Coolant Leak Issue, Near Throttle body.

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M

muleski

10 Year 15 Year
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May 27, 2008
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This is a strange one. 2003 LC. Our second LC. 135K miles. Drove our 2000 to 288K miles. I am not as clueless as I'm going to sound! Do a lot of my own work; it's in great shape. Wife's DD.

Two nights ago in the driving rain, my wife calls me to tell me that there is steam pouring out from underneath the hood. Thermostat looks normal. Car is driving fine. I meet her and follow her the three miles home. Take a quick look under the hood. Reservoir empty. Odd. Decide to check that radiator after the rain. Today. I did notice what looked like orange fluid under under the engine? Huh? Could it be RainEx.

So a couple of hours ago, I was able to look at it. The fluid has dried or evaporated. No clue. The radiator was low, and filled it to the top of the fins, and also added the right amount to the reservoir. Start it up, ran perfectly.

Once it warmed up, I noticed a ton of steam and cooling smell coming out from under the engine cover. Off it comes, and I expected to find a hose. BTW, I replaced the T fittings again last summer. Nope. No hose issues.

However, I did find what is shown in the picture. Here's where The clueless comes in. This is uncharted territory for me.

Note the open hole and the loose plug next to it, right in front of the manifold. Looks to me like a plug might/could be missing. So...what is it?

What caused it? What is the fix? And what else should I be concerned with?
I'm hoping that this can be a fairly simple fix. Like not a new entire TB housing.

BTW, the hose in the pic is in better shape than it looks in this night shot. I have no idea what the pinkish stuff on that metal plate is. Almost like white lithium that was tinted by coolant?

BTW, bought the car in Denver, and had Mr. Slee perform a very detailed baseline on it before driving East. Had 90K one owner miles, and decent service records.

Any thoughts? Thanks!

IMG_3040.webp
 
Rusty,
Can you expand on that for me....like I said pretty "thick" and in need of help and direction on this.

Like what am I missing, what do I need, etc.

Thanks......everybody/anybody!
 
Pink crusties = dried Toyota coolant

I'm not exactly sure what's supposed to be there, oring or otherwise. My 98 looks a little different:

Coolant lines

Coolant lines

  • Media owner camino70
  • Date added

I'll take a look at our 04 this morning.
 
Best case, it may be one of the two by-pass coolant lines that run to the TB or the single bypass line that runs in a loop out and back in to the TB spitting fluid under the PCV and evap lines. See if all the hoses are seated and clips are tight. If not then maybe one of the plugs on the throttle body is leaking.

Lines.webp
 
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That clamp on the coolant line under the braided hose, also looks crusty. Might check that for a leak. The manifold also looks different compared to @camino70 picture- no holes or plugs- is that open hole leaking?
 
As previously mentioned the 'pink' powdery looking residue is dried coolant. IF that hole on the left is open (not a blind hole), then clearly it needs to be plugged. Almost looks as if it is supposed to have a plug like the one to the right of the open hole.

Perhaps someone with a similar year model can look at their's and reply here.
 
That would be a big help. The plug on the right is loosely in place. It looks to me almost like a freeze plug, of a plug meant to release under some pressure. I have NOT tapped in back into place, yet.

The hole on the left does not show any "flow" or leakage, but I obviously is meant to be plugged, with something. There is a wear "ring" around the hole sure makes it look like something was in place there.

The hole on the left is much smaller is diameter than the one on the right. Flying blind on this one.

A picture of a 2003 {Maybe a 2004?} with the plugs in place would help.

Then of course the holy grail would be any info of whether they can be ordered as replacement parts.....or some other long term solution. Throttle bodies are not cheap. It seems insane to need to replace it.

The last thing that I really want to try to figure out is "why?"

I have a really good Indy shop that does work for me. Good guys, but not real LC guru's. None that I know of near/north of Boston. I have no Cristo Slee here.

Ideal feedback is "you're missing this. The other cap popped, and can be reused {or should be replaced.} It probably happened because of this. And you need to check out these things..."

I'll obviously check all of the hoses. They may all get replaced a bit sooner than I had planned. I had planned doing all of the hoses and clamps this spring. Preventive stuff. The flash and camera make them look more neat than they are.

I saw no leaking last night. But a lot of evidence of leaking in that area.

Thank you all for any ideas and help. Much appreciated. Normally I have a pretty good handle on the details. This is our second 100. I though I knew most of the truck!

A pic or two of a 2003 would be a big help, I think!
 
Have you observed the area in question with the engine running? Have someone start the car while you observe the area, then turn it off once you've done this. My suspicion based on what you've described is that the leak is smaller, rather than bigger as would be coming from an open port the size of the one in question.
 
Hi,

I just had a chance to check a few things out, closely. First of all ignore any discussion of the left hole. It is actually a recess in what looks like a machined plug that is a permanent part of the housing. Happened to be full of red coolant.

Added a small amount of coolant....about a quarter inch over the fins. Reservoir is half way between the marks. Started car and let it warm up.
Ran very smoothly.

Once it was hot, I noticed a pretty constant mist coming from the plug on the right, which had been very loose when I noticed this the other day. I seater it by hand when cool the other day. It's not tight enough, so when cool, I'll need to tap it tightly in place. As is, while it looks like a fine mist....it will all add up. Found a couple other places where we may have had a slight leak.

But I think the culprit is that plug. So what would cause it to pop? I can reseat it, but it bet it's a one time fix. I doubt if one can buy a replacement.

So as I am observing this. I notice that the fan has been on the whole time, I check the top hose, and it's hot, and I can feel water moving. Then I go to check the temp gauge, and it's HOT.

Hmmm. Odd. Might be the sending unit for the gauge? I let it sit for 15 minutes and start it. Get a CEL. Pull the code. P0117. "Engine Coolant Temp Circuit Low Input"

I restart, and despite it being warm, the gauge is at rock bottom cold. Hmm. Clear the code. 20 minutes later it climbs to the max! So I'll to figure that out.

At first I thought I might have a partially stuck or stuck thermostat. It's only four years old, and I have not had that problem.

So I'll spend some more time on it.

I guess my big question has to do with the plug on the right. What's the design and why would it pop under pressure?

I'd like to know that piece.

Water pump is OEM, done 4 years ago at 90K. Same time as the thermostat. Radiator was flushed at that time, /and once two years ago. Fans work. Guess I'll need to do the usual diagnostics on that all. Will see what happens with heat on.

Have been fortunate to have had no issues like this with the previous cruisers. Just did the proactive maintenance.

Air temp was 40 degrees, BTW.

Thanks!
 
Maybe a long shot but check radiator cap for proper function- maybe too much system pressure from a bad cap causing that leak.
 
muleski said:
But I think the culprit is that plug. So what would cause it to pop? I can reseat it, but it bet it's a one time fix. I doubt if one can buy a replacement.
Click to expand...

I looked thru the parts catalogs I have access to and the FSM and havent seen any replacment option other than the $700-800 for a new throttle body:meh:

Or, if there are no other problems with the TB you could just bypass the bypass temporarily while you figure out what you are going to do, as long as your local temps arent too cold.

Let us know of the tap-tap-tap-a-roo fixes it.
 
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I have looked all over as well, and have poured through my FSM. Nothing. Sort of surprised this hasn't surfaced. I have done A LOT of searching. Seems odd that the solution is a new throttle body. I think the plug is aluminum. $1-2 part.
Has to be a source. Fingers crossed that I won't need to find out.
I will report back on my progress, and if anybody has an insight on this, thanks in advance.
Mystery.........
 
Does it look possible to drill and tap the hole for the missing plug, and just add a pipe plug...or maybe a metric bolt with a copper washer?
 
If you look up a few posts, false alarm on the missing plug. There is no hole. It's a recess in the housing that had filled with leaking coolant. So no worries there. Cleaned it out tonight when I got "into" the engine bay.

Now the other one is odd...I need to determine why the plug "popped". It's aluminum, and looks like it's made to release under pressure. Odd. And if it's true that one can't buy another, I need to reseat it the right way, and/or contemplate a fix other than a new throttle body.

I'll report back....
 
muleski said:
Now the other one is odd...I need to determine why the plug "popped". It's aluminum, and looks like it's made to release under pressure. Odd. And if it's true that one can't buy another, I need to reseat it the right way, and/or contemplate a fix other than a new throttle body.
Click to expand...

Probably a factory assembled configuration for the LC/LX, maybe for the GX/4Runner/Tundra that had the 2UZ-FE it is different:meh:

A little JB Weld will fix that s***;)
 
From looking at the parts diagrams, the only coolant getting to that area is via the bypass hoses into the throttle body. So either you have a leak at one of the hose connections, a pin hole leak in one of the hoses, or the cooling bypass in the throttle body is restricted/clogged and or leaking some where from a casting crack (not likely). That "freeze" plug looks really clean, and it doesnt seem to me your leak is coming from there.

Pressure test the radiator cap to rule that out as the contributor. Pressure test the cooling system. Thoroughly clean the entire throttle body area, check hoses, maybe replace clamps on the upper connector. Start and run the engine to operating temps and watch for leaks.

Last, since Slee did the base line for you why not give them a call and ask for some advice to point you to a solution.

Good luck-
 
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