Hello all,

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.

 

300 or 400?

 

A common problem is the coolant reservoir is leaking. As they age, they tend to leak at the seams. Also, don't buy a used one, it will probably leak.

 

300, sorry

 

It is a significant loss of coolant, approximately 10 ounces a week. If you're referring to the overfill reservoir, that's almost always empty anyway. I see no leaks out of the radiator either.

Anyone know where to get the right size test cap for the radiator? I canning find one and need to conduct a coolant pressure test.

Thx

 

I would start with a leakdown test to check the headgasket first. To either keep from chasing down option after option to only have worst case scenario or possibly give you some peace of mind.

 

Leak down. Also check heater hoses beside cylinder 6 . Can leak a ton and you'd have virtually no signs

 

Ok, will do. I'm taking a look at it on Friday. I guess if all else fails, I'll conduct a compression test.

Thanks.

 

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.

 

I suffered from disappearing coolant on my 300 too.
I kept adding coolant periodically until one day I just lost too much and it overheated causing my HG to fail.

Believe it or not it was by radiator cap that started it all. It had failed allowing minor leakage under pressure. But in time lead to a major failure.

$10 part will eventually = $1000 HG job

 

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.

Not fun.

You can try one of these too, I had trouble when I did it because the leak was small so I got mixed results.
http://www.shopperschoice.com/item_n...FSiCQgod2hgA8A

 

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.