ON Topic: 88 Supra overheating...

Replace the cap while you're at it.

I think it comes with one.

I was thinking about that, but the cap is openeing up and letting the coolant flow into the bottle.

The coolant I saw in the shroud was the stuff that was being purged out of the bottle...

I think I might actually get a real Toyota cap, if it fits. They're only $11...

=?iso-2022-jp?q?Hachiroku_=1B$B%O%A%m%=2F=1B=28B?= wrote in news:dZFNn.21379$ snipped-for-privacy@newsfe17.iad:

Yeah, but is it opening at a too-low pressure? If it is, the coolant will boil and spew all over the place. Bad juju, bwana...

Either a bad rad-cap, or you've got a blown head gasket. How's the stuff in the bottle smell? Rubbery? Or like paint-thinner?

You use /aftermarket/ rad caps? Eww, gross. OEM-only, for me.

DO NOT say this!!! We're talking a Supra here! Not that a 1986-1991 Supra would *EVER* blow a head gasket!!!

This is the one thing I'm praying it's not...

AFAIK, the head gasket has already been replaced and the bolts torqued to the new spec. I'm praying REALLY hard... (Although it doesn't look like that hard a job. I was already 2/3 of the way there when I replaced the spark plugs...)

AARRGGHH...

How do I know if I?ve blown a gasket?

The most usual means of detecting a BHG is by noticing your temperature gauge skyrocketing. A BHG does not directly cause the engine to run hotter

- the break in the gasket allows combustion gasses to leak into the cooling system, forcing radiator water out into the overflow bottle.

and when it does that, the bubbles in the system mean less liquid volume in the cooling passages, thus you get overheating...

get one of those chemical leak test kits. the pH of the coolant changes if the gasket is leaking - provided you haven't masked it by changing the coolant too recently.

I haven't changed it, but I added some the day before.

We found the BHG in my Soob by removing the rad cap and sticking the hydrocarbon probe at the Emission Inspection station in the radiator. I don't know if they have them any more since it's all OBD-II now...

A bad cap will open too soon so the cooling system doesn't maintain pressure, and if the cooling system doesn't maintain pressure, the boiling temp goes down, more coolant gets pushed out, air gets in, and temps rise.

A blown head gasket can allow combustion gases into the coolant, which pushes coolant out, and temps rise.

Look for oil in the coolant, either in the radiator or a milkshake appearance in the oil. Either symptom can indicate a BHG. If the coolant and oil are pristine, then you have a leak somewhere in the cooling system - radiator, hoses, cap, or heater core.

While you're poking around make sure coolant isn't weeping or leaking from the timing cover, a sign of a leaking water pump.

A gas leak detector will work.

with open deck designs, like honda d-series for instance, you only occasionally get oil/water mixing. with open deck, leakage vents exhaust gas straight into the coolant. the only symptoms are bubbling, even when cold as it gets bad, and the coolant pH test. and latterly of course, blown hoses and catastrophic coolant loss.

=?iso-2022-jp?q?Hachiroku_=1B$B%O%A%m%=2F=1B=28B?= wrote in news:O6ZNn.39700$ snipped-for-privacy@newsfe16.iad:

How's the stuff in the bottle/rad smell? Rubbery? Or like paint-thinner?

"Ray O" wrote in news:hu9ui8$81p$ snipped-for-privacy@news.eternal-september.org:

Like this one?

The coolant in the bottle looked OK. The coolant in the radiator...couldn't be seen. It must have blown a lot of it out. Last time it took a quart.

I have a new SPI radiator (I know, I know, but it was $123 compared to $487!) so I'll remove the rad, drain and flush the cooling system, and then replace and refill, and cross my fingers...

And, of course, after being nice yesterday and today, it's going to rain all weekend, and then be really nice for the next four days after...

BTW, I haven't checked the oil yet. I'll do that tomorrow.

Hey! I have one of those! Oh, wait...um, never mind...

If you overheated it , whatever the original cause, you are LIKELY now looking at another head gasket - and be VERY sure you have the head checked for warpage when it is off. They are a fantastic engine, on the whole - but not terribly forgiving of massive overheating.

It's not the PH it is checking - so having changed the coolant 2 weeks ago will have NO effect on the test.

On the M series engine it is not uncommon for a blown head gasket to NOT show up as either oil in the coolant or coolant in the oil. The exhaust sniffer at the rad cap is a pretty good diagnostic - but make sure NO antifreeze gets into the sniffer - the dedicated test kits that check for combustion byproducts works quite well - but just putting the rad pressure tester on a warmed up engine and loading the engine will tell you FOR SURE. If the needle climbs quicly on an engine running at normal operating temperature, you have a combustion pressure leak - guaranteed.

The sound you just heard was my bubble bursting...

I have a new radiator. If the rain holds off this weekend I'll put it in (it was needed anyway...) and then take it for a spin. It takes over 25 miles for the engine to start to creep up in temp.

Yeah, I think a new HG is in order...I'm hoping I can get through this summer OK and do it over the winter.

NOT something I was looking forward to doing...I believe it was replaced once, a year before I bought it in '04.

=?iso-2022-jp?q?Hachiroku_=1B$B%O%A%m%=2F=1B=28B?= wrote in news:IxiOn.33028$ snipped-for-privacy@newsfe24.iad:

Not a great idea. Leave it too long and you get corrosion and gas-cutting on the block surface,both of which will most likely render your engine uneconomic to repair. Unfortunately, you need to either park your ride or get this fixed, both ASAP.

So, uh, have you taken a whiff of the expansion bottle yet? It only takes seconds to do that, and the result could change the entire tendency of this thread...