Topic: XJ exhaust systems - New question (3/11)

[TrueBlueXJ]

Don't know how many of you XJers have run into this dilemma before, but finding a cat-back exhaust system for a 2.5 XJ is real PIA. Some mfgs like Magnaflow say their system will fit the 4.0 and the 2.5 XJ, while Dynomax says 4.0 only. How can one setup fit both and the other one only fit one?  The simple solution would be to just go with the Magnaflow, but I don't have $438. Has anyone here ever run the Dynomax kit without complications? I imagine the only difference in systems would be the exit pipe diameter, but that still doesn't explain the inconsistency.  Any advice?

[chrisfranklin]

I know you are talking "XJ" and not CJ/Wrangler. 

I've used the Dynomax Cat-Back and the Borla Cat-Back.  And, the Dynomax Cat-Back I bought for a 2.5 YJ Wrangler was the same one sold for the 4.0L YJ - same tubing diameter, etc.  So wouldn't be surprised if the Dynomax system for XJs is the same regardless of whether engine is 2.5 or 4.0L. 
Frankly, I think the Dynomax Cat-Back is better suited for the 4.0L given the tubing diameter (2.5"?), but Dynomax seems to be ok with people running that on the 2.5L (perhaps you see some low end torque losses, etc). 

[yellowta]

On my 2000 XJ, the exhaust from the cat back looks to be exactly the same as a 4.0. It's just the down pipe that's a smaller diameter. That's how it is on mine anyway 

[TrueBlueXJ]

I think I'm just gonna buy it and make it work. There can't be any real difference, except that maybe Dynomax just didn't test fit theirs to a 2.5L so they don't say it fits one.

[TrueBlueXJ]

Well, the Dynomax 4.0 cat-back system came this week, and I put it on this morning. Bolted right up with no problems. FINALLY there's no back pressure at low rpms, so she takes off a hell of a lot smoother, and she's purring like a kitten. Sounds sweet when I hit 3rd gear    Put a K&N hi-flow filter in too.

[TrueBlueXJ]

Well, as I said in the last post, it's on an it sounds great.

BUT... now there's a nice stream of white smoke coming out the tailpipe. Not a lot of it, but it's there, and it's constant. My girlfriend seems to think it has a bluish tint to it. Normally I would think either cracked head = coolant or water in the exhaust, OR bad seals = oil in the exhuast. But it seems fishy that it's never done it until the second I fired it up with the new cat, muffler and tailpipe on. Should I be freaking out, or is it just something that comes with new exhausts? It's the Dynomax, so it's "aluminized" which sounds like a dipping process, like galvanizing. Sooo, could it just be that the "aluminized" particles are just burning out on the inside?

Has this ever happened to anyone else?

[chardrc]

i know when you get new exhaust it usually smells bad for a while.. so it could just be that the exhaust is new and needs to burn in..

[TrueBlueXJ]

I just made a trip to Advanced to pick up some oil, and asked my regular guy about it. He said they use oils and stuff on the inside of the exhaust parts, and that it will typically smoke for a while while that stuff burns out. The coolant's full up to the neck, and I just topped off the oil, which was about as low as it should be since I changed it about 1500 miles ago. So for now, no worries. 

[lanulos89]

they where talking abut sea foam, its good stuff defiantly recommend it

[TrueBlueXJ]

they where talking abut sea foam, its good stuff defiantly recommend it

I've heard that name thrown around a few times. What is it exactly?

[yellowta]

Sea foam is a detergent you can buy in a can that you suck into the motor, usually through the brake booster vaccuum hose. It breaks a lot of carbon inside the engine lose and causes an absurd amount of smoke for a few minutes. I seriously doubt that was inside your exhaust pipe. But yes, the new pipes will have an oily residue on them from the factory to help prevent corrosion and what not. Every cat back I've ever put on did that for a couple days. Also, you may notice more condesation in the exhaust due to the increased diameter of the pipes. Don't worry, your straight