Cooling systems woes - I fear insanity - HELP!!!

[lunar_underground]

I've been prepping my winter beater, a 1990 Honda Civic DX Hatchback for inspection and such for the past month. I've managed to hack my way through all obstacles - seized wheel bearings, stuck brakes, disintegrated rocker panels, etc, etc - except for a nagging overheating problem. It's driving me crazy. Just when I think it's fixed, back it comes. The problem was originally a temp gauge that would occasionally spike up and then quickly dropped back down. On hot days however the car would overheat and eventually just overheat all the time after 20 or so minutes of use or under heavy load or acceleration. Suspecting a faulty thermostat, I switched it out, but the problem persisted. I did a compression test and came up with very strange numbers - 210 -215 - 180 -185 - Honda says it should be 140. I retraced my steps and checked the thermostat again and suspected it may have been cocked in the housing a bit, so i replaced it again. No change. (The lower radiator hose has been cold throughout this whole process - all other hoses have been normal.) I spent an hour jacking the car in various ways to bleed the system for fear of air bubbles being at the root of it all and finally got the lower hose to heat up consistently and imagined the problem solved. However on the way to the inspection station my overflow filled up again, although the temp was at usual operating temperature, and on the way home she started overheating again. Now she's cooling down and I'm despartately trying to follow suit. No smoke. No bad hoses. No leakage noticable when parked, running or otherwise. Both hoses to the heater core appear fine with no leaks evident under the dash. Coolant has been drained and flushed with water twice. Please help . . .

[pkbinplano]

clogged cat converter ? Have you had the coolant system pressure checked for possiblr bad head gasket ?

[SteveJ]

The Stant cooling system tester is one of the BEST tools I have ever purchased. I think I got the Model ST270 and it cost about $50 used, on ebay.

They give you several tests to do- Pressurize the system and see if it bleeds down. Allows you to look for loose hose clamps on a cool motor. Also, pressure test for the rad cap, and another test to see if you have exhaust gasses pressurizing the cooling system.

If you suspect that last one, there is another tester called a Block Chek that you fill a syringe type probe with a special fluid. Then you put it in place of the rad cap and draw in some air while the motor is running. The fluid changes color if exhaust gasses are present.

[f1reverb]

(nt)

[lunar_underground]

I've got a stant on loan from a friend - didn't come with any adapters and i thought i had the problem fixed around the time i received it, so i've yet to use it. i guess that would be the logical next step though. has anyone had any luck with the two step coolant flush products? i'm not sure the best way to rule out a clogged radiator. i'm curious about the clogged cat suggestion also - haven't heard that one before. . .