shooting coolant out of reservoir/defunct heater

[sd88supra]

After replacing my blown headgasket, car ran perfect for about a week. Then I noticed coolant would shoot out of the reservoir, so I first thought it was trapped air, so I parked it on a steep hill and burped it. Stopped shooting coolant out of the reservoir for about a day or two. Then it started again, so I thought air was getting in through somewhere. Replaced the cap, and it stopped for a few weeks until now. I went to go burp it again only now I noticed that the heater doesn't work (because I never use it here in San Diego)! I don't think its the heater core since I don't have any coolant leaks (inside or out). I think its air getting in through somewhere. Unless its a bad thermostat, but I it doesn't overheat (could it be stuck open?).

[tsupranami]

What kind of HG did you use? Metal, OEM toyota, aftermarket fiber type? Did you surface the head? Did you use ARP bolts/studs? What did you torque the bolts too?

If you didn't surface the head, and/or if you used an aftermarket "stock" fiber style gasket, it may well be blown again. Same if you didn't up the torque to 85lb/ft.

Even the OEM Toyota HG won't hold much past stock boost on a properly prepared head and block.

[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.

[sd88supra]

yes, the engine was pulled. I'll do a compression test.

But what about the non-working heater?

[spudz29212MKIII]

This is really stupid but just my two cents. I took my res. out once and cleaned it good even replaced the rubber tubing and scrubbed the cap. I accidentally reversed the cap which has the two nozzles so instead of going into the res tank it would shoot out all over the place. Switched the hoses and worked fine.

that prolly wont help lol but im just saying.

[tsupranami]

Engine pulled. Check.

Was it a complete rebuild? Did you or the shop pull the crank & pistons? Are the new pistons stock? Oversized? Same compression ratio?

Was the block deck resurfaced? If so, how much was taken off? Was the head milled also? How much was taken off of it?

Does FelPro make HG's in different thicknesses?

No heat. Check.

No heat = no hot water in heater core *and/or* airflow blocked by debris in ventilation system.

No hot water in heater core = no water flow(control valve(s) not operating) *and/or* no water (air in system.)

No water flow = control valve(s) not operating(firewall hvac and/or thermostat) *and/or* heater control unit not operating (dash unit and/or vacuum actuator)

No water in heater core = incomplete fill and bleed *and/or* leak in cooling system

Incomplete fill and bleed - Did someone forget to have the heater on (heater core valve open) when the system was filled and bled?

The heater hose into the control valve at the back of the engine is higher than the cap. Trapped air here causes lots of problems on the 7M's. Sounds like you're aware of that, though.

Leak in cooling system = internal *and/or* external

No external leaks and all other systems are good (thermostat, radiator, cap, water pump, no collapsed hoses, etc.) = engine is overheating (abnormal timing / fueling) *and/or* there is an internal leak.

Internal leak = water in oil/oil in water *and/or* water in cylinder(s)

Water in oil/oil in water = Milkshake of Death

Water in cylinders = air in cooling system *and/or* cracked head (<1%), cracked block (<0.5%), BHG (98.5%).

Clear as Mud? Check. lol!

Hope that helps. Good luck! Keep us posted.

[sd88supra]

Well, I finally had some time to do a little more research, and it occurred to me that the thermostat could be stuck open. So I went to go start the car cold, and sure enough, there was coolant circulation in the upper hose right away. It's raining now, but when it stops I'll go to Toyota to get a new radiator cap and thermostat. I'll give you guys an update after I install them and purge it.