MontegoRx

Well, I started working on this downpipe over a month ago, and the damn thing still isn't working out for me. I got a pipe and intake hose for $150 shipped. Not a bad deal. Gasket was supposed to be included. When I open the box, there's no gasket.

First weekend... I went ahead and re-used the gasket and studs that I had from the stock pre-cat. The pipe fit like ****, and I had to tug on the entire exhaust to try to get the studs to line up. I ended up only getting two studs in, but I had been working on this thing for about 6 hours, so I decided to call it a day.

Second weekend... I emailed the seller and he offered to ship me a gasket since he didn't include it in the first package. I received the gasket and picked up some new bolts. Now I can't seem to get the stud out and the nut is rounding, so I pack it up again.

Third weekend... I took the car to a shop to have them zip the stud out. Paid $40 for about 15 mins of work, but it was worth it since I couldn't get it myself (I need a torch badly for times like those). I brought the car back home with only two bolts snugged down (about 1/2 mile) anticipating putting a new gasket on and using new bolts. When I pulled the pipe off this time, I compared the gaskets and realized that the seller sent me the wrong gasket. I have no idea what the gasket he sent me even fits, but it sure as hell isn't the one I needed. After alot of cursing, I managed to get all four bolts installed.

Couple weeks later (today).... The gasket started leaking not long after I put it all back together, so I sat around and weighed my options. I decided to go cheap and easy and get some copper RTV to make a gasket. Pipe came off no problem, but that RTV is hard as hell to try to squeeze in the tight confines of the turbo/downpipe area. I managed to get a nice bead (if you can call it that) around the entire surface. Now I decided to be a thinker, so I used a ratchet strap to pull the exhaust forward while I lined up the two bottom bolts. I smeared the RTV, but I think it should be ok. The bottom two bolts started just fine, and now I can't seem to get the top two to line up. I fought with it enough that the RTV has gone through the 1-hour setting-up period. I still can't get the top two bolts in, and I'm assuming that there's probably some gasket maker in between the pipe and turbo by now, but since I had the bolts in and out so much, I might've cleared it all away.

Now it looks like I'll probably be removing the entire downpipe, scraping the gasket maker off, and attempting this whole thing again either this afternoon or tomorrow. I'm almost tempted to break out the credit card, order an entire exhaust, including a new downpipe that might fit better, and start from scratch. This damn downpipe is killing me!

cliff notes: downpipe doesn't fit well, seller sent wrong gasket, and now only two bolts are holding the dp in place and the gasket maker is probably useless at this point.

MontegoRx

Ok, I think I beat it like a red-headed **** this time.

I pulled the entire downpipe off, cleaned all of the gunk, and re-gunked the manifold. I put the dp on the mani first, to make sure all four bolts started. Then I got the trusty ratchet straps back out and used them to pull the midpipe studs through the dp. I also had some RTV on the dp/mp join, so everything SHOULD be sealed up tomorrow. Cure time is 24 hrs at 70°F - 50% Rel.humidity, so I think it should be fine tomorrow afternoon.

tphan

Wow that sound like a nightmare compared to my HKS installation experience. What dp are you installing?

As for the gasket I have an used one from my 94 if you want it.

dgeesaman

iTrader: (7)

Ugh, that sounds like a lot of effort.

Sometimes it can help quite a bit to loosen the bolts on the back side of the cat, so that there is a little more wiggle room in the whole series.

Unfortunately I don't think the RTV is gonna hold up. I've tried it on each end of the cat, and it always ends up burning up before too long.

There are few things as aggravating as exhaust components that don't fit, or chasing exhaust leaks.

Dave

Ledfoot

iTrader: (1)

...I tossed the studs and nuts and use allen head header bolts. For me this made things a little easier. Use 1/4 drive to get them snug, then 3/8 to torque them down. I may have kept 1 stud, which ever is the easiest one to get to...I forget. Make sure to use bolts designed for headers or exhaust.

The RTV thingy...I doubt that will last very long, try cutting out a gasket from asbestos gasket material, it's not metal but it's bound to last longer and seal better that RTV. You could even try cutting a gasket from and aluminum sheet. cheap and effective temporary solution.

MontegoRx

Here's the description of the Permatex RTV I used.

For 4-cylinder, turbocharged or high-performance engines. The most advanced, high temperature RTV silicone gasket available. Sensor-safe, low odor, non-corrosive. Superior adhesion. Three times more oil resistant than conventional silicones; eight times more flexible than cut gaskets. Temperature range -75°F to 700°F intermittent; resists auto and shop fluids and vibration. By Permatex.


It mentions specifically that you can use it for headers, and also mentions turbo cars, plus I've heard from a buddy that it works pretty well. I guess I'll be the guinea pig on this one!

dgeesaman

iTrader: (7)

I've used that RTV. I went through a phase of trying to find a better gasket than stock (RTV, sheet materials, etc) The problem is that EGTs often hover around 1000f on this car, and the downpipe gasket is precisely in the hottest area.

What you can do is take your old gasket, clean the surfaces with emery or crocus cloth, and then use a sturdy thin knife (utility knife). Work the knife between the layers and gently leave a little separation between them. If you push the blade all the way to the inner edge you can also stretch the inner metal ring apart. By using the knife to restore some thickness to the whole thing, it will crush and seal better.

Dave

mazda6girl

Yeah I know what you mean about exhaust heat. I was assuming somewhere in the 900 degree area just judging from the coloring I saw on my old TII's turbine housing. I was thinking of trying to "repair" the gasket, but it got pretty screwed up and the sheets were starting to separate, so it would've been pretty futile to try to reuse it.

edit: forgot I was on the wife's computer.

RotaryEvolution

iTrader: (30)

more than likely the flange is warped now, i would take the whole downpipe off and take it to a machine shop to have it resurfaced, the RTV will not hold up for long regardless of what the maker sais it will hold up to.

wouldn't be a bad idea to take a dremel and clear out the bolt holes as well a little bit since it sounds like it is an extremely close tolerance fit.

MontegoRx

Well, for anyone that searches to find info on the copper RTV, I have a verified answer for the Rx7 community. Permatex Copper RTV gasket maker does NOT hold up for more than a few gears worth of boost.

I let the car warm at idle, and all seemed fine. I took it out for a spin, and after about 20 minutes and boosting a bit, the leak is back. This is all after following the instructions to a T from the packaging.

I figured it might be a crapshoot since it was only rated to 700°F, but what the heck, at least now I know. Now I suppose I'll be making another thread in a week complaining that I tried the asbestos-type gasket material and it leaks too

White94RX

So what kind of downpipe was it??? E-bay no name? If so, that's your problem.

MontegoRx

I don't know what kind it is. It was from a forum member and doesn't have a brand name on it. I'm still debating scrapping it and getting a full exhaust for the car (one that won't need a new ECU).

MontegoRx

"Hey i got a top speed downpipe for sale. fits stock. snug but without modifications and bolts to cat noproblem."

is a direct quote from the PM

RotaryEvolution

iTrader: (30)

did you read my last post?

dgeesaman

iTrader: (7)

Mr Gasket products don't work either, just to save you the hassle. Even the Ultra Seal (metal mesh with graphite material) won't last more than a few hundred miles as a regular exhaust gasket, and probably less if used at the dp/turbo joint.

If you find a true asbestos gasket material (Klingerit makes some, although it may be very difficult to buy in the US), I'd be curious to hear about it. Apparently the EPA has never tried to buy parts for an FD.

Dave

alexdimen

iTrader: (13)

lol

White94RX

Screw it and get an HKS downpipe. It has a shaped area at the top to clear the steering shaft on a right hand drive car, which makes it a lot easier to install. Plus HKS fitment and quality is top notch. About $200

KINETIK_FD3S

if you dont want to spend much money and want to have good fitment get the TSUDO downpipe-midpipe fits very well, i baught it to see how bad a US-spec downpipe would fit around my steering shaft (RHD) and try to get it to fit so i took off the steering shaft and bolted both the midpipe and downpipe and they fit perfect till i tried to fit the steering shaft i ended up beating the s*#t out of it and getting a HKS downpipe.

Nat6c

iTrader: (1)

hey montego. dont' blame me for the d/p. it fit perfectly fine on my fd. never had fitment issues like you did. i do apologize for forgetting the gasket. and i sent as promised. if there was an issue you should pm'ed. or emailed me. i woulda fixed it. or helped you out. you never pm'ed, emailed. nothing so i assumed everything worked out fine... post a pix of the gasket. if it's the wrong one ill send you the correct one.

Los.

p.s. i has all for 4 fac studs in place and downpipe fit fine.

tphan

IMO HKS DP is great...fit better than stock.

As for gasket sealer I used Permatex Ultra Copper (orange stuff) on my 408 cid SC cobra...held up pretty good. Much better than Felpro exhaust gaskets (blew 2 in less than 3 mths apart).

dgeesaman

iTrader: (7)

I think the EGTs on a S/C V8 are far lower than 1000f.

CantGoStraight

The biggest problems I've seen when people try to install there downpipes is that they try and do it with the main cat bolted to it or just in the way. You should bolt it to the turbo's without having anything else in the way or hooked to the down pipe.

RaPtOr-T

I thought the HKS fit well, but didnt really have the best flow? Anyways Im sure anything is better than the stock nuclear reactor. Do yourself a favor, and do this RIGHT! You dont want to be constantly going under there, it is hell. Get a/the factory gasket, and take it to a shop that can lift the car in the air and get it on right! When I did my downpipe I took out all 4 studs, but could not get 1 of the bolts all the way in and it causes a little leak. Since I already removed all 4 studs, I didnt have any worrys of the shop breaking a stud or anything like that, plus I took it into a high performance truck shop (trucks are ALL about turbo this and that). They had to retap the one bolt I could not get , because in my attempts I had cross threaded it! All together it was about 120 dollars to install, expensive, but atleast I can drive my car without worrying about the thing falling off or leaking! From now on anything exhaust I have done by someone that can lift the car, I just dont have the tools to work on exhuast.

RotaryEvolution

iTrader: (30)

the problem of sealing isn't the gasket it is usually warped flanges, loose bolts cause exhaust leaks, exhaust leaks cause warped flanges, you get the picture... no sealer i have used yet has ever worked for semi-permanent exhaust sealing purposes, they usually leak within 100 miles, usually a lot less regardless of their 1300F claims.