Leaking Coolant 7MGTE - Compression Good

[quasiinsomniac]

For the last two years, I've had coolant disappearing (I only drive this car in the summer). A compression check tests ok per the TSRM. Last year (May 09) the hose that goes from the bottom of the thermostat into the engine block started leaking then exploded (split) on me. Two months after replacing that hose, the rear coolant host that goes into the back of the upper block burst as well. This season, the same front hose that goes from the thermostat to the engine block is starting to leak again. I did a coolant flush last year with the garden hose, but past that I don't know what's wrong. After I drive the car for a while, I turn the engine off and the coolant is dripping out from that hose connector. After about an hour with the engine off, the coolant reservoir is drained dry. It seems like there is a blockage and the pressure is splitting those hoses. Also, throughout the spring, summer, early fall, the heat sometimes works and sometimes doesn't. It may not work on an evening short drive, but after a short stop, come right on for the return home.

Thanks everyone.

 

[quasiinsomniac]

I went to consult the TSRM to see if I could find anything. It looks like both those front and back hoses are on the same coolant line. And judging from the flow, it almost seems as though there is a blockage in the bottom of the thermostat housing where that front 90' hose goes into the bottom of it. Any more ideas are welcome. I'd like to know if there was a problem with the pump, if that would cause a blockage in just a specific channel of the coolant system. Thanks again.

 

[kingrichard]

have you changed the thermostat? or even tried to run with out one to see if the problem is still there?

 

[Heavy D]

not the gasket for the thermostat housing to the head of the motor? also there are 2 bolts that connects to the back of the water pump that is next to the 90* bend, check that, it happen to me when i got my car running, just one bolt was loose and i was dripping antifreeze.

 

[bombinuass]

CHECK YOUR EXHAUST MANIFOLD GASKET!!!! this happened to me and the heat from the exhaust manifold gasket leaking was causing my hoeses to bust.

---------- Post added at 03:59 PM ---------- Previous post was at 03:56 PM ----------

does the car overheat WITH coolant in it? blockage is very possible but those hoses are strong and if you just replaced them i dont see the pressure making them explode. but i guess its possible. but check your manifold gasket. heat could be making them expand and burst.

 

[quasiinsomniac]

Thanks for all the replies. In order of suggestions,

1. I have not replaced the thermostat or tried running without one. According to the TSRM, the wax stuff in the residue should keep the coolant regulated at 190'. I am not experiencing overheating so it appears the thermostat is allowing fluid through at least some parts of it once it is getting warm enough.

2. Both of those bolts are tight, I redid them when I did the timing belt last month. The gasket appears to be good as there is no coolant leaking out from that seam. I shoved a cloth under that 90' bend that goes from the front of the block to the thermostat. After running for about 15min. I removed the cloth and it was drenched with coolant.

3. These are Toyota hoses which I'm told are very good. I don't know exactly how to check the exhaust gasket without removing it. But since both hoses front and back are being affected and only one would have direct heat on it should there be a bad gasket, I don't think that's the problem. I could replace the butterfly clamp where it is leaking with one of those snake clamps, but I'm afraid that doesn't fix the problem if there is something more serious going on.

How would I check for a blockage in the bottom of the thermostat?

 

[ians13]

how come no one say pressure test the system.
Well I have been losing coolant for a year for some reason I thought it was the heater core so I just kept the valve closed, that did not help. So I pressure tested the system and it starts to drip from the water pump. The only time this would leak is after a drive and the car is turned off because it gets hotter before it cools down. The pressure in the system would build and some coolant loss would happen. When water is lost air is introduced this causes the system get hotter and possibly boil which will then again result in more coolant loss.
If I were you I would replace every coolant hose on the car with new hoses then pressure test the system to make sure there no leaks.
Air in the system will cause the reserve tank to overflow then it will go empty when the system cools down. Also have your radiator cap tested.

 

[quasiinsomniac]

Yeah, I've just about replaced every coolant hose so far!

I guess I should clarify that there is definitely a leak (so no pressure test is necesary), and its right at the front coolant outlet that goes into that 90'. Last time it started leaking, it eventually burst. It's like the leaking is a symptom and the cause is a blockage.

 

[quasiinsomniac]

Update: I started it up today after doing a coolant flush, and checking the thermostat per the TSRM (boiled it on the stove). There were traces of white smoke coming out the back at early idle and under throttle blip. Me suspects a blown head gasket even though compression tests good. Or the turbo has some coolant seals going bad (does it have coolant seals that go bad?). Thoughts anyone? I thought you had to have bad compression to have a BHG?

 

[kingrichard]

i had one that had great compression ran great and everything but if you drove more than 40 mins it would overheat, other than that i had no problems with the car...you could try bypassing the coolant to the turbo if you suspect the turbo and see where that leads you.

 

[quasiinsomniac]

What ended up being the solution to your problem with the overheating past 40 miles? And BTW, I think I mentioned this before, there is absolutely no overheating while driving and upon inspecting of the coolant flush, no oil mixing with the coolant; very strange.