FAQ: The Exhaust Thread

Quote :

AA, do you still have a slight tick or did the wrap take care of yours?

The original wrap around the flex joint quieted things a lot. I've been running this for many years. But I always had a tick in the low RPM range that wouldn't go away. It seemed to get louder over time. When I pulled the engine last summer I found my EGR tube cracked - I'm almost sure that's what it was.

When I reinstalled the engine I wrapped the primaries and replaced the cracked EGR tube with a temp patch (exhaust weld). This was dead quiet for a couple weeks. The patch then failed and the tick came back. I replaced the entire EGR bracket + tubes with a used one from Morad, but not sure it sealed up very well. The tick is now faint but still there, only in the lowest RPM.

I'm almost certain it's the still the EGR tube, either cracked again or not completely sealed. The only other thing it could be is the crossover pipe, which I did not seal with RTV this time around, but I really doubt it. The clamps are on there really good.

Thing is, some days it goes away, then comes back when the engine warms up. Almost like the leak is so small that it's affected by temperature, or it builds up a thin layer of carbon that gets blown out after a few minutes. I intend to locate it when it gets warmer, but it's not that annoying - still 50% better than before.

mine is cracked too.i use high temp red permatex.works great.been holding for allmost 7 months now.

I've never checked my EGR tube, thanks for the suggestion. Maybe thats my problem as well.

When I put header wrap on the flex joint, I'd agree that it cut all the sound decibels I was hearing by around 50 percent. But I'm so picky and anal about things that I HAVE to find the source of this ticking. Next time I'm home, I'll definitely check the EGR tube for cracks.

https://www.youtube.com/watch?v=FQB8IInHQaU

Setton wrote:

https://www.youtube.com/watch?v=FQB8IInHQaU

I hear belt chirpin'!

I'm startin' to hear a tick during light throttle myself. It sounds like an egr thing as well. Mine's blocked off but I feel it's more leak-prone blocked off. The plates they give you to block off the exhaust side kinda suck - basically just a flat plate that you're supposed to seal with copper rtv or something. There's nothing to even hold it into place while you tighten it down. I'm wondering if it'd be any better with a gasket or if I made another one that has a knob on it to stick out into the egr delivery tube of the exhaust manifold like snuggish but not press-fit so that it'll keep it in place nicely.

wonder if i could get it to fit on the rivi! lol got a dual 3" for the trans am so i am debating weather or not to try it on the riviera the rivi exaust is all stock and it needs to go!!! might be better off buying a system from a local shop had a buddy do a full 3" on my GTP for 400 but his shop burnt down and he lost all his stuff... haven't had any luck with the trans am getting a good system so i had to go with a TSP..

How the crap do you get the exhaust manifold off? Is it possible to get to it from above or do you have to take stuff off to access it? The middle bolts on the manifold looked easiest. The outside bolts did not. Especially passenger side. The metal shield around the far Pside bolt? What's that about? Cross over pipe looks like a cakewalk compared to the front manifold!

Does the crossover pipe have to come off first before the front manifold?

Today I confirmed the source of my ticking sound with use of the mechanic's stethoscope and funnel attachment. This lets you listen to the air around the engine, rather than touching metal parts (screw driver method). A small area of black soot at the location gave visual confirmation. I'll sleep better now knowing this will be an easy fix.

Where was it leaking?

Oh, sorry. EGR, where it connects to the header. Here's a pic. You can see the soot around the flange.

Link to write-up for fix: https://rivperformance.editboard.com/t10072-write-up-egr-gasket-fix-for-tick-tick-tick

Im debating on keeping the dual exhaust or dropping down to a single. What are the pros and cons of both

Go true duals!!!!  

I think duals are aesthetically pleasing. Most performance cars have duals also...

The 3800 doesn't really justify 'true dual' exhaust - by which you mean the front and rear cylinder banks have their own down, center and tailpipes. Which is not what any of the FWD 3800s have, unless completely custom built.

Our dual muffler/tailpipes doesn't serve much purpose beyond looks. The same performance can be achieved with a carefully selected muffler and appropriately sized mid- and tail- pipe (Single in Single out)

Keep in mind that 3800s sound like crap when they are loud (IMO). I believe the dual makes it easier to select a quieter muffler.

Well I've been running 2 2 and a half 30 inch glasspacks. I'm thinking about moving down to one. just want to cut some weight down and Get rid of the 1 7/8 split at the back

deekster_caddy wrote:

Keep in mind that 3800s sound like crap when they are loud (IMO). I believe the dual makes it easier to select a quieter muffler.

The raspy jobs do. Camaro exhaust makes all the difference. Deep and burbly

Wow what size is the piping on that

2.5" down to 2.25" I believe. Not too far off from a riv. Our 91 Reatta has the same mod and sounds even more growly than that one. Think 308 Ferrari meets chevelle

Less pipe=less weight. Main reason i went single.

The purist performance approach is to replace the OEM dual exhaust with a single larger dia outlet, similar to the Regal GS. The F-Body Camaro SS of the '90s used a single exhaust in place of the true dual set-up of the Z28. At that time the SS was a considerable upgrade for the Camaro; the single exhaust reduced weight as well as increased exhaust flow.

However, there are some good reasons for keeping the OEM dual configuration. First, it is quieter than a single, larger dia tube. Buick had good reason to keep these cars quiet: the market was looking for efficiency, low Noise, Vibration, Harshness (NVH), not a gurgling muscle car. If you don't like the sound of a 90º V-6, keeping stock duals will make you a happier Riv owner.

Another reason that gets overlooked a lot is weight distribution. The grassroots racing mentality is to cut weight at all costs to make the car quicker, but there are some good reasons for having weight in certain areas, mainly F/R weight distribution, which on our Rivs is between 60/40 and 65/35, depending on the year and SC option. The OEM dual exhaust set-up adds weight to the most desirable part of the car from a balanced handling standpoint: very low and rearward. This helps a heavy FWD car like the Riv take corners more like a RWD car. You can see other attempts by Buick to shift weight to the rear, like the battery location and the aluminum hood. The more weight you can keep in back, and the more you can remove up front, the closer the F/R weight distribution will be to 60/40, a respectable number for a FWD car. Having some weight in back helps rear wheel grip.

Lastly, if you've been modding 3800s very long, especially Bonneville or Riviera, you know that our OEM exhaust flows very well, and gains very little from upgrading, aside from downpipe or headers. It's one area they got right from the factory. Until you are flowing 350-400 HP, the flow gains are probably less than 5% unless you are opening up to 3"+ dia = LOUD. We know the downpipe is restrictive, but from cat back it's very good at containing noise while flowing more than enough for good power.

I have this impression that opening the exhaust catback makes it sound better?.

Am I close? Off?

All the dudes running 2.5" or > off a 3" sounds noticeably different than the stock 2.25"?

Depends on what you think "better" means. Imo, quieter is better. Some folks like the 3800 V-6 sound, raspy exhaust, drone, etc. I know of at least one member who carefully assembled a quality aftermarket exhaust system, then went back to stock.

A cam can make it sound better, more lopey, less like a 3800.

I've got exhaust coming in my cabin right now. It's either from the two bolt holes that hold the back seat back rest down or I have a leak somewhere. I can't imagine the smell is coming from those 2 dime size holes? My exhaust was welded together and now I have this doubt that there may be a leak..
I will plug the 2 holes tomorrow just to rule it out, I looked at the welds and it looks fine.
Any sure way to test besides jacking it up and inspecting?

 

I'm sure there's some fancy equipment out there, but I would jack it up and inspect it. Another thing you could do is to take one of the O2 sensors off and run a smoke machine through the hole. That way any leaks would be obvious without you needing to start the car. Not sure if the smoke machine could cause damage though..