Landon303

iTrader: (25)

Hey guys- Expecting the worse-

Bought a used engine, as it was cheaper this way than rebuilding, but looks like it was a risk. Prior to buying, I did a coolant pressure test of just the block. Held @ 13 lbs for a few minutes until the silicone between the front iron & WP housing block off plate failed. Engine was removed from an NA in prep for a T2 swap.

Anyway, I have it installed in the car now.

-All ducting is in place
-New coolant
-OEM clutch fan
-Aftermarket copper tank radiator, had blown out by a rad shop & pressure tested, held.
-injectors all cleaned
-New thermostat 180*
-No leaks when pumped to 13lbs w/ pressure tester.

*water pump was re-used, however, new gaskets are in place, & again, no leaks

Here's what's going on: The car comes up to operating temps (it's an 87, so 1/4 up the gauge) rather quickly- in only about 3/4 a mile of driving from a cold start. However, it doesn't stop at 1/4. It will continue up to the 3/4 mark on the temp gauge, a confirmed 220*F w/ an infared thermometer measure at the rear iron's outter surface, and 231*F at the top tank of the copper rad. The gauge sits at 3/4 no matter if I'm at a stand still or going 60 on the freeway.

Other than exhaust gases getting into the cooling system from a bad o-ring which lets combustion in, but not coolant out, I think the problem could be from:

-Thermostat not opening fully/at all
-bad water pump? Though the upper rad hose has plenty of pressure when up to operating temp..

Any help would be great- I'm prepared to pull this out again & actually open it up/rebuild this time, so if that's the case no big deal, just some $ & time wasted. But if that's avoidable, that would be great!

TL;DR: Engine slowly creeps up to a 220*F temp when measured w/ an IR thermometer at the rear iron. All shrouding/fan is in place, no leaks as tested with pressure tester, new thermostat, radiator has been blown free of clogs.

Thanks!

MIDNFauciUSN

iTrader: (8)

If you've verified that the cooling system is holding pressure, it sounds like the thermostat isn't opening fully, or the water pump may be bad.

Did you get the thermostat from Mazda? I was in a pinch and went to Autozone to hold me over. I asked for the 180 degree one, and their stock system was screwed up... they actually gave me a 195 one.

In any case, make sure you've got an OEM one.

Landon303

iTrader: (25)

Its not a Mazda but I did obtain it from a mazda service shop locally here. It has 180*F stamped on it, the bypass blockoff when opened, and a jiggle pin in the fsm posistion. It may be not opening fully/at all, I'll have to pull it & boild some water to see.

Waterpump is definitely a possibility, though the impeller looked fine when I had it off

SpikeDerailed

iTrader: (7)

How many times did you heat cycle the engine? It took my car 4 times after putting the koyo rad in to full bleed the air out.