Question about 1994 Toyota 4Runner
Posted by Anonymous on
Lodhi Auto is correct about pressure testing the cooling system. However, the system should be checked at the same pressure that is listed on the radiator cap of your vehicle [ie 13 to 16 psi] Many leaks are intermittent, because the leakage only occurs when the system pressure is near the maximum. Testing a 16 psi system at 10 psi can often miss these types of leaks. Inspect ALL the rubber hoses in the system. Replace ANY hose that is bulging or swelling [larger outside diameter]. This usually happens close to the hose clamps. Typical life expectancy for rubber coolant hoses is about 10 years.
When I have a customer come in with a ruptured hose and the hoses are 10 years old or older, I advise that they change ALL the hoses. Otherwise, the remaining hoses will fail one by one, causing multiple failures, great aggravation & larger overall expense for you and needless down time of the vehicle. FYI, the aluminum & plastic radiators used in modern vehicles have a life expectancy of about 12 years.
Posted on Apr 18, 2015
Pressure test the cooling system when the engine is cold and the radiator is topped up. After pressurizing the system up to 10 psi examine the leakage all around the engine, radiator and all the joints.
Posted on Apr 13, 2015
Do as Lodhi Autos said and find whether it's the thermostat housing gasket that is initially leaking or could just be the hose clamp needs tightening if it's leaking at the hose. Also the rubber hoses seem to leak right next to where the clamp squeezes it to the thermostat nipple and you may be able to cut a little off the hose and move it down then re clamp it as a temporary fix if that is the case just until you can replace the hose. I would start there because it's the first thing you mentioned in your original post.
Let us know how you do? And good luck as overheating an engine is shortening it's useful life to the point that too hot can seize it up.
Posted on Apr 18, 2015
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Posted on Jan 02, 2017
1. Look up along the lower radiator hose. It will plug into a metal
tube on the engine side. Follow the metal tube. It goes to a housing.
The housing is kind of buried in the driver's side of the engine. There
are 2 smaller coolant tubes plugged in above it. You do not need to
touch those, although it looks at first glance like you do.
2. Disconnect lower radiator hose at the metal tube.
3. Disconnect fan switches 1 and 2. These are on elecrtical harnesses going to this housing.
4. Disconnect a sensor on the front of the engine, just above the lower hose. I believe this is the knock sensor, but I'm not sure.
5. Now for the fun part. There are 3 bolts holding this housing on. You can see one at the top. There are 2 others underneath it, such that the bolts form a triangle pattern. You will have to get the bottom 2 out by feel (blind). They are 10mm.
6. Also, if you look to the front of the housing, you will note another 10mm bolt on the front holding down a black plastic leg. This is a wiring harness duct. Remove that bolt. Trace back along the duct. There is one more bolt on the driver's side retaining the duct. There is also one on the back of the engine at the firewall / driver's side. Remove these 2 as well.
7. There is a 12mm bolt holding the metal tube from that housing to the driver's side. Remove that bolt.
8. Gently pry the plastic wiring duct toward driver's side, and back toward firewall. You have just enough to get it off of the stud on the thermostat housing.
9. Now you can pull the housing. It will not come all the way out. It will come loose enough to give you just enough clearance to remove the thermostat (barely). Once you remove the thermostat, you have to pass it downward and toward the firewall to fumble it out.
By the way, you will notice that the metal tube is kind of wiggly in the thermostat housiung. This is normal.
10. Pass the new thermostat in the same way you got the old one out. Make sure when you plug it in that it has an air bleed poppet, and that this poppet is facing up.
11. Reassemble by reversing removal. Getting the nuts / bolts back in blind is... fun...
I don't know the torque spec. You can get a torqure wrench in there barely if you get creative with extensions, knuckles, etc. I wouldn't go abouve 8-10 ft-lb.
Posted on May 01, 2009
SOURCE: coolant leaking
Hello Kasalama :
Is it possible to wash off the engine while protecting the distribuutor and other electronics so we can start with a clean and dry engine ? . * Make sure that your radiator is full and that the Radiator/ Coolant overflow reservoir is at the proper level . * I would put a large piece of cardboard on the floor and along with a bright flash light or shop light use it to guide you where the leak s coming from .
If that is not helpful , I would perform a pressure check on the cooling system . The pressure check can be performed as a diagnostic tool . Put the truck in park and apply the parking brake . Attach the pressure diapham and Start the engine . You will have to manually pump it to a specified pressure as indicated on the gauge/ manometer .
The pressure diaphram usally attaches where the " radiator cap " is . Applying pressure can show leaking hoses, pipes and leaks in the radiator or fittings .
Be mindful that you can also have a leaking Intake manifold Gasket .
I hope that this info has been of help to you .
Posted on May 31, 2009
I had the same problem, whole new radiator, new hoses, new thermostat, and still overheating. What the problem was for me...bad radiator cap...all that money and a $20 fix...try it?
Posted on Oct 01, 2009
Testimonial: "YES... I HAD THIS DONE ALREADY... BUT IT HAPPENED EXACTLY AS YOU SAID... THANKS ANYWAY!!!"
There is a heater core bypass pipe that runs from the block (under the manifold) to the bacl of theengine where you will see a flat rectangular "sheet metal" thing with a pipe coming out of it. The a rubber hose connects. You need to pull the top air plenums and intake to get to it. The p[ipe flange bolts to the block with silicone rtv as a sealant.
Posted on Nov 27, 2009
its on the driver sidde of the engine. You will see the radiator hose running to the thermostat housing. You must remove the radiator hose and thermostat housing to see it. also make sure your radiator caps seals aren't leaking, especially the one on the top passenger side of the engine!!
Posted on May 10, 2010
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