GX470 Coolant loss with no visible leaks (4 Viewers)

[OH Oh no]

I am starting this open discussion to document the issues with my GX. Hopefully it will be helpful for others. I have noticed an abnormal consumption of coolant (2004 with 204,433K). It's "winter" here in Northern OH and my truck sits outside. It's a daily driver so I have cold starts every morning. The cabin heat is weak. I have no misfires, no white smoke from tailpipe. No coolant or gasoline smell (in cabin). No visible leaks on radiator. The water pump is new as of August of 23. Engine oil is normal in appearance but that doesn't mean coolant isn't leaking into the block. I'm hoping for a stuck thermostat. I inspected the truck up on ramps but didn't crawl around behind the water pump. I am dropping it off at my buddies shop tomorrow and will post updates.

 

[fvedmo]

Mine was leaking from the WP area behind the TB cover, so I saw very minor leak signs at the radiator but nothing that would account for the amount of fluid lost each week. There was a ton of pink popcorn behind the TB cover when I replaced it all.

Ultimately it looks like the person who did the WP replacement for the PO didn't clean the old paper gasket off fully so it wasn't well sealed.

 

[white_lx]

Rear water bypass pipe gasket leak? Pretty common on the 2UZ. Very often passenger side. From underneath the vehicle it looks like a head gasket failure as the coolant runs along the block. Look up from behind the wheels to the back of the engine.

 

[FeastorFamineMoto]

Some seepage from the water pump seal is normal when very cold, even on a brand new pump(unfortunately). If you have a borescope camera you can look into the valley of the motor to verify none of the coolant passages are leaking into it. Another common phantom leak is the drain valve(petcock) on the bottom of the radiator, the o-ring collapses overtime and results in a slow drip. A pressure test when cold may be your best bet to find the culprit. If none of that works I would suggest an oil analysis to check for coolant contamination, but head gasket problems are uncommon for this motor. Best of luck.

 

[OH Oh no]

Thanks. Yeah the 2UZ is an engine you can count on. I just spoke with my friend. The radiator has a leak that I missed. Driver side upper. He said it took him a bit to find. Looks like I will do the thermostat with the radiator and knock it all out at once. No other issues. I forgot to mention the engine was running "cold" not hitting normal operating temp based on the temp gauge.

 

[Rednexus]

I'd suggest also replacing the heater/radiator hoses while you are in there and replacing the coolant. They are pretty inexpensive if you buy Gates ones (won't last 20 years like the originals but should easily go 10+ years). You can also get a new Denso radiator on Rock Auto for around $200.

 

[OH Oh no]

I'd suggest also replacing the heater/radiator hoses while you are in there and replacing the coolant. They are pretty inexpensive if you buy Gates ones (won't last 20 years like the originals but should easily go 10+ years). You can also get a new Denso radiator on Rock Auto for around $200.

That's exactly the radiator I was looking at. I did get new hoses and I keep Toyota coolant on hand. We are a Yota family. Not a difficult fix overall. It's pretty much like scheduled maintenance. Thanks for the recommendations.

 

[CarGuyCarl]

Dealing with this as well. Very very slow disappearing coolant, however, no heat issues. Looks like I need to inspect behind the TB cover.

 

[Dirkster]

I am starting this open discussion to document the issues with my GX. Hopefully it will be helpful for others. I have noticed an abnormal consumption of coolant (2004 with 204,433K). It's "winter" here in Northern OH and my truck sits outside. It's a daily driver so I have cold starts every morning. The cabin heat is weak. I have no misfires, no white smoke from tailpipe. No coolant or gasoline smell (in cabin). No visible leaks on radiator. The water pump is new as of August of 23. Engine oil is normal in appearance but that doesn't mean coolant isn't leaking into the block. I'm hoping for a stuck thermostat. I inspected the truck up on ramps but didn't crawl around behind the water pump. I am dropping it off at my buddies shop tomorrow and will post updates.

I recently found a coolant leak that was hidden for years.

It was leaking between the thermostat housing and the intake manifold. It was an O-ring that had dried out. When it leaked it would create a small puddle between the intake manifold and the head/valve cover.

The leak finally was bad enough to drip on the ground so I was able to trace it back to the source.

The auto parts store had trouble ordering the part but we found a ford v6 O-ring that was close enough.

 

[OH Oh no]

I recently found a coolant leak that was hidden for years.

It was leaking between the thermostat housing and the intake manifold. It was an O-ring that had dried out. When it leaked it would create a small puddle between the intake manifold and the head/valve cover.

The leak finally was bad enough to drip on the ground so I was able to trace it back to the source.

The auto parts store had trouble ordering the part but we found a ford v6 O-ring that was close enough.

Glad you finally found it.

 

[5280 Lexus]

hopefully its just the radiator as thats a much simpler fix. I had a water pump fail within a year of replacing it and then I had to redo the whole tb/wp job major PITA. Same symptoms at first

 

[CarGuyCarl]

So I know you can remove the TB covers up top to take a peek into the belt situation. Is there a way to view the WP from below for those in thread who poked around to check? My TB/WP was replaced in 2020 about 40k miles ago.

Thank you all!