lavondag

I finally got the sensor out and changed but just had to work around the cover to do it. I had all the bolts out and never did figure out what was keeping me from getting it all the way out. Oh,well. It was the small louvered cover that is over the left end of the spark plug wire tray. Thanks for the picture link cause I will definitely be able to use that in the future =)

Shiryo

Saw this thread before I bought a LS a few months ago. I must say, keeping this in mind was a great idea. Read about a lot of people replacing this and experiencing positive outcomes.

After reading the whole debate on AutoZone vs OEM. I couldn't find anything negative about the AutoZone product, heard it was manufactured by Wells and I can verify that it is when I got the package.

They go for ~$25 at AutoZone. I looked on eBay and found one for $15obo and offered $10 shipped and got it for that a couple days later.

I must say, the job is very straight forward and only took me about an hour to do, but I was slowpokin it and whatnot. Snap-On CTS561CL was used on this job, made it go by very fast, first job I got to use it on, must say that if you ever want a cordless screwdriver, that's the one to get. Make sure you get a 1/4 hex to 3/8 socket adapter, got a DeWalt for less than $5 at my Lowe's down the street.

Another tip. The sensor is 19mm and 3/4". I was trying to use my snap-on 19mm socket but couldn't get the socket all the way down to line up the nut. Grabbed a Craftsman 3/4" and found that Snap-On sockets have a "sleeve" inside whereas Craftsman sockets are fully hollow inside, was able to get the new sensor on with a breeze. Seated the sensor down then did a bit shy of half a turn to snug it down. Used the old washer off the old sensor.

Went for a short drive, I can't tell if it's placebo or what, but it definitely feels like the throttle is far more responsive. Should in-turn give me better fuel economy as i'm not on the throttle as much.

I HIGHLY RECOMMEND THIS SERVICING!

Jasvin

Hi,i own a '90 ls and am from Malaysia.i have browsed through the thread and am thinking of replacing the ECT on my car as well only i am not too sure if this is the problem plaguing my car.the problem i have with mine is that the temp gauge reads hot and always indicates a level slightly more than half and stays there and the engine runs fine.however,this in turn is causing my car to run really rich to compensate and the fuel consumption is really unbearable at this point.can anyone help?i havent replaced anything in the engine yet bar the plugs.

any advice and help would be deeply appreciated.thank you.

Jasvin

anyone???........

LScowboyLS

Sorry we somehow missed your question last month

I would first replace the low cost gauge sensor that sits right beside the ECT (the gauge sensor is the single wire one) with the genuine Toyota part, that way you will know better what the REAL engine temp is. (maybe is actually too cold, but reading is wrong)

also, you car is old enough that the real Toyota ECT sensor would be a very good idea!

generally it is when a car runs too COLD that it runs rich and consumes a lot of gas!

also I would replace the thermostat with genuine Toyota thermostat as well and ensure the cooling fan is coming on and that there is no obstruction such as dirt or bugs in the condenser (what looks like the radiator when viewed from the front of the car)

if you need Toyota part numbers for the parts mentioned above, let me know!

timmy0tool

iTrader: (7)

could also be air in the coolant lines. simply change the gauge sensor first and see.

Jasvin

thanks lscowboyls and timmy0tool,i will try replacing those parts and see where that leads me,or i may start with the cheapest first.if it helps in troubleshooting,i have had the car for about 5 yrs and this problem has been plaguing me ever since.the whole engine had been replaced with a whole front cut which includes the wiring,dash,gbox,etc prior to me purchasing the car,the front cut came in from japan and i am wondering if that has anything to do with the temp running so high in this country as we only have 1 season,which is hot all year round.my suspicion has always been on the thermostat.do you have any idea if the thermostat for the US and Japan differ from the one suitable for our climate?

lscowboyls,i understand that the engine would run rich when the engine is cold,but would it also run rich when the engine is hot to reduce or control the engine temp or am i mistaken?

also,i have noticed that some of the ls400's in this country have 2 additional cooling fans at the front of the radiator which can bee seen when standing at the front of the car between the bumper and radiator support and where the ac lines pass through.mine has only the one at the back.can this be the issue?

sorry for the 20 questions guys.....

cobalt91

Hello, jasvin. First, i dont think that the thermostat is goin to be different from country to country or region to region. The thermostat is going to contol engine temperature. The 1UZ stock thermostat is pretty efficient. It is goin to keep it at optimal temperature for combustion. The cooling fan on your car is going to remove heat from the radiator. Now some ls400's have different fan setup from others. I dont know which one is better. Start by checking all your fluids. Both level and condition. If that is good check the sensors. There are two on front top of the intake manifold, behind the top ignition coil. One or both may be malfunctioning. Is there a tank for fluid marked for the fan?

LScowboyLS

thermostat opens at a predetermined coolant temperature, it doesn't care what the temperature outside is

no, varying the fuel mixture is not used for temperature control on LS400, only thermostat, fan clutch or hydraulic fan speed and electric fan control are used in this way

you need to put it back to the stock configuration of the 90-92 models as far as electric fans and their location, is normally one or two fans on front side of radiator on most LS400

also if it turns out you are actually running too hot, here is the order in which I would replace things:

● thermostat (make sure jiggler hole is at 12 o'clock for proper auto-bleed)
● radiator cap
● clean A/C condenser if dirty (condenser is what you think is the radiator when viewing from front of car)
● make sure all electric fans are continually running anytime time gauge is near halfway or A/C is on
● radiator coolant temp sensor for electric fans (located near bottom of radiator at one corner)
● fan clutch (or change fluid if you have hydraulic fan)
● change coolant - use 50/50 Toyota red coolant & distilled water (fill at the FILL BOLT (large bolt facing downward behind thermostat housing)
● if condenser or radiator fins are bent - they need to be straightened back out carefully - they make a tool for this
● if none of this solves it and car has over 200K, you may need a new radiator if previous owner did not use Toyota red coolant
● engine issues can also cause overheating

I know they are expensive, but shop hard and only use genuine Toyota parts for your cooling system

part numbers are available here - register and log in and give Club Lexus username to get large discount

always check part number through Toyota dealers, usually cheaper than Lexus dealers

Jasvin

Hi cobalt91,thanks for your input.the fluids in my car are always at the optimal level and checked and replaced when necessary,i have also drained the fluid form the radiator before to eliminate any air that may be in the lines to no avail.i always use original toyota parts which i get from an authorised toyota parts retailer here including the red toyota coolant.the sensors you are referring to is the ECT and the single wire gauge sensor right?judging from everyone's response here i think those 2 sensors and the thermostat are my best bet to replace as well as the one at the bottom of the radiator.as for the fluid for the fan,iirc there is one and i have also drained that before and replaced the fluid but it didnt help.

Jasvin

so what do you reckon lscowboyls,should i replace the thermostat, ECT sensor,gauge sensor and the sensor at the bottom of the radiator first or revert my fan config?and should i fit 2 or 1 big fan at the front?

if the radiator cap is at fault,wouldn't it leak coolant?my car's AC needs servicing at the moment so i'll be sure to clean the condenser this time as i have never done it before.as for the fan i've ensured it continuously runs at the required time.fan fluid has been changed to no avail.as for the coolant,should i still go 50/50 for such hot weather?i think i made a mistake as i always fill the coolant from the spare tank.will do it from the fill bolt behind the thermostat this time.the radiator fins look fine and straight.i cant say if the previous owner used toyota coolant as i have no service records whatsoever and the mileage is only just approaching 200k km's so would it be necessary to get a new radiator?as for engine issues.i have some white smoke on start ups but only some times which i think are due to the valve seals perhaps?any ideas?

thanks for the part numbers' link mate.will need it.i always use genuine toyota parts that i obtain locally from an authorised toyota parts retailer so no worries there.

LScowboyLS

I am very frugal and not one to spend any money without good reason, and the gauge sensor, ECT sensor, thermostat and radiator cap were the first 4 things I replaced on my LS400 when I bought it - the radiator cap is one of the most overlooked items, because it is very critical for the LS400 to properly bleed itself of any trapped air to work correctly, and in our cars the radiator cap is often 20 years old and this part wears out!

and yes, always use 50/50 mix year round and use Toyota Red coolant p/n 00272-1LLAC-01 + distilled water --- this will save you from buying radiators!


also make sure that the jiggler hole on the thermostat is positioned at 12 o'clock for proper self bleeding!


did you use Dexron III type transmission fluid for the fan fluid change?

as far as the electric fan configuration, I do not have the specifications on the electric fan configuration for the JDM model, but I suggest locating the original factory repair manual and bringing the car back to the original factory configuration of electric fans in both number and mounting locations and part number if it is not now this way - these fans and mounting brackets are often in good condition on junked LS400 cars, so are often low cost at the wrecking yard.

another good thing for engine life and fuel economy is to use a 5W-30 synthetic engine oil from a big name brand such as Pennzoil, Mobil, Castrol, or Valvoline and even 0W-30 weight is also great, and yes I understand it is always hot in Malaysia, 10W-30 is pretty much obsolete with modern oils.

gauge sensor = p/n 83420-16020
ECT = p/n 89422-20010
radiator cap = p/n 16401-50071
thermostat = p/n 90916-A3003

Gene01

Check out the Power Steering valve (which is vacuum operated) regarding the white smoke on startup.
There is a very extensive thread on the subject.

luischaves

Hi Jasvin, did you found out what was wrong with your car? My 1992 LS400 has the same problems...the temperature gauge is most of the times on the mark above the middle and has horrible mpg. In the city I get around 12 mpg and I drive really slow.

TDIGREEN1

I hope the people reading this thread have thick skins:

What is wrong with some of you guys? I have a '93 LS400 and it is a wonderful car - but you must put in the time and effort to enjoy it.

It only takes an hour or so to read this thread through. Read it. Read the other threads. Try all the suggested fixes - ok, that takes longer. But really, these are nice old cars that drive like a dream - but all old cars insist that either you or your well paid mechanic become intimate with tham on a regular basis.

I've changed two of the three coolant temp sensors (and now my coolant temp gauge is low so I replaced the T-stat but no change - that means I should change the coolant gauge temp sensor). I changed the two rear 02 sensors - good results. I changed the tranny fluid and installed a tranny fluid cooler before finding out my ignition rotors and wires were the problem with the 'bucking' under accelleration.

I had a mechanic diagnose and replace the ECU ($500)(apparently with a used one) only to have it fail a few years later. So, I had it rebuilt with the new caps ($200) (whatever - not an electronics guy) so now all is well three years later.

I replaced the instrument cluster ($500 - Lexus) only to have it fail 25,000 miles later. Had it rebuilt by some guy in CA - so now all is well 50,000 miles later.

The Nakajima amplifier in the trunk failed, slowly over two years, and stunk the car up so bad I thought I would have to sell it. Pioneer to the rescue for $500 plus my effort replacing the speakers - do not reuse the sub-woofer in the rear deck lid - it sucks and is the wrong ohms - all is well - and I have Blu-tooth and a USB port for the Ipod/smart phone.

BTW - replace the radio antenna with a power boosted unit super-glued to the rear window up high - huge improvement. Leave the old antenna in place and down to prevent water ponding in the drivers side rear wheel well - that will stink up your car as well.

Contact the wheel company in CA and swap your rims for hard chromed ones - again - $500. Please don't mess up the suspension geometry with the wrong aftermarket wheels.

Had the leaky rear main engine oil seal replaced (again $500) only to learn the guy set the new one exactly in the same groove as the old one (if you do this don't drive the seal all the way to the stop - offset it at least 1/8 inch to the rear) - guess what, still leaks - daaauuummmnnn - now I run oil level at half full and made a nice tampon holder to catch the leaking oil - change the tampons once a month.

The rear struts got so bad I had them replaced (not the air shock version - if you have those you are screwed). Good results.

The exterior paint and interior leather (with minor nicks and wear) are in great condition - although the drivers side seat gets a little firm after an hour or so. The original floor mats are in excellent condition.

Do not argue with the wood trim pieces on the arm rests when the adhesive releases and they warp up - drill little holes and put in little screws to hold them down front and back (with epoxy or similar adhesive underneath) - paint the screw heads brown to match.

Replace the weak hood lift struts with the cheap aftermarket struts you can get off Ebay - just have to work with them a bit to make them fit.

If your coolant fan shroud plastic cracks, reglue it with gorilla glue - tape it in place and slather the glue on the broken bosses - the intake air duct hides the mess anyway. The sad thing: still on the original coolant hoses...

Keep the plastic underliner in place under the engine - these cars had a very low CD when they were new - that underliner helps.

My wife loves this car. I could buy her a new one tomorrow for cash but she doesn't want it.

Windshield 20 years old? Replace it and use those high dollar single piece windshield wipers - they last three times as long.

Ok, thats about it - did I mention the 'shrimp sandwitch?' My apologies to Forrest Gump.

I pay liability insurance only. The taxes are nothing. MPG is about 16 - 22+

I just got back from flogging this biotch up and down the Smokey and Blue Ridge Mts - passing most of the traffic up and down - 700+ miles - in the rain - less than two tanks of gas.

Like what you just read? Like the way she drives? Learn her. Care for her. Enjoy her.