Lexus-Toyota 1UZFE Variants
 

Article by: Rod Garnett (Zuffen)

There are 6 variants of the engine. Crown (pre-96), Crown (post-96), SC400 (or Soarer for JDM versions), SC400 “active” or UZZ32, LS400 and Celsior

To assist in engine identification the vehicles model numbers are handy.
The cosmetic differences are quite wide ranging and you should ensure you check for as many indicators as possible to positively identify an engine.

Toyota Crown:
Crown Royal Saloon (1989-1992ish) UZS-131 cut off dates are probably September but no one is certain.
Crown Majesta (1992-1996ish) UZS-141 & UZS-151

Soarer:
Air suspension UZZ-31 (is identical engine wise to SC400 so will be treated as an SC400).

SC400:
Coil and air suspension UZZ-30, UZZ31
Active (hydraulic) suspension UZZ-32

Lexus:
LS400/Celsior UCF10, UCF11, UCF20, UCF21 & UCF30

Engine badges/signage: 
Crown - plenum has a “4 CAM 32” badge on the plenum and the plug covers say "Toyota".
SC400 - has the Toyota logo on the plenum and “V8 FOUR CAM 32” on the plug covers
LS400 - has an "L" badge on the plenum and "V8 FOUR CAM 32” on the plug covers.
Celsior - has the Toyota logo on the plenum and “V8 FOUR CAM 32” on the plug covers.


Engine mounts:
Crown (pre-96) - Traditional steel mounts with a rubber isolating block with 4 fasteners.
Crown (post-96) - cast Alloy "ears" that stick straight out with a rubber isolator with one stud each end.
SC400 - cast Alloy "ears" that stick straight out with a rubber isolator with one stud each end.  Same as Crown (post-96)
LS400 - cast alloy "ears" that sweep forward and out with a rubber isolator with one stud each end.
Celsior – as per LS400

Sump:
Early Crown - UZS131 has mid bowl without an oil level gauge. Dipstick runs down thru head to sump.
Crown Royal Majesta - UZS 141 & UZS151 has front sum like an LS400
SC400  -Rear bowl sump with oil level gauge. Dipstick in an external tube.
LS400 - Front bowl sump with oil level gauge and dipstick in an external tube.
Celsior - Front bowl sump with oil level gauge and dipstick in an external tube.
Oil pans are not interchangeable without the alloy intermediate plate. Swapping sumps requires the oil pan, intermediate plate, windage tray, oil pickup, oil level gauge (where fitted) and dipstick/tube.

Intake:
All plenums are the same except for the badge on top.
Crown – all have traction control on Throttle body.
SC400 - may or may not have traction control depending on model in range.
LS400 - all have traction control.
Celsior - all have traction control.
Resonance chamber is different between all three engines.
Intake pipe is different between all three engines.

Air filter assembly:
Crown UZS131 - use round assembly.
Crown UZS 141 & UZS151 – uses rectangular assembly.  
SC400 - uses rectangular assembly.
LS400 - use round assembly
Celsior – use round assembly

Fuel lines:
Crown and SC400 fuel lines enter and exit from behind the cam covers.
LS400 fuel lines enter and exit lower on the engine.  They enter and exit under the exhaust manifold

Fuel rails:
The early 1uz 1989-1994 have billet fuel rails.
The later 1uz 1995-1997 have cast alloy fuel rails.

Injectors:
Crown UZS131 - 215cc
Crown UZS 141 & UZS151 – 215cc
SC400 - 251cc
LS400 - 215cc
Celsior – 215cc

Cooling fan:
Crown - has viscous fan driven from an idler above the crank pulley
SC400 - has hydraulic fan driven by a pump in the same location as the Crown idler.
LS400 – has viscous fan driven from an idler above the crank pulley
Celsior - has viscous fan driven from an idler above the crank pulley
The belt idler mount (the alloy spider fitting) on the engines are different to allow for the different fan arrangements.  Whilst different they can be interchanged so you can use a Crown on any engine and vice versa. 
The Active Sc400 UZZ32 uses a unique front cover to support the suspension pump and other ancillaries.  It runs 2 serpentine belts.

Oil filters mounting assemblies:
Crown UZS131 - has the filter mounted at the rear of the engine with a long rigid adaptor bolting to the front of the engine and supported at the rear.
Crown UZS 141 & UZS151 - same as SC400
SC400 - have filter mounted below air conditioning compressor
LS400 - have filter mounted below the air conditioning compressor like the SC400 but slightly further back.
Celsior – have filter mounted below the air conditioning compressor like the SC400 but slightly further back.

Power steering:
Crown UZS131 - p/s pump has the reservoir attached to it.
Crown UZS 141 & UZS151 - p/s pump has the reservoir attached to it
SC400 - uses remote reservoir.
LS400 - p/s pump has the reservoir attached to it.
Celsior - p/s pump has the reservoir attached to it.

Thermostat housing:
Crown UZS131 - no bleed line off the housing.
Crown UZS 141 & UZS151 - no bleed line off the housing.
SC400 - has 1 bleed line from the housing
LS400 - has one bleed line to the reservoir.
Celsior - has one bleed line to the reservoir.

Wiring Harness:
Crown UZS131 - does not have provision for oil level gauge.
Crown UZS 141 & UZS151 –Oil gauge in alloy intermediate plate below alternator
SC400 - some models do not have Trac so a different loom
SC400 - Active is unique and won’t interchange to another engine.
LS400 – same as Celsior.
Celsior – Same as LS400

Whilst you can interchange the harness between different engines some differences do occur.  Oil level gauge sender on LS400 and Celsior models are on the right hand side at the front (behind the power steering pump)whilst the gauge sender on SC400’s is in the centre of the engine on the left hand side (behind the air conditioning compressor).

Compression Ratio:
Early 1UZ 1989-1994 10.1:1
Later 1UZ post September 1994 10.4:1 

Power output:
The Crown puts out less power (around 10-15hp less) than the SC400 or LS400 partly because of the restrictive exhausts. 

ECU:
Crown UZS131 -  has two modules the ECU runs the engine and the ECT runs the transmission. The ECU is happy to run without the ECT
Crown UZS 141 & UZS151 – has single ECU/ECT and can be hard to run without the transmission or external sensors.
SC400 - uses single ECU/ECT.
LS400 - uses single ECU/ECT.
Celsior - uses single ECU/ECT. 

Whilst the Crown UZS 141, UZS151, SC400, LS400 & Celsior use a combined ECU/ECT they are not interchangeable.

Exhaust:
All three have different, but nonetheless inefficient headers/manifolds. Cats mount in different locations as well.
Crown -  by far the smallest least efficient setup. Good if room is tight.
SC400 – the in between set.
LS400 -  neat “LOG” style headers that should fit in some tight places.
Celsior – as for LS400