928 (S4,GT,GTS) Buyer Tips

This is a sorted compilation of things to do or check when buying a 928. It does not pretend to be complete, but will prevent you from making obvious mistakes of which a 928 owner would say..... You should have asked...... Now you've done it......

Generic checks

  • Check original documents and maintenance records. Who did maintenance in the last years? Call them!!! What repairs have been carried out.

  • First engine still in? No rebuilds or exchanges? Mileage on dash is mileage car?

  • Check if maintenance records, mileage statements on repair documents are consistent and realistic.

  • Timing belt, water pump, rollers and tensioner maintenance date and mileage (80.000km or 6 years) Retensioned at?

  • Brake pads, discs, fluid replacement done? Date and mileage?

  • Torque tube rebuild done? When? Check for noise and grinding sounds. Pressure relief operation done regularly

  • Last Oil, what type, Oil filter, spark plugs, T-belt, water pump, air filter, AT fluid, Transaxle bearing?

  • Windshield and headlight washers ok? Valves are often stuck or filthy, causing leaks or lack of spray-power.

  • Check for the on-board kit, spare wheel, air-pump, safety kit, car-lifter. Complete?

  • Exhaust ok, no leaks, and in good condition?

  • Climate refill? What product... R12, R134a? Works ok ? Test it!

  • Does pressure stay on the coolant system? Check CO in coolant if possible (head leaks).


  • Check the seats on movement to the full extend. (often problems getting stuck) Does the seat memory work?

  • Coach work ok? No visible accident damage? No stains or rust? Look underneath the engine!! The 928 engine belly is not hit?

  • Check the operation of the electrical window and sunroof. Should work perfect. Try to open the window half and check for play. Should be firm. Window rattle can easily be felt and heard when driving. Common problem.

  • Is the little plastic "disk-type temp.fan" in the center top of the dash broken? They always break... Negotiate, or get a new one.

  • Does the fuel indicator indicate 3/4 when full? Good! Almost all 928 suffer from this ridiculous bug. No problem though.


  • Engine behavior, idle rpm should be stable at 700rpm, cold or warm. No black smoke? No gas smell when warm?

  • Check for proper power delivery. The 928 easily moves you up to 240 km/h. Almost linear. 270 Should be max speed. Be careful driving at this speed in an unknown car, but try to get a feeling of the car accelerating. The flappy valve should modify the intake at 3500 rpm, providing a linear torque. The AT should hold to redline when accelerating max (flooring, engaging the kick down switch). The car is (or should be) very, very stable when driving fast.

  • Make sure the car idles at 700 rpm or so. Switch on the AC. The idle should be corrected and controlled by the idle stabilizer due to increased engine load from the AC compressor.

  • Temperature readout: would normally be no more than the first mark, and stays there.

  • Look for leaks under the engine. Famous is the belly-pan seal leak, and the seals at camshaft and driveshaft. Look for any crash damage on the belly pan. Use a flashlight because it is hard to see with the cover-plate mounted underneath the engine. Remove the cover plate if possible to have a good look here and at the steering parts.

  • How about the hoses? Not brittle? Original or replaced? Some have a date stamp on them....


  • Both fan's should start to run when the engine is hot. Test if they do, and if they stop after a minute or so.

  • Does the electrically-controlled louvre in front of the radiator open when the car is hot? The systems should engage to open when the car is on operating temp. Check at cold and warm status.

  • Watch for sudden internal blower activity (magic blower syndrome). It switches to full by itself, caused by a thermo switch.

  • Check out the dash-pod. Watch for burned out bulbs. Look at the AT gear selector indicator in the dash. Do these lights work ok? Check the indicators cold and warm. A lot of stories are known regarding electrical gremlins, and damaged gears in the ODO. Check if the ODO works.

  • Check the battery. 100% ok? The 5L engine needs a lot of power! How old is the battery?

  • Checkout the seat memory and mirror's on functioning. Expensive!

  • Checkout the de-frost electrical heater on the windshields and the mirrors.

  • Check the cruise control. It stays on the required speed perfectly when it is engaged! Try it.

  • Does it have a digital instrument POD? Good! Is it clear in the readout?

  • Is the stereo gear ok? Make sure it is not the old stuff, but check if it has been replaced during the years.

  • Does the hatch open when pulling the hatch-release switch? (often does not, good for a discount, easy fix)

  • Is there a car alarm system mounted? Certificate? Operational? Key-less entry system?

Drive train

  • Check the exhaust condition, look for rust and damage. Is the O2 sensor wiring ok?

  • Look for leaks underneath the engine and the AT. Have any leaks fixed!

  • Check the boots at the rear axle carefully. Good condition? Watch for grease in the wheel area indicating a damaged axle-boot.

  • Check the boots on the tie rods at the steering rack. No oil leak? Squeeze. Still no leak? Steering works fine when care is idling?

  • Turn the steering wheel full to left and right several times. Still no leaks? No strange humming noise? No vibrations? Check steering behavior.

  • Feel the brake disks. Are they not worn too much? Is braking fine? Try the ABS if you are allowed to do so.

  • Are the tires ok? Look also on for damage on the sides of the tire.

  • Headlight height adjustment mechanism ok? (most of the time it is not... but it's good for a discount. You won't use it)

  • How is the ride height and the shock's? This heavy car seems to lower when time passes. Have it put back to specs.

  • 5speed? Clutch ok? Often causing problems. Also check first and second gear for smooth operation.

  • AT? from park to reverse should engage in 1-2 seconds. More delay indicates improper pressure that can be caused by a worn-out pump in the tranny. Also the switching of gears should be very gentle and swift. ATF oil should never look black. You may want to have a good look underneath the car using a flashlight on the transparent plastic reservoir.


  • Put the AC on and temp to min. No hot air should be noticeable. Check the front dash grill out on the lower left corner. Should be COLD! Any warm air is a problem. Check the door grill. Same cold air? Does the floor flap work? (flaps vacuum operated)

Make a checklist and work your way down.

Otherwise the 928 will turn out to become a money-pit...

or "...you race towards an early grave..." (pink floyd)


Which type of 928 do I best buy? What about mileage? What's important?

Here's Porsche official 111 Points checklist: 111 Point Check.pdf

You are absolutely right that 135K is higher than 40K and on car less then 5 years old it is one of the first things I consider. As cars age it becomes much less important. My 78 has 43K and when I got it out of storage after 15 years it would not run. It looked great. The problems came from rot. Almost every rubber component on the car needed replacing - all the hoses, the timing belt (which was new when the car went into storage) most rubber gaskets and even the hood insulation. It took a long time to make the car reliable.

I will admit there is a difference in how well the 928 manages mileage based on the year model. The early cars especially from 1980 on do not take well to high mileage. With the S4 Porsche made a concerted effort to improve quality. All things being equal I would rather have a "high" mileage S4 than a "low" mileage earlier car. At least after you get done replacing all the things that need replacing you will have a better car. Probably the most important improvement with the S4 is in the wiring!

A well maintained 928 can easily go 300K miles without major expense. If you are buying a car with 100K on it and driving about 10K a year then you can expect to get 20 years out of the car. By then most of us will either bored with the experience or have our license suspended. Would the premium you paid for such low miles be worth the difference in price? Sure if you just park the car in the garage for the next 20 years and look at it then it will still be a low mileage car - one that will not run but still a low mileage car. But if you drive it the difference between 240K and 300K in value is not going to buy you a McDonalds.

What you do when you pay a premium for a low mileage car over one of equal condition with higher mileage is simply depreciate the additional cost at a more rapid rate. For years I have purchased "high mileage" Mercedes  and driven them until the wheels fall off. It is the cheapest form of transportation you can get and you are driving a Mercedes!. The 928 may not be the cheapest form of transportation you can buy, but I would rather put the difference in purchase price into making the car top notch than pay for depreciating value.

Dan the Pod Guy
Portia's Parts


For New 928 Owners (compiled by Jim Morehouse)

Many new owners are unaware of the number of sites and boards that are available on line to help you evaluate and work on your shark, so I thought I’d put together this list as a starting point. It is certainly not complete, and over time some of the links may no longer be valid. If you run into this, please let me know at jim928@ptd.net.

I. Buying Guides and Pre-Purchase Inspection (PPI)

II. 928Sales

III. Parts Vendors:

"The Big 3"

In addition these sites have tips and technical info pages.

These are the only vendors I’m aware of who focus exclusively on the 928 and because of that, they are also very knowledgeable on technical issues. My personal belief is that we should make these vendors our ‘first stop’ when buying parts….let’s support the vendors who are supporting us.

Parts For All Porsches: (I’ve added ‘used’ if I’ve been told they also sell used parts)

More by category:

Other Parts Sources:

      Rennlist Classifieds: Go to www.rennlist.com and follow the links. In addition to vendors, there are people parting out cars and selling spares

      Ebay: Lots of parts/wheels/cars come up. Hit or miss if you need a part quickly but worth watching if you have the time. Search on porsche (928,928*) to see the listings

IV. Bulletin Boards:

Rennlist Message Board: This is different than the email list since it’s a bulletin board. Again, a good place to ask questions and see what others are doing.


Frames Free version of Rennlist BB is at:


V. Email Lists:

      Rennlist Mail List: Here you get a bunch of emails every day that covers a wide range of questions/responses/comments. If you’d like, you can elect to get a single file daily (digest mode). There is sometimes a lot of off topic or non-928 discussion but the technical content is excellent. In addition, there is a searchable archive that allows you look up previous posts on the topic of interest.

      Go to www.rennlist.org/main/areas/member/index.htm and signup. This page gives the specifics of what you get for a paid membership versus a free one. Annual memberships are $17.95 (as of 12/01) or $32.00 for two years. Although you can access many features for free, this is such a valuable resource that I hope you will support it by joining. The people on this list have helped me a lot.

      For both the mail list and the bulletin boards, you’ll be pleasantly surprised by how knowledgeable and helpful these folks are. Note that when you post a question, it’s important to include the year of your car, transmission type, and mileage as well as a complete description of the problem. You might want to check the archives as well before posting.

      Great Britain Mail List: From our friends in the UK



These contain some of the best info out there since they’re put up by people who have BTDT (been there, done that) rather than ‘trained Porsche mechanics’. This is just a sampling and I know I’ll leave out some important ones but it will get you started

Here are some Maintenance Sites. The sites may be duplicated under "More" but since these were given to me as relating to Maintenance I thought I’d include them below. This list is certainly not complete and you’ll find sections on various maintenance procedures as you browse through the sites listed under "More".



Good luck, and welcome to 928 ownership and to the 928 "Community"!

Jim Morehouse



Deutsche version:

Zustand aussen:

O Hängt der Wagen? Beide Seite vo. u. hi. Messen, Auflagefläche Rad zum unteren Kotflügelrand
O Spaltmasse prüfen
O Unfallschäden: Schlecht reparierte Unfallschäden werten jedes Auto ab, kann man wohl nicht als Schwachstelle beim 928 bezeichnen.
O Scheinwerferbereich, Blasenbildung
O Radläufe: Blasenbildung
O Hydraulische Scheinwerferhöhenverstellung: Eigentlich immer kaputt!
O Reifen, Profil, wie alt? Gleichmässige Abnutzung?
O Stossdämpfer vo. und hi., i.O.? (Wipptest)
O Zustand Lackierung
O Kontaktkorrosion Türen: Im Insiderjargon "ALU-Fraß" genannt, betroffen sind hauptsächlich Türen und Vorderkotflügel, nichts "TüV-relevantes".
O Sind die Spaltmaße an Motorhaube, Kofferraumdeckel und den Türen gleichmäßig? Wenn nicht: Finger weg! Es handelt sich meist um unsachgemäß
reparierte Unfallfahrzeuge. Zur Überprüfung der Spaltmaße bietet sich ein Vergleich mit der jeweils anderen Fahrzeugseite an. Die Türen können
unter Umständen etwas hängen (ist aber selten). Hierbei auf jeden Fall Scharniere prüfen, ob diese eventuell durch einen Unfall verzogen sind
(im Zweifelsfalle eine MB-Werkstatt konsultieren).

Zustand innen:

O Funktion und Hebelweg Handbremse
O Alle Funktionen ausgiebig testen: Sitzverstellung, Memory, Heizung, Beleuchtung, Schiebedach, Zentralverriegelung, Warnanlage, Fensterheber,
Scheibenwischer vo. u. hi., usw.
O Verstellung Lenksäule testen
O Ersatzrad rausnehmen und Karosserie prüfen? Unfall?
O Ersatzrad, Kompressor und Werkzeuge vorhanden?
O Innenausstattung: Fahrersitz häufig verschlissen, Nähte an Lenkrad und Schalthebel mürbe.
O Komfortfunktionen: Die Zahl der elektrischen Helferlein ist groß, der Ersatz meist sehr zeitaufwändig und Ersatzteile teuer. Bei Kaufbesichtigung alles in Ruhe ausprobieren.
O Zustand Innenraum
O Wegfahrsperre, Diebstahlsicherung, Alarm.

Motor anlassen:

O Bordcomputer testen
O Tickern des kalten Motors kurz nach dem Anlassen? (Ölrückhalteventil, Hydrostössel)
O Außentemperaturfühler Klimaanlage: Sitzt im Radhaus unterhalb des linken Hauptscheinwerfers. Ist häufig vergammelt oder fehlt komplett, die Temperaturregelung von Heizung/Klima kennt dann nur noch zwei Modi: Voll heizen oder voll kühlen!
O Klimaanlage: Häufig ohne oder mit verminderter Kühlleistung.
O Alle Anzeigen i.O.? Keine Fehlermeldungen?
O Funktion Wegfahrsperre (falls vorhanden)
O Scheinwerfer-Höhenverstellung OK?
O Leerlauf 775 +- 25 für manual Getriebe, 650 +-25 für Automatik


O Reifenluftdruck i.O.? Es gibt Spezialisten, die vor einer Probefahrt den Luftdruck ablassen; die Reifen federn dann weicher verschlucken so manches Verdächtige Geräusche (Getriebe, Hinterachse)
O Spurtreue bei Probefahrt
O Lenkungsspiel
O Spiel Kupplungspedal
O Spiel Bremspedal
O Spiel in der Schaltung
O Beobachtung Öldruck während der Fahrt (5bar bei 2000rpm, mindestens 2 bar bei Leerlauf)
O Bei voller Fahrt Gas wegnehmen, sagt es dann ?Klick? im Getriebe oder Differential, dann sind die Zahnräder runter, oder die Lager haben zuviel Spiel
O Spurtreue beim Bremsen
O Rücklauf des Lenkrades nach einer Kurve testen
O Kilometer- und Tageskilometerzähler fallen gelegentlich durch altersschwache Kunststoffzahnräder aus (=Tacho ersetzen).
O Funktioniert der Tempomat?
O Übergang Erster-Zweiter Gang (smooth operation?)
O Scheibenwischanlage OK? Düsen?

O Geräusche und vibrationen Motor und Antrieb?


Nach der Probefahrt:

O Auspuffgase beim plötzlichen Gasgeben blau oder schwarz? (Ölverbrauch bzw. Einstellung)
O Laufen beide Kühlventilatoren?


O Klima umgestellt auf R134a? Funktion?
O Servolenkung, alles dicht? Insbesondere die Anschlüsse unten am Vorratsbehälter?
O Zustand Keilriemen?
O CO-Test des Kühlwassers machen lassen hinsichtlich Kopfdichtung i.O., oder Drucktest
O Kontrolle aller Gummimanschetten
O Kühler, Schläuche, alles dicht?
O Kompression prüfen lassen. (12.5-13.5 bar +-0.05bar)
O Auspuffanlage: Eigentlich (fast) unzerstörbar, wenn sie hin ist, wird´s empfindlich teuer
O Antriebswellen: Siehe oben.
O Lenkgetriebe: Nach zehn und mehr Betriebsjahren werden sie gern mal undicht, Austauschteil incl. Einbau kostet gut 2000 Euro, also Augen auf!
O Zusatzluftpumpe: Sitzt im Motorraum in Fahrtrichtung vorn . Der zugehörige separate Luftfilter wird meist nicht gewechselt und ist deshalb in der Regel total verdreckt. Folge ist das ausschlagen und anschließende Festgehen der Pumpenlager, da sie im Luftstom liegen. Folge der Folge: Der vom gleichen Keilriemen angetriebene Kühlerventilator fällt bei gerissenem Keilriemen ebenfalls aus. (Beim S bis S2). Also Filter und eventuelle Laufgeräusche der
Pumpe kontrollieren.
O Spiel in der Aufhängung
O Auspuff dicht, Aufhängungen i.O.?
O Motorbereich oben und unten, alles trocken?
O Getriebe und Hinterachse, alles trocken?
O Ist O2 Sensor Verkabelung OK?
O Gummimanschetten dicht?


O Originalbrief?
O Noch 1. Motor?
O Scheckheft, alles glaubhaft, gerade auch Laufleistung?
O Wo wurden die Servicearbeiten durchgeführt?
O Zahnriemen, Spannrolle, Umlenkrolle schon mal erneuert? (Nach 80.000 km bzw. 6 Jahren), wann nachgespannt?
O WAPU schon mal erneuert?
O Wie alt ist die Batterie?
O Welches Motoröl, wann gewechselt (Scheckheft)
O Absolut unfallfrei?
O Wartung/Ölwechsel: Hauptschwachpunkt sind die Besitzer, die die aufzuwendenden Wartungskosten scheuen. Wartungsintervalle betragen 20 Tkm
O Zahnriemen: Wechsel alle 5 Jahre oder 80 Tkm, Wechsel relativ kostenintensiv (ca.600-1000 Euro), WaPu-Wechsel im Verbund sinnvoll. Anfällig ist der Steuerriemen eigentlich nicht, wenn man ihn konsequent vernachlässigt ist halt irgendwann Feierabend (=kapitaler Motorschaden)
O Zustand Bremsbeläge, Bremsscheiben, Bremsflüssigkeit wann erneuert?
O Stossdämpfer
O Was wurde an Klimaanlage ausgetauscht? Dichtungen? Wieso funktioniert sie nicht?
O Unterlagen zur Spurvermessung
O Wird Getriebe versiegelt?
O Was wurde am Getriebe repariert?
O Gibt es Doku zum Front- und Heckschaden?



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