Why does the power steering on my Lexus LS 400 groan when I turn?

Short answer: A groaning or shuddering LS 400 steering can come from the pump, worn internal seals in the steering rack, a slipping drive belt, a clogged hose, or even non-steering parts like dry sway bar bushings or worn upper strut bearings. One owner paid $545 for a new pump and still had the groan. Narrow down where the sound comes from before replacing anything big.

Symptom: A groan or vibration through the wheel when turning, especially at parking-lot speeds, sometimes with steering that gets hard to turn. Another owner had a shudder on sharp low-speed turns and a sawing sound when turning at a standstill.

What to check first

1. Check the power steering fluid level and look for leaks, especially where the hoses connect to the rack.
2. Check the drive belt for slipping or glazing. A slipping belt can make the steering shudder at full lock.
3. Use a mechanic's stethoscope (or a length of hose) to find where the noise is coming from.
4. Push down hard on each front fender. If you hear the groan, it may be the sway bar bushings, not the steering.
5. Put a hand on each strut tower while someone turns the wheel. A rough feel points to worn upper strut bearings.

Likely causes

1. Worn steering rack internal seals. A member said seals bypassing inside the rack cause groaning and stiff steering.
2. Power steering pump. Often blamed first, but replacing it didn't fix this owner's groan.
3. Slipping drive belt. Most noticeable on sharp turns at low speed.
4. Hose leak or restriction. Leaks often start at the rack hose connections.
5. Sway bar bushings or upper strut bearings. Can groan when the car's weight shifts during a turn.

What it usually costs

One '99 owner paid $545 for a new power steering pump, and the groan remained. A member's relative was charged $800 for a pump when the real problem was the horn contacts squeaking. Prices come from owner posts.

Is it safe to keep driving?

Usually drivable short-term if the fluid is full and steering effort is normal. If steering suddenly gets heavy, leaks a lot or the pump whines loudly, get it checked soon, because losing assist mid-turn is a real risk. Verify with a mechanic.

DIY or shop?

DIY for fluid checks, belt inspection and the fender and strut tower tests. Pump and rack replacements are usually shop jobs.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists no recall for power steering on the Lexus LS 400 in the model years we could check on 2026-10-24 (the recall lookup returned an error for 4 model-year queries). Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• NHTSA complaints: 37 keyword-matched complaints for Lexus LS 400 1990–2000 (of 335 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-24; keywords: power steering, steering, groan, whine, noise, pump, rack). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Power Steering groan on 99' Lexus LS400 on Car Talk, a shop replaced a '99 LS400's pump for $545 and the groan stayed. Members suggested the rack's internal seals, hose connections, dry sway bar bushings (push on each fender to test) and worn upper strut bearings, and stressed pinpointing the sound with a stethoscope. The shop ended up replacing the pump again and was worried about the rack.
• In Lexus Power Steering Problem on Car Talk, a 1990 LS400 still shuddered on sharp low-speed turns after a new pump, rack, hoses and cleaned screens. A member suggested the pump's drive belt might be slipping and to check or replace it.

Quick tip

A groan isn't always the pump. Spend 15 minutes finding where it's coming from before spending hundreds on a part.

Vehicle focus: 1990–2000 Lexus LS 400.

Safety / mechanic note

Sudden heavy steering can be dangerous; get it checked promptly. Verify with a mechanic.