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Boost leak in cabin?

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10+ Year Contributor
1,073
1
Sep 2, 2012
Findlay, Ohio
I have been chasing down boost leaks and have found a decent amount with the soapy water method, BUT when I'm driving and getting on the highway or just accelerating fast, I get a "HISSSSSSSSS" when above 7 psi or so, and it sounds like its coming from the vents on the driver's side by the door, but I wouldn't see how it could. I know the fpr solenoid and brake booster are right there, but I can't think of anything else. Could it be normal too? I don't think the gauge is leaking, cause its computerized (right?). Ideas? ALSO to save extra threads, I'm thinking about getting a different BOV, and I found this one for really cheap Ebay BOV, is it gonna break my car? I don't care if it doesn't last long, just want something for a few days or weeks, if the unit does fail, could it cause damage to other things as well? Thanks guys!
 
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I cant answer your first question, but depending on your gauge, if the hose plugged into it isn't fastened properly it could leak some air.

And why buy a cheap one just to replace it later. I personally wouldn't trust it. The first thing I saw on the "compatible cars" list was a 2011 Eclipse. Those don't even have turbo's LOL.
 
I cant answer your first question, but depending on your gauge, if the hose plugged into it isn't fastened properly it could leak some air.

And why buy a cheap one just to replace it later. I personally wouldn't trust it. The first thing I saw on the "compatible cars" list was a 2011 Eclipse. Those don't even have turbo's LOL.

The stock gauge doesn't have a hose going to it, it is an electronic gauge that is controlled by the ecu.

As for hearing a boost leak in the cabin, the only place where that would be possible would be from the brake booster, but there is a check valve in the booster hose that should prevent that.
 
The stock gauge doesn't have a hose going to it, it is an electronic gauge that is controlled by the ecu.

As for hearing a boost leak in the cabin, the only place where that would be possible would be from the brake booster, but there is a check valve in the booster hose that should prevent that.

Hmmm, well another thing, when I'm idling and my car decides it wants to start dying, the brake pedal goes up and down (stiffens and softens) and when I let go of it before I hit the gas, the RPMs dip then too. Could that be something, or just a result of some other boost leaks?

I cant answer your first question, but depending on your gauge, if the hose plugged into it isn't fastened properly it could leak some air.

And why buy a cheap one just to replace it later. I personally wouldn't trust it. The first thing I saw on the "compatible cars" list was a 2011 Eclipse. Those don't even have turbo's LOL.

Lol, the compat is kinda really broad LOL, but I'll buy it and let you guys know. I just want something thats a little louder, cause I'm going to a car meet soon and just wanna seem a bit cool
 
The stock gauge doesn't have a hose going to it, it is an electronic gauge that is controlled by the ecu.

Oh I didn't even think stock gauge, was assuming it was a real one.


Get those leaks fixed before the meet, you wont look so "cool" when your car stalls from leaks ;)
 
Lol, I'm waiting to see if the guy here is going to send me his old tester. Prayer keeps my car from stalling, its only done it once, in reverse, up hill LOL. To stop the stalling, I unplugged the throttle closed switch thing, I just have to deal with it revving to 3k randomly when in park and I have to pump the brakes a lot to make it calm down, but yeah LOL, gotta find those leaks.

You can kinda hear the "leak" here:


http://www.youtube.com/watch?v=bghjtw7N28I&feature=player_detailpage#t=78s

Go to 1:18 if you don't want to hear me talk uncontrollably. Goodness do I hate my voice.
 
id definitly go with it being your brake booster. there is a one way valve on the brake booster. its where the large hose goes into the booster. if that valve got stuck open then thats what is causeing your issues during boost. your brake booster is only supposed to get vacuum.
 
To which question?

I beleive I said yes to both questions.
And yes the check valve is a good place to start. But I would also check to see if the master is leaking. I've had the master leak so bad that it leaked into the booster and ruined the rubber diaphragm inside.

All you have to do is take the two nuts off holding the master to the booster and inspect the back of the master to see if any fluid is visible.
 
I a similar situation, my hose from the intake mani to the brake booster did not have a check valve. Had to add on and the prob went away.
 
Alright, I'll check everything out later on and see where that darn snake is
 
Can't find anything without being able to do a boost leak test I guess. I don't even know what this valve looks like LOL, but if it helps your guys's theory more, after I do a pull and get to like 8-9psi and start to slow down, the brakes feel stiffer and aren't as effective
 
Can't find anything without being able to do a boost leak test I guess. I don't even know what this valve looks like LOL, but if it helps your guys's theory more, after I do a pull and get to like 8-9psi and start to slow down, the brakes feel stiffer and aren't as effective

IF the brakes feel stiff after boosting than the valve likely isn't there. You won't be able to see the valve, it is built into the hose.
 
Ahh, alright. Well would one of the previous owners have removed it for some reason, or could it just have been sucked into netherspace? And where would I find another one of these hose valve things? Nevertheless, think you could post a pic pointing the valve/hose thing? I really apologize about my noobness, just haven't messed with critical components this much before.
 
Ahh, alright. Well would one of the previous owners have removed it for some reason, or could it just have been sucked into netherspace? And where would I find another one of these hose valve things? Nevertheless, think you could post a pic pointing the valve/hose thing? I really apologize about my noobness, just haven't messed with critical components this much before.

Most random people that work on these cars don't know that there is a valve in the hose, so they probably just stuck a piece of random hose on there. Go look at the brake booster and you will see a hose coming out of it to the intake manifold. That hose should be a molded hose with a valve built into it, you won't see the valve, it will just look like a hose.
 
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=O, you so good. How do I go about getting one of these hoses? Can I get any hose with a check valve,does it have to be branded?
 

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=O, you so good. How do I go about getting one of these hoses? Can I get any hose with a check valve,does it have to be branded?

Yeah, that is definitely a random hose. You will need either a used hose from one of these cars, or a new one, the part number is, MB668201 . They are pretty expensive, like 40 bucks, i would look in the classifieds to find someone parting out a turbo car.
 

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Thank you thank you. So what issues exactly are being caused by the check valve not being present? Could it be contributing to my crappy idle, or am I not that lucky? LOL
 
Thank you thank you. So what issues exactly are being caused by the check valve not being present? Could it be contributing to my crappy idle, or am I not that lucky? LOL

The idle problem i would say isn't likely caused by this. If there is now a leak in the booster because of the valve missing than it could contribute, but i don't really see that happening. I would more assume that your iac is damaged, or the biss screw isn't set properly. I would replace the hose, check for boost leaks and then see how it idles. Is your bov recirculated? If it still idles bad than i would test the iac valve than adjust the biss screw. I've actually got a 1g brake booster hose with a good valve in it if you want it.
 
The idle problem i would say isn't likely caused by this. If there is now a leak in the booster because of the valve missing than it could contribute, but i don't really see that happening. I would more assume that your iac is damaged, or the biss screw isn't set properly. I would replace the hose, check for boost leaks and then see how it idles. Is your bov recirculated? If it still idles bad than i would test the iac valve than adjust the biss screw. I've actually got a 1g brake booster hose with a good valve in it if you want it.

BOV looks stock and is recir, I've tried adjusting biss screw, but it seems to have no effect. Its all the way down right now. Is that closed or opened? are the iac/isc the same? How do I test for damaged isc? and I will take it for a decent price. PM me. I'm limited on moneys right now due to college and this forsaken machine LOL
 
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