shooting coolant out of reservoir/defunct heater

[sd88supra]

Everything was machined, I used a Felpro aftermarket headgasket. I don't get why the bhg-like symptoms didn't appear until now (it was replaced back in Oct.). Its an N/A, so I used the original bolts. I think 85 ft*lb (not ft/lb!) is too much for the stock bolts. I told my mechanic to torque it to 70 ft*lb as recommended, but even if he did use the factory specs I don't think it would blow again after 800 miles (it took 125k to blow the first time!).

It's also strange that I'm not getting the waterfall sound behind the dash when cold. Makes me wonder if there is indeed trapped air. Could it be a coincidence that both radiator caps crapped out (one is a Toyota the other one is an aftermarket, but neither new)?

I know the defunct heater is related. Any ideas?

[CyFi6]

if you have trapped air in your system it would suck fluid from the overflow, the only way its going to shoot fluid out is if something is expelling out of the engine into the cooling system, or if the coolant gets hot enough to boil. Sounds like exhaust gasses in the cooling system. It could be anything from a defective gasket to a mistake by the installer. Get a block tester kit from napa and check for combustion gasses in the cooling system.

[tsupranami]

Bad Cap. No O-Ring! Gotcha, not a turbo. Still high compression, just by piston design instead of forced induction. And machining of surfaces makes squish area smaller, which increases cylinder pressure (unless compensated by thicker gasket).

You could be onto something, though. I don't like aftermarket rad caps. New OEM Toyota has been the only thing that can hold the pressure when mine gets hot. Cheap fix to test the theory ~$10 at magauto.com, ~$15 at local dealer.

Same with the combustion gas test kit like CyFi6 mentioned. Cheap but effective test.

You could also have a good shop pressure test the system to test the cap/HG.

You say you replaced the head gasket. Did you pull the motor? Rebuild it? Did you disassemble the block, too? Because I don't know of any way to surface the block without pulling it out of the car and taking it apart completely.

I've done half a dozen Supra HG's, turbo's and N/A's. Every one had grooves worn into the block/head mating surface from the previous HG. How deeply grooved and corroded seemed to depend on if and how long the gasket was leaking prior to disassembly.

Iv'e done mine three times now, two times wrong. Once with OEM gaskets, no machine work, just cleaned extremely well, lasted a few months. Next was Titan MHG and ARP bolts with fully surfaced and lapped head only. I just cleaned the block again. That lasted until I went past 12psi boost. Then I lived with a mild BHG for 2 more years. Waterfalls and gurgling streams, ahhh....the memories! Good thing about the MHG's- even if they leak a little, they don't deform or deteriorate nearly as fast as the fiber style (OEM, FelPro, RockAuto, etc.).

I just finished a complete rebuild, fully machined and lapped surfaces, ARP studs, no leaks, no drips, no errors, @ 16psi so far.

I sure hope yours is just a bad cap! But if, heaven forbid, it's another BHG, go MHG w/ARP. It's money well spent.

[Bill UK]

I couldn’t agree with you more, well said tsupranami.