landerfree

So ive spent a couple weekends with my 2000 ES300 (100,000 miles) performing a dreaded knock sensor replacement. After removing intake manifold i decided to replace plugs, alternator, knock sensors (both Factory Toyota), as well as the knock sensor harness (Factory Toyota). Also did all four brake pads and rotors in the spirit of not having to worry about my Lexus

After replacing trans cooler back in its slot as well as torquing all engine components in place, i received the old P0300, 0302, 0304, 0306. After a bit of hunting i found a vacuum line to the EGR assembly broken. Ran and grabbed a new one as well as inspected plugs.

Drove it a good 30 minutes around town and parked it in the garage for the night. Next morning i pulled out and received a P0305 (missfire Cyl 5) and shortly after the temp began to climb. Expecting this may happen i had a couple of jugs of coolant ready to go, as i had the entire cooling system drained when i was taking care of those pain in the but knock sensors.

The missfire is the least of my concerns, after about 6+ gallon jugs of coolant, i decided id better search for a leak. Low and behold there was a ton of coolant near the back of the car. the next day i brought my coolant pressure tester from work and hooked it up and gave her a good pumping. It would loose pressure immediately without passing 10psi. thinking HOLY ****** i have a major leak i peaked under and there was a relatively continuous coolant leak from the rear cross member almost 30 minutes after my pressure test of the system.

Where the heck is the coolant coming from? Its not fuel, also when i check underneath, the fuel lines are all dry, dusty and undisturbed. I dont see any coolant lines in the area.

Do any lines go into the cabin for the heater/climate control and if so do you have a diagram?

Does the coolant overflow go out near the rear wheels?

Any thoughts would be appreciated
Thanks

Oro

Yes, that's how heat gets into the cabin. Check your heater hoses and heater valve.

I don't know your model year in exact detail. Our 90s model GS had a fiber-cored heater valve body that decayed with exposure to coolant over time. Later ones were ABS but I don't know when they switched.

speedkar9

So your finding the coolant leak under the rear suspension?

Have you traced the wet spots up the exhaust pipe and back into the engine bay?

My bet is that coolant by pass hose under the intake (did you replace it?) is leaking and coolant is dripping on the exhaust.

It should be steaming when it hits the hot exhaust though.

landerfree

Yes, i will look into the heater valve, ty. Im just boggles by the coolant coming out at the rear suspension?

landerfree

I havent been able to trace it back to the engine bay, and if your talking about the hose between the heads under the intake manifold, i replaced that as a precaution while doing the work and i felt certain it was good and tight. The back of the engine is dry from what i see. There is also no smoke/steam coming from the engine at operating temp. I will look into it, it does sound like bubbling when pressurized with the pump (coolant pressure tester) Would the leaking coolant follow down the exhaust manifold of bank 2 (fire wall side)?

landerfree

Hey Speedkar, i got the car up to temp and did a pressure test with the aesthetic plastic cover off. The hose you mentioned seems to be bone dry at both ends.

I also had a good look at the hoses on the fire wall as well as under the dash (drivers side), and these seem dry as well. Here are some pics. It doesnt drip when car is off. It drips slightly as it heats up, and then after a few minutes (opp temp) it pours. Also with the pressure it pours. Above the cross member are some typical fuel and evap lines that are bone dry. The inside of the cabin is also dry. I have never seen anything like this before.







I removed the heater core, and the ac duct it slides in to is dry and quite clean. Also the heater valve, near fire wall in engine bay is dry and nice. There was hardly any coolant in the heater coil, should i be concerned. usually the coils are full of juice.

fortitude

Place the rear of the car on ramps. Or if you are in a garage, back the car in with just the rear tires inside the garage. That should have enough pitch toward the front of the car
Start the car and get underneath the rear end to see exactly where it is coming from. If it is just gravity traveling toward the back, it should now move the coolant drop point toward the front of the car. This will confirm if it just traveling on the exterior of a part such as fuel lines, etc..

In the current location where the coolant drops is the evap canister. If the coolant is traveling inside a vacuum line, one would think it would trigger a code??