SC300 Coolant leak - Can't find source
 

Thanks in advance for your comments and suggestions.

The most obvious problem is coolant is pooling under my car when I run it in the garage. It appears to be coming from behind the engine. It is dripping from the lateral support beam but on both sides of the transmission. I put her up on jack stands and slithered underneath. I had a friend crank her over but all I could see was evidence of dripping, no source!

I checked the heater hose from behind the head to the valve, from there to the firewall, from the firewall return line to the metal tube under the back of the engine. That entire system seemed dry on the outside. There is no evidence of coolant on the firewall, at least not where I can see with a headlamp by crawling on top of the engine.

I SeaFoamed the engine last night and boy did it smoke and choke AND the SES light came on! I serviced the K&N filter, cleaned the MAF and Throttle Body, replaced the spark plugs, cleaned the distributor cap and rotor with MAF cleaner (not sand paper) and reassembled her. When I went to drive off this morning, she fired up but was running rough. I thought it was just that she needed to relearn my ways. However, when I got back about 20', I could see she was leaking something. I remembered putting new "no tool" hand tighten only clamps on the upper radiator hose because I had wanted to try them. I pulled back in and reinstalled the old clamps. When I started this time she was REALLY rough and, it turns out, still leaking coolant. She died and I had to push her into the garage this time.

1993 SC300 with 181,000 miles. I have had her for a decade and taken very good care of her.

BTW, I checked the coolant hose to the bottom of the throttle body. Then, just to be certain, I put paper towels over the exhaust cover and cranked the engine; dry as a bone. I know that probably was the first thing to come to mind for many of you.

BUT...I failed to check the hose to the FRONT of the throttle body and, despite looking straight at it, never noticed it was peeing all over the top of the engine and the coolant was running down the back of the engine from there. I do not know yet whether that solves any of the other symptoms because I have to wait until the dealer opens to purchase a distributor o-ring and two of the rear heater hoses that are hard to get to any other time. YEP, I feel a little sheepish. OTOH, if this doesn't do it, the full gasket set will be here by Monday...

seems like a water linkage between you heater hose to your throttle body is leaking.