fhb5032

Bad ground??

Debra, I'm not sure if there are casting core plugs, but the leak is most likely from the water pump. In any case, that cover is the timing belt cover and to get it off and get to the water pump the radiator, hydraulic fan and pump, timing belt, and tensioner, harmonic balancer and a number of lesser parts have to be removed to get to the water pump - or the front of the block if it is a casting plug that's leaking. Depending on the mileage, or the condition of the timing belt, you should replace a number components. They're not that expensive and it's better to do them all at the same time because of the labor involved. It's not that hard a job, but quite complex and, if you want to do it yourself, start by getting a copy of the shop manual for that engine. They come up often on ebay and aren't very expensive and very useful if you intend to do all your own maintenance.I don't know much about the non-oem manuals - Haynes and the like, but because this is a very sophisticated engine it's best to go with the factory books. I had to do the same thing last fall and it's reasonably straight forward - if you have the book. Good luck. Hugh

Could be the sensor that measures fuel pump pressure. If the computer doesn't get a value within range, it won't turn on the other systems.That would explain why different ecus don't make any difference. I don't have a wiring diagram for that year or model. Good luck.

I would walk away, unless you can do the work yourselves. Although the problems are not particularly serious, diagnosing and fixing them will be very, very expensive and the price that they are asking is only justified - in the current market - for a nearly perfect, low mileage car. You'd spend another $3000 getting it to that condition. The timing belt alone would probably be close to a $1000 from an experienced shop and even though it's a non-interference engine (meaning that the engine won't be destroyed if it breaks) it will stop suddenly, with no warning. Keep looking. They are great cars and will increase in value over time if they are well cared for and maintained. Hugh '93 SC400

If it just passed emissions testing, you don't have to do anything immediately. Did Autozone give you the actual codes? If not, go back and get them. Then google the codes, and post them here. There may be pending codes, too. Have him clear the codes and see if they come back and if they're the same each time. I don't have a book that's specific for a '97, but the codes are the same for all OBDII. That should provide some additional information to get a better idea what's going on rather than just "probably".

Probably, but why risk it? These cars are completely computer controlled and most likely not having the cluster gauges hooked up would not be a problem. That said, I once cooked a computer on an '89 Toyota just running without a back-up light switch. Seemed the grounding to the transmission controls/sensors into the computer ran through the switch. Extra current loads on other sensors into the computer overloaded it. New or rebuilt computer $1200 - fortunately I found a used one in a junk yard - $200 and I was luck enough that it still worked. No telling what a Lexus computer will cost. Who knows what circuits would be affected in the SC300 computer without the cluster and all the open circuits. Moreover, suppose there is some malfunction that could cook the engine - coolant loss for example - that you'd miss until it was too late. Let us know how it turns out.

It is probably caused by one of the many sensors that feed in to the ecu. could be coolant temperature, intake vacuum or?? Might be a bad connection to a sensor or a failing sensor. I've had various driveability problems when I had a leaky water pump and low coolant levels in the cylinder heads. The temperature sensor was intermittently in air then coolant. BTW, you might want to check that the cooling system has been properly bled of air. (Check to see if the coolant is full at the plug on the thermostat housing at front center of the engine.) Least likely culprit is the ecu. You might try to find a shop manual for the engine. Good luck.

Usually white smoke in the exhaust, is coolant, blue smoke is oil and black smoke is unburned gas. From what you've described, at the very least it has a bad head gasket. That's almost certainly the cause of the white smoke in the exhaust. That would also explain rough running. Oil leaks from the cam lubrication channels could also come from a bad head gasket, also, but I don't know that much about the configuration of the six to comment definitively about it out the intake ports. Obviiously, if it's loosing oil, you don't want to run the engine anymore, but start by pulling the intake system and the head. Good luck..

There are repair services offered on e-bay to re-do the needle illumination. I have never used any of them. Any of those who have will have posted a rating, I suppose. Hugh '93 sc400

I've got a set of '93 shop manuals - somewhere. I'll try to get back to you sometime this weekend, when I have time to find it and look up the codes. I assume that the codes will be the same Hugh '93 sc400

All the data comes in from the computer as far as I can tell from the wiring diagrams and related stuff. It must be an electromechanical problem in the cluster.

If the needle is that erratic, then it's probably not the sensor - since that sensor is probably working for the computer also. That much intermittent operation would almost certainly set a code. I've had a TRAC or ABS code set if one of the tires has low air pressure. It sounds like an intermittent problem with what ever mechanism is driving the needle movement. So it would be in the instrument cluster. I will try to find time to check the book and let you know.

I really doubt that it is mechanically driven by a cable. given how much these cars are automated with sensors at each wheel, the drive shaft and transmission, but, I don't know for sure. On the other hand, it's hard to figure how a sensor/computer problem would create the wandering needle characteristic of the old spinning magnet on a cable mechanism. I do have shop manuals. If I get a chance tomorrow and no one has posted an answer by then, I'll research how the speedometer operates and post what I learn.

Oh, I should have noted that the needles are illuminated, and the illumination is what's failing not luminous paint.

Apparently a very common problem. My recently purchased '93 sc400 has a dead speedometer needle.and flickering tach needle. There are several re-builders on e-bay who use LEDs that don't die. Can't comment on their reliability, but they are out there. Other possibility is a used one from a "re-cycler" AKA junkyard. But then you face the same problem again.

I've experienced similar problems with non-working gasoline vapor controls. If it's not working properly, as gasoline is taken from the tank, a vacuum develops that can cause fuel starvation. I don't know enough, yet, about ecus in pre-ODB II 90's era Lexus to know if this would set ecu codes or a check light. I doubt that it would, but the next time it happens, loosen or remove the gas cap and listen for a hiss. If you hear one, then this is a possible cause. It's unusual, but worth investigating.

Thanks again. It occured to me that in all my review of the timnig belt and water pump replacement in the shop manuals I had never encountered any warning against turning the crankshaft if the camshaft timing was either off or out of synch - which would be expected if the engine there was an interfenence problem. So, I finally got wise and read the manual more carefully. There are two very relevant statements in the engine overview from the Lexus shop manual. Paraphrased: - the valve springs are such that no "float" will occur under any circumstances. - the pistons have depressions which prevent interference with the valves. So it can be confidently stated that at least the early 1uz-fe engines are not interference engines and timing belt failure alone will not damage the valves or pistons. Nor will valve spring failure. Anyway, I just finished running the engine and testing everything that could be tested before I started digging in to change the pump and belts. Everything is fine except there is no heat from the heater. I am sure this is because of an airlock in the system and the lack of coolant circulation.

Good advice '90sl400! Just what I would have commented. Guess I wasn't clear in my question. I wasn't concerned about driving it to the last and catching it just before it breaks, but just the opposite. If I'm going to breakdown I'd like it in my driveway. I just bought this car - 206000 miles. Don't have any idea of the condition of the belt. No documented new belt since 89500, water pump is failing. Once I was satisfied that the engine ran, didn't miss, knock or smoke, I shut it down, bought it, flatbedded it home courtesy of AAA and won't restart it until I have the new belts and waterpump installed since there doesn't seem to be consensus about interference in this engine. I'm not sure if any other systems need work - power steering pump, alternator, ac compressor, etc I'd like a compression and oil pressure check. It would be nice to know what state they're in before I start so I can replace or repair them when I'm "in" that far. It would be helpful to know whether I could chance starting the engine again and testing them before I start tearing it down, so having a look at the belt early on, could give me confidence about whether to start the engine and check things out before I begin the work.

UHHHH, just how is it resurrected? No, seriously. Can you describe what's happening? Do any of the accessories, lights, etc still work? Does the check engine light come on? Does it re-start right away or after some time? Does the engine "crank" when you try to restart it? What does happen when you try to restart it? Is every "death" and resurrection just the same sequence?

Yes, thanks about the water pump advice. It's already failing as noted, so I'm going that far in. I have a shop manual, so it's straightforward, but lengthy. Another question, though. Does anyone know if, once the timing covers are off, is it possible to inspect for a damaged timing belt or impending failure? Won't make any difference to what I have to do, but just curious for future maintenance and useful information for the group.

Well, I'm not at all sure how this comes out. I just purchased a 1993 sc400 with 206,000 miles. The last verified timing belt change was at 89.500 - both on the sticker in the engine bay and in the service list at Lexus.com. (Many thanks to the member who posted that link.) I guess the prudent thing is to not take a chance and have the AAA bring it home so that I can change the belt. Just doesn't seem worth the risk of ruined engine. However, while I have it "open" I'll hand turn the crankshaft through two complete revolutions and see if I encounter any resistance. I'll post the results. Won't be absolutely definitive, since if a belt breaks at high rpm, there might be valve float that would jam valve or hole a piston. Needs a water pump, too. That's defninitely leaking.