Jack Murphy

Hello everybody, I have a 2000 civic EX and just yesterday I started experiencing weird Phenomena with power loss, overheating and strange exhaust grind noise.

First off, yesterday evening I was forced to drive farther than I would have liked to on barely any gas, and my car already hard starts sometimes with less than ¼ tank, so I suspect I put some strain on my fuel pump. During that drive, some weird things happened. First of all, my exhaust did some small backfires sometimes when upshifting (Automatic), and I felt a significant power loss over time. On top of that, when I was stopped at a long light, my heat gauge started rising! This was all so weird to me, because I drove 1000 miles round trip two weeks ago with no problem, through all kinds of heat. I also Just replaced the radiator with a Denso replacement and put in all new coolant.

I investigated for a minute when I got home, and I saw one of the lower nuts on my exhaust header was halfway unscrewed. I tightened it and cranked down all the other ones. I thought this might be it. The next day driving to work the power and back pressure felt fine, but there was a strange small grinding like noise around 2k rpms when I press on the gas suddenly or back off the gas suddenly. The heat also behaved for the most part, but then towards the end of the trip at an extra long light it started to creep past the normal mark. AAgh!

What I know:
Performance problem:
-Grinding noise in exhaust with sudden changes in throttle
-Manifold exhaust nut was loose, may have burned gasket
-test pipe instead of cat
-occasional backfire with upshift
-loss of power
-new NGK plugs
-I have a two piece eBay header but I had it welded to be one piece , so leaks are only possible at donut gasket and manifold gasket

Heat problem:
-New Radiator and coolant (done by me)
-Coolant is full to the brim, if it is leaking it’s not very much
-New water pump with job (professional)
-Fan Does come on
-only overheats when idling a long time, will stay normal heat at idle for 2-3 minutes but then creeps up
-both coolant hoses are hot when car is idling

Possible factors:
My car burns a bit of oil recently, maybe a quart of oil every two or three weeks, at halfway between dots now
I don’t usually baby the car when I drive it, but I do keep up on maintenance.

Possible causes I’ve come up with:
-Bad radiator cap
-early head gasket failure
-bad O2 sensor (Denso about 5 months old)
-Loose bolt somewhere in exhaust.

If you have any suggestions or Ideas please let me know