macfly4

Hey all. Have an interesting problem that just happened suddenly. My 1987 s4 had been running perfectly but I decided to get an oil change since I wasn't sure when the last one was. I took it into the shop and brought 9 quarts of mobile 1 15- 50.
everything seemed fine, the mechanic said the car looks great underneath. And off I went. Later on when I try to start it from cold the Engine seemed like it was lugging and before I could really get into an idol it just shut off. I had to start it a couple of times and give it some gas and then it seem to stay on OK and I could drive it, with the engine lugging/surging settling down after it heated up a little bit. I'm not sure if the oil before it was a lighter weight.

docmirror

You aren't going to like this.

Search here for "thrust bearing failure".

Advise if you have ever had the torque tube flex plate checked.

another possible is MAF failure.

Imo000

It could be just about anything at this point. However, the alternator wires are right next to the oil filter so....... it's possible that if the filter was on tight and the mechanic used a filter wrench, the wiring could have been disturbed that causes the alternator not to charge.

James Bailey

You have a 30 year old car.....the reasons why it would not run far, far exceed the reasons why it should. Yes it is a Porsche and Porsches are way cool but all the incidental bits and pieces like relays, wiring, sensors, computers are well beyond their initial designed life. Porsche was NOT making them to run for 30 years....The comment about the engine harness and it's location near the oil filter is a good one.

macfly4

Thanks for the info. I do remember the mechanic showing me the filter while it was up on the lift and noting that it looked pretty old. Maybe something got jostled. Anyone here up in the Bangor, Maine area or in the state? Would be great to get some seasoned eyes on it.

FredR

Your last sentence description is somewhat ominous if it is an accurate assessment.

It is easy to relate what you experience as being somehow connected to the service and maybe it is but do not let that throw you.

If you know about TBF you might be suspecting it and said so, that you did not mention this suggests possible lack of awareness. To be clear, there is nothing at the moment to suggest that is what your problem is but as Docmirror quite rightly states you need to be eliminating that possibility from your line of enquiry and [I suspect] you need to be taking mitigations to prevent such irrespective of what may ultimately be troubling the car- this all assumes that your S4 is an automatic [which it may not be].

I have run my motor with a jumped alternator belt- if there is an alternator problem it should be pretty obvious from the gauge on the dash- if it shows 12V or less then maybe you have an issue in that department that has caused [or will cause] your battery to drain- not convinced that would answer your symptoms though.

In situations like this it always helps if you have access to another LH computer and a MAF to help eliminate those items from the usual list of suspects that inevitably boil down to either fuel supply or ignition issues.

macfly4

would thrust bearing failure do this on a cold start? i thought it was generally once an engine is warmed up that it occurs.

FredR

If TBF had occurred a number of weird things may happen but worrying about such is well down the list at the moment.

As the owner of a S4 auto you need to be aware of the subject matter, the state of your motor and if you are sensible, have mitigations in place to ensure it damm well does not happen.

There are plenty of threads with pics describing this and what to look for. In summary you need to ensure that crank end float is about 0.2mm [anything greater than 0.4mm suggests trouble], the front clamp has not slipped, the front flex plate is not bowed and the rear pinch bolt is sound. Replacing the front and rear pinch bolts is now considered std practice.

If those items prove OK then you are in good shape and can then concentrate on what to do longer term to ensure it does not occur. Whether or not you have an issue in this regard, these measures must be taken.

As to how this curse presents itself seems to vary- the first some folks know about it is when they have difficulty starting or the motor will not turn because it has seized solid. Some folks know squat has happened until someone measures the crank end float and finds it is in the region of 1.0 mm and when that happens the motor is for all intents and purposes history. Repairs have been effected by some with the kit to do so but with huge effort. Fine as a labour of love but not as a commercial proposition.

So, keep a positive outlook, eliminate this possibility from the line of enquiry and then focus on what else may be in difficulty. If you can, open up the inspection cover on the bell housing and take a photo of the clamp and flexplate.

macfly4

Well that's why I am scratching my head at this point. I literally have had no problems with this car and I've started it up at least 100 times this season with no issues. It was literally the day after the oil change that I started noticing it. I tried to start it today to get it over to the shop and the same thing was happening but usually once it warms up for a little bit everything seems to run somewhat smoothly. Today I got it out of the driveway and it started stalling and had a hard time just getting it back up into the driveway. Now I'm waiting for a tow truck.

FredR

Just about everyone who has had an issue with TBF did not have a problem- until the day they did and for those examples that do have this issue it seems to happen around the mileage of your example [and thereafter] but not before. Happened to the previous owner of my current 928- I diagnosed and confirmed TBF in 30 minutes flat. That I had the only viable 32 valve motor in this part of the world worked in my favor during "negotiations"!

So, if you are taking the thing into a garage get them to check for TBF and eliminate the possibility that such might have happened irrespective of anything else and quickly get yourself one of the established mitigations in place. Needless to say it helps if you can take it to someone who understands the 928.

Whilst at the garage carry out any checks you wish to have carried out including for any signs of damage in/around the areas they worked on previously. I doubt there will be any issue to the alternator wiring that would explain your symptoms but it always pays to keep an open mind until the root cause of a problem is established and eliminated.

It is a pity you are not closer to someone like Stan [Mr Merlin]- I think he is the wrong side of New York relative to where you are. I dare say one of our US based knowledgeable folks will be close to your neck of the woods- to me you are all on the "far side of the moon".

SwayBar

If TBF is in process, there should be debris in the oil.

Pull the dipstick and look very closely for something out of the ordinary. Powdered aluminum will show up as dark spots.

FredR

You might check if Dave C [Worf 928] is in your neck of the woods - he lists as being in "New England" territory albeit you are towards the Canuck end of the block or so it seems.

Ed Scherer

Could be a fuel pump / filter issue, couldn't it? I seem to remember similar symptoms when my in-tank fuel pump was crapping out. I think the pumps can change their behavior as they warm up.

The problem happening immediately after an oil change might be a coincidence.

M. Requin

Yep, post hoc ergo propter hoc is a seductive argument, but generally worthless.

OTR18WHEELER

9 quarts of oil?,
8 is what is required with a filter change.