oldskewel

Well ... there have been a number of past threads on this and other forums where people have reported using plastic alternator shields on gen 1 LS400's for quite a few years without them causing any problems. Here is a thread from 2003 with photos of a couple of the nicest plastic alternator shields I've seen: http://us.lexusownersclub.com/forums/index...amp;#entry30429 The Aluminum should conduct heat away better than plastic ==> better cooling if all else were equal. But ... the good thing about a Clorox bottle is that it is not likely to get dented in and close off some critical air circulation. Even if you are able to get the Aluminum designed and installed perfectly (perhaps it is, as in the photo), there may be a good chance that when you wrestle it back into the car, you may bend parts of it in towards the alternator, reducing the air flow that is critical to keeping it cool. Especially since others have reported success with it, I believe that the Clorox bottle fix can provide protection while still allowing sufficient air flow. It is a fix that is on my todo list, even though I do not have any PS leaks now. A related concern with the Aluminum pan fix is that with the A-belt right there, I would not want anything that might be deformed and move into contact with the belt. I think this would be more likely with the Aluminum pan than with the Clorox bottle. But it was a nice idea, and good thinking to ask others before putting it in. You may want to save it to help cut out the holes, etc. in the right spots for the Clorox fix if you decide to do that.

I'm about to rebuild the MC in my '91 LS400 with ~170k miles. Not sure if this will fix the dragging problem I've got, but I've tried almost everything else, it seems. I just got the rebuild kit from parts.com. The box was opened, so I don't know exactly what was supposed to be in there. But the individual 3 bags are still sealed. Two spring/pistons with new rubber seals, and a bag with 2 screws, 2 washers, and a c-clip. I'm expecting to do the rebuild and have no change, but we'll see.

Very nice, methodical series of tests you did there. The most important result from those tests is the constant pitch (frequency). That should rule out many possible causes. From looking at all the responses, I think curiousB's initial thought on a resonance is probably closest to what's going on. My guess is that there is some effect, probably aerodynamic, that causes a self-limiting instability, which is nonlinear. This is the same physical phenomenon that causes venetian blinds to rattle suddenly when the wind blowing through them suddenly reaches a certain speed. They then hold pretty much the same rattling frequency until the wind speed drops and they stop rattling completely. This seems to fit your frequency results - it starts at some speed, holds that frequency regardless of higher speed, then changes frequency slightly and stops at a lower speed than the initiation speed. A related phenomenon caused the Tacoma Narrows bridge to collapse (that famous black + white film we all saw in science class back in school). I used to teach engineering students how to analyze these and similar problems in a class on Dynamic Behavior at Stanford University several years ago. It could be related to your antenna, if you have an external one - that's an easy test. If not, there could be some loose wire or flap under the car or in the engine compartment. It could even be something like air getting past a gap between a grommet and a wire. Look for something that is fairly tight (that you could see might vibrate at the humming frequency), but has some free play so it can rattle. You might test for aero-related effects by waiting for a windy day and going upwind then down wind to see if the initiation speed is different. It could also be non-aerodynamic. Any self-limiting instability would have similar dynamic behavior. It could be that some vibrations that are linear in frequency with car speed (e.g., due to an imbalance) are providing excitation to another subsystem that has this constant frequency property. So if you fix the first problem the second will never appear. It might also be some similar hydrodynamic effect in the transmission, although your shift to neutral test almost rules that out.

There's a photo in http://us.lexusownersclub.com/forums/index...showtopic=59750 Discussion on that thread points out the IACV. It's the cylindrical thing a few inches forward of the Lexus logo on the engine.

I think this reply makes the most sense. I agree. If you look at the photo in http://us.lexusownersclub.com/forums/index...showtopic=59750 you can see the two vacuum lines in question, as discussed in that thread. That "idle-up" valve was replaced on my '91 with 165k+ miles right before I bought it, but it still has the original PS pump.

Hi Billy, I hope the job is going well. Regarding your question, earlier in the step 39 instructions, he says the belt is not lined up right, so ignore the "L-CAM" mark on the belt itself. He's just lining up the crank pulley with respect to the cam pulleys. Those marks on the belt are supposed to help, but don't matter as long as the other parts are aligned. I can't see too well in his photo, but it seems there is a mark on the front face of the cam pulley (at about 2:30 in the photo, where straight up towards the top of the photo [not the car] would be 12:00) that is lned up with a mark on a black plate behind the pulley.

On my '91, the PO's dealer skipped the water pump on the 90k T-belt service, then the pump went out at 122k, requiring a whole new T-belt service. All the other advice you're getting here sounds right to me. I believe the fuel filter is a 60k-interval replacement, so if yours was done at 60k, you don't need it yet. Same thing (I think) with the electrical things like distributor caps+rotors. But if you don't know they were done at 60k ...

Your Porsche has a Bosch L-jetronic fuel system, using a swing valve air flow sensor. The Lexus uses either an optical air mass meter, or in the later cars, a hot wire air mass meter. In either case they are quite unlike the primitive (by today's standards) L-jetronic of the Porsche, or other Bosch equipped engines of the 1980's. You're right. I should have looked it up first. My '91 LS400 has an optical-based meter (page FI-47 of the 1991 manual). For some reason, I recalled looking up the part for my 911 and seeing a Toyota on the compatibility list (a Supra, I believe). When I got the Lexus, they looked similar enough that I thought it could be the same. Porsche used that flapper-based sensor on the 911s from 84-94, so it was not obsolete back when our cars were made, even though it may be now. Regarding getting the right tools - yes. As soon as I get any car, first thing I buy is the best service manual available. You save enough $$ by doing the work yourself that buying the right tools is often justified.

I admire the attitude. Good luck in fixing this. I haven't had this problem on my '91, but here's a theory in case the fuel pump issue does not fix it: there may be a problem with the air flow sensor - PN 22250-50010 http://www.toyodiy.com/parts/p_U_1991_LEXU...EPGKA_1703.html I believe this unit is almost identical to the air flow sensor on my other car, a '85 Porsche 911, which I also keep away from professional mechanics. On that car, I would have seemingly intermittent dead spots, and would sometimes have trouble getting over 5000 rpm. Somehow I traced it down to this air flow sensor. Basically the sensor is a flapper that opens wider with more air flow. The opening flapper moves wipers along a resistive surface, just like a potentiometer. Over time, grooves had been worn in this surface, leading to dead spots and spurious air flow readings. With bad air flow readings, not enough fuel will be injected, limiting the rpm, and in general causing driveability problems. An easy test is to connect an ohmmeter to the right two connectors (not sure which) on the air flow sensor. Power can be off, nothing has to be plugged in. Move the flapper with your hand and see if the resistance changes continuously and monotonically (no dropouts, jumps, or going down after going up). It should, if not, your unit needs repair or replacement. Since it is a $1k+ part (as for the Porsche - they really may be identical), repair may be better. If you narrow things down to this, I'll pass on a trick I used to repair mine on the 911. It drove like a brand new car after I made that change (and still does).

Yes, Jack at the smog shop was giving you some bad info there. But all the info you're getting so far on the list here is correct. The PCV valve can be seen to the left of the "32" on the valve cover. That big Intake Air Connector Pipe (IACP) is indeed one big plastic piece. The thin (~1/2" OD) black hose that comes forwards and then returns next to it goes down to the infamous idle-up valve on the PS pump. The thicker black hose running from left to right goes from the IACP to the Idle Speed Control Valve or Idle Air Control Valve. On my '91, those thin hoses to the PS idle-up valve had become so brittle that one of them cracked and I figured I should replace them both. When I removed the one from that plastic barb sticking out from the IACP, the barb broke off with it. It looks to me that this is what happened to your car as well, and the zip tie sort of holds it in place. It's not a big deal to have a slight crack there - it's just that a slight amount of air will come in that is not filtered or measured. Should have no effect on engine performance. But I fixed mine anyway - here's how: I bought a segment of straight 1/4" OD (I think) hard brake line at Pep Boys for like $5. Cut a ~1.5" length off one end (it has a slight flare on the end to keep the fitting on). Remove the fitting, keeping the 1.5" end length. Drilled a hole in the IACP where the barb used to be (slightly enlarging the hole that is already there), sizing it so this brake line end is a snug, almost press-fit (the flared end is sticking out). Put the vacuum hose over the new barb, hose clamp it on there, and it's good as new. If you decide to fix it like this, just so the smog guys can't ding you for it, and you haven't already done it, replacing those vacuum lines with new ones is probably a good idea. I think I used 7/32" ID hose (generic, like $5 for 6 feet of it).

Agreed with the comment on the solenoid filter. Big improvement for me when I did it on my '91. To clarify on "fill with ATF": the PS system uses DEXRON III ATF. DEXRON is a specification, not a brand, so many companies make it. Not to be confused with the Toyota Type T-4 ATF that goes in your AT. Don't put DEXRON in the AT, and don't put Type T-4 ATF in the PS (may not be a problem, but DEXRON is way cheaper than the Toyota stuff, and the Lexus calls for DEXRON III in the PS system).

But if you're doing a drain + fill (not a flush), it will be closer to 2-3 qts. By the way, I'm right down the freeway from you. Putnam Lexus charged me $7+/qt for the first 2 qts I needed after buying the car. Since then, I've learned I can get it for $4.50/qt by the case at the Toyota 101 dealer. This is one of those things that it is best to stick with the factory spec: Toyota Type 4 ATF. Don't go with Dexron III or anything. Good luck.

Yes! Inspect + repair first, then align. This excellent post has info on inspecting suspension: http://us.lexusownersclub.com/forums/index...p;p=342677&

Has anyone heard of a T-belt breaking on one of these cars? If so, what mileage, etc.? Not that I'm doubting the 90k, I just want to know how conservative it is. Also, on my 1991 gen 1, with the non-interference engine, it seems I don't need to be as cautious as the 95+ cars. How about stories of other T-belt related parts failing (or not), to help decide what should be replaced during the T-belt change? Water pump idler #1 idler #2 tensioner seals Here's one data point from my car: Water pump failure at 122k. 1991 LS400, all dealer maintained (by PO) through a T-belt change at 90k: replaced the belt, tensioner, idlers, etc., but NOT THE WATER PUMP. At 122k, the water pump failed, leading to a second T-belt change, with belt, tensioner, idlers, etc. Since I'm asking so many new questions, here's another: any actual experiences with non-OEM vs. OEM parts? I'm not really looking for "advice" (e.g., I know you can't go wrong by using OEM parts at the specified intervals and replacing everything you touch), but rather information about incidents of actual failures or unusually long duration without failure.

EXACT same thing happened to my on my '91 w/ ~160k miles. Not only was the inside part of the hose apparently melted onto the metal barb, but the outside of the hose was brittle. When I tried to pull it off, the hose cracked, and was still stuck. Took some major surgery to remove it, completely destroying the hose in the process. I replaced the hose with standard ATF hose I got at Pep Boys for a few $$. The part from Lexus is custom shaped and has a foam sleeve, and cost $100+. Later (but would have been easier right then), I put a Magnefine filter in-line with the PS return hose right there. A little extra filtering of the PS since this is a known problem area. http://www.emergingent.com/magnefine/order_page.htm So if you're sure you're going to go ahead with it, I'd plan on destroying the hose in the process, so have the replacement stuff ready. Also, even when you destroy it, it does not come off easily, so it may be worth it to remove other parts to give yourself easy access. Good luck with it.

Also, from replacing the mounts on my '91, I can say that the trans mount is 10x easier and 1/3 the cost of the 2 engine mounts. With very low mileage like that, you may want to try just doing the trans mount first (an easy job with any DIY experience) and see if it fixes the problem. The two jobs (engine mounts vs. trans mount) are completely separate, so there is no benefit to doing them both at the same time, other than lifting/jacking the car up. If you really do need all 3 mounts, as I recall, the discounted prices I paid were like $100 each for the engine mounts and $60 for the trans = ~$260 total. Trans takes < 1 hour, engine mounts took ~2+ hours. So depending on the labor rate and the fact that you'll be paying full (or higher) price for the parts at the dealer, the price is not out of line, but I agree that you can probably find an indy to do it cheaper. In general, while you can save money by buying good parts at a discount, and by having a good independent mechanic do the work (if not yourself), the best way to save $$ is to avoid doing unnecessary work. Unfortunately, professional mechanics don't have much incentive to steer you away from this. They do the job, make $$, you feel like something was done, stimulate the economy, and possibly have wasted some perfectly good parts. Makes cash for clunkers look efficient.

Sorry, just the stuff listed here. The only Lexus I've owned is this '91 LS400. Good luck. I should add that my listing of model + year compatibility in the list may be conservative. It could be that these parts will work for many other models + years and I just don't know. Best to go off the part numbers I list and check for yourself if interested. Thanks for the interest.

Glad it worked well for you. I have edited the original posting to make it more readable, and updating for the parts still available.

I called the local Toyota dealer and the service advisor said there is "no filter to change. It's a metal screen." They said $69 for drain and add. Does my 94 LS400 really have a replacement filter? Is he mistaken? My 1992 has a filter. Same transmission, I don't see why yours would be different. Realize that service advisors are not technicians, they don't know all that much. I replaced the "filter" on my '91, and yours should be the same. Drain the AT fluid from the drain plug. Remove the AT pan. The filter can then be removed and replaced. It is a metal screen/strainer, but is inside a metal housing, so I'm not sure if it could be cleaned as good as new. I just replaced mine with a new OEM one: PN 35330-50010, "transmission oil strainer", $41.66 about a year ago. There are 4 strong rectangular magnets on the pan that you can wipe free of metal shavings. If you buy an aftermarket filter, it may come with a rubber AT pan gasket, but I used the OEM FIPG (form in place gasket, which is a tube of sealant) PN 00295-01281, $18.57 about a year ago. The tube seems like it will make at least 5 gaskets, maybe 10. Should be a lifetime supply. I could not agree more regarding the fear you should have regarding places like jiffy lube. The price of $69 for a drain+fill seems a little high, as that is easier than an oil change. Takes about 3 qts of Toyota Type-4 ATF, which may cost $20, but other than that, it's a matter of draining from the drain plug and filling into the dipstick tube.

Sounds to me like it is you idle air control valve (IACV). I have not had this go out on my Lexus, but have had very similar symptoms as you are describing on two different cars. Search around for instructions to remove and clean it. It may just have carbon build up, which you can remove with brake cleaner or similar solvent. Sometimes the cleaning does not hold and you'll need to buy a new part if the problem returns quickly. Good luck.

I've had similar but not nearly as bad problems on my '91. Still working through things carefully. Rebuilt calipers, turned rotors, and balanced wheels fixed the pulsing, but it still pulls right even after an alignment (3 actually). Regarding the brake hose theory ... here's a way to test for it without just R+R'ing the hose: If the wheel is locked after driving it as you say, open the bleed valve on that caliper. If pressure in the caliper was still high due to a brake hose problem, the bleed valve would release the pressure, freeing up the wheel. You'll be lucky if that's it - relatively easy to replace compared to other things it could be. Related to that, if both front wheels are locked and opening one bleed screw frees them both, it indicates a problem with the brake master cylinder (that is holding pressure high when it should be released). I'd be interested to hear what you find out regarding the ABS. If you've thought of everything else and nothing looks right, here's an idea: maybe there's some play in a suspension component that creates an instability at some speed, allowing the whole wheel to wobble, which then leads to some other bad response.

I wouldn't get parts like that from a junk yard - they're likely to be as brittle as yours. Fuel line and vacuum line are different things - you want vacuum line in this case. Just get some generic line of the right diameter from your favorite auto parts store and cut it to the length you need. I just replaced the two lines going to the PS air valve on my '91 yesterday. I used 7/32" Inner-Diameter vacuum line from Pep Boys ($4.99 for 6 feet). There are some protective sleeves around the line that I re-used with no problems. Sure the new lines don't have the custom bends in them, but they don't really matter. If you're making 50k cars you can afford to custom bend the lines so they fit nicely and keep the engine compartment neat, but the generic stuff will work just fine and is far cheaper, more convenient to keep on hand, etc. Good luck.

I replaced mine yesterday in my '91. Followed some of the instructions in the shop manual, but in case anyone else tries, they tell you to remove a few things you don't need to touch. It took a while to get to it. When removed, it measured ~2k Ohms, which is ~right on spec for room temp. There was no crust or scale at all on it. Slight, almost oily film on it that wiped off with a paper towel. Nothing that would impede heat transfer. Old part in hand, I then went to Kragen and got a replacement (non-OEM for $13.99) that looked like a perfect match and also measured ~2k Ohms at room temp. I put the new part in. Sorry to foul up the scientific value of this test, but with the throttle body exposed after removing all those other parts, I could not resist cleaning it. Toothbrush on a stick, spraying in solvent, paper towels, etc. got a lot of black stuff out of there. As far as I can tell (I'm 2nd owner, but have all records from previous owner) this is the first time the TB was cleaned and the temp sensor was replaced. The car sure felt lively on a quick test drive, but nothing I can quantify yet. I log my gas mileage, so I'll see if it improves over the next tank or so. I'll also do a test over the full temperature range of the part I removed to see if anything is out of spec. So - it seems like I removed and replaced a perfectly good part - car feels more responsive (purely subjective, maybe because I'm a believer) - I also cleaned the TB, meaning if performance improved, I won't know which change did it. I just measured (on the old, original, 18 years and 160k+ miles part) resistance of 240 Ohms at 100*C (boiling water). From the '91 manual, page FI-68, the spec range for this temp is ~120-250 Ohms. So it is within spec, although at the high end of it. At room temp, ~2000 Ohms measured, spec range is ~1700-2800 (the ~ in the specs is because I'm reading off a log-scale plot). So this looks like I replaced a good part. No regrets though. Also, no CEL's ever (I've actually never ever seen one on this car - I guess that's what I get for staying ahead of things).

I replaced mine yesterday in my '91. Followed some of the instructions in the shop manual, but in case anyone else tries, they tell you to remove a few things you don't need to touch. It took a while to get to it. When removed, it measured ~2k Ohms, which is ~right on spec for room temp. There was no crust or scale at all on it. Slight, almost oily film on it that wiped off with a paper towel. Nothing that would impede heat transfer. Old part in hand, I then went to Kragen and got a replacement (non-OEM for $13.99) that looked like a perfect match and also measured ~2k Ohms at room temp. I put the new part in. Sorry to foul up the scientific value of this test, but with the throttle body exposed after removing all those other parts, I could not resist cleaning it. Toothbrush on a stick, spraying in solvent, paper towels, etc. got a lot of black stuff out of there. As far as I can tell (I'm 2nd owner, but have all records from previous owner) this is the first time the TB was cleaned and the temp sensor was replaced. The car sure felt lively on a quick test drive, but nothing I can quantify yet. I log my gas mileage, so I'll see if it improves over the next tank or so. I'll also do a test over the full temperature range of the part I removed to see if anything is out of spec. So - it seems like I removed and replaced a perfectly good part - car feels more responsive (purely subjective, maybe because I'm a believer) - I also cleaned the TB, meaning if performance improved, I won't know which change did it.

Those numbers sound pretty low. My '91 idles smoothly at 600 when warm, maybe 1000-1200 when cold. AC on/off will affect this as well. It seems almost impossible that your car could really be idling at 200 - seems it would be very rough and stall. Does it seem smooth at 200? Assuming it does, my first guess would be that your Tach needle is off by about 400. So it's really idling at 600, but indicating 200. Do you have an easy way to test this separately (e.g., timing tool around an ignition wire)? Here's another way - I've noticed that redline for my '91 is spec'ed at 6000, but in a WOT startup, it will shift at 6200. If you do this test (professional driver on a closed course private road with helmet on, of course) and you notice it shift to 2nd at 5800, it would be another indicator of the needle being off.