1996 3800 series II, elusive Vaccuum leak
#1
Member
Posts like a V-Tak
Thread Starter
1996 3800 series II, elusive Vaccuum leak
Found my vaccuum leak VIA a smoke machine. This one was a tough one to locate.
Anyone ever run accross this before?
It'* only been off and on twice, each time for the lower intake gasket replacement.
Anyone ever run accross this before?
It'* only been off and on twice, each time for the lower intake gasket replacement.
#3
DINOSAURUS BOOSTUS
Expert Gearhead
I constantly suggest pulling that tube and looking for that to tons of folks. Vaccum or P0171 ...this is a very common cause and you can't typically find it with carb clean testing.
#4
Member
Posts like a V-Tak
Thread Starter
I just replaced the tube with a brand new one. GM part# 24508516. I still have the problem but not as bad.
Smoke test did not reveal any other leaks. I did notice that the new pipe ends were not compressed as the original, which makes sense as it is brand new. looks kind of like a compression flange. When tightening the flanges I noticed that the flanges on both ends of the tube do not sit flush right at the tube side of the flanges, but the flanges are flush at the bolt ends and the bolts are tight. the flanges just don't seat squarely. I'm thinking that after a few heat cycles they should seat better. No? I took it for a short test drive and it stalled only once on decel. The problem seems to be getting better but I have my doubts and hoping. I did disconnect the battery overnight hoping to reset everything. I do not see any information, even on dealer world, about installing this pipe. I may have to go in for another smoke test if the problem persists.
Any thoughts on the pipe flange issue? If it'* an issue at all.
The annoying part about this whole thing is the fact that there was no driveability issues prior to the upper & lower intake reseal. It was just preventative maintainence. Go figure.
Smoke test did not reveal any other leaks. I did notice that the new pipe ends were not compressed as the original, which makes sense as it is brand new. looks kind of like a compression flange. When tightening the flanges I noticed that the flanges on both ends of the tube do not sit flush right at the tube side of the flanges, but the flanges are flush at the bolt ends and the bolts are tight. the flanges just don't seat squarely. I'm thinking that after a few heat cycles they should seat better. No? I took it for a short test drive and it stalled only once on decel. The problem seems to be getting better but I have my doubts and hoping. I did disconnect the battery overnight hoping to reset everything. I do not see any information, even on dealer world, about installing this pipe. I may have to go in for another smoke test if the problem persists.
Any thoughts on the pipe flange issue? If it'* an issue at all.
The annoying part about this whole thing is the fact that there was no driveability issues prior to the upper & lower intake reseal. It was just preventative maintainence. Go figure.
#5
DINOSAURUS BOOSTUS
Expert Gearhead
I'm assuming this to be a 3800 Series II NA motor, but your sig suggests that might not be the case. What car/motor are we talking about?
#6
Member
Posts like a V-Tak
Thread Starter
#8
DINOSAURUS BOOSTUS
Expert Gearhead
Please post your issue in a new thread that you start.
GRTP, have you checked the O-ring on the back of the upper intake? With engine movement this hose to the brake booster might flex...might only happen in gear and under load.
GRTP, have you checked the O-ring on the back of the upper intake? With engine movement this hose to the brake booster might flex...might only happen in gear and under load.
#9
Member
Posts like a V-Tak
Thread Starter
Not sure. Need to sleep on it.
Any ideas? I'm determined to find it as it is a challenge.
Thanks.
#10
DINOSAURUS BOOSTUS
Expert Gearhead
I've got one more trick... the elbow at the brake booster is a check valve. If it goes bad...you have a vacuum leak.
I'm stretching pretty far here, we gotta get this one soon.
And I wouldn't expect the smoke to get past the pcv checkball either. It'* in there to keep the crankcase from pulling air.
I'm stretching pretty far here, we gotta get this one soon.
And I wouldn't expect the smoke to get past the pcv checkball either. It'* in there to keep the crankcase from pulling air.