FAQ: Vacuum Hoses & Lines (Series II SC)

I had to replace those 2 coolant elbowss that are integrated in the tensioner assembly. Once I took everything apart I ended up replacing the tensioner assembly as well. THe tensioner assembly purchased at AZ actually included both coolant elbows. It sure was a pain. Might as well check your pulleys for squeaks or play at this pont and replace those if necessary

chitown_riv98 wrote:

I had to replace those 2 coolant elbowss that are integrated in the tensioner assembly.  Once I took everything apart I ended up replacing the tensioner assembly as well.  THe tensioner assembly purchased at AZ actually included both coolant elbows.  It sure was a pain.  Might as well check your pulleys for squeaks or play at this pont and replace those if necessary

Keep an eye on the plastic elbows that came with the tensioner. Guess who probably made em...

I've never seen them, they are apparently made from "unobtanium". Dorman doesn't even make one what with all of the different kinds of vacuum fittings they make. You have to cobble a bunch of crap together to replace it, or else buy the complete "vacuum harness" from the dealer.

deekster_caddy wrote:

I've never seen them, they are apparently made from "unobtanium". Dorman doesn't even make one what with all of the different kinds of vacuum fittings they make. You have to cobble a bunch of crap together to replace it, or else buy the complete "vacuum harness" from the dealer.

While it is still available, best move is to buy the "vacuum harness" from the dealer. The tees are "glued" on. It is as likely as not that it'll cost less to do so, than the cost of getting a tee that will work.

That said, you can get a hard tee and some couplers fairly easily at almost any auto part store.

Thanks all going to order harness from dealer u think it all comes complete can't tell from pic's

Does anyone know the part number for a 96 supercharged riviera vacuume harness i have been looking all over for one!

So what vacuum hoses would i be looking for? Everyone says they are very likely to break so im looking to pick up some spares, are they something that you can find at an everyday auto parts store or only through order?

I created my own from thin plastic vacuum line and rubber 'T' fittings, couplers, and adapters. I found all of these items at AutoZone for probably $10 or so.

Ah, thank you. I was a bit worried since alot of people were warning of the hoses. but at least they are easily obtainable. Is there any specific ones that you would recommend?

I can't exactly say, because I bought a few packs of various connectors and just fit them together. It can be done different ways, as long as the connections are in the correct places - follow your old tubing and use as a map.

Here are some of the parts I used (note there are several pages of parts):

http://www.autozone.com/autozone/accessories/Dorman-AutoGrade-1-8-in-dia-x-3-ft-length-multi-purpose-tubing/_/N-25ry









I hate to use the cliche "be creative", but that's pretty much all you need to do. Experiment and try a few different things. You might mess up the first try, but these parts are pretty cheap. Check it periodically to see if anything is rubbing/wearing/broken apart. If not, you'll be good!

Can't seem to find this info anywhere.

In PSI, what should I be seeing at vacuum at idle?

Do aftermarket cams affect vacuum readings?


I see ~-7PSI at idle and up to -9PSI coasting on the highway.

I had to repair some of my T fittings and I want to make sure I dont have any leaks.

Thank you

Yes, higher lift cams affect vacuum readings at idle and cruising speeds. A lot of HUGE cammed cars need to install a separate electric vacuum pump to operate normally. You do not.
It isn't -7psi, it's 7in/Hg, or vacuum. Just sayin.

I'm not sure what the reading should be with your cam, but a "negative" # is normal.

my scanner isnt reading in/Hg it's PSI.

~-7PSI @idle = -14.252175 in/Hg
~-9PSI @ highway coast = -18.324225 in/Hg

If I remember right, -14.x is right for idle. So I think I am good with my vacuum. I have electrical tape sealing my T lines.

I don't know what the scanner is reading, but I can tell you with complete certainty that a stock untouched engine will pull a full 20" of vacuum at idle, fully warmed up in Park.



An aftermarket cam may have more intake and exhaust valve duration. Duration is the amount of crankshaft degrees that the valve is open. It may also have a narrower lobe separation angle (LSA). LSA is the angle between the camshaft intake and exhaust lobe center lines. Both of these can increase overlap. Overlap is the amount of crankshaft degrees that both valves are open. Overlap decreases engine vacuum at idle. It also helps in cylinder scavenging and air flow in and out of the cylinder. It would be interesting to see what the actual specs of the cam you installed are. You need a minimum of 10" of vacuum to operate the power brakes, so I doubt the scan tool is displaying inches of mercury as my Autometer boost gauge is.

Does anyone else here on the Riv forum even run an XP cam?

I would like to know where everyone else's vacuum readings are at.

I am changing the scanner to read in/Hg for negative PSI values now and see what I get after work.

If one had a vacuum leak.. would you expect to see 16.4LTFT immediately at startup, in park, idling?

Or does it need to reach operating temps before you'd see the 16.4?

Why not go back to the basics with carb cleaner or something and spray it around the vacuum lines watching for the idle to spike?

matt270avian wrote:

Why not go back to the basics with carb cleaner or something and spray it around the vacuum lines watching for the idle to spike?

Did that. Emptied a shit ton of carb cleaner and had my ear to the stethoscope for too long. Couldnt find a thing.

The last time I was pegging 16.4+ LTFT I found the vacuum leak almost immediately with the stethescope and confirmed with the carb cleaner.

Although this issue is showing similar symptoms.. I just dont think it's a vac leak.

For example, I adjusted the MAF tune down low where I am seeing the lean 16.4. Well, I adjusted it a little too much and went 180 degrees. Started seeing -18 LTFT.
I am at work and just tried that on lunch break. I will try another MAF tune when I get home and try again.

Also, when I do peg 16.4 I will sometimes see it hover 10-12+ for a while then peg 16.4.

Sometimes I get lucky and I can coast at 12+ without hitting 16.4

I also know with the cam I need to tune the VE table and I am sure that will help too. Overall tho, the car is running great. Even with those 16.4 low throttle spikes.
I just want perfection.

I will keep posting about this until I find the simply answer that's right under my nose. (Just like it always is)



5/6/15 EDIT:

It was my MAF afterall...

so my vacuum was ~4psi for the last couple months so i knew i had a problem. I went straight to the T at the LIM because it has always been an issue. I pulled off the old one and made some autozone dorman fix....

I am now seeing 8psi at idle and 10psi at cruise! Ive never had vacuum this high before! Brakes feels awesome now.

It was sad to see the stock T fitting go because they are so rare and precious. My fix doesnt look as nice but works!