Whats this? Its on top of the thermostat housing

[storm.surfin]

[storm.surfin]

the blue piece thats broken...is it some kinda sensor?

[Grego 92]

That looks like a BVSV on my v6, is that from a 4cyl.?

Mine are located on my water by pass outlet, not the thermostat housing.

I think it stands for Bimetal Vacuum Switching Valve and it opens closes depending on temperature.... I THINK.

I'm sure you can google bvsv and it will tell you what it does.

[Doctor J]

It is located on water outlet (the thermostat is located under the alternator) and this valve opens above 60 degrees C and purges fuel vapor storage canister. So when it is broken it may affect idle /acceleration quality due to the vacuum leak

[storm.surfin]

i read on the interweb that some have just connected the two hoses and bypassed the thing. is that okay?

[nopain00]

I've broken the BVSV too when working on my dizzy. As Doctor J said, the charcoal canister stores fuel vapors from the gas tank. When the engine gets to running temperature, this valve opens and the hydrocarbons from the canister are absorbed and burned, preventing release of HC to the environment.

If you leave it broken, you do have a vacuum leak. if you connect the hoses together you get rid of this problem. I'm not sure exactly what will happen to the charcoal canister over time if you simply leave it disconnected. It will continue filling with liquid and gaseous hydrocarbons. I assume that over time it will reach a maximum pressure and not absorb any more, which will increase pressure in your fuel tank as well. Over a certain pressure, it will release the fuel vapors and liquid to the environment.

I swapped my broken one for one from a junked car for <$20. They are interchangeable among many of the cars from the 90s. If you search ebay, you'll come up with a lot of hits. Pick-and-pull type yards will be even cheaper.

[holmesnmanny]

They are also called ported vacuum switches. I had both of mines(there are two switches) broken for a bit and never experienced any driving issues. The nipples seem to get brittle and break over time.

[white90dx]

Originally Posted by nopain00

If you leave it broken, you do have a vacuum leak. if you connect the hoses together you get rid of this problem. I'm not sure exactly what will happen to the charcoal canister over time if you simply leave it disconnected. It will continue filling with liquid and gaseous hydrocarbons. I assume that over time it will reach a maximum pressure and not absorb any more, which will increase pressure in your fuel tank as well. Over a certain pressure, it will release the fuel vapors and liquid to the environment.

If you connect the hoses together, it will always vent the charcoal canister to the intake manifold. The only chance for releasing fuel vapors to the environment would be if you capped the lines instead.

There is a second BVSV on the water outlet neck that has a similar purpose for EGR (keeps the EGR from functioning until the motor is warm).

-Charlie

[nopain00]

Originally Posted by white90dx

If you connect the hoses together, it will always vent the charcoal canister to the intake manifold. The only chance for releasing fuel vapors to the environment would be if you capped the lines instead.

There is a second BVSV on the water outlet neck that has a similar purpose for EGR (keeps the EGR from functioning until the motor is warm).

-Charlie

Yeah, you're right. I had it backwards. Oops.