Coolant leak from what appears to be center rear of motor. (5 Viewers)

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Noticed coolant was a bit low, looking under the truck I saw a bit of pink fluff on the trans bell housing. Looking down from the driver side rear of the motor I then see some more pink fluff coming from what seems pretty close to the center of the motor. Its pretty tight in there and view is limited also due to the hard line that seems to be there. I am going to grab a extension mirror and see if I can investigate further but wanted to see if anyone has any idea what back there could be leaking very slowly. I guess it could also be something in the valley under the IM leaking and flowing backwards but not sure. Have looked online trying to find a diagram of the full cooling system including the back of the motor but cant seem to locate a complete diagram of the system.

Most online searches for 5.7 coolant leaks keep coming back with water pump but that was changed about 2k miles ago and nothing else was leaking at that point.

If anyone have any ideas or has access to the diagrams it would be greatly appreciated.

Just for perspective, pic is my phone stuffed down the back of the motor on the driver side looking down at the back of the motor. This was the first time ever I thought man a selfie stick would have come in handy to get a close look lol...
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I had a coolant leak in my '08 @120k miles that was in the valley under the intake manifold. Found it incidentally while replacing chewed wiring harness on knock sensor.
 
Do you happen to recall what the issue was? A leak under there thats flowing backwards seems very plausible and we are at about 112k, also an 08.
 
found some nice cut away pictured of the 3UR. Looks like the only thing kind of under the manifold is the crossover pipe but that seems to be towards the front from what I see but i guess it could be flowing back. Should be easy to see if its leaking without removing the manifold I would think. Will take a closer look tonight.

Tundra 5.7L Engine (Cut Away) - Lextreme: Lexus-Toyota V8 Forum

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nothing on the back should leak coolant from what I can see.

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The leaking spot was driver's side front but can't remember too many more details. It was very hard to see.
 
The leak lives in here, somewhere around the perimeter. This is what Toyota calls a heat exchanger cover, or a valley plate cover in normal speak. The valley plate coolant leak is becoming known across the UR series V8s. There is also a slight chance the two hose/tube connections on the left could be the culprits. If you need any other pics of this, or what needs to be removed, I can oblige.
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Thanks you, this makes sense the way its dripping off the back. Will check the two pipes if I can but guessing its the cover and the IM will need to come off. If you could let me know whats involved and any pics that would be great!
 
Looking into the valley through the small opening on the driver side I think I found the leak and it is the heat exchange cover as you said.

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Mine did exactly the same. It was the heat exchange cover. 750$ at Toyota shop.
Mine is a 09 with 65k miles.
 
So if one is afflicted with this, is a one time repair all that's necessary or is there a deeper flaw that will cause the leak to happen again?
 
The main parts to remove are the intake manifold, air injection parts, and the large plastic crank case oil separator.

I have do not have much info on a definite cause for the leak. Toyota simply re-seals the cover. They do charge a crazy amount of money for the Threebond manufactured sealant... It a 1282b for LLC and SLLC coolant, but $80 for a tube... 1207b is rated for engine oil and both coolants, and is far less expensive... Perhaps the factory used the 1207b, it doesn't hold, and now the 1282b is utilized? We need to dig deeper.
 
Just called my buddy at Toyota and I guess this is quite a well know issue they see a lot in the Tundras being they sell so many compared to the LC but he said the same, remove IM and reseal it. Said about 5 hours. Also said that its leak so little generally that engine failure is not a concern and to watch the level for now and will take care of it next time I take it in.
 
Argh, just noticed I'm also losing coolant, about half reservoir bottle per 500 miles, it was easy to notice as I just completed 2k miles. I thought it was the water pump but didn't see any pink residue down there with a mirror. I'll have to check this back area tonight.

125k 08

Brian, is your's leaking?
 
What coolant are you using?

I know we've talked about the long life coolant from Toyota as possibly being problematic with the water pump. Seems fair to say may be implicated in this leak as well. Going to be replacing my radiator soon (preventative) and don't want to put in the wrong stuff!
 
Argh, just noticed I'm also losing coolant, about half reservoir bottle per 500 miles, it was easy to notice as I just completed 2k miles. I thought it was the water pump but didn't see any pink residue down there with a mirror. I'll have to check this back area tonight.

125k 08

Brian, is your's leaking?

If you take off the engine cover, you can peek under the manifold from the driver side front of the motor as the picture above shows and if leaking that much it should be quite apparent. The mileage seems about right, this should probably be added to the things folks should look for when looking for a 200 along with the water pump leak as it seems to be a pretty common occurrence on the 3UR motor.
 
What coolant are you using?

I know we've talked about the long life coolant from Toyota as possibly being problematic with the water pump. Seems fair to say may be implicated in this leak as well. Going to be replacing my radiator soon (preventative) and don't want to put in the wrong stuff!

I use the SLLC pink, but only because I wasn't doing a full flush back when I was adjusting the ratio.
 
I did remove the cover and checked both sides on top of the engine and didn't see any pink residue. I may not be checking the right area, is it on the back side by the firewall?

I may also be approaching the 40:60 ratio as I find myself adding distilled water every couple of weeks.


edit: re-read, back of motor, will check today again.
 
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The leak I had starts under the manifold so its not on top. You need to look in the little gap on the right side of the throttle body (when facing the car) and there is a gap where you can see under the manifold and above the block. You can also look on the back of the motor from above and see if you see any residue.

Mine leaked there and then flowed back so there was residue on the back of the motor going down to the transmission so was very apparent on the back of the motor making me think thats where it was coming from but ended up being the leak under the manifold that was flowing backwards and coming down the back of the motor.

Also at first it was thought it was not that big a deal but when they took it apart they said the leak was actually pretty bad so not one to put off for too long.
 
I went in for the known issue with the Radiator crack at top and they found the "Valley Coolant" leak issue. Toyota really messed this 5.7 up on coolant issues- Known issue with water pump leak, radiator and now this. $$$$

08 with 94k miles.

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