Where does the vacuum hose from the power brake boost go? - Volvo Forums - Volvo Enthusiasts Forum

Volvo 850 Made from 1993 to 1997, this Volvo line was available in both a wagon and a sedan, both with were graced with several trim levels.

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Old 04-24-2010, 06:07 PM
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Join Date: Oct 2009
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Default Where does the vacuum hose from the power brake boost go?

Hi all I'm back to diagnosing my 94' wagon cold start problems. Today, I took it into the Walmart tire center to have them do their "fuel injection clean." Apparently they plug their cleaner into the vacuum line for the brake power assist, because on most cars this goes straight into the intake manifold. On the 850, however, the hose makes a right-hand turn and goes off under the coil, ABS computer, and intake manifold, and then goes... where, exactly?

I'm hoping that someone else on here has already played a game of, "where does this hose go?" and can tell me so I can avoid tearing up the right half of the engine to get a conclusive answer.
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Old 04-24-2010, 07:49 PM
Join Date: Apr 2010
Posts: 80

They all go to the vacume t right by the throttle body. Pop the plastic cover off over the throttle body and you will see a plastic thing that has about six vacume lines plugged on to it.

By the way you got ripped by Walmart because there is no way they did an injection cleaning like this. In order to clean the injectors they need to induce the chemical cleaner into the fuel rail itself. The cleaner must pass through the injector to clean it. The only thing that this would do is just have a little attomized cleaner to pass by the tips of the injectors. What they did is essentially, a "Seafoam" worth about $8.00. It's effective at cleaning the intake manifold, valve seats and piston tops but does virtually nothing to the injectors.

Moreover, if they knew anything about cars, they wouldn't have yanked off the power brake booster hose on your 850 because of the vacume t there about five other lines that are easier to get at. The guy who did probably just got promoted from cart pushing to Walmart ASE (Always Stupid Errors) Master Tech.

Last edited by bostongrun; 04-24-2010 at 07:58 PM.
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Old 04-24-2010, 08:27 PM
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Join Date: Oct 2009
Posts: 10

Huh, so that big fat hose coming off the assist turns into one of those little lines at that crazy vacuum T?

Anyway, I wasn't charged for their incompetence, just wasted about an hour while they farted around. So, next question is: how do I go about doing an injector clean? I put some STP "fuel system cleaner" in the tank, but can't say that I've noticed any difference at all.

The reason I'm chasing this particular wild goose is that i bought the car second hand from a less-than-honest dealer about a year ago, and I have no idea what the maintenance history of the car is. I'm having really rough cold starts, with no error code in the computer, have checked the fuel pressure, and replaced the plugs and distributor with no real improvement. I'd like to eliminate any kind of crud in the injectors, cylinders, and valve guides as a cause of this problem, hence why I took it in for the cheapo "magic fix" at Wally World.
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Old 04-24-2010, 10:44 PM
Join Date: Jan 2010
Location: Montreal, Canada
Posts: 58

If I'm not mistaken, and I might be...I think the thick brake boosted vacuum line goes under the Throttle Body, its a thick hose attached right under it. I tried following mine, and it looked like it went to the brake booster...I didnt follow it exactly cuz I didnt feel like removing the Air Box, etc...but it looks like thats the one

Can anyone confirm this? Under TB to Brake Booster?
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Old 04-24-2010, 11:11 PM
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Join Date: Aug 2009
Location: Evansville, IN
Posts: 106

Yes, the brake boost goes to an elbow on the bottom side of the intake after passing under the air box and wrapping around the steering column for luck.

My two cents: Injector cleaner that you dump in the gas take is really good at working crud loose in the fuel filter to help it clog your injectors. Buy gas from reputable places, change your fuel filter at the recommended intervals and you shouldn't end up with clogged injectors.
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