2004 V8 coolant leak near back of motor randomly

henduford

New member
I have a 2004 4runner sport edition with the v8. I have had the water pump and timing belt replaced a few months ago. Just this last weekend i noticed my engine was running hot. Come to find out it was low on coolant and had a lot of air in the system. I have recently filled up the radiator and the overflow. Every so often when I first start it, there will be some leaking that appears to be near the rear of the motor that will leave a little puddle on the ground. It doesn't seem to leak when the motor has been running for awhile and doesn't happen every time i start it either. I have replaced the radiator cap. Any other thoughts on what could be causing it to leak just randomly when the runner starts from sitting for a long time? Could there still be air in the system that is causing problems still? Could there be something on the back side of the motor that would leak only at random times? Any help would be much appreciated.
 
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I had my timing belt and water pump done last December. I was sure that I was leaking fluid, as the level in the overflow was low. They topped it up, said it was air in the system, and since then it has been fine.
 
If you're sure it's coming from the back side of your engine, check the rubber hoses that run to (and through) your firewall to the heater core. Since rubber expands as it warms up, it's possible that you have a hole in one of your hoses that semi-seals itself as it warms up.

There aren't too many places on the back of the engine where coolant could be leaking from. My only other guess would be that it was leaking from the front and just running back along the frame or something and making it appear that the leak was in the back when it really wasn't.
 
I had my timing belt and water pump done last December. I was sure that I was leaking fluid, as the level in the overflow was low. They topped it up, said it was air in the system, and since then it has been fine.

Thanks for the response! I'm hoping that is the case and it just needs to happen a couple times, but still not sure if seeing the puddle on the ground every so often makes a difference.
 
If you're sure it's coming from the back side of your engine, check the rubber hoses that run to (and through) your firewall to the heater core. Since rubber expands as it warms up, it's possible that you have a hole in one of your hoses that semi-seals itself as it warms up.

There aren't too many places on the back of the engine where coolant could be leaking from. My only other guess would be that it was leaking from the front and just running back along the frame or something and making it appear that the leak was in the back when it really wasn't.

First of all, thank you so much for your response. I guess i'm not completely sure if it actually is on the back of the motor but thats where it looks like its coming from. But you are right, i have the skid plates under there and it could be running along them and dripping from there, however i cannot see any signs of leaking up front. it almost looked like it was coming down right where the transmission meets up with the engine. I will try and get under there when i can see it dripping on the ground and see if i can get a better understanding of where its coming from. It's really frustrating.
 
The block drains are also on the back of the motor, since both rad hoses exit near the top of the motor the shop may have drained the block. They are way up there but not really that hard to access.

They have a small pipe maybe 3/4 inch that is just curved towards the ground, enough to get a small hose to slide on.

You might even be able to see them through the wheel well
 
The block drains are also on the back of the motor, since both rad hoses exit near the top of the motor the shop may have drained the block. They are way up there but not really that hard to access.

They have a small pipe maybe 3/4 inch that is just curved towards the ground, enough to get a small hose to slide on.

You might even be able to see them through the wheel well

Thank you I'll check it out!
 
I just don't understand why it will leak after the runner has been sitting for a long time? It doesn't leak when it's not running or after it starts. Seems to be only as the engine primes to start or starts and it leaks quite a bit, then no signs of it afterwards? Any other thoughts or ideas from anyone? Thank you!
 
After having my timing belt and water pump changed I was also getting a leak and it showed up at the back of the motor dripping off of the front of the transmission. It would leak from top of water pump along the top of the motor and run down the back. Hard to find at first. the randomness could be heating cooling expansion causing the leak at a sweet spot in the process. My fix was at the front and to put a new gasket on the water pump the one in the kit was cheap and failed right away.
 
My water pump leaked right after I replaced it. The gasket that was provided with the pump had a rivet in the multilayer steel part that was directly under the webbing in the pump not allowing the pump to sit flush on the gasket. Pulled it all off, clearenced the water pump webbing just enough to clear the rivet, and reinstalled. All sealed up. The coolant trickled out and down the front of the engine, although it dripped onto the skid plate and eventually dripped out of the back of the skid plate onto the ground near the rear of the engine. I would pull the cam gear covers off and take a peak to see if there's any pink residue around the water pump since it's been off.
 
After having my timing belt and water pump changed I was also getting a leak and it showed up at the back of the motor dripping off of the front of the transmission. It would leak from top of water pump along the top of the motor and run down the back. Hard to find at first. the randomness could be heating cooling expansion causing the leak at a sweet spot in the process. My fix was at the front and to put a new gasket on the water pump the one in the kit was cheap and failed right away.

That sounds exactly like what mine could be doing. I have it at the shop that did the water pump and timing belt and they are saying they believe it's the freeze plugs and they need to take off the transmission to fix coating $855 And then whatever freeze plus need to be replaced? Does that seem legit that it could be the freezer plus and you have to pull the transmission to get to them? Also I know nothing about this so I wouldn't even know how to check the water pump if that's where is coming from. I guess I could ask the shop that did it and that had it now to check that first? Any help is much appreciated!
 
After having my timing belt and water pump changed I was also getting a leak and it showed up at the back of the motor dripping off of the front of the transmission. It would leak from top of water pump along the top of the motor and run down the back. Hard to find at first. the randomness could be heating cooling expansion causing the leak at a sweet spot in the process. My fix was at the front and to put a new gasket on the water pump the one in the kit was cheap and failed right away.
This is exactly what it was. It was hard to find and luckily I did find the actual problem because I would have been out a grand for something that wouldn't have fixed it. I almost told them to do the work on the freeze plugs but decided to have my uncle look at it first. I just got my runner back and they fixed it for free since they replaced the water pump and timing belt last November and warranty their work for 12 months thankfully.
 

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