88porsche928

hi, I am getting close to getting my car back from European Coach "hopefully this week". Anyways I am planning to get every thing fixed all by another mechanic with a good reputation. Ill start with my power steering. I don't have any. I see its missing a belt, lets assume the power steering pump is bad. If I buy a new one and a new belt will the power steering work? Is their any thing else that wll prevent me from having power steering? I am also getting an anti lock brake light. What does it mean? Is their a bad sensor? Are the brake pads low? I am planning on replacing the pads and rotors. Now the timming, I am going to buy belt, waterpump, tensioner. Now how often does the timming belt lower idle go bad. What do you recommend i replace. also when i try filling my coolant full it leaks half way down what do you recommend i do

WICruiser

Sounds like a mess.

You need to determine where the coolant is going. If it is going into the engine through a bad head gasket you may want to pull the engine and do the TB/WP while it is out.

Before you do anything with the power steering or brakes I would do the TB/WP and confrim all is functional as far as engine operation goes. There is a very good TB/WP write up that describes all the required parts in the FAQ so start there.

Brakes would be next. Antilock brake light could mean a number of different things but I don't have anti-loack and am not familiar with the system. Diagnostics would be a good place to start.

Power steering could be a lot of things, check to see if the pump is seized because that may be why the belt is gone.

Good luck.

dr bob

The best 928 wrench in the socal area is Greg Brown at Precision in Anaheim. There are others that some of the SD folks might recommend closer to you, you decide if that's worth the tradeoff in skill.



Cutting the belt off the power steering is done when there's a leak, so the pump doesn't get damaged running with no fluid. It's possible the problem is with the pump itself, but that's just the beginning of the list of possible leakage locations. For grins, buy a belt, a new filter/reservoir, and a few quarts of Dexron ATF. Put the belt and reservoir on, fill the reservoir and charge the system, and see where/if it leaks. Then decide what to fix. There are inexpensive rebuild kits for the pump. The hoses are likely original, and may be old and crispy. Hard to keep fluid inside the system with hoses like that. The steering rack wears, and the seals fail. Peek underneath at the boots on the ends of the rack. Look for cracks, and possibly ATF that's collected in the boots.




Sensors and connectors often cause the ABS light to come on. The sensors read wheel speed at a toothed ring that's in each rotor/hub. They get fouled with crud and metal sometimes, so an early step would be to clean the rings and sensors. Easy while you have the pads/calipers/rotors off. There are wear sensors in the pads, and the sticky pads that go on the back of the brake pads when you are ordering parts. Have your VIN handy so you get the right sticky pads. Both the ABS and pad wear sensors plug in to connectors in the wheel well. Be sure to disassemble and clean the connectors, as those can cause the ABS light to go on even before the car moves if the system senses a failed sensor.


Timing belt surgery on the 928 is not for the timid, and there are a few specialized tools needed. The front crank bolt needs to come off, and that almost always requires a 3/4" drive socket and a big breaker bar. There's a flywheel lock tool to buy, used to lock the engine in the correct position while you loosen the bolt and replace the belt. There are a couple options for a tension gauge for the belt once installed. The best/easiest/cheapest is the Kempf tool, a mimic of the early factory tension gauge that's NLA from Porsche.

There are two rollers on the arm that the tensioner pushes, plus there are two lower guide rollers that get new bearings installed. The tensioner itself can --usually-- be rebuilt with new seals/gasket/boot. A new one is pretty spendy so explore the rebuild option first.

On the way into and out of the timing belt project, you'll want to at least be aware of the long list of other WYAIT things to do. Cam seals, oil pump seal/o-ring, possibly worn cam, crank, and oil pump drive gears. Caps and rotors. Coolant hoses. And of course the water pump itself should be replaced if you don't have knowledge of its last change.

Most important is a copy of the pertinent workshop manual pages, copies of the instructions from the various tips pages, and best of all a copy of jkelly's detailed step-by-step instruction with pictures.


The "normal" working coolant level is about half way up the bottle. The system pressurizes as it gets hot, causing coolant to escape at the reservoir cap until the system is no longer hydraulic. It's a good idea to replace the reservoir cap as a regular PM item whenever the coolant is changed, along with the heater control valve. The small hoses in the heater circuit, along with the ones between the engine and the reservoir are likely past due for replacement, so add those to your parts purchase list. You'll have all the belts off, so a set of new replacements is likely in order. Including the PS belt listed above. You'll have the power steering and alternator console (the big cast support for those two items...) loose from the engine for the belt surgery, so that is a great time to take care of teh PS pump rebuild and the hose replacement. The PS reservoir will be loose too, so replacement is rather simple as part of your TB effort.

88porsche928

update on european coach. After they installed new fuel injector harness, hall sender unit, knock sensor, and cam sensor they now claim the computer is bad. The computer has a JDS Porsche sticker on it and it was from 928srus. So I mailed it to Roger Tyson and he said he will look at it.

88porsche928

It amazes me to think I destroyed the entire electrical side of the fuel injection system of my car. Its like I took all the sensors out and beat them with a hammer then put them back in and expected it to work.

Mrmerlin

whew, thanks Bob for answering this thread

dr bob

I posted a few diagnostic steps a couple weeks ago regarding finding shorts or opens in the wiring between the LH brain and the injectors. It's aimed at '89+ cars with the protection relay, but with a little sleuthing in the wiring diagrams some applies to the earlier S4 cars too. While it's possible the LH brain was damaged by shorts in the harness, it's somewhat unlikely. When Roger gets the brain in Texas, he'll plug it into an otherwise good-running car and know quickly whether yours is functional. If it isn't, be sure to use an ohm meter on the LH plug to the injection harness to verify that there are no shorts/melted wires between the brain and the injection harness. That wiring loops through the central electrics panel on the passenger side floor, so replacing just the injection harness may not be the whole cure to wiring damage. A few careful electrical measurements will help you eliminate possible collateral damage done when the original harness was damaged.

88porsche928

dr bob I thought the fuel injector harness plugged directly into the brain. The fuel injector harness was replaced.

88porsche928

dr bob do you have a PHD in Porsche-Peformology

88porsche928

dr bob I am starting to wounder if you designed the 928 yourself

dr bob

The injection harness for your 88 is way different from the one in my '89, and from the diagram looks like it does indeed plug into the LH box. There's other wiring in that harness besides the connections to the underhood stuff, that's what I was referring to.

-- Engine speed/running signals come from the EZK (ignition) box (4 connections)
-- Central electrics panel connections for starter motor run indication , fuel pump relay energize, LH relay energize for injector nozzle power, EZK relay energized indication, kickdown relay energized indication, power feed direct from the battery (no fuse!!!!)...

You get the idea. Lots of stuff to connect and check out --before-- the battery is reconnected and you twist the key.


No. 30+ year old computer science degree, with ME and EE underneath. Outdated for sure. A passing certificate from Romper Room might be worth more.

Nope. can't pin that on me. I'm innocent, I tell ya, INNOCENT!!


Seriously, a set of the factory workshop manuals with the wiring diagrams will go a long way toward helping you understand a lot of this stuff. If you haven't done so already, get Jim Morehouse to sell you a copy of his Most Excellent CD with the manuals and a huge collection of tech pubs and other stuff. Well worth the money! You really don't stand much of a chance trying to troubleshoot electrical stuff on the car without the diagrams and at least a mid-level knowledge of how some of the stuff was thunked up in the first place.

How did your LH box do with Roger?

SteveG

Dr. Bob is single-handedly saving another shark. Is this Dangler? Nevermind.

I'm not sure what the "timming lower idle" (sic) is. If it were mine (not knowing any hist) once you get the covers off, replace everything that touches the belt, moving things that is. You shouldn't have to replace the tensioner itself, unless the mating edges are buggered, just get a rebuild kit from 928 Int'l. I would strongly suggest John Kelly's TB manual if only for the pictures to help you id the parts. Join so you can post pictures. It will make things here a lot easier. Good luck.

ROG100

The LH did not test good in my GTS or an 88.
Its on its way back to JDS for further investigation.
Very unusal for the LH to fail especially as it was a recent rebuilt.
We should know in a few days.

the flyin' scotsman

many of us can relate Bob.

It be great to discuss with our professors of back then as to how we're applying all our learnings.