Ok,
Gunna revive this older thread with a doozy. Figured this was the best thread to put it since it can easily be found with Search. Here is goes......↓
The FJ60 distributor ventilation VCV is a very important control valve, yet (as noted) it is no longer available new. 30 year old degraded used valves are still available from a few places & I have purchased a couple of used ones in the past too.
Since 30 year old used VCVs have an an accelerated End Of Life Expectancy and the their availability is drying up, a brand new VCV, if it could be purchased, would be a far better solution.
So may I humbly present… the venerable 90925-03192.
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The 90925-03192 is a brand spankin new, cross-compatible Toyota VCV which is still available new from Toyota as of May, 2015. This VCV is used on the 1FE-FZ engine in the FZJ80 Land Cruiser for EVAP control. It can also be used as a direct replacement for the 2F EVAP VCV.
>>>
The only noteworthy difference between this newer FZJ80 VCV and the NLA FJ60 VCV is that pipe 'S' is oriented 180º on the other side of the valve. All the pipes on the VCV function in the exact same manner as the original FJ60 VCV and even have the same labels on them (X, Y, Z, S). The pipe O.D. is the same on each pipe as well. The two valves function identically. The FZJ80 VCV seems like it is actually a better valve and appears to be an engineering "upgrade" from the FJ60 valve.
View attachment 1072766
The body of the FZJ80 VCV also has the same important dimensions as the FJ60 VCV as it snaps perfectly into both the stock distributor and EVAP spring VCV holders in the FJ60 engine compartment.
View attachment 1072765
>>>>
Now it's time for...
<mytheory>
<mydigression>
View attachment 1072768
The distributor VCV (I believe) fails due to the strong oxidizing properties of the ozone it transports out of the distributor. Ozone literally eats away the internal valve of a brand new VCV in less than a decade.
When the VCV is functioning correctly, vacuum applied to pipe 'S' when the engine is running, opens the passageway between pipe 'Y' and 'Z'. Ozone saturated air that is constantly being generated inside the distributor cap is then vented out via those two pipes. It is important to note that pipe 'S' on a good valve holds a vacuum and does not free flow. Pipe 'Y' leads up to the air cleaner and pipe 'Z' along with pipe 'X' lead down to the distributor cap.
When the VCV malfunctions, pipe 'S' no longer will hold a vacuum and will create a continuous vacuum leak to the intake manifold. The failed valve opens a direct passageway to pipe 'Z' and 'X' from pipe 'S' yet pipe 'Y" (leading to the air cleaner) will remain closed.
• What does that mean?
It means that when the VCV fails, the engine will continuously pull air & a little bit of highly reactive ozone out of the distributor cap directly into the intake manifold, bypassing the air cleaner. This vacuum leak will be in essence an 'enhanced' vacuum leak due to the extra ozone the air contains.
If you've ever heard strange 'popping or snapping noises' randomly emanating from around the intake manifold while the engine is idling, take a look the at the distributor VCV. If it's malfunctioning, it could be injecting an ozone enriched vacuum leak directly into the intake manifold.
If you've ever heard the small 'pop' or 'snapping' sound inside the cabin below the glove box when first starting up the engine, that is a sign that the distributor VCV has failed.
My theory as to what is happening when you experience cabin farts (of the dissy kind) is that when the engine shuts down with a malfunctioning distributor VCV, hot unburned gasoline vapors in the intake are pushed up through the 'gas filter' on the intake manifold, through the vacuum piping, through the faulty valve via pipe 'S' on the VCV and down pipe 'Z' into the cooler distributor cap where they collect.
Then, when you start the engine the next time, those explosive vapors containing gasoline and maybe a little ozone are ignited by the spark inside the distributor cap and explode in a mini explosion and fart out through the dissy breather hose located in the cab.
• Why is this bad?
Of course flammable gasoline vapors are not a good thing to have sitting around inside the distributor cap, but water vapor, aka humidity, later on in the cooling cycle of the engine, can find it's way into the distributor cap as well when there is a bad VCV.
Since a bad VCV creates an un-sealed, open-air circuit between the dissy air filter in the cabin and the gas filter port on the intake manifold, any differential in temperatures between the two end points (cool cabin and hot manifold) will create a pressure gradient. This means air & any moisture it contains will flow (albeit slowly) through the distributor venting plumbing.
• Why is this bad?
Ozone is created inside the distributor cap when the high voltage spark jumps from the rotor to each terminal post. When this highly reactive ozone mixes with any moisture laden air in the cap, it creates Nitric Acid. Nitric Acid is extremely corrosive to iron containing metals… and… well… it can corrode the hell out of the distributor innards.
That's why.
OZONE:
[Excerpt]
Highly reactive, ozone concentrations above 15% can explode on contact with organic substances, especially strong reducing agents.
Ozone is a powerful oxidizing agent and oxidation with ozone evolves more heat and usually starts at a lower temperature than oxidation with oxygen. It reacts with non-saturated organic compounds to produce ozonides, which are unstable and may decompose with explosive violence. Ozone is an unstable gas which, at normal temperatures, decomposes to diatomic oxygen. At elevated temperatures and in the presence of certain catalysts such as hydrogen, iron, copper and chromium, this decomposition may be explosive.
</mydigression>
</mytheory>
is for you.
