Catalytic converter

[DanZ3]

I did quite a bit of searching and didn't find what I was looking for. I had a head gasket leak and sent coolant through the exhaust. The cat is I assume dead and besides likely fairly clogged after 37yrs. the back section was rotted so I have an OE style section ready to install. I also bought a new Bosal cat section. It hasn't arrived so I cant comment on fit etc. but will FU. My question has to do with the lack of heat shielding on the new pipe. Is all that necessary? What have others done?

[clarkitect]

The heat shielding mounts to the body above the exhaust, you should have that in place on the car, not on the exhaust.

I just replaced the rear exhaust and had the old cat welded up nice. Hopefully will hold for the rest of my life. Used a walker stainless exhaust that came with the paint pretty beat up. You can see the heat shields here.





Unless you are talking about heat shields on the underside of the cat, in which case they are gone if they ever existed.

[DanZ3]

I have all the body mounted shielding in place. I was looking specifically the shielding around the cat section top and bottom.

[superj]

which section is missing on the new piece?

[DanZ3]

See the pictures. The OE section includes a lot of heat shielding all along the down pipe through the cat. The new one (only showing the cat section) has only shielding on the cat.

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[superj]

that's 325e cat in the picture, along with the piping. yours is an 325i, right? that's the wrong one in the picture if yours is an I.

but that other shielding up along the manifold part by the flex pipe is fine. it usually gets rusty and loosens and rattles. that part along the front of the cat, also. you can add shielding if you wish but its not needed unless you are parking in tall grass

[DanZ3]

Mine is an eta. Thanks. I didn't think all that was necessary. The hot cat is shielded and the floor of the car has the heat shields in place. Should be good.

BTW the Bosal head pipe fit well after wiggling the flex section a bit so it could be maneuvered over the studs. The cat is a Magnaflow branded. I'll post some pics when done. Changing the diff is adding some time to the exhaust work.

[superj]

i have heard that from others, that the bosal kit comes with a magnaflow cat. we changed the diff on our recent 325e and it made such a difference in the car. light to light, it was a rocket with the 4.10 under it

[DanZ3]

What diff did you install? I’m working through speed sensor fitment. I’m installing a 3.07 from a Z3.

[superj]

we used a 4.10 from an early e30 318 because there was nothing local to us. we wanted a 3.73 but people think those are made of gold. the 4.10 made highway gas mileage about 20mpg but if you were only city it was more fun to drive and a little better than the eta stock 2.93 or whatever got us

[DanZ3]

I have an early eta with a 2.79 open. I’m installing a 3.07 from a 3.0 Z3. Trying to decide on the cover to use. E30 or Z3. The speed sensors are different. I only want to do this once.

[superj]

I would go with the e30 cover so your speed sensor plugs in

[DanZ3]

Decided to go with the z3 cover. 2 reasons. First the diff and sensor match so will work together. Second, if the current e30 (1984 and NLA) sensor fails a new one doesn’t fit the casting. That would require changing the cover anyway. Hope it all works. I just need to change the sensor connector.

[superj]

sounds like a fine plan to me. let us know how cool it drives with that ratio

[DanZ3]

Finally got the exhaust installed with no leaks or rattles. The fit of the down pipe section wasn’t great. I ended up having to use 2 gaskets on one of the manifolds to get it to align well enough to fit without leaks. The cat fits fine and seems to do it’s job. The connection to the down pipe is just below a bracket under the car so eliminating contact was tough. The Ansa back section fit as good as OE so no issue there. Sounds like stock as it should. One side benefit is that prior to the change my idle was high. Steady at about 1100 when warm. The new exhaust including cat and O2 sensor seems to have corrected the issue. Now when warm I’m idling about 7-800. I’ll report back on the diff performance once I get some gear oil and connect the speed sensor with a new connector.

[superj]

awesome.

[DanZ3]

Had a chance to get the car out for a short drive. The diff doesn't transform the car (face it its an eta) but does make it infinitely more drivable. Going from a 2.79 to 3.07 helped a lot in 2nd-3rd gears. Still nice do drive at highway speeds and passing is more comfortable. The exhaust still has contact somewhere under the car at random times but I can work with that. Overall worth the time. Very happy with the results.

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[superj]

That's good

I have always been a fan of that engine. Yes, it's not the high hp I motor but it's a solid fun to drive engine that gets great gas mileage, even against vehicles of today