How hard is the timing belt on a Porsche 928, and is it expensive to own?

Short answer: The 928 timing belt job is much more involved than a typical belt change. Do the belt, tensioner and water pump together, follow a detailed guide, and turn the engine over by hand several times to check the timing marks before starting it. Expect high ownership costs: owners say about 19 mpg is good, and parts and labor are priced like the expensive car it was new.

Symptom: The belt is due or the history is unknown, or you're thinking about buying a 928 and want to know what it costs to keep.

What to check first

1. Find out when the belt and water pump were last done. No proof means do it.
2. Get a pre-purchase inspection from a mechanic who knows 928s.
3. Check for coolant leaks at the water pump.
4. Price insurance before you buy.
5. Read the factory procedure and an owner guide before starting the belt job.

Likely causes

1. Timing belt, tensioner and water pump due. The timing belt keeps the cams and crank in step. On the 928 it's a long belt with a tensioner, and owners do the water pump at the same time.
2. Deferred maintenance on a used 928. These were expensive cars new, and parts and labor still cost like it. Neglected cars are common.

What it usually costs

Owners in these threads didn't post prices for the belt job. One owner said 19 mpg is doing well on these cars.

Is it safe to keep driving?

A belt past its interval can snap without warning and stop the engine, and on some engines that also bends valves. Don't stretch it.

DIY or shop?

Possible for a skilled DIYer with the factory manual and patience. Most owners will want a 928 specialist.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists 85V084000 (engine carrier weld, 1985) and 89V106000 (heat shield above the catalytic converter, 1985-1987) for some 928s. Neither is about the timing belt. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 0 keyword-matched complaints for Porsche 928 1978–1995 (of 4 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-30; keywords: timing, belt, tension) (NHTSA returned no data for 9 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 1984 Porsche 928s Timing Belt Replacement on Car Talk, an owner of a 1984 928S planning the timing belt, tensioner, water pump and drive belts asked how hard it is. Members said it is much more involved than a typical belt job, pointed to a step-by-step guide on Rennlist, and advised turning the engine by hand several times and checking all the timing marks before starting it.
• In Is a Porsche 928 s4 a reliable car for a first car? (1987) on Car Talk, a parent asked if a 1987 928 S4 was a good first car. One former owner said no: about 19 mpg is doing well, it's expensive to fix, and parts and labor didn't drop with the car's price. Others said reliability depends on how it was serviced, to get a pre-purchase inspection from a mechanic who knows these cars, and to check insurance first.

Quick tip

Budget for the belt and water pump on any 928 with no paperwork, and treat it as part of the purchase price.

Vehicle focus: Porsche 928, 928S, S4, GT and GTS, 1978-1995.

Safety / mechanic note

A broken timing belt stops the engine. Verify with a mechanic.