1995 SC400 Overheating problem. Need solution HELP!
1995 SC400 Overheating problem. Need solution HELP!
hi everyone who has concerned of my problem. i need help regarding of my sc400. i have an overheating problem which is a coolant was empty pretty fast. first i thought i was any leaking problem but i've seen nothing leak. but once i put a full tank of coolant than i drove it for ONE minute, coolant is all gone. who can figure it out what is just happened to my SC? thank you so much
Lexus Test Driver
Joined: Aug 2009
Posts: 1,520
Likes: 1
From: CA
Cross your fingers but check engine oil dip stick. Hope you do not have a head gasket problem and water is going inside the block down to the oil pan. If not that, there has to be a leak somewhere.
Lexus Test Driver
Joined: Aug 2008
Posts: 865
Likes: 2
From: SATX
Mine leaked in that area (as well as others).
Fixed everything BUT the waterpump. Radiator was cracked and fixed, thermo, hoses, yada yada.
Clean off the cars underside where you suspect it and check around the water pump after starting/driving and look for the leaks origin.
Fixed everything BUT the waterpump. Radiator was cracked and fixed, thermo, hoses, yada yada.
Clean off the cars underside where you suspect it and check around the water pump after starting/driving and look for the leaks origin.
You can check for the water hose underneath the sparkplug wires or the water bridge, but it's more likely the bad water pump because its seal is leaked. When you replace the water pump, it's a good idea to replace the timing belt, cap and rotors, too.
today i found a leak spot which located under, right next to engine oil pan. Could someone exactly specify what happened to my car after i found coolant was leak out from reservior tank. And how much would it cost me to repair which are parts and labor. THANK YOU SO MUCH FOR ALL THE EXPERT COMMENTS
Wow! You don't need to take too many pictures. 
The only coolant area around the back of the engine (next to the firewall) is the heater hose sized 5/8" if I"m not mistaken, the gaskets of the water bridge (casted aluminum housing that connects between the left head and the right head), the smaller hose sized 1/4" protruding from the water bridge and goes to underneath the throttle body, and one more 1/4" hose from the water bridge that goes to the EGR.
The only coolant area around the back of the engine (next to the firewall) is the heater hose sized 5/8" if I"m not mistaken, the gaskets of the water bridge (casted aluminum housing that connects between the left head and the right head), the smaller hose sized 1/4" protruding from the water bridge and goes to underneath the throttle body, and one more 1/4" hose from the water bridge that goes to the EGR.
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This is your 1UZFE engine. Don't ask me how I have this photo. It's because it's my engine that I rebuilt before putting the turbo system on. 
I'm highlighting the hose connections that could be leaked in the red rectangles. You can try to touch those areas to see if there's any coolant around them. Hopefully it'll just be the heater hose (the 2 bigger hoses) because they're on the top and easier to replace than the smaller hoses below. Also check the heater hose connections before they go into the firewall. If the water bridge gaskets are leaked (very rare), then you'll need to remove all upper and lower intake manifolds to access those gaskets, alon with the main wiring harness that's right on top of it. That's when you'll pay big dollars. I hope that won't be your case at all, and you won't have to sell your car.
Be very careful with the clamps because if they're messed up, they're very hard to be removed. All the main tools that you need is a pair of straight needle pliers and a pair of L-shape needle pliers.
I'm highlighting the hose connections that could be leaked in the red rectangles. You can try to touch those areas to see if there's any coolant around them. Hopefully it'll just be the heater hose (the 2 bigger hoses) because they're on the top and easier to replace than the smaller hoses below. Also check the heater hose connections before they go into the firewall. If the water bridge gaskets are leaked (very rare), then you'll need to remove all upper and lower intake manifolds to access those gaskets, alon with the main wiring harness that's right on top of it. That's when you'll pay big dollars. I hope that won't be your case at all, and you won't have to sell your car.
Be very careful with the clamps because if they're messed up, they're very hard to be removed. All the main tools that you need is a pair of straight needle pliers and a pair of L-shape needle pliers.
The 1UZ is a very good engine and underrated, so don't throw it away while you can fix it.
Pit Crew
Joined: Sep 2003
Posts: 170
Likes: 6
From: Arkansas
I have the same problem, but the leak seems to stop when temperature is in the range of 40F+.
These photos were taken about a month ago. The leak actually stopped since we've had warmer weather, but now it's leaking really bad since we've had extreme colder temperatures( 13'F today).
I was thinking one of the scenarios below:
1.) The seal leak has become worst from time(1 month).
2.) The new non-OEM thermostat that was installed months ago is now becoming stuck and the heating/pressure effect is pushing more coolant out of the small leak. I was driving to work this morning and my temperature gauge moved to the 3/4 mark while driving 40mph. This was just after driving 80mph for 45mins. My heat was coming and going during my 40min trip too. I was ready to pull over and turn off the car, but then it suddenly dropped back to the normal operating temperatures.
3.) Maybe the small leak has allowed enough air in the system over time to not allow the thermostat to work correctly.
Bottomline: I need to order the Water pump kit & Timing belt stuff before I become stuck. I was trying to wait until tax returns, but I think I need to get all the OEM parts on hand and drive up to a good mechanic that can do the job.
Does the Houston Toyota Dealer still offer discounts for the Water pump / Timing belt parts ?
What do you guys think?
MemphisDave
These photos were taken about a month ago. The leak actually stopped since we've had warmer weather, but now it's leaking really bad since we've had extreme colder temperatures( 13'F today).
I was thinking one of the scenarios below:
1.) The seal leak has become worst from time(1 month).
2.) The new non-OEM thermostat that was installed months ago is now becoming stuck and the heating/pressure effect is pushing more coolant out of the small leak. I was driving to work this morning and my temperature gauge moved to the 3/4 mark while driving 40mph. This was just after driving 80mph for 45mins. My heat was coming and going during my 40min trip too. I was ready to pull over and turn off the car, but then it suddenly dropped back to the normal operating temperatures.
3.) Maybe the small leak has allowed enough air in the system over time to not allow the thermostat to work correctly.
Bottomline: I need to order the Water pump kit & Timing belt stuff before I become stuck. I was trying to wait until tax returns, but I think I need to get all the OEM parts on hand and drive up to a good mechanic that can do the job.
Does the Houston Toyota Dealer still offer discounts for the Water pump / Timing belt parts ?
What do you guys think?
MemphisDave