92 SC with about 87k gentle miles. I've been noticing a significant amount of coolant loss that I cannot find the source of. The concern is that I see no smoke (from the exhaust or under the hood) or drips and do not smell anything. My fear is that it could be the head gasket but the car runs perfectly and I see no signs. I attempted to rent a pressure test gauge from Pep Boys and Advance Auto but none of the supplied test caps fit the radiator.
Does anyone know where I can find the appropriate test cap for this radiator? Also, are there any common areas for leaks in the SC?
Thanks for any help in advance - if you need any more info, let me know.
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Usually with blown headsket if its eating coolant means that coolant is entering the cylinder and vise versa . Therefore you would push coolant into overflow then it will not
Return because there's a leak and engine is not creating vacum to pull coolant back into radiator
Check out my tread 93 Blown head gasket it will give you a lot of insite as I went thought almost the same thing. 3 Things to check. First look at the heater hose behind cylinder 6 as another member mentioned and also when you start the car cold look at the heater control valve. Its always leaks at the lever where there is a screw that hold it. third if all check out ok do a leak down test. Mine was eating the coolant throught one of the cylinders and the head gasket has a small breach but enough to eat the coolant and evaporate it. I had no signs of coolant in the oil. I Also found when taking off the head bolts that some when not that tight. Replace all with ARP bolts from a Supra. I only had 94K on mine and it was liked that when i bought it.
its simple if you keep filling your reservoir and it keeps disappearing, drain your oil and look at the color.
you can also check the radiator to see what the fluid on top looks like (WHEN IT IS COLD).
if either looks and smells like a oil coolant milkshake, then they are mixing.
Depending on the type of BHG, it may or may not show up in the exhaust but thats the easy one to spot.
1995 Lexus SC300 5spd Na-T ( TT Ecu Mod + a few others)
2003 Lexus GX470 AWD (Prepping for build)
I will add this, there seems to be enough evidence from the posts over the years (and my own experience) that the head gasket on the #5 or #6 cylinder (closest to the back) breaks and coolant starts to seep down.
I started losing a significant amount of coolant, and it actually started before I noticed it and the car was overheating. Then I got white smoke from the exhaust on startup, then I started getting rough idle..it just got worse and worse real quick. It had about 125K at the time.
Just saying, there's a pattern with the 300 and it's most likely your HG.
A random shop quoted me $1,800. I did it with family help for $300 but it took about 3 days.
I've had trouble in the past on 2 different occasions finding blown headgaskets. Neither showed oil or coolant mixing, both had good compression, a block test didn't show anything, vacuum was just fine. The most definite way I found was a leakdown test.