FAQ: Vacuum Hoses & Lines (Series II SC)

yes you can branch off #4 to the FPR and trans.

Derek, that is from a 96. ours are slightly different due to the vac controlled transmission.

I am unsure of what you need the vacuum for??
Did you say you need manifold vacuum for the trans?
If so, try a tee from that port (manifold vacuum) and see how the trans responds.

Disregard the above. I posted too late and wasn't sure about the situation.

Awesome!! Thank you all very very much!!

I originally wanted to replace the oil pump (Showed signs of wear, the oil light would go on at idle, and it was worn when I looked at the old one) and replace a bad S/C (Huge knocking noise from inside). Then figured while I'm at it might as well replace the lower intake gaskets, so I don't have to later (One port was ready to go anytime) and replaced the water pump (Why not, it's all tore out anyway). Now, I should have no problem getting plenty of trouble-free miles, since I repaired or replaced the most common problems with the 3.x motor.

Rickw wrote:

I am unsure of what you need the vacuum for??
Did you say you need manifold vacuum for the trans?
If so, try a tee from that port (manifold vacuum) and see how the trans responds.

Disregard the above. I posted too late and wasn't sure about the situation.

The manifold vacuum source (No. 10) is missing from this newer model S/C. So I am going to "T" the accessory (No. 4) to t other lines

96Super wrote:

Rickw wrote:

I am unsure of what you need the vacuum for??
Did you say you need manifold vacuum for the trans?
If so, try a tee from that port (manifold vacuum) and see how the trans responds.

Disregard the above. I posted too late and wasn't sure about the situation.

The manifold vacuum source (No. 10) is missing from this newer model S/C. So I am going to "T" the accessory (No. 4) to t other lines

Oops, didn't see your edit. So yeah, that's what is going on. Should be able to start it up in about 2 hours or so (Still need to flush coolant, and change oil)

Ohh, and I replaced the Power Steering Pump too!!! Right off this has been a project, only had the car for a few days now LOL, but that's all why I got it so cheap!!

Did you replace all the pulleys while you were at it.
They are known to fail by about 100K miles and it is good preventive maintenance to replace all at the same time with serpentine belts.
There is a very good Write Up on here for that job and also a pic of the engine pulley set-up with Dayco part numbers.

Are you sure the knocking noise from the SC wasn't just the coupler.
Also known to go bad and cause a loud knocking noise from SC snout area.
You might want to take the snout off your old one and check it.
Could be all you have to do is replace the coupler (cheap) and have a good SC to keep or sell.

Rickw wrote:

Did you replace all the pulleys while you were at it.
They are known to fail by about 100K miles and it is good preventive maintenance to replace all at the same time with serpentine belts.
There is a very good Write Up on here for that job and also a pic of the engine pulley set-up with Dayco part numbers.

Thanks I did find the Write-Up, but didn't know it was a 100k thing. I know the lower intake is. I'm done with the parts store for now, I'll go ahead and wait a couple weeks to do the pulleys. Thanks for the heads up!! I guess I missed one lol

Rickw wrote:

Are you sure the knocking noise from the SC wasn't just the coupler.
Also known to go bad and cause a loud knocking noise from SC snout area.
You might want to take the snout off your old one and check it.
Could be all you have to do is replace the coupler (cheap) and have a good SC to keep or sell.

The coupler is bad on the old one, but the noise was coming from the turbines not the snout. After I removed it, I put it upside down and spun it by hand and it was defiantly coming from the turbine fins or fans whatever they are called. I am still keeping it for a core if I buy a rebuilt down the road, the junk yard didn't charge me a core, so why not. Or I can play with it and learn how to rebuild it or repair it.

Edit: Plus side by side, I couldn't feel air coming from the old one, but plenty of air in the new one. And spinning the old one by hand hard would spin about 1 revolution when my hand left the pulley. The new one would spin 2-3 revs. So the bearings in the old one are definitely bad!

If you don't mind me asking - how much did you have to pay for the boneyard SC ?

Rickw wrote:

If you don't mind me asking - how much did you have to pay for the boneyard SC ?

No worries, paid 95 + taxes, and I got it out of a 99 Pontiac Grad Prix GTP (I think that's what they are called)

Well, just finished up with the Main bearings. But.... The car is not running right, and I am sure the issue is still vacuum. As I said earlier I replaced the Super Charger with a newer one that does not have the vacuum tree. Is there anyone who has done this before? Or does someone have a vacuum diagram from a 97 or newer car? Or anything else I can do. My wore case is I have to put my broken Super Charger back on and see if runs better, but I really really don't want to do that!!!


So any help anyone can offer would be greatly appreciated.

Oh yeah, and the Traction Control is stuck in the off position, but it was working fine before, and I am pretty sure that is vacuum related also...

What year is your car again, I can't remember.
I know the SC is off a newer one but need to figure out proper hose routing based on the year of base engine with the Gen 5 SC.
When you installed the newer SC did you install your original throttle body and MAF.?
If so, did you use a TB adapter?
It is my understanding that a Gen 5 SC has a 75mm inlet diameter and our stock Gen 3 is something less. This can cause an issue.
Please refresh our memories of what got installed and modified as far as the top end goes.
Also please put some basic vehicle info in your sig. and post some pic's of your current SC set up and vacuum hose routing, it could be helpful. I wouldn't jump to fast and put the bad SC back on. I'm sure everyone here that has swapped to a Gen 5 can help with this issue.

Rickw wrote:

What year is your car again, I can't remember.
I know the SC is off a newer one but need to figure out proper hose routing based on the year of base engine with the Gen 5 SC.
When you installed the newer SC did you install your original throttle body and MAF.?
If so, did you use a TB adapter?
It is my understanding that a Gen 5 SC has a 75mm inlet diameter and our stock Gen 3 is something less. This can cause an issue.
Please refresh our memories of what got installed and modified as far as the top end goes.
Also please put some basic vehicle info in your sig. and post some pic's of your current SC set up and vacuum hose routing, it could be helpful. I wouldn't jump to fast and put the bad SC back on. I'm sure everyone here that has swapped to a Gen 5 can help with this issue.

My car is a 1996.
Kept my original TB and MAF, everything matched up, so I didn't use any adapters.

I don't have a digital camera with me at the moment, but, earlier I posted a vacuum diagram, and noted what I was attempting to do, use a T adapter connected to the extra vacuum source from on top of the super charger to compensate for the missing vacuum tree.

I think part of your problem other than figuring out some vacuum source issues is the stock TB and MAF bolted to the GEN 5.
Maybe someone with more experience on here could provide some insight into what needs to be done.
I have a Gen 5 I'm going to install soon, but I'm going to use the Northstar Kit from ZZP. I know it isn't necessary but it matches the inlet diameter and flow requirement of the Gen 5 as opposed to the Gen 3 TB and MAF.
I was told somewhere along the way that at minimum I would at least need to use an TB adapter plate, also available from ZZP.
Might want to look at their website and see if has any useful info regarding the adapter. In the meantime maybe someone else can chime in with some technical info.

Rickw wrote:

I think part of your problem other than figuring out some vacuum source issues is the stock TB and MAF bolted to the GEN 5.
Maybe someone with more experience on here could provide some insight into what needs to be done.
I have a Gen 5 I'm going to install soon, but I'm going to use the Northstar Kit from ZZP. I know it isn't necessary but it matches the inlet diameter and flow requirement of the Gen 5 as opposed to the Gen 3 TB and MAF.
I was told somewhere along the way that at minimum I would at least need to use an TB adapter plate, also available from ZZP.
Might want to look at their website and see if has any useful info regarding the adapter. In the meantime maybe someone else can chime in with some technical info.

Wow, I wouldn't of thought it would be that complicated. I figured since both S/C's were the same model, minus the vacuum tree thing.

I believe rick misunderstood what blower you are using.
i thinki can clear things up some.
You have a 96 riv, but you swapped out the blower from a 99 car. both blowers are m90 gen III superchargers, BUT the 96 has an extra vac tree on the front since we have a vac controlled transmission.
you shouldnt need any adapter or new maf/tb to run a 99 gen III blower.
later i will take a pic of my vac routing on my "stock" 96.

Mr.Riviera wrote:

I believe rick misunderstood what blower you are using.
i thinki can clear things up some.
You have a 96 riv, but you swapped out the blower from a 99 car. both blowers are m90 gen III superchargers, BUT the 96 has an extra vac tree on the front since we have a vac controlled transmission.
you shouldnt need any adapter or new maf/tb to run a 99 gen III blower.
later i will take a pic of my vac routing on my "stock" 96.

Awesome, thank you very much for clearing that up, I was pretty worried about getting an adapter, especially since I would need to wait for it in the mail. And all I really want to do is drive the thing. I have owned it for about 2 weeks, and only drove it 2 days!!

A pic of the sock vacuum routing should be pretty helpful.

To further diagnose all possibility's, do you know how to test MAP Sensor?

Yes, your right, I misunderstood what blower he installed.
Sorry for offering more confusion to an already somewhat confusing situation.

Rickw wrote:

Yes, your right, I misunderstood what blower he installed.
Sorry for offering more confusion to an already somewhat confusing situation.

Not a problem, still good info if I end up with an even newer blower down the line.

I'm also throwing around the idea of taking the guts out of the new one, and swapping it with the old one, just so I don't have to deal with this vacuum thing!

96Super wrote:

I'm also throwing around the idea of taking the guts out of the new one, and swapping it with the old one, just so I don't have to deal with this vacuum thing!

I'd be cautious about doing that. It isn't just the lobes that wear it's also the inside of the case. If anything the ID of the case will wear more than the rotating lobes as the case is of a softer material.
Unless you can accurately measure the bores in the case and the OD of the lobes I wouldn't swap components.
Just my 2 cents.

Rickw wrote:

96Super wrote:

I'm also throwing around the idea of taking the guts out of the new one, and swapping it with the old one, just so I don't have to deal with this vacuum thing!

I'd be cautious about doing that. It isn't just the lobes that wear it's also the inside of the case. If anything the ID of the case will wear more than the rotating lobes as the case is of a softer material.
Unless you can accurately measure the bores in the case and the OD of the lobes I wouldn't swap components.
Just my 2 cents.

Good point. Maybe not then....


I am looking at the vacuum diagram, and it doesn't really show where the bottom large vac line on the the TB or the bottom line of the EVAP Canister Purge valve.

I guess I'll just wait for that pic of the stock layout to see. I really really hate vacuum lines!!

little late, but here is what's on my car. (pics taken literally 5 min ago, so sorry about the dirty engine
I tried to color code it as best i could. the only one you cant see where it goes is the one under the snout on the lim.

Referring back to the picture I posted:


No. 6 is the Throttle Body, then look lower on the picture, I only see one hose that comes off the TB and leads to the (14) EVAP Canister Purge Valve. What connects to the Vacuum hole under that one on the TB? Is it a T splitter added to the tree/trans?

Also no (2) EVAP Vacuum Switch. I see 2 hoses that come off that and go somewhere, but there is a 3rd spot underneath it that looks like it should be plugged into somewhere. Is it like no 14 and 8 where it has the plug, but nothing connects to it?

I basically followed this diagram, and then replaced the 3-line tree that I am missing for a 3-way splitter that connects to the No.5, that was unused before. But this diagram leaves me confused about the other throttle body Vac, and the EVAP Switch missing connections.

I hope this explanation with picture helps, because I am lost here!!