Re: ON Topic: 88 Supra overheating...

Maybe your thermostat has gotten lazy... and is not allowing the engine to fully warm up. Test the thermostat. If need be, replace with OEM.

First heat wave of the season... climbing grades in NH... weak rads rear their ugly head. How many cycles of overheating did you put the car through? Maybe the head gasket has been compromised. Test to see if the head gasket is sound.

Hachiroku $B%O%A%m%/(B wrote in news:dZFNn.21379$ 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.

Only two. This year. I had three episodes three years ago when the fan clutch went bad.

How do you test for a BHG?

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.

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.

Hachiroku $B%O%A%m%/(B wrote in news:O6ZNn.39700$ snipped-for-privacy@newsfe16.iad:

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

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.

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.

Hachiroku $B%O%A%m%/(B wrote in news:IxiOn.33028$ 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...

In addition to the above, I think a compression test is also appropriate.

snipped-for-privacy@FreeNet.Carleton.CA (M.A. Stewart) wrote in news:huckbr$gun$ snipped-for-privacy@theodyn.ncf.ca:

More appropriate: a PRESSURE test. This is where you feed shop-air into each spark-plug hole in turn (valves closed) and see if bubbles appear in the rad. The one that makes bubbles is the bad one.

normally, by the time a compression test shows anything, the gasket is so far gone, you have plenty of other symptoms telling you what the problem is. besides, compression tests can't easily differentiate between gaskets and burnt valves.

works well in later stages, but not definitive in early stages. particularly since the test is done cold and some gasket problems only appear when hot.

the definitive test is the chemical test of the coolant. see my response to clare. you can save yourself a lot of money just buying the reagent from a chemical supply house rather than the massively inflated prices for the "auto" version where they carefully don't tell you what it is.

If the head gasket is leaking and you value the engine AT ALL - DO NOT continue driving it. You WILL cause further damage. Ride your bicycle for a week - a head gasket replacement on even a 7MGE is only a good day's work for a decent do-it-yourselfer. Add a day for the machine shop to check (and possibly plane) the head and you should be able to do it over 3 days - working evenings.

Hachiroku $B%O%A%m%/(B wrote in news:iLFOn.137251$ snipped-for-privacy@newsfe07.iad:

Nothing good.

It means PARK IT AND PULL THE HEAD.

Hachiroku $B%O%A%m%/(B wrote in news:3vZOn.123160$ snipped-for-privacy@newsfe09.iad:

Delay this fix and you'll get a nice crusty spot of corrosion on the block where the breach is. At that point, the new gasket may or may not hold; it's a crapshoot.

I'd get it apart within 2 weeks - and if you clean up and lightly grease or oil the block deck surface (as well as the cyls) you can take your time about putting it back together. Make sure you get the surface PERFECTLY clean.

Get ALL of the antifreeze out of the cyls and put ATF around the rings.Wipe down the cyl walls with a clean oiled rag (I usually use ATF for this too) Cover the engine with a good clean cloth to keep dirt out.

Not sure what that means, but why wait?

As long as you take care of covering up the block, you can leave the engine open as long as needed. Like if you want to get the head planed.