When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Alternator and Power Steering Pump Service SC400 - 1UZ
After finishing my Cusco LSD service and getting the SC400 back on the road I discovered that I was having a charging issue.
Battery dropped to 10.5V and is a fresh battery. So charged it and found that the fuses were all good.
Started the engine and removed the ground cable and the engine promptly died so I figure alternator is the culprit.
Got the car up on stands and removed the alternator. Turns out I have a power steering leak.
I replaced the rectifier in the alternator with an upgraded 50a x 8 diode model and kept everything else stock. Brushes looked good.
I’ll go get it tested soon and see if that fixes it. Hopefully that does the trick. Could still be a voltage regulator I suppose and it’s easy enough to swap later if testing shows it’s still faulty.
If you still have issues and need to replace your alternator I would recommend upgrading to an OEM Toyota-Denso unit from a later model Lexus SC430.
NOT the early model year SC430 alternators. Those are only 3-phase just like your stock SC400 alternator.
It will give you: 6-phase power, 130 Amps and the same oval type connector as in your SC400.
If your SC400 doesn’t already have a stock 150 Amp alternator fuse you can buy one of those from a dealer.
This is a bolt-in swap with no changes needed for any UZ engine. I installed one onto my 2JZ but had to shave one unused mounting ear off and shave -5mm from one of the rear mounting ears. For a 1UZ it will bolt right on as-is.
I also combined my alternator upgrade with a “Big Three” upgrade (additional alternator positive to battery with 150A in-line fuse, additional block to battery negative ground and additional battery negative to chassis ground) but this may or may not be necessary for only an additional +30A over stock since some SC400’s already came with stock 3-phase 120 Amp alternators.
Overhauling an old PS pump is a very good idea on an SC400 or any UZ powered vehicle since a leaking pump tends to take out the alternator below it.
It sounds like your alternator has been fully repaired so you won't have to change it for another one unless you want to
The benefit of a 6-phase alternator is that it has much better idle amperage closer to its maximum output throughout its rev range. This can help a lot in general with more stable power and whenever power hungry accessories or modified circuits kick on (ie: extra high current draw electric cooling fans, higher output stereo equipment, higher capacity fuel pumps, etc.).
The older tech 3-phase alternators have far fewer amps at idle and don't ramp up in their potential to put out more up to their maximum without revving the engine out. In stock configuration this is almost never an issue (although 2002-2003 Lexus SC430's *did* have issues with their 3-phase alternators and the problem was only corrected a model year or two later when Lexus gave them 6-phase units) but it's a very good upgrade to have in general.
The ability to get newer 6-phase alternator technology from an OEM Toyota/Lexus Denso alternator also keeps the factory reliability that your original alternator is known for.
This upgrade is also popular with Supra MKIV owners who will modify certain model year Tundra, Sequoia, LX470 or SC430 alternators in order to fit their JZ engines in order to have a modern OEM Denso 130 Amp or 150 Amp upgrade to the 3-phase OEM Denso 80 Amp, 90 Amp, and 100 Amp factory alternators that are made for JZ engines. Aside there is a Japan-only 6-phase 130 Amp alternator that was made for certain JZ engine powered cars... but Toyota wanted nearly $1400 USD each for those imported from Japan last someone checked into it. So everyone went for these various far more affordable OEM Denso 6-phase UZ alternators and modified them to fit.
In your case you don't need to modify anything to get one to fit! But only the 130 Amp SC430 type (later SC430, not early) has the correct oval connector that most of our SC's use.
Nice! Does the sc430 alt make the windows roll up and down any faster when sitting in a parking lot?
I don't think it will do anything like that unless for some reason your overall electrical system is already taxed right at the edge of what it can provide. Your window motors will do what they will be capable of so long as they have a steady +12V applied to them. The advantage of a 6-phase is just more plentiful amperage *availability* (available to meet any current draw demands that is) from idle up through the rev range instead of *just enough* juice at idle and plenty more through the rev range.
However alternator amperage is drawn, not pushed... so anywhere in the car's electrical system if there is any heavy additional load the 6-phase Denso alt will be able to better compensate.
If your electrical system and engine are pretty much stock then you probably don't NEED this upgrade... but with an SC400 it's a very, very easy bolt-in affair with an OEM Toyota-Denso alternator. Again, some SC400's (not SC300's) came with 3-phase 120 Amp alternators and a 150A Alternator *fuse* from the factory and it's easy to install one of those fuses if yours doesn't have it already. Therefore installing a Denso 6-phase 130 Amp alternator shouldn't be any big stress on the stock alternator positive wire. Although you could do a "Big Three" upgrade at the same time if you wanted to.
If you were to instead install the Denso factory UZ-type 6-phase 150 Amp alternator from a Sequoia, LX740 or Tundra then you'd definitely need a "Big Three" upgrade with its own in-line fuse on the extra alt positive cable in addition to just installing the alternator.
With many additional electrical circuits added over stock it can make much more sense to go for one of these alternators. It's especially a thing for MKIV Supra an SC owners who have heavily modified and upgraded fuel systems, upgraded additional coolings fans, a switch to IS300 dual OEM electric cooling fans and or additional extra cooling fans (such as high amperage draw Spal aftermarket fans).
In general it's a good OEM to OEM upgrade with all the expected stock reliability to have in our SC's since all modern cars today come with 6-phase alternators if you think you may want the extra peace of mind.
With a 100% stock 1UZ-FE and 100% stock or barely added onto SC electrical system it's probably not necessary.
For me it made sense to do this upgrade on my JZ setup (with modification needed to make it fit a JZ engine that is not needed to fit it onto any UZ) since I did have a lot of changes and additions to my electrical system.
I removed the airbox and intake tube to gain access to the PS pump. Ps pump out. 4 14mm bolts. One is actually a nut. Two on the front and two on the side. Very easy job. Did it all from the top. Not Lil’ Pump. ODP : ol dirty pump Pulley removed . 17mm nut. Couple taps with a ball peen hammer on the nut. Looks to me like the internal seal is bad and this is where the junk is coming from. It’s blowing out the shaft and past the bearing and it’s seal. This is a seal on a bearing. Not the seal that seals the power steering fluid! Don’t do what I did and ruin the bearing’s seal… I didn’t know at the time that this was a bearing. I thought it was a seal when I removed it. Had to order a new bearing and thats going to hold up my progress another week. Live and learn. Cleaned the pump. I hate working on greasy, dirty junk. Back housing. Remove these 4 to get inside the pump. That round provision is where the flow valve lives. Thats the high pressure outlet of the pump on this side. Exploded view diagram of the pump. I think it’s a Ls400 pump. A little bit different but similar. Bearing I had to order. You can see the vane pump inside. You have to remove the shaft and bearing from the other side to gain access to this. Flow valve removed. Taken apart and cleaning. Got stuck here. Need to pull this shaft. Need to make a coupling to attach my slide hammer. Need to adapt my slide hammer to get this shaft out. Trip to the hardware store tomorrow.
KAHNBB6 : can you rename my post please? I didn’t know it was going to take on a side quest to include Power Steering.
“Alternator and Power Steering Pump Service SC400 - 1UZ”
You got it! Done
Very clean and professional rebuild of your PS pump! I agree... when doing a job like that I want my assembly to be clean and fresh as well. This will be the last of your problem probably for as long as you own your SC400
$40! Ouch. But it made life simple. Chopped off 1.5” of the end with a sawzall and made my coupling out of that. Coupling for the shaft puller. Pump disassembled. Bearing removed from the shaft. I used a big socket and a hammer to knock it off the shaft. I’ll probably use the old bearing to install the new bearing when it arrives. This is the seal that is the culprit. I need to remove this seal and drive in a new seal.
Very clean and professional rebuild of your PS pump! I agree... when doing a job like that I want my assembly to be clean and fresh as well. This will be the last of your problem probably for as long as you own your SC400
Thank you for changing it and also thank you for the kind words.
Drove the old seal out the back. Now each oring, seal and snap ring is present and accounted for in the rebuild kit. The side plates of the vane pump are tricky. There is an internal oring that was very brittle and tough to remove. I used a razor knife and got my best results. The spec on the spring length is >36mm. I still need to measure that. I’m pretty much on hold at this point until the new bearing arrives.
Pump all ready to go. Bolts torqued! Happy with how this turned out. Now that I know what I’m doing I wish I could do more of them. New bearing installed! I used the old bearing, a socket and a hammer to install the new bearing. The hard part is removing and installing the C clip bearing retainer on the pump shaft. New connector for the alternator. The clip on mine was broken and all oily and greasy. I’ll replace this next, do a little cleaning and then reassemble everything.
Old connector was embrittled and damaged from oil and heat. Fresh new connector, tape and all cleaned up and ready to go!
Alternator is back in and all buttoned up. The alternator connector is very close to the exhaust manifold. Power steering pump is all tightened up. Need to do the reservoir and the air intake and coolant overflow yet. So far I’m at 1hr15mins on the reinstall including the connector rebuild.
Found the PS reservoir tube in storage. I’ve had it for 10+ years waiting for my roadside repair piece I made to get me home to fail.
It never did. But since I’m here, I might as well open the bag and use it!
Anyone know where the harness is that plugs into the coolant tank? I’ve got a plug here and I don’t recall where it goes?!! I’m 2 hrs in. It’s 10pm. Time for a shower and hit the sack. I’ll finish up the belt and airbox tomorrow. I’m missing 2 10mm bolts too lol.
10-08-22, 08:52 PM
Alternator and Power Steering Pump Service SC400 - 1UZ
