 11:47
> Subject: oil in coolant
> To: Vanagon List <vanagon@gerry.vanagon.com>
>
>
>
> 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
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.gowesty.com%2Fproduct%2Fbundles-and-kits%2F24210%2Fcoolant-bleed-ring-replacement-kit&data=04%7C01%7C%7C2ce68480f01b421722bf08d8b0134c5c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637452944224975778%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=R0XqI68KvTxHb1qkJy3aN%2F6zkf62RJLO%2Bz76%2Bt1kf5A%3D&reserved=0>
>
>
>
> 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
>
>
>