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re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
No idea how old it is. I've had the car about a month. Ran great for a while but has had the exhaust leak. Started to look into the exhaust leak and not on cold start up it misfires for a second and then runs great. Pulls fine and gets good mpg. so I wouldn't think the car was to bad. This is kind of my beater car that I've been fixing up and trying not to put much money into.
re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
Originally Posted by RonJ
Given you know almost nothing about the car's history and that some engine misfiring is evident, there's a very good chance that the cat is toast.
Are additional CEL codes thrown?
Bone stock 96 Civic LX or has it been modified?
That is the only code present. The car is bone stock but the motor has been replaced and has 180k miles. The body of the car has 301k miles haha. I don't have much money in it and don't want to spend $200 on a new converter if I don't need to. It is still a d16y7.
re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
Also once the car has ran for about 10-15 seconds or even less the misfire goes away. Havent looked into that problem yet as it doesn't always happen. Only sometimes. I was going to take a look at the plugs for that problem and go from there. I drive the car 120 miles a day for work five days a week lol. It does great other than the misfire at start up. no problems after an hour of driving with cruise, ac and stop and go traffic.
don't want to spend $200 on a new converter if I don't need to.
That's up to you.
Your thread has been entirely focused on an exhaust leak, which may be causing cat code P0420. I've given you an alternate theory to explore.
Originally Posted by 96Miata!
Also once the car has ran for about 10-15 seconds or even less the misfire goes away. Havent looked into that problem yet as it doesn't always happen. Only sometimes. I was going to take a look at the plugs for that problem and go from there. I drive the car 120 miles a day for work five days a week lol
After purchasing a used Civic, the first step is generally to do a tune up, especially the ignition system (plugs, wires, cap, rotor, ignition timing). When this is done, inspect the plugs, which may reveal that the engine is running rich.
If the cat is clogged, the exhaust leak may be due in part or entirety to high exhaust back pressure.
Edit: Discard this^ idea because a clogged D16Y7 cat would only increase exhaust back pressure upstream of the cat, whereas your exhaust leak is downstream of the cat.
There appears also to be a donut gasket located between the exhaust manifold-cat unit and exhaust pipe A. Did you try just replacing the donut gasket to see if the leak stopped?
Last edited by Former User; Sep 7, 2016 at 08:50 AM.
Re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
Use an old tin license plate as a new gasket. Trace the outline of the old gasket into the license plate, then cut out the correct size. After getting the size correct use copper gasket spray to coat your license plate gasket on both sides. Let the spray dry, and install on the cat to manifold connection. Be sure you scrape off any old gasket material that is left on the manifold and on the cat before you put in your license plate gasket
The tin will compress enough to be considered a gasket, the gasket spray will ensure that there is no leaks and there is a good seal
I was going to suggest home depot for a generic tin sheet, but I think an old license plate will be the correct size. Just sand it down first and get any colors off of it. In texas our plates are just flat pieces of tin, not sure if your state uses raised letters though
Re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
Originally Posted by chrysler kid
Use an old tin license plate as a new gasket. Trace the outline of the old gasket into the license plate, then cut out the correct size. After getting the size correct use copper gasket spray to coat your license plate gasket on both sides. Let the spray dry, and install on the cat to manifold connection. Be sure you scrape off any old gasket material that is left on the manifold and on the cat before you put in your license plate gasket
The tin will compress enough to be considered a gasket, the gasket spray will ensure that there is no leaks and there is a good seal
I was going to suggest home depot for a generic tin sheet, but I think an old license plate will be the correct size. Just sand it down first and get any colors off of it. In texas our plates are just flat pieces of tin, not sure if your state uses raised letters though
Ohio has raised letters on all of its plates except vanity plates. I don't have any vanity plates laying around.
Edit: Discard this^ idea because a clogged D16Y7 cat would only increase exhaust back pressure upstream of the cat, whereas your exhaust leak is downstream of the cat.
There appears also to be a donut gasket located between the exhaust manifold-cat unit and exhaust pipe A. Did you try just replacing the donut gasket to see if the leak stopped?
I did not notice the donut gasket before in the Dorman product. I thought it was only for oem cats. IF you read earlier in this thread autozone/advance auto actually sold me a donut gasket just like that. I could not get it installed. It seemed barely to big of an OD to fit. Is there a specific way to install those? When I originally took it apart there was no donut gasket there.
I can't see how that's possible based on your pictures unless the leak is at the head/manifold interface. And if that's true, the cat is almost surely toast.
Originally Posted by 96Miata!
autozone/advance auto actually sold me a donut gasket just like that. I could not get it installed. It seemed barely to big of an OD to fit.
Post pics of the end of exhaust pipe A where the donut gasket belongs.
Re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
You can weld it if you want, but then youre going to have turbulent air flow into the cat, the exhaust gas would cone out to the welds and would not be directed into the cat. Because you would be welding iron the weld would not have the same expansion properties and eventually crack.
Seriously just go to home Depot and buy a piece of tin to use as a gasket.
re: 98 Civic D16Y7 - Need gasket between exhaust manifold-cat unit and exhaust pipe A
