theubster

So, I've combed the forums and can't find an exact match anywhere, so here's where i'm at.

I purchased a 1992 Lexus LS400 from a guy back in October. Its my first automobile. It has 234,000 on it, but my folks have the same model off by 2 years that ran til 400k, so I wasn't worried. The guy we bought it from said that he'd replaced the water pump a couple years prior. The transmission sounded really strong; no hiccoughs or anything.

I have very little knowledge of cars, so i'll describe whats happening as best I can.

Last night I was driving about 10 minutes on a main road at about 35-45MPH with multiple stoplights. It was cool with some drizzle.

I noticed steam coming from the hood, and checked the temperature gauge, and it was at H. There was a gas station two blocks away from the place where i'd pulled over, so i went back to it to get coolant.

When I opened up my hood, i saw steam coming from the coolant/ reservoir thing. It dissipated within a minute of opening the hood. However, the coolant inside the reservior was bubbling. I went inside to get coolant, came back out, and the bubbling had stopped, and the coolant was at a normal level.

I turned the car back on and everything went back to normal.

I drove to my destination, and the heat fluctuated up and down, but never all the way to H again.

Driving home it hit H as i arrived, but drove totally fine otherwise.

Then, today, hoping it was a fluke, I drove to work. It made it the 10 minute drive no problem. A little warmer than usual, sure. But, otherwise, fine.

Then on my way to a meeting across town I had it at H and steaming, so I pulled over to give it time to cool off since I was only 3 minutes away. It looked the same as the previous night, bubbling and all. A friendly stranger helped me check the engine, and the cooling fan isnt' spinning. after letting it cool for 45 minutes, I tried to start it up, the car idled real low and then died. I tried it again, got it to reverse, got out of my spot and died. I tried a third time and had no problems at all. Normal idle and everything.

I made it back from my destination (15 minutes) with no problems other than high heat.

Its had some "shudder" before all of this, right when i started the car. but, once i got going in a day it'd go away.

So. Ideas with what is wrong? Friends and family have told me that its water pump, water pump hoses, head gasket, radiator, and cooling fan. I just want to make sure that I dont' get screwed over by a mechanic....

I have no idea what is happening. Any help is greatly appreciated!

LScowboyLS

there are a number of things that can cause your LS400 to overheat, but the most common for your year/generation of LS would be the temperature switch down on the bottom corner of the radiator below the battery area

this part is cheap at advance auto parts, autozone, o'reilly, napa etc. and is easy to install for a backyard mechanic

make sure to use Toyota red long life coolant (from the dealership) and distilled water in a 50/50 mix when refilling!

as a check, next time it is getting over halfway on the gauge, open hood with car running and see if both electric fans are running, if they are not, then this switch is highly likely to be the issue

fourstars

Bubbling is never a good thing in a possible over heating situation. Bubbles are created by air… and what I think is happening is air is coming out from your radiator to your reservoir. Why? Because, 1, you have an air leak in your coolant system, or 2, you did not bleed the coolant system and there are air pockets… if there is a leak, it can be from your radiator hose, to a tiny hair size hole, to even a crack in your head, or head gasket... I would try bleeding all air first then do a leak down test to confirm.. BTW, you dont need Toyota red long life coolant... regular coolant is fine with 50/50.

LScowboyLS

actually, you do need Toyota red coolant and distilled water if you like your radiator and heater core to last 300K+ miles

in that light, Toyota red coolant is the best bargain I can think of, even at $25/gallon!

cobalt91

What year did Toyota start using toyota red? My owners manual calls for ethalene glycol for my 91.

LScowboyLS

All coolant is is either propylene glycol (the low-tox type) or ethylene glycol based

the difference between green, Toyota red, GM DEXCOOL orange, and several other colors is the make up of their additives (ethylene glycol and propylene glycol are actually colorless liquids)

I prefer Toyota red on all cars because it has an anti-corrsion/additive package that makes radiators, heater cores and water pumps last a long time, as long as you change your coolant every 4 years or so.

You can use Toyota red or regular ol Prestone/Zerex/Peak green in your 91, but whatever you use, flush the whole system by running straight water a few drain and fills with the heat on, especially if you are changing from one type to the other!

Also, other "red" coolants are NOT equivalent to Toyota red chemically or in protection from corrosion and clogging.

and for the final 50/50 mix, be sure to use distilled water, rather than tap water, you can buy it at Wal-Mart for about 85 cents/gallon

python

iTrader: (4)

this simply is NOT true..Toyota red causes corrosion if left in too long,it needs to be changed out every few years.

TaffyK20si

Oh boy... You aren't going to want to just throw parts at the car hoping to remedy it.... but, I would start cheap and work up to more expensive and labor intensive parts. First, check for air in cooling system(bleed out if present). Second, check for trash or foreign objects in the bottom of your coolant reservoir (this has happened to me before). Third, replace thermostat. Fourth, remove and inspect water pump (replace if impellers do not spin freely or have damage to them). Fifth, if none of the above have help any, pull the heads off and have a good look at the head gasket and where the combustion chamber meets the head. If you find anything out of order there, take the heads to a machine shop, buy new head gasket kit and head bolts. Might as well change the timing belt and water pump while you're at it . Best of luck.

RA40

iTrader: (6)

With any recently purchased car that the history is uncertain, a fluid replacement is one of the areas to do for the peace of mind. That means tranny fluid, oil, differential and cooling system service.

Have the coolant, thermostat and radiator sensor replaced. Check that the airflow through the radiator is clean of debris like leaves or other foreign objects. The coolant will last beyond 30K miles though it is preventative maintenance to have a thermostat installed every 30K miles. When this is done, fresh coolant will be used. As well, that the electric fans are operating.

If the system is being drained, replace the radiator drain **** and O-ring. About $15 at full Lexus retail. The O-ring on ours seems to last 60K miles before it becomes compressed and allows coolant to leak out the drain tube. The nylon-plastic drain ***** become brittle as well. If doing the coolant routine, nothing more frustrating to find that as you give the plug that final snug, it sheers off in your hand.

LScowboyLS

Oh it's absolutely true that no other coolant is equivalent to Toyota red chemically, it's patented and exclusive, and no other will preserve your cooling system components as well, and of course you need to change it out regularly, that is why I explicitly specified a 4 year recommended change interval in my earlier post - pay attention!

LScowboyLS

Oh I can tell you something more frustrating, driving around to several Lexus and Toyota dealers (this same exact o-ring is used on most Toyotas and Lexus models ever made) and finding that no dealerships have it in stock and they all have to order it! - Aren't they doing hundreds of radiator flushes per year? - they should be using hundreds of these o-rings each year if they were competent.

DaveGS4

iTrader: (2)

LScowboyLS, exit this thread. I've asked you several times to add Python to your ignore list if you cannot respond politely and maturely. The rude attitude in the post above will cause nothing but continuing conflict and it needs to stop. You could have easily made your point about the interval without being rude.

steve2006

IIRC wasn't there also a problem with the coolant reservoir/header bottle developing cracks allowing coolant to escape on the early models and also the pressure cap could be responsible.
With the steam escaping from this area it may be worth checking this first.

RA40

iTrader: (6)

I had to drive around to find that O-ring as well.