Annoying Overheat Problem Nobody Can Figure Out

[TMundo]

Hello,

I have a white 1994 lexus LS 400, with a strange overheating problem, and it's gradually getting worse. I bought this car from a man while he was in the process of dying from cancer. It was winter when I bought the car. The car handled fine all year and throughout the summer it was fine. Another winter passed and all was good. It wasn't until the weather began to get warm a second time, that troubles began to surface.

This summer is a lot warmer than the last. It got hot early in the spring, and I turned on the air conditioner, but after about 10-15 minutes I began to notice an overwelming musty odor. I would later realize it was the odor of an overheating radiator, but at the time I could not place the smell, an the engine was not smoking. I stopped at a random repair station (lets call him mechanic R), and the mechanic R did me a favor and sprayed some anti-mildew spray in the air ducts. This did not work, because the next time I used the air conditioner, the smell was back. I was told by a fellow who worked for an air conditioner company, to change the air filter and let the air conditioner run for a while. I let the car sit while turned on for a few hours, and let the air conditioner run with the windows open to avoid the stench problem. This seemed to solve the problem, temporarily, as the smell issue went a way for a while.

The next hot day I put the air on, about 10-20 minutes later the smell was back. I drove around with the air on and the windows open, the smell went away. I went to run a few errands and when I went to turn the car on again it began to stall. I decided to take it to my mechanic (lets call him mechanic M), it took me about 10 minutes to get there. As I pulled into the mechanic M's station, the car began to smoke like crazy. I popped the hood and we let it cool. I left the car overnight and mechanic M said the radiator had a hole in it, he said he replaced it and that was that.

Now when I drove the car, the engine was making a louder sound. It was no longer quite and purring like a kitten. It was sputtering and would seem to want to stall when I would start it and accellerate in the morning and after work. Yes, It had trouble accellerating, but it would be fine after I drove it for five minutes. It would have trouble accelerating every time I used it, after a few hours of non-use.

Any use of the air conditioner would produce the same overheating after 20 - 30 miutes of driving with the air on. The fan clicked on when I used the air conditioner. So it wasn't that. I took it to the mechanic who repaired it for the original owner (lets call him mechanic O). He said he had tried to figure it out but could not. He said the original owner had given up on them and went somewhere else. He took the car, said he ran it for 30 minutes with the air on, said he ran it in the shop with the air on as well. He said he could not find anything. He told me the radiator looked old, and like it was the one that came with the car. I had suspected my first mechanic had not replaced the radiator, this confirmed my suspicion. I also beleived my first mechanic had not changed the oil much earlier. This newer mechanic also did not have time to change the oil. So how much attention could he have given the car, other than running it. A friend had suggested that a lexus has a second speed setting on the fan that clicks in on extra hot conditions and is sometimes affected by the fuses. This newer mechanic said this wasn't it. But how much time could he have dedicated to it to know that.

I was running out of options, the previous owner had experienced the same issues and had brought it to two different mechanics with no success. I had brought it to two different mechanics with no success (although one had been used by the original owner and one simply cheated me.) I thought abouit going to Lexus, but tales of high prices were discouraging me. I drove another week with no air conditioner use and for the final 3 days of that week it was very hot outside. A strange vibration was comming from the engine, I could feel it through the steering wheel when I started the car after work. The temperature gauge always seemed in the middle so I figured I could get by for a while if I didn't use the air. I stopped at a store on my way home from work and the strage vibration I had felt through the steering wheel was back. I shut the engine off, and as I began to walk from the car, I noticed smoke comming out. I went and got some water fronm the store. The radiator was so hot and empty if I added water it would evaporate and shoot back out. I left the car at the store. The store is close to mechanic R (who had first helped me with the smell in the air conditioner. I now recognized this smell to be an overheating engine. It must have sucked the vapor into the air conditioner system.

Notes:

- Initially the car would only overheat on a hot day when the air conditioner was in use, but now additional damage has been done with the engine being louder.

-The water level must be dropping, but my ride two and from work is not filled with traffic. I must have slowly been loosing water for the car to overheat without the air on.

-The car doesn't overheat when I am driving. Only when I stop and turn the car off. Then the fan is off too.

-The oil needs to be changed

-Mechanic R is close to the store Ileft the car at, but I am confident when I fill the car up with water, I can drive to the lexus dealer.

-It is a busy summer season where I live, and mechanics are busy making fast money on out of town customers, not spending time on people from the area who have problems that don't have a simple solution.

-I don't have a lot of money to burn.

Any hints or suggestions or solutions are welcomed at this point, I believe I will take it to the lexus dealer.

-thanx

[noby76]

Hi TMundo easy option is sell the car and buy another LS400 or best to book it into Lexus leave it with them to use their high tech gadgets to figure out exactly what the problem is and parts which needs replacing, then go to another Lexus dealer buy the parts and take it to a mechanic who can work on Toyota/ Japanese engines to have the new parts fitted. depending on how much the car over heated they could sometimes take the headgasket with them as well if the car is not cooled enough or turned off immediately after it started smoking so chances are it might be the headgasket. but rather than pump money into it without knowing the exact issue have it towed if possible to Lexus for them to diagnose first and you can weigh the options if its worth fixing and keeping or letting it go for another LS400. Hope you get it sorted.

[Keith Bowler]

Yep sounds familiar, had very same problem with my GS300. Problem turned out to be the aircon rad and fan not operating properly, in fact the fan packed up.

I fancied a change so rather than spend around £1500 to get the car up to scratch (it needed other work and a cambelt change) so I bought an LS instead!

if you are anywhere near Surrey I can recommend and excellent Lexus independant mechanic that will know what the problem might be.

[ROYT]

Check the coolant level,then try a run for a few miles with no air con and then check the coolant level again.

Repeat this and if the coolant is getting less, often with lots of exhaust steam, it sounds like head gasket/s.

Check the engine cooling fan this is in front of the engine and is nothing to do with the aircon fan/s.

Also check the trans fluid level is correct.

If the temp stays normal, look at the aircon system.

Sounds like poor maintenance, so change the oil and spark plugs yourself or

get mate to do it!

If the engine is not firing on all 8 you will get weird problems.

Also check the thermostat is opening correctly, and the water in the radiator

is circulating when the engine is revved, if not possible water pump fault.

[Dave76]

The poster is not in UK so temps might be very different & lexus spares or buying another might be a different enterprise to here.