oaklandish_WRX

iTrader: (10)

Need some help here... Apologies for the book, but this transpired over the last 3 ****ing days...

TL/DR at the bottom...

Info: 2002 WRX wagon, 127K miles, basically stock save for Koyo all Al radiator and some suspension goodies. Never had any cooling issues in 4+ years with the Koyo and stat the seller put in when he fixed a small leak at the outlet housing.

Problem: I was set to do the coolant/thermostat/coolant temp sensor and some other things while oil and water were drained (Oil cooler gasket at block and its hoses; with oil/filter change, too).

I drain oil and coolant, no problems. Removed the radiator and fans for working room. Wrestle the oil cooler out and clean off the oil residue, 'twas nasty. Replace gasket and cooler hoses, re-assemble and refill with oil. All good. Pulled the timing belt driver side cover and rotated the crank a few revs to inspect belt (looked fine, def not an original OEM (Gates T328)). Cleaned Crank sensor face (not as bad as I feared) and Cam sensor with belt cover off. All good.

Remove thermostat housing and besides some pretty rusty bolts, no problems. Yanked out the old t-stat. and replaced with OEM subaru stat and OEM stat gasket, correctly with bubble valve upwards. Stat housing back on and torqued correctly.

Popped the altern off and changed the eng coolant temp sensor in the coolant crossover pipe with a AZ/Duralast ("Sankei", made in Nippon) - figured what the hell, its a thermistor, how wrong could it be? More later...

With all this apart, I put on a lightweight crank pulley; used starter bump with IGN fuse out - first try and it was loose. All good. Put new Dayco belts on with new A/C idler (gates metal) as pre-emptive move (old one was "raspy" when spun). All good.

Filled block through the top hose, then connected to rad (obv. back in the car, fans connected) and continued filling (OEM coolant with 1/2 bottle OEM coolant conditioner and distilled H2O at ~50:50 ratio) while squeezing the top hose and getting plenty of bubbles out. When about 2 gall go in, I bumped the starter 2X with IGN fuse still out to prime the oil pump, since it'd been dry and REALLY drained with oil cooler off so long. Fuse in and starts right up no problem, no external leaks seen (oil or water). Heater ON and fans on high...

Fun begins...

I notice that temp gauge is rising to "normal" very quickly (~65*F ambient). OK, I think, got a bubble in there. Go back to upper coolant tank ('02, so only a rad cap on the turbo/upper tank - yuck) and start adding water. Adding more H2O and squeezing hose, seems to keep taking it (like a good girl - smirk), but temp gauge rising to 2/3rds mark, keep adding water... blipped throttle and coolant drops in upper tank, then returns. Lots of SMALL bubbles in filler neck. Temp rising to almost RED. I freak and turn eng off. Lower coolant hose is COLD as ice; upper hose is HOT, soft. Fans never came on. Let it cool a bit.

If I recall, when first re-started after coolant filled, it was making a bit more noise than I'd expected from the water pump oil pump area. Not 100% on this as I am not under it with the splash shield off very often and running motor.

Tried it again and temp jumps up again very quickly to 2/3rds and climbing... At this point, with the cold lower hose, I guess that the stat is stuck closed. Shut it off. Parts places closed, get an aftermarket stat the next day along with a "block tester" kit to see if the head gasket died during initial surge in temp. No coolant smell or steam from exhaust.

Cold motor, re-starts fine and I test for HG leaks with block tester fluid kit - DOES NOT show HC's in the coolant, checked 2X. Verified the fluid (brand new bottle) works using my stanky breath... I know these kits are not 100%, but at least gives me some confidence.

So, figure the OEM (grrrr!) stat is stuck. Let it cool and swap the damned stat with boiling-water-method verified GOOD aftermarket stat (also verified the OLD stat I pulled out *still* worked in ~170*F water). Before installing aftermarket stat, I checked the new OEM stat - DID NOT OPEN at all, even at 180+*F via a digital temp gauge (kitchen type). RAGE!

Put the new stat in, filled with coolant mix (saved in a clean bucket) and started her up.... temp jumps to "normal" (just above 1/3rd mark) pretty quickly and stays there for quite a while. Think I am out of the woods.

Then temps start rising, while I am adding more distilled and massaging the hose (wink wink). Still getting lots of very small bubbles/FOAM out the filler neck. Think windy day at the ocean foam on the sand like stuff. Temp gauge rising and can't add any more water despite hose manipulations. Upper hose hot, lower kinda warmish, both soft. Even when in the "red" motor didn't *seem* to be very hot on the exterior.

Stumped...

TL;DR - Coolant changed with stat and coolant temp sensor, can't seem to get verified good stat to open even when gauge says "she 'bout ded".

Is the janky coolant sensor throwing off the gauge reading and making me stop the motor too soon? (still have the old sensor I can put back in pretty easily).

Is my water pump dead (killed by persistent air bubble or the dry start bumping)?

Super-mega air bubble in there somewhere?

Head gasket?

halp...

She goes to the shop tomorrow unless you fine folks can point me in a direction soon.

Thanks for reading!

oaklandish_WRX

iTrader: (10)

FIXORED

YISSSS!

Following the sage advice obtained elsewhere, I put the old OEM sensor back in this morning. Started and let it idle w/o touching the throttle. It took ~9 min. to get to the first guage mark and ~12 min. to get to the normal mark (~60*F ambient, in the shade with a breeze). Heater fans were on full and set to full heat.

It never got above the Normal temp area! I actually had to siphon some coolant out of the filler funnel on the upper tank since the coolant expanded. I did work out some good sized bubbles and the "foam" was much less today - I think it was pretty well burped from before and I didn't lose too much mixture when I pulled the AZ sensor out (plugged the hole with a rubber handled tool while I swapped the copper washer back.

So I let it idle for ~30 minutes and then started revving to ~2K for a minute or so. Lower rad hose started warming a bit; I think the Koyo racing rad is just SO much bigger that it takes, at idle, a lot longer to get it all up to temp and open the stat. The junky AZ sensor had me freaked out so I never let it go long enough to get even a working stat to open and the fans to kick on.

It stopped bubbling so I put the rad cap on and turned the heater fan off. About a minute later the rad fans came on and cycled for ~1 minute. Whew...

Back together and all is well. Lesson learned.