(1994 LS400)
Hi all. Could use some thoughts and opinions.
Yesterday while driving on the highway I heard squealing and ended up throughing a belt. Drove 3 more miles to the next exit where my car coasted to a stop. Instrument panel was going haywire prior to the stop. Car turned itself off, reason for the coasting stop.

Towed the car to a shop where they replaced the belt and idle pulley. Then gave the car a "block test". Tech said the car barely failed the block test...meaning after several minutes of the test it then started showing signs of exhaust in the coolent.

Thoughts? Is this 100% a head gasket crack/issue? Is there any chance a minor problem within this LS400 system can be fixed to correct things?

 

If you're not going through coolant, the cars not requiring coolant on a regular basis and its not overheating I'd just drive it. If I'm reading it right your drive belt and pulley had a problem. Exhaust in the coolant is different then exhaust in the oil, there's different ways a head gasket can fail. I lived for years with a similar issue on a older honda not saying that's the right way to handle it of course, its not, question is, is there a chance it could be a minor problem easy fix. Probably not because it seems it's coming from a combustion chamber is my guess. I don't know where else it would get in to the coolant like that other than say a hairline crack somewhere on the head ports or its a head gasket itself. It can super-heat the coolant that's a problem, imo better than getting into the oil. How many miles does it have, and is it having issues with consuming coolant and running hot?
Someone else can sure help too here I'm sure too I'm just giving my personal view doesn't mean its right of course.

 

My car has 151,000 miles. I've owned it 5 years and have NEVER had, and still dont have, a temperature problem. Car has always warmed up to that common halfway mark and stays there. But, the tech did say he needed to put more coolent in, about half a gallon, to get the level up to full when he was testing it for the block test.
Thank you so much for your thoughts on this. Just not quite ready to retire the car if I can avoid it for a while longer.