Safe to drive with vacuum leak? [Archive] - SaabCentral Forums

: Safe to drive with vacuum leak?


agtmadcat
24th December 2007, 09:01 PM
Hi, I have a quick question... I'm pretty sure my '93 900S has a vacuum leak (I'm going to test it when I get home), but I'd like to drive up to my parents' for Christmas tomorrow, which is a distance of about 40 miles. Should it be safe to drive the car a total of about 80 miles tomorrow? A quick response would be apprecaited if anyone has any ideas!
Cheers,
-AGT

Ron Hamperehill
24th December 2007, 09:14 PM
"A vacuum leak" is a pretty vague description of your problem but I would think that unless you are referring to a leak at the brake servo you will encounter no difficulty driving and even if it is brake servo keeping speed down to a reasonable level, braking early with far more foot pressure than normal would see you through.

dasander
24th December 2007, 09:28 PM
Why do you think you have a vac. leak?

c900
24th December 2007, 09:55 PM
Hi, I have a quick question... I'm pretty sure my '93 900S has a vacuum leak (I'm going to test it when I get home), but I'd like to drive up to my parents' for Christmas tomorrow, which is a distance of about 40 miles. Should it be safe to drive the car a total of about 80 miles tomorrow? A quick response would be apprecaited if anyone has any ideas!
Cheers,
-AGT

As already pointed out, unless the vacuum leak relates to a problem with the brake booster, it should be fine to drive.

If it's somewhere in the small-bore vacuum lines around the engine, you should be able to work out fairly easily where the leak is coming from by looking at the end of each piece of hose and if it's effortless to remove, that could be the leak, or there could be a crack or break in the rubber elsewhere.

If it's one of the rubber bushes that go into the intake manifold, they won't give any problem unless the hose connector piece that fits into the respective bush actually comes out when driving, which is unlikely unless the rubber of the bush is very badly decayed.

If you could give a bit more info it'll help narrow down what the problem might be, but apart from a brake control issue, you should be able to drive the car.

Craig.

Matt88S
24th December 2007, 10:40 PM
Well there is the chance it would stall the car and you would loose brake and power steering and crash the car and die in a spectacular firey crash. :o

I've had ones before where you'd let off the gas and the motor would die. Haven't had the firey crash yet though. :D

As the others have said, whats the symptoms?

Ron Hamperehill
25th December 2007, 07:42 AM
Power steering is by hydraulic pressure pump driven by engine so that won't fail. My experience of the rubber grommets at the manifold failing is that the mix is then so weak you won't be able to drive it anywhere.

900t
25th December 2007, 01:49 PM
Well there is the chance it would stall the car and you would loose brake and power steering and crash the car and die in a spectacular firey crash. :o

I've had ones before where you'd let off the gas and the motor would die. Haven't had the firey crash yet though. :D

As the others have said, whats the symptoms?

You wouldn't lose brakes either since it is electric on a 93 900 S. But you should be strong enough to press anyway, if not go to the gym :lol:

Matt88S
25th December 2007, 02:33 PM
Power steering is by hydraulic pressure pump driven by engine so that won't fail. My experience of the rubber grommets at the manifold failing is that the mix is then so weak you won't be able to drive it anywhere.

It will if the engine stalls. ;)

on my vert, if the dizzy vacuum line is on the wrong side of the butterfly, it will occationally stall when you let off the throttle, and seemly every time you go to turn is when it decides to stall, and usually the first you'll notice of it is you have no power steering, which makes things fun. :D

You wouldn't lose brakes either since it is electric on a 93 900 S. But you should be strong enough to press anyway, if not go to the gym :lol:

Good point on it being a 93. But anyway, yes I am, haven't been to the gym in a while but last time I was I was doing reps of 250-300lb leg presses. :D Sounds impressive to some people however I weight almost as much as that lower number so... :lol: I never tried to see what the max I could do was. I will however admit I can't bench much over 200, which is sad, but I was never into benching things and whatnot, just overall good shape was my goal.

For some people though, stopping or steering a car without the power assist is a serious issue.

900t
25th December 2007, 02:45 PM
It will if the engine stalls. ;)

on my vert, if the dizzy vacuum line is on the wrong side of the butterfly, it will occationally stall when you let off the throttle, and seemly every time you go to turn is when it decides to stall, and usually the first you'll notice of it is you have no power steering, which makes things fun. :D


No the steering won't have any issue if it stalls since the engine and pump are still spinning. Unless you have an automatic in which case it may or may not still be spinning.

But the steering assist isn't very much at speed anyway. If you are parallel parking you'll be like "damn this is heavy" but if you are flying down the highway you can't even tell the difference.

Matt88S
25th December 2007, 03:40 PM
No the steering won't have any issue if it stalls since the engine and pump are still spinning. Unless you have an automatic in which case it may or may not still be spinning.

But the steering assist isn't very much at speed anyway. If you are parallel parking you'll be like "damn this is heavy" but if you are flying down the highway you can't even tell the difference.

I usually hit the clutch when I let off the throttle. In that case, if it dies the engine will not still be spinning nor turning any pumps. And yes its not much, but it helps on those tight fast corners.

TheRedBaron
25th December 2007, 03:44 PM
Bring a pack of gum in case the leak gets so bad that you can't drive it (stalls left and right). Listen for the leak, use the gum to plug it.

agtmadcat
26th December 2007, 05:27 PM
I ended up getting a lift, and have only just now returned to the land of the internets. My vacuum hoses attached to the top of the engine are pretty old and worn, however the prior problem seems to have vanished. What it was doing was simply this: The revs on the engine would not drop unless I forced them down (for example with a high gear). So this meant if I revved to 2000, it would stay there after I released the throtle, likeise at 3k. When I first started it it idled properly at around 800-900, but when driving it was weird to never have the revs fall off. I asked a mechanic and he said it was probably a vacuum leak, and I'm getting it serviced tomorrow anyway, so I'm going to have them replace the old hoses. Of course, now all of a sudden it's leaking oil something fierce, so I'm going to have to look into that... could that be related to the prior problem?

Thanks guys!
-AGT

900t
26th December 2007, 05:30 PM
Squirt WD-40 on the throttle and move it with your hand, you see where the cable connects to that half-wheel with the spring on the engine? Move that thing around and squirt WD-40 at the spring part.

agtmadcat
27th December 2007, 03:45 AM
Ah, good thinking... I'll have to give that a go, cheers!