Tired Supercharger???

Hey guys, I'm new to the forum and have recently committed to fully restoring my 95 Riviera SC. I have noticed over the past few years that my supercharger has gotten tired meaning it does not have the boost that it once had. It doesn't make any rattling noise like it's broken or anything. It still has a little boost and makes a slight whine however it lacks the "suck me back in the seat" punch and whine it once had when I got it @ 80,000 miles. I'm now @ 155,000 miles and it feels like I don't have a supercharger at all. Does anyone know what's wrong with it? How can I fix / clean it to make it work like new again? Does it need to be replaced? Thanks.

Is your service engine soon light on? If so a code could determine your problem. Otherwise things like a dirty throttle body and/or bad plugs could hurt your performance along with many other things.

155 miles is a good time to have your injectors cleaned/replaced.

Might want to buy or borrow a MityVac and check the vacuum lines on the engine. Sounds like the vac line to the boost control or the control itself little black can on the blower) is leaking maybe.

Other thoughts?

Welcome Drew

Are you saying that you literally have lower boost numbers than you did before or do you mean boost metaphorically like the car just doesn't feel like it has the power?

Hey guys thanks for the responses. I understand the basics of superchargers but have never really worked on one....

@ Ridzriv: No light on. Just changed plugs and wires. How would you go about cleaning the TB?

@ Robotennis: I've run 2 containers of chevron techron recently. Is that good enough to clean them out? Engine runs smooth as silk other than no power from the supercharger. No misfires, no codes, steady MPG. Still recommend changing injectors?

@ Alberj: I have a little hand pump used for bleeding breaks, will that work? Should I just pump air through the lines and see if I hear a leak? I actually just remembered, there's an irregular shaped black box (about 12'' x 6'') that's mounted back against the firewall that has an air hose lead going to I believe the intake area. This box has fallen off. I still have it but its not attached (hose is just dangling). Could this have something to do with my problem? Seems like an air filter to me.

@ Turtleman: I just don't have the power or pull I once had. Feels like the supercharger isn't even on the engine. The car used to have really good giddy-up now not at all.

werdstrave wrote:

Hey guys thanks for the responses. I understand the basics of superchargers but have never really worked on one....

@ Ridzriv: No light on. Just changed plugs and wires. How would you go about cleaning the TB?

@ Robotennis: I've run 2 containers of chevron techron recently. Is that good enough to clean them out? Engine runs smooth as silk other than no power from the supercharger. No misfires, no codes, steady MPG. Still recommend changing injectors?

@ Alberj: I have a little hand pump used for bleeding breaks, will that work? Should I just pump air through the lines and see if I hear a leak? I actually just remembered, there's an irregular shaped black box (about 12'' x 6'') that's mounted back against the firewall that has an air hose lead going to I believe the intake area. This box has fallen off. I still have it but its not attached (hose is just dangling). Could this have something to do with my problem? Seems like an air filter to me.

@ Turtleman: I just don't have the power or pull I once had. Feels like the supercharger isn't even on the engine. The car used to have really good giddy-up now not at all.

The blackbox is a vacuum reservoir and Yes that would have something to do with your problem.

While you are in there you probly should replace all the vac hoses. It won't cost much, there's not that many feet of hose. a meter or 2 each of the popular sizes will do it. When I did it I did not know what size hoses I needed, I asked a parts counterperson about it. He went out to the the car, looked under the hood at the hoses, sold me a few feet each or 1/8. 5/32 and 3/16 ID hose I think they were, and a box of HELP! tees, a box of HELP! adapters and another box of HELP! vac caps. Took me maybe 1/2 hour to replace all the lines and glue/fit replacements for the fitted lines.

A suggestion, I'd make certain it's got a clean air filter, then check the rubber duct from the filter box to the throttle body and make sure the engine hasn't been "dusted" due to improper sealing of the filter.

If it's been dusted and been run long enough in that condition, that will kill the rotor to housing clearances. Nothing you can do with that but replace it.

Then, move on to your fueling. Check your injector rail pressure and change the fuel filter just for the heck of it. Fuel pump may be getting tired.

Next in line is a possible clogged cat.

And on and on down the line...

I dont know if a clogged injector throws a code? it dont on my machine. Techron does nothing imo. its a waste of money.Modern fuels have enough detergents in them to keep everything clean.if you must put something other than gas in the whip,buy a big bottle of ,Lucas fuel cleaner.its good stuff.

albertj wrote:

werdstrave wrote:

Hey guys thanks for the responses. I understand the basics of superchargers but have never really worked on one....

@ Ridzriv: No light on. Just changed plugs and wires. How would you go about cleaning the TB?

@ Robotennis: I've run 2 containers of chevron techron recently. Is that good enough to clean them out? Engine runs smooth as silk other than no power from the supercharger. No misfires, no codes, steady MPG. Still recommend changing injectors?

@ Alberj: I have a little hand pump used for bleeding breaks, will that work? Should I just pump air through the lines and see if I hear a leak? I actually just remembered, there's an irregular shaped black box (about 12'' x 6'') that's mounted back against the firewall that has an air hose lead going to I believe the intake area. This box has fallen off. I still have it but its not attached (hose is just dangling). Could this have something to do with my problem? Seems like an air filter to me.

@ Turtleman: I just don't have the power or pull I once had. Feels like the supercharger isn't even on the engine. The car used to have really good giddy-up now not at all.

The blackbox is a vacuum reservoir and Yes that would have something to do with your problem.

While you are in there you probly should replace all the vac hoses. It won't cost much, there's not that many feet of hose. a meter or 2 each of the popular sizes will do it. When I did it I did not know what size hoses I needed, I asked a parts counterperson about it. He went out to the the car, looked under the hood at the hoses, sold me a few feet each or 1/8. 5/32 and 3/16 ID hose I think they were, and a box of HELP! tees, a box of HELP! adapters and another box of HELP! vac caps. Took me maybe 1/2 hour to replace all the lines and glue/fit replacements for the fitted lines.

This sounds like a possible culprit. I took the vacuum box out because the mounting broke off. The hosing was all chewed through as well. I will take a look and see what I need for hosing. I would assume it has to be pretty heat resistant. Do you know where to get it? I'm assuming the dealership would have those or can you get it from an autozone? It would be nice if someone else could help out with your HELP!s from your post above as I don't know what they are...

I have to side with albert on this matter at the moment. IF you have a vacuum leak somewhere in the vacuum line system, you will absolutely loose boost. The Boost Bypass Solenoid needs vacuum to control boost....as well as other sensors.



The HELP things albert is referring to are literally hard parts you can buy at the store. Autozone (or equivalent) has a HELP section with an array sleeved packages full of goodies. They usually have an entire "spinny thingy" completely devoted to vacuum tees and such...and their cheap.

Abaddon wrote:

I have to side with albert on this matter at the moment. IF you have a vacuum leak somewhere in the vacuum line system, you will absolutely loose boost. The Boost Bypass Solenoid needs vacuum to control boost....as well as other sensors.



The HELP things albert is referring to are literally hard parts you can buy at the store. Autozone (or equivalent) has a HELP section with an array sleeved packages full of goodies. They usually have an entire "spinny thingy" completely devoted to vacuum tees and such...and their cheap.

Thanks guys. I just looked under the hood and found the broken hose leading to the vac box (which I still have). It's 7/32'' and easy to replace. Does anyone have a S/C hose diagram. I am worried there are other hoses that have met the same demise and want to make sure everything is connected. Any help would be appreciated. I searched "96 Riviera S/C Hose Diagram" on buickforums.com. There is a short thread. They seem to exist for the 97.

Here is a vacuum diagram. Someone let me know if it's wrong. For some reason Mitchell doesn't have a Riviera diagram, so I looked up a '94 PAU with the Series I S/C motor.....I don't see why it would be different. At least this will point ya in the right direction.

Thanks a lot for the help. Just picked up some vacuum hose from Autozone yesterday and some small brackets from Home Depot so I can remount the vacuum box, or what this diagram calls the "ACSRY"?? Anyone know why there is a line that goes to the master cylinder area called "VAC BRAKE BOOSTER?" Just curious. I'm going to get under the hood tonight and make sure all my lines are there according to the diagram. I'll post back on what I find and my fixes and maybe a picture if I'm stumped.

werdstrave wrote:

Thanks a lot for the help. Just picked up some vacuum hose from Autozone yesterday and some small brackets from Home Depot so I can remount the vacuum box, or what this diagram calls the "ACSRY"?? Anyone know why there is a line that goes to the master cylinder area called "VAC BRAKE BOOSTER?" Just curious. I'm going to get under the hood tonight and make sure all my lines are there according to the diagram. I'll post back on what I find and my fixes and maybe a picture if I'm stumped.

-

Line to vac brake booster - it is the vac line to the round canister that sits behind the MC and is where the booster gets the vac from to power the brakes.

To the rest of you - I don't have a '95. If any of you can take a picture of, or point to a picture on this site of a 95's vac hose routing (showing the lines to the vac box and such) and post it that would be **great** so werdstrave gets the lines in right the first time.

Werdstrave - are you sure your vac box is good? Might have to repair or replace it. Without it you're not going to generate sufficient vacuum under power, like when driving up long inclines on the interstates, to keep the parts dependent on vacuum (the transmissions vac modulator, for starts) working.

I am not sure my vac box is good. There is no real way to test it or even open it from what I can see. No electrical connections, nothing. It's been rolling around in the back of my car/trunk for years. Do you know what's inside of it? It doesn't seem like there are any mechanical parts that could be damaged and the only way in is through the little nipple that the line connects to. Do you think there are parts that could be damaged in the chain from not having the vac box installed for so long? I hope not. The engine still runs well and accelerates, just lacks the supercharger punch. Man there is a lot I need to learn about superchargers...

werdstrave wrote:

I am not sure my vac box is good. There is no real way to test it or even open it from what I can see. No electrical connections, nothing. It's been rolling around in the back of my car/trunk for years. Do you know what's inside of it? It doesn't seem like there are any mechanical parts that could be damaged and the only way in is through the little nipple that the line connects to. Do you think there are parts that could be damaged in the chain from not having the vac box installed for so long? I hope not. The engine still runs well and accelerates, just lacks the supercharger punch. Man there is a lot I need to learn about superchargers...

question is, will the box hold a vacuum? You should be able to test with a Mity-Vac. Really, it's just a box-shaped tank.

Also - they are listed in the Trademotion catalog (1995 Buick Riviera - Collision catalog) but are listed as Discontinued. The expedient thing to do is contact a GM dealer. It is likely that a dealer will know where to get one of these. However, you may have to ask at more than one dealership. Some dealerships actively discourage sourcing of obsolete parts. If the parts person you talk to seems cooperative, you can ask them to check with Vintage Parts to see if one can be found. By the way, the tanks were less than $20.00 before being discontinued.

You may also need the "hose connector" that the tank is supposed to be attached to, those are showing available on monsterpartsonline.com and cost like $5.00 each.

Here is an image of the system if it helps, the tank is #11:

http://www.shopgmparts.com/schematics/A/AD95105.gif

If you get into the Trademotion catalog via monsterpartsonline.com or gmpartsdirect.com you will be able to see the diagram along with the names of the different parts. Many dealers use their own customized version of the Trademotion system but the results they get on a search vary - can vary a whole lot - depending on which parts sources they choose to list behind the Trademotion catalog.

A comment on this tank - primarily it's to be a vacuum reservoir for the cruise control servo. It became obsolete when GM went to an electronic servo instead of the vacuum servo for the cruise on the Riv, I think in '96 or '97.

My current guess is that in removing the box some vac hose or another got misrouted or misconnected, but I can't say. Plus, at the 10-ish year mark it's past time to refresh the vac hoses.

Albertj

I've got some good news to report and a couple questions. I was able to attach a couple brackets to the vac box and mount it to the original screws it was on. I then attached a new vac hose to it from Autozone. It worked! I got my boost back and can hear the SC turning away. One thing I did notice after punching the pedal a few times: There are certain RPMs where when I punch the pedal the SC will kick in and certain ones it won't. I'm assuming this is normal but don't fully understand it. Also, right off the line, I notice sometimes the SC will kick in but the transmission will hang up between gears and kill my acceleration. Does anyone know what could cause this? Also is there any literature on the 3800 type supercharger I could read up on so I can learn more about it?

werdstrave wrote:

I've got some good news to report and a couple questions. I was able to attach a couple brackets to the vac box and mount it to the original screws it was on. I then attached a new vac hose to it from Autozone. It worked! I got my boost back and can hear the SC turning away. One thing I did notice after punching the pedal a few times: There are certain RPMs where when I punch the pedal the SC will kick in and certain ones it won't. I'm assuming this is normal but don't fully understand it. Also, right off the line, I notice sometimes the SC will kick in but the transmission will hang up between gears and kill my acceleration. Does anyone know what could cause this?think you might re-check yoAlso is there any literature on the 3800 type supercharger I could read up on so I can learn more about it?

...do you think you could re-check the replaced vac lines for routing and connections. Any connection that is not tight will suck wind.

...also if the transmission has not been serviced in say the last 30-50,000 miles you may benefit from fluid/filter change. Hanging between gears sounds like starving for fluid. The trans pumps fluid to work when accelerating, there is no mechanical lockup under acceleration, so if the fluid is not moving neither are you...

albertj wrote:

...do you think you could re-check the replaced vac lines for routing and connections. Any connection that is not tight will suck wind.

...also if the transmission has not been serviced in say the last 30-50,000 miles you may benefit from fluid/filter change. Hanging between gears sounds like starving for fluid. The trans pumps fluid to work when accelerating, there is no mechanical lockup under acceleration, so if the fluid is not moving neither are you...

Right. The trans vacuum line may have a hole in it, or is broken down and sucking itself together under "extreme" vacuum.

Thanks guys. I drove it a little bit more over the past few days and it seems to be working fine. I'll check the lines again for leaks but they all look pretty intact. I will also check the trans fluid level. Last time I checked it was full and red. Might be time for a flush though. Again, thank you everyone for all your help. This is an awesome forum with some great people I can tell. I have a few more unrelated supercharger issues that I will post about and I will be sure to add my 2 cents to other peoples issues as well.

Abaddon wrote:

albertj wrote:

...do you think you could re-check the replaced vac lines for routing and connections. Any connection that is not tight will suck wind.

...also if the transmission has not been serviced in say the last 30-50,000 miles you may benefit from fluid/filter change. Hanging between gears sounds like starving for fluid. The trans pumps fluid to work when accelerating, there is no mechanical lockup under acceleration, so if the fluid is not moving neither are you...

Right. The trans vacuum line may have a hole in it, or is broken down and sucking itself together under "extreme" vacuum.

Any of those hoses that got oil soaked and softened probably will suck itself shut if you have decent vacuum. If you need help replacing molded vac hoses just repost, it's not tough but requires some finesse.

I'm all ears!

werdstrave wrote:

I'm all ears!

Basically for the ones that do not have molded in bends you have to get vac hose of same inside diameter and simply replace them.

There are a couple with funky little fittings on the ends (obvious when you pull them off and look at them). There are boxes of assorted "reducers" at most auto parts stores, and full line ones (the older NAPAs with racks of parts) will have them you can buy one-by-each if you specify size. So for the vac hoses that have those fittings (I think there are 2) what you do is get stock hose and reducers, then glue the reducers onto (actually, into) the hose using any good RTV gasket compound (usually Permatex Black). **be sure the reducers fit snugly on the vac fittings as well as in the vac hoses you are installing and **be sure to cement them in place.

For the larger vac hoses that have molded in bends one thing you can do is use straight hoses and plastic elbows, and cut/trim them to fit as you are installing them under the hood. This allows you to get the lengths and bends right. The 30, 45 and 90 degree elbows that you need will be available at most full-line auto parts stores, you most likely will have to ask at the counter. You conceivably could drive to the parts store *then* pull off the hard-to-copy hose and figure out how to make one up to fit. also depending on the size of that vac hose you can use extra hose and route it differently so it does not kink. Don't go nuts and use way too much hose (too much = appx. twice the original installed length, less for larger diameters).

It might also be that some of the molded hoses will be available. If your hose is original it may have the GM part number stamped on it, and the counterperson may be able to look it up in their cross reference and get you a copy of it.

Albertj