Coolant Valley Plate Leak
#31
Yeah.. I would call water pumps a little common considering how many of the regulars have dealt with it ....including myself.... the valley leak quite rare but can occur.
I never monitored mileage on those with valley leak. I wonder if more common over 100K miles with stock coolant?
I never monitored mileage on those with valley leak. I wonder if more common over 100K miles with stock coolant?
#32
Here is a good article on issue:
http://carspecmn.com/gx460-coolant-l...in-the-engine/
Underneath the GX460’s intake manifold, Lexus engineered a cover plate that houses a coolant galley to pass coolant between the cylinder heads and heater core. With the intake manifold and a great deal of secondary air injection tubes removed, you’re looking at something like this:
Valley plate leaking coolant
The circled areas indicate coolant leaking from the valley plate that covers this coolant galley. With the plate removed the leaks are a bit more obvious. In the photo below the plate’s perimeter is indicated by the red line:
Valley plate removed
And the leaks more closely:
Coolant leaks up close
The valley plate is sealed with Toyota’s special 1282B fix-in plate gasket specifically designed for Toyota cooling systems. It works incredibly well when applied properly. With the plate cleaned of residual gasket and resealed with fresh 1282B, the problem should not reoccur.
http://carspecmn.com/gx460-coolant-l...in-the-engine/
GX460 coolant leak – a hidden leak from deep in the engine
The Lexus GX460 and the 4.6 liter 1UR-FE engine can, as it ages, develop a coolant leak from the valley of the engine. This can cause pooling of coolant in the engine valley, often running down the back of the engine between the flex plate and transmission, or down the transmission itself. Diagnosing the cause of the leak is tricky because it originates deep in the valley of the engine.Underneath the GX460’s intake manifold, Lexus engineered a cover plate that houses a coolant galley to pass coolant between the cylinder heads and heater core. With the intake manifold and a great deal of secondary air injection tubes removed, you’re looking at something like this:
Valley plate leaking coolant
The circled areas indicate coolant leaking from the valley plate that covers this coolant galley. With the plate removed the leaks are a bit more obvious. In the photo below the plate’s perimeter is indicated by the red line:
Valley plate removed
And the leaks more closely:
Coolant leaks up close
The valley plate is sealed with Toyota’s special 1282B fix-in plate gasket specifically designed for Toyota cooling systems. It works incredibly well when applied properly. With the plate cleaned of residual gasket and resealed with fresh 1282B, the problem should not reoccur.
Do I need to order other parts that will break in the process when removing the valley ? I also assume that I need the sealant only to fix this:
BLACK LIQUID GASKET FIPG - Lexus (00295-00103)
as the 1282B is not manufactured anymore. Please chime in.
#34
maybe depending on the area you live as well? We got ours in Phoenix and I swear it did have a little coolant leak. Since I’ve lived in Ohio the reservoir hasn’t needed to be topped up at all. Dealer found it when we got the 2nd air pump replaced but I don’t think it’s leaking anymore.
#35
It seems that multiple vehicles with the same engine have the same problem - its mileage, happens around 100k. I am not 100% sure it is this type of leak, but it leaks somewhere from the block or from beneath one of the cylinder heads and drips on the front of the engine.
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CamelKool (07-21-20)
#36
Super Moderator
IIRC coolant valley more often than not leaks off the rear of engine. Water pump leaks are typically cause of the front leaks.
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CamelKool (07-21-20)
#37
With the coolant valley leak, does coolant enter the inside of the engine or is this just an external leak similar to the water pump leaks ??
Didn't know if this would show up with an UOA ?
Didn't know if this would show up with an UOA ?
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CamelKool (07-21-20)
#38
Super Moderator
It is just an exterior leak from what I have seen. Coolant level in your recovery tank is a good check item as well. Water pump shows itself a lot easier with pink stains on front skid or cotton candy around the water pump that is visible from topside. If coolant valley is draining off rear may be harder to notice unless you are looking on back & underside of motor or coolant loss from recovery.
Not saying coolant valley leak can't come off front but I hear of more reports being seen off the backside & below.
Not saying coolant valley leak can't come off front but I hear of more reports being seen off the backside & below.
Last edited by Acrad; 04-03-20 at 09:54 AM.
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CamelKool (07-21-20)
#39
Driver School Candidate
V8 engine valley coolant leak
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CamelKool (07-21-20)
#40
Super Moderator
DIY of Repair at IH8Mud
A couple IH8Mud members repairing themselves.
If one performs this repair themselves in the future this is what a Lexus Master Tech had to say on GXOR:
I asked: " Beyond the intake manifold removal does this place you right at the valley plate? Here is FSM on intake manifold removal. https://lexusgxor.com/_media/general:460_intake_removal.pdf "
Response: "Nope. You have to remove the EGR cooler which is held by 2 12mm bolts for the cooler itself and 2 12mm nuts for the EGR pipe that goes to the rear and 2 10mm nuts for the front. The heater pipe which is held by 2 10mm bolts, the oil separator which has 4 10mm bolts. Once all that is removed then you will get to the knock sensors. Knock sensors are 4 sensors held by a 12mm bolt each and the sub wiring harness. Once that’s removed you will see the cover. Cover is held by 12mm bolts and 2 12mm nuts and 1 10mm bolt. Once the bolts and nuts are removed you need to remove the threaded studs with a external torx socket E8."
"Here you can see the EGR cooler (metal square)"
"on the GX we normally do 6-8 hours. The LS and ISF is more complex due to the direct injection."
"2-3 gallons of pink Toyota SLLC (coolant) and one tube of 00295-00103 FIPG."
"the third one down EGR cooler No1 you only need one gasket"
A couple IH8Mud members repairing themselves.
If one performs this repair themselves in the future this is what a Lexus Master Tech had to say on GXOR:
I asked: " Beyond the intake manifold removal does this place you right at the valley plate? Here is FSM on intake manifold removal. https://lexusgxor.com/_media/general:460_intake_removal.pdf "
Response: "Nope. You have to remove the EGR cooler which is held by 2 12mm bolts for the cooler itself and 2 12mm nuts for the EGR pipe that goes to the rear and 2 10mm nuts for the front. The heater pipe which is held by 2 10mm bolts, the oil separator which has 4 10mm bolts. Once all that is removed then you will get to the knock sensors. Knock sensors are 4 sensors held by a 12mm bolt each and the sub wiring harness. Once that’s removed you will see the cover. Cover is held by 12mm bolts and 2 12mm nuts and 1 10mm bolt. Once the bolts and nuts are removed you need to remove the threaded studs with a external torx socket E8."
"Here you can see the EGR cooler (metal square)"
"on the GX we normally do 6-8 hours. The LS and ISF is more complex due to the direct injection."
"2-3 gallons of pink Toyota SLLC (coolant) and one tube of 00295-00103 FIPG."
"the third one down EGR cooler No1 you only need one gasket"
Last edited by Acrad; 01-27-21 at 07:33 AM.
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natehack (07-12-20)
#41
If one performs this repair themselves in the future this is what a Lexus Master Tech had to say on GXOR:
I asked: " Beyond the intake manifold removal does this place you right at the valley plate? Here is FSM on intake manifold removal. https://lexusgxor.com/_media/general:460_intake_removal.pdf "
Response: "Nope. You have to remove the EGR cooler which is held by 2 12mm bolts for the cooler itself and 2 12mm nuts for the EGR pipe that goes to the rear and 2 10mm nuts for the front. The heater pipe which is held by 2 10mm bolts, the oil separator which has 4 10mm bolts. Once all that is removed then you will get to the knock sensors. Knock sensors are 4 sensors held by a 12mm bolt each and the sub wiring harness. Once that’s removed you will see the cover. Cover is held by 12mm bolts and 2 12mm nuts and 1 10mm bolt. Once the bolts and nuts are removed you need to remove the threaded studs with a external torx socket E8."
"Here you can see the EGR cooler (metal square)"
I asked: " Beyond the intake manifold removal does this place you right at the valley plate? Here is FSM on intake manifold removal. https://lexusgxor.com/_media/general:460_intake_removal.pdf "
Response: "Nope. You have to remove the EGR cooler which is held by 2 12mm bolts for the cooler itself and 2 12mm nuts for the EGR pipe that goes to the rear and 2 10mm nuts for the front. The heater pipe which is held by 2 10mm bolts, the oil separator which has 4 10mm bolts. Once all that is removed then you will get to the knock sensors. Knock sensors are 4 sensors held by a 12mm bolt each and the sub wiring harness. Once that’s removed you will see the cover. Cover is held by 12mm bolts and 2 12mm nuts and 1 10mm bolt. Once the bolts and nuts are removed you need to remove the threaded studs with a external torx socket E8."
"Here you can see the EGR cooler (metal square)"
#42
Super Moderator
I am not losing any coolant but wonder if one could snake a borescope under the intake plenum to inspect?
#43
Driver School Candidate
Coolant valley leak
I just discovered I have this leak on my 2011 GX today.
Every time I get fuel I check fluids and do a general inspection while the tank is filling. It is a habit I will probably never break since living in, and traveling the country in a VW campmobile for a few years several decades ago. If you didn't check your VW out at every possible opportunity, parts would fall off, or you would be stranded or both.
I filled up with fuel a couple of days ago and noticed the coolant level was about halfway between the L and f marks in the overflower reservoir. I usually fill the reservoir and all fluids for that matter as needed, with each 5,000 MI service. The last couple of services I had added a small amount of coolant to the reservoir and didn't really think much of it. Although, I should know better that coolant does not get consumed or just disappear without a reason.
I drove about 300 mi and then came home to do the 5,000 mi service and tire rotation etc. When I got home, the fluid in the coolant reservoir was below the L mark!!!
I changed the oil and rotated the tires and crawled around underneath it to look for any evidence of leaks. Water pump dry. Hoses all dry. Radiator seams dry. No pink or other fluid on the bottom of the skid plates or on the transmission bellhousing, all dry. Also, no noted antifreeze smell.
So I did some searching for "UR engine coolant leak" and I got a lot of pages on the IS engines having this problem.
I have one of those cheap flexible inspection cameras that runs from Wi-Fi to Android so I hooked it up and put it in the small recess under the intake manifold just medial to cylinder number two and posterior to the throttle body. Snaked it in there, and you can't see a lot of places and recesses, but sure enough, found my lost coolant.
it's a pretty slow leak, or at least it was until this week. I would encourage everybody to check it out, or if you don't have stuff to do that, have a reputable shop give it a look if you're around 90-100k. Most of all, check your coolant reservoir! If it's dropping slowly, something is going on and it may not be obvious for quite a long time!
Best thing is I have a 10-year 100,000 mi warranty on mine and currently have 99,250 MI and until January 1 2021 til it expires. They say they are going to cover it!
Glad the leak declared itself this week!
Every time I get fuel I check fluids and do a general inspection while the tank is filling. It is a habit I will probably never break since living in, and traveling the country in a VW campmobile for a few years several decades ago. If you didn't check your VW out at every possible opportunity, parts would fall off, or you would be stranded or both.
I filled up with fuel a couple of days ago and noticed the coolant level was about halfway between the L and f marks in the overflower reservoir. I usually fill the reservoir and all fluids for that matter as needed, with each 5,000 MI service. The last couple of services I had added a small amount of coolant to the reservoir and didn't really think much of it. Although, I should know better that coolant does not get consumed or just disappear without a reason.
I drove about 300 mi and then came home to do the 5,000 mi service and tire rotation etc. When I got home, the fluid in the coolant reservoir was below the L mark!!!
I changed the oil and rotated the tires and crawled around underneath it to look for any evidence of leaks. Water pump dry. Hoses all dry. Radiator seams dry. No pink or other fluid on the bottom of the skid plates or on the transmission bellhousing, all dry. Also, no noted antifreeze smell.
So I did some searching for "UR engine coolant leak" and I got a lot of pages on the IS engines having this problem.
I have one of those cheap flexible inspection cameras that runs from Wi-Fi to Android so I hooked it up and put it in the small recess under the intake manifold just medial to cylinder number two and posterior to the throttle body. Snaked it in there, and you can't see a lot of places and recesses, but sure enough, found my lost coolant.
it's a pretty slow leak, or at least it was until this week. I would encourage everybody to check it out, or if you don't have stuff to do that, have a reputable shop give it a look if you're around 90-100k. Most of all, check your coolant reservoir! If it's dropping slowly, something is going on and it may not be obvious for quite a long time!
Best thing is I have a 10-year 100,000 mi warranty on mine and currently have 99,250 MI and until January 1 2021 til it expires. They say they are going to cover it!
Glad the leak declared itself this week!
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Acrad (10-26-20)
#44
Driver School Candidate
Valley pan leak inspection port
Not a great photo, but end of the pointer was where I ran the camera in
Again, not a great photo, from the inspection camera, but there's my coolant!!
hope this helps someone!
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#45
Will replacing pink with red coolant prevent this leak
Will replacing pink with red coolant prevent this leak. Saw on one of the GSF video, guy saying that pink is not compatible with silicone used in the gasketing compound. He was replacing OEM pink with old red OEM coolant at 26k miles on GSF. Any one heard this to be true.