19psi

if that o ring is leaking, you'll see teh coolant everywehre around it. red coolant leaves behind pink stalagtites everywhere it leaks. very obvious. sounds like it's time for a pressure test. that's the easiet way to find where your leak is.

margarita

Ok, good to know what to ask for. Is the sensor o-ring on the outside of the reservoir? Where do I look for the o-ring? You could use the pic posted earlier to describe location? Thank you.

link13

Where are you in CA? If you're in SoCal, you could take the car to Son Nguyen at Dynamic Auto Services in Midway City. He is extremely proficient with all Lexus models and his prices are reasonable.

AzHotLS

iTrader: (1)

margarita, did you click on the "Coolant Tank Leak" link I provided?

Post 10 of that thread has pics of the sensor and o-ring. Post 7 says that you unscrew the sensor to remove it from the resevoir (after disconnecting the electric connector).

margarita

actually, i found those photos through a google search before even logging on here. great pics btw. didn't know that was the sensor. i will see if I can do that tomorrow. lexus sells that o-ring for about $4 (called earlier today).

margarita

thanks for the referral, but that's too far from LA to be do-able.

GSteg

iTrader: (15)

When do I get my $5?

I've been to the shop many times before and I've seen LS400 with headgasket issues. This is not just by looking at the exhaust, but actually looking at the block once it's taken apart. Its not as common, but trust me, it does happen. I've seen it with my own eyes

But because margarita said the oil looks fine, the HG is probably not his problem. My dad's 93 V6 camry has the same issue. Coolant level will be lower all the time, so I keep on having to add some in. There are no visible leaks, but the hell with it..we're about to sell the car

Lexushead

It's either a small crack in the overflow tank where the sensor is or the o-ring. I've been working on this issue for a while now. At first, for almost a few years now, I keep adding coolant since it started out slow. Now the leakage is more pronounced. I can smell the burn-off while driving on the highway. I replaced the o-ring. That didn't work. I still couldn't see the crack but it bubbling from underneath the rubber(sensor). I replaced the o-ring again and tighten it a little more. Took it for a long test drive and now I can see a 1/4" crack line. I may have tighten it too much and the crack expanded beyond underneath the rubber. Long story short, you need a new overflow bottle or a used one. I got a used one and I haven't had time to work on it. I've traveling and it's too dang cold. It's been a long long winter.

margarita

Update: After refilling the coolant yesterday, I checked it again after the car had been sitting almost exactly 24 hours. The level of coolant had dropped about 1.5 inches. No drips anywhere. On startup in the afternoon (typical morning condensation had had time to dry off), there was no white color at all in the exhaust. Car operates normally in all other respects.

Took it to dealer, who gave me a freebie quick look (unheard of) up on the rack. They checked the coolant tank and looked in the drip pan and everywhere and no fluids.

They also had no explanation for the dampness/sign of fluid around the rubber cap, but said it looked almost as if someone put that there. Even though the car is parked on the street, I don't think anyone can get under that hood with the car locked up every night. Mechanic suggested cleaning the sludge off and see if it reappears.

My instructions are to watch it for another few days. If I have to top it off more than three times, they asked me to bring it back. He saw that I had replaced the water pump, radiator and all manner of other work and said that it is possible it's taken all this time for air bubbles to work their way through the system to the coolant tank.

I will be surprised if this problem goes away, but I hope he is right. He never did look at the sensor o-ring (I asked repeatedly if he could check that). He looked at the rubber cap and said it appeared to be in good shape, so he didn't think that would be the problem.

When I clean things off tomorrow, I may see if I can check that myself. Is there any danger in trying to disconnect those two wires? Do they carry any kind of charge?

Thanks for all comments. Will post back when I know more.

margarita

One more thing. . . he said if it were the o-ring I would see the pinkish color crusting up somewhere and there's nothing. The mystery is where that brownish gummy fluid inside the rubber cap, and brownish fluid on top of the tank came from. After I clean it off and wait a bit, I should know more. The mechanic said if I had any manifold problems that that could cause that, but he said I would be having all kinds of other signs if that were the issue. So, it's wait and see for now. His guess for now is air bubble(s).

margarita

I had headgasket seal issue about four or five years ago. They had to replace. One sign of it was a lot of soot on the headliner. It's entirely possible that that is a problem again, since it's been awhile. I was told the heat in LA is really hard on all kinds of seals in cars. If parked somewhere, I try to keep it out of direct sunlight on hot days for that very reason.

margarita

Undercarriage was checked today and no fluids in the belly pan or anywhere else. They also don't see any leaks in the coolant tank. For now I am monitoring for another few days to see what happens. Lexus said it could be an air bubble (or two). Yes, replaced water pump 1.5 years ago, along with all kinds of other work (see other post). Thank you for the info. Every little bit helps. It's like playing detective. Kind of fun!

margarita

Update: Coolant level held at same level as 24 hours ago (checked this morning). Whoo-hoo. Still no white-ish burnoff in exhaust. So far, so good.

Last night, cleaned off brownish gummy residue from inside the rubber cap on the coolant tank, and off the top of the white disc (top of sensor?) that you see when you lift the rubber cap. Not a lot of it there, but what was there was VERY viscous and hard to get off, as if it's been there a very long time. There is still brownish gunk in those two small holes where those electrical wires come out -- may try later to remove with toothpicks or something. Still a mystery as to where that stuff came from, but it does not seem to be coming back.

The one thing I did notice...at the outer edge of that white disk where the wires come out, there's a ring of raised plastic (not rubber) -- and two pieces of that raised ring lifted up along with the gummy stuff. Looks to me like it's disintegrating. So at the very least I probably should replace that cap.

Also checked all power steering fluid (normal and clean), and the transmission fluid. The latter is registering 1/2 inch above the 'hot' level (when the car isn't hot...warm more like)! The car was moved a short distance to the alley, then sat for at least 20 minutes before I checked the tranny fluid, so by no means would be 'hot'. So transmission overfill can't be good. I think the dealership would have been the last shop to replace that fluid, and it was probably done at the same time they did all the work on the timing belt. I will have to ask. The fluid color appears completely normal -- reddish, if slight dirty.

Correction: Checked my records. Have never had any head gasket problems or repairs (as I stated in an earlier post). Instead, it was an ENGINE VALVE SEAL leak -- happened four years ago and cost close to $400 to repair.

LiCelsior

iTrader: (32)

so what did u do to stop the drop?

so they changed the valve cover gaskets..very common on the 1LS..hell its happening to mine also but i was running verrry light oil so it was leaking. i think i was running the mobil1 fuel economy 0w-30. now i changed to 5w30 though. i also have that rubber cap leak and probably going to call up the dealer and get that oring.

margarita

I've done nothing to stop the leak. Just topped if off a few days ago and that's it. Again, the mechanic said maybe an air bubble or two from when all that work was done (radiator replaced, etc.), that finally got up to the surface and displaced the coolant. Still too early to tell whether the coolant level is stabilized. Let's see what happens tomorrow.

After seeing the overfill on the tranny fluid, I started reading up and found this (see link), which is really interesting. The author states that overheating of the transmission fluid is the single most common reason for transmission failure. I guess keeping the fluid at proper levels (not overfilled!) and ensuring that it's still doing its job of lubricating is critical. I will definitely be watching that more carefully in future. They mentioned an add-on that can reduce fluid temperature too. I might look into that. I was told by a mechanic long ago that 1st Gen runs hot.

http://autos.yahoo.com/maintain/repa...ques123_0.html

Dealer gave me a quote on the coolant rubber cap + sensor at $33. A discount shop gave me a quote of $18, but by the time I pay s/h, it's only $4 less than the dealer, so not worth the wait.