2002 LX470 coolant leak question (1 Viewer)

[virtue22]

Posted this question in club lexus but thought i may have better luck over here.

Had a chance to try and track down a coolant leak on my 2002 LX with 155,000 miles (TB/water pump changed at 90k). It seemed to be getting worse so I started from the bottom and worked my way up. The bottom looks pretty bad but the only evidence of the leak I could find was from the upper coolant inlet port where the metal port physically attaches to the inlet. Has anyone else seen a leak form here, seems like an odd place. Any suggestions on how to fix it here, I didn't think there was an o-ring or gasket here (please see pics). Like I said its the only place I can see where the leak may start and its the highest point on the engine with any evidence of a leak. It's leaks about a cup of coolant every 1000 to 1500 miles.

Thanks for any help / advise you can offer.

 

[marshotel]

the only evidence of the leak I could find was from the upper coolant inlet port where the metal port physically attaches to the inlet. Has anyone else seen a leak form here, seems like an odd place. Any suggestions on how to fix it here, I didn't think there was an o-ring or gasket here (please see pics).

I believe that there are indeed o-rings in there and that this could be the source of your leak (pictures 1 and 2 in OP).

In addition to the o-rings, you might want to replace the upper coolant inlet port while you are in there.

It is a $100 part, and I have seen two that have leaked after >100k miles due to bad casting/ porus metal on that part. like you said, about a cup of coolant every 1000 miles or so.

 

[APKhaos]

There are two seals in that area, and its not clear from your pics if one of these two is leaking or if the water pump gasket is the problem:



The upper circle is the coolant inlet console connection to the block, which is sealed with a large square section o-ring. This should have been replaced when the water pump was done. Take a good look around using a light and a mirror, but from your pic it looks dry.

The lower circle is the coolant inlet console seal to the water pump, which is sealed with Toyota FIPG compound. If this is done properly its good for the life of the water pump, but it looks as if it might be leaking. Once again, take a good look around to confirm.

If the leak is at either point on the console its fairly easy to remove the console, replace the upper o-ring and reseal the console to water pump with FIPG. Its a job.
FWIW, I replaced the upper o-ring seal and re-sealed the console to pump with FIPG at around 230K miles when replacing the water pump. Its still bone dry now, so I would not be too worried about replacing the console unless the sealing surface looks rough.
Its worth confirming that this is where the leak is coming from before doing this work. Its possible that the water pump itself, or the water pump gasket could be the problem, so take a good hard look first.

 

[virafp]

Coolant leak finally identified!

For a few weeks now, I have been losing about a cup of coolant a week. I noticed a drip on the driveway three days ago, that looked like a coolant and engine oil mixture. My first thought was head gasket, but reading on here, realised that it was an unlikely issue with these motors. Checked the oil, and saw no signs of coolant, so was very relieved!
Yesterday I removed the plastic protector tray, and found the issue. It is a small rubber pipe that connects what looks like a transmission cooler line. This leak was dripping on to the plastic protector plate, where there was residual oil in the tray from a valve cover gasket leak, and that was mixing with the coolant and dripping down.
What is amazing and most impressive to me, is that at 180K, there is not a leak anywhere in the drivetrain.
Hope this can help somebody diagnose a similar issue!

 

[virtue22]

Thank you, I knew I could count on I8MUD members to help me out. I don't know why I did not to think to look at a schematic to realize what's in there. Looking at it I do believe it's the O-ring leaking (part #16323C). Now I just have to decide if it's worth tearing into now or wait until I replace TB/water pump in 45K? (That's 1&1/2 yrs the way we drive) I'll keep my eye on it and at least wait until spring, it should make for a nice afternoon. And thanks for the tip on poor castings on the water inlet after 100k, it should be worth it to replace for only $100.

Thanks again for the help

 

[jonharis]

Thank you, I knew I could count on I8MUD members to help me out.

I would not recommend eating it.

 

[Rahul]

Coolant leak finally identified!

For a few weeks now, I have been losing about a cup of coolant a week. I noticed a drip on the driveway three days ago, that looked like a coolant and engine oil mixture. My first thought was head gasket, but reading on here, realised that it was an unlikely issue with these motors. Checked the oil, and saw no signs of coolant, so was very relieved!
Yesterday I removed the plastic protector tray, and found the issue. It is a small rubber pipe that connects what looks like a transmission cooler line. This leak was dripping on to the plastic protector plate, where there was residual oil in the tray from a valve cover gasket leak, and that was mixing with the coolant and dripping down.
What is amazing and most impressive to me, is that at 180K, there is not a leak anywhere in the drivetrain.
Hope this can help somebody diagnose a similar issue!
View attachment 700158

I think you solved my problem so what did you do replace the clamps?
https://forum.ih8mud.com/media/possible-leak.44346/full