joepechin

Using the carb cleaner method to identify the source of my idle problems, I have discovered a vacuum leak somewhere around the back of the intake manifold. Since the fan blows the cleaner around, I can't identify exactly where it is leaking. It may be the mainfold gasket or somewhere below it. My hose schematic is fairly vague. Are there any hoses below the manifold or directly behind the throttle body? 1995 4Runner with 3.0 v6. Thanks in advance!

blake.nemitz

yea under the manifold in the back there are two that attach to your bvsv one goes to the charcol canister and the other goes somewhere. if this is the culprit you can just run a line from the canister to wherever it goes and bypass the bvsv" bi-metal vacuum switching valve" it only closes when the motor is cold like upon initial start up and opens when switched into open loop. i ditched mine cause a tab broke off and it runs exactly the same as far as i can tell

joepechin

Thanks for the quick reply. Sounds like that be the culprit. I assume the bimetal switch is located somewhere in the water jacket near the rear of the motor? I'll take a look when I get home tonight. Thanks again for the help!

joepechin

New issue. I got home tonight and carefully sprayed carb cleaner around the intake. I found a significant vacuum leak at the base of the intake air chamber. Are there any major issues to be aware of in pulling the IAC and replacing the gasket? I hope that is the problem and not warpage of the IAC. Thanks in advance for suggestions!

MudHippy

If you can take some pics of where all the vacuum hoses are supposed to be beforehand, that's always a good idea. You may need to remove a few of them to make things easier. You're also going to need to remove the EGR valve, the bracket(Air Intake Chamber Stay)connecting it to the head, and all the coolant hoses that run to it, before you'll be able to get the plenum chamber up and out of the way enough to service the gasket. But try and leave as many things still connected to it as you can. You don't need to remove the throttle body from it, it can stay attached to the plenum(you may want to remove the accelerator cable from it though). Then just set it aside, or prop it up and out of the way somehow, before removing the old gasket and installing the new one.

Oh, and I wouldn't worry too much about warpage. That's just a myth(I've never heard of it happening in real life).

Here's the FSM link for reference.
http://personal.utulsa.edu/~nathan-b...68cylinder.pdf

joepechin

I am thinking of using a thin coating of Hylomar in addition to the gasket to be on the safe side. Thanks for the help!

Andy A

Great stuff and good idea. The one beauty of hylomar is gasket removal. The gasket, 99% of the time comes off in one piece and cleaning any old gasket off the surface is minimal. Works best on paper type gaskets. I just finished a HG job on my 3vze and used it on the upper to lower intake gasket.

MudHippy

I've been experimenting with a similar technique.

Coat a paper gasket with a very thin layer of your favorite flavor RTV/FIPG. Basically try and wipe most of it off, just leaving a thin film. Then hang it by one of the bolt holes to let it thoroughly dry.

When dried you end up with a home-made rubberized paper gasket, that won't squeeze out any goop that could possibly cause any flow restriction. I have one of such being used for the gasket we're talking about, and the one for the throttle body too, on my 3vze now. And also on a couple of other people's cars I've worked on recently. On both those they were used for sealing coolant systems(thermostat gaskets for a Pathfinder and an Eclipse). They all seem to be holding up just fine. And removal, if needed, should be hassle-free as well I'm guessing.

RTV: Room Temperature Vulcanization

Suprising how few folks know that.

joepechin

I completed the replacement of the gasket over the weekend and the idle is now perfect. Thanks for everybodys help!

buck bridges

So just bypassing the BVSV altogether and plugging the line from the canister all the way to the throttle body will not cause any EGR error codes, (EGR System Malfunction code 71?)

scope103

The TVV (or BVSV, same thing) just pulls the vapor out of the evap canister. It has nothing to do with the EGR (and certainly nothing to do with EGR gas temp, the cause of code 71). Bypassing the TVV should make the engine run a little rough when cold, but as others have mentioned you might get away with it.

If you have code 71, I can't imagine that it has anything to do with the TVV.

buck bridges

Scope103,

Thank you for your response. Not to hijack this thread but I have a 95' 3.0 V6 with a 71 code. After checking the EGR valve, vacuum modulator, hoses, and testing the VSV, all was in working order. Finally took in to a shop for diagnostics and was told the EGR temp sensor was bad. Ordered the part, ($116 bucks) and while I was waiting, I decided to replace all the vacuum hoses just to be safe.

While trying to remove the hose from the canister to the TVV, the plastic port on the TVV snapped off. Grrrrrr.... I found the thread about how to repair the plastic port and that would have worked great except while trying to remove the TVV from behind the manifold, the plastic TVV just turned to dust and literally crumbled. Now I have the TVV, (just the nut... plastic component turned to dust) still in place and the two hoses, (one from charcoal canister & one leading to throttle body) are without a home.

If I am just able to run the hose from the canister to the throttle body and the only repercussion is a rough idle when cold, I will deal with that. I just wanted to make sure the broken TVV wouldn't contribute to the "EGR System Malfunction" and it seems it won't.

I can't say it enough... I love this forum. Thank you for your input and best of luck to anyone having the same problems.

scope103

It's only a $50 part; why don't you just splurge!
http://www.toyotapartsoverstock.com/...092505047.html

buck bridges

Again, thank you for the suggestion. I was looking around for the part online and seems I was looking in the wrong place. 50 bucks ain't bad.

Now, how do I get that sucker off... I can't really use a wrench as there isn't room and I put a socket on it and turned pretty hard. Last thing I want to do is bust that thing. Any thoughts?