First the background:

95 SC 300 with miles 100K+ miles. One day on the way home the car overheats. I pulled over immediately and it was out of radiator coolant. Filled it up and it was fine for a few days (monitoring the coolant level). I then noticed a small leak in the radiator and ordered a new one.

GF borrowed the car and i get a phone call later that day that the car has broken down. I get to the scene and find radiator fluid everywhere. There is no telling how long she was driving with the engine overheating (I guess long enough for the engine to stall). I filled the radiator up and it started with no problem. I then drove it home and now the radiator is spraying water out, so I park the car until the new radiator arrives.

Radiator, new hoses, thermostat, and radiator cap arrive and I install them (pretty easy job). Drive around and it overheats again.. Now I was confused, but in short it turned out the radiator cap was not sealing so the coolant system would not pressurize. I replaced the cap and then it would run fine.

A few weeks later it overheats again!???!?!? No external leaks can be found, but opening the radiator cap shows it is almost bone dry. So where is the fluid going? It is disappearin fast now. I would say 2 days of driving to work and back and I have to add water.

It is clear that coolant is leaking internally and getting burnt off. There is some white smoke on startup, and a light amount of white smoke while the engine runs.

Where do I start? I am hoping it is just a gasket, but what are some other opinions?

 

anyone?

 

This may be a task for your trusted local auto repair ... one whom you would trust with an engine rebuild, if needed. One understands one's limitations; it should be preformed by professional mechanics.

The spark plugs should be your first indication where the leak is. Remove and lay them out in order of removal, knowing which cylinder they were removed from. The ones leaking should look wet with coolant.

With the radiator cap removed so all pressures can equalize, second is to check and compare the compression of each cylinder with a screw in compression guage. Expect the leakage to be in just one or two cylinders. The leaking cylinder will be significantly lower on the compression reading; it will leak down quickly when starter is stopped.

Third is to check the pressure capacity of the cooling system by performing a pressure check on the system using the correct hand pump pressure tool. This may be available as a loaner from a local auto parts. See how fast it "bleeds down" the pressure. A leaking cylinder leaks down quickly. Limit this test to 10 psi, as not to damage the radiator or enlarge the leak..

These three checks should confirm coolant is leaking into one or more cylinders and which they are..
(Head gaskets are replaced in pairs if it's a"V" banked engine)

 

Thanks for the response. I am perfectly comfortable in the garage and taking the engine apart. But i am used to Nissan engines. I mostly wanted to know if these are typically symptoms for the SC300 with a blown head gasket, or what other potential problems it could be.

 

Have you checked if there is a leak in the coolant reservoir? This is a common problem for SC's
and I had mine replaced about a year ago.

 

Yes. There are no external leaks. I have taken care of all of them, yet coolant is still disappearing. There is white smoke from the exhaust, so it suggests coolant is leaking into the engine.

My question is: What are the possible ways the coolant can get into the engine? Head gasket? Warped head? Others ?

 

Working my way into the engine i ran across this valve that was glued on? Definitely looks like a cheap patch job. The glue was loose. Could this be causing the fluid loss? Or is this just one of many problems I might find as I move deeper into this?

 

I confirmed there is coolant in the oil.

 

The head gasket is leaking coolant.

 

I think I am going to give this a shot before going much further.

http://www.barsproducts.com/product.cfm?id=14

 

Don't do it. Those product may cause you more trouble in the future. The proper is remove the cylinder head, check for any warped on the head and block, replace all the gaskets and seals and replace head gasket.

 

bah i wanted an easy fix. Looks like the head will take awhile to remove.

 

any idea what a shop would charge to do this ?

 

Agreed, don't use the sealer. Once the engine overheats, checking the head for warping is a must. The part you showed up top is the PCV valve. Looks like it was changed, but someone forgot to replace the rubber grommet it fits into and decided to patch it into the valve cover instead of getting the proper rubber part. You can order the part through Toyota. Might as well do it correctly as you'll have the head off the block.

Sorry, no idea how much a shop will charge.

 

Thanks. I will order the valve grommet. I have taken the engine apart down to the cams. I was reading through some supra forums and most say the Head comes off pretty easy so I will tackle that today and/or tomorrow.

Wish me luck.