Devils_son

I'm considering the purchase of a 964 C4. Until now it seems to be in good condition. But when testdriving it today I noticed that the oil pressure at idle was only 0,8 bar after a 20 min. drive (outside temperature appr. 25 degrees). From appr. 3000 rpm it sits at 4 bar and stays there. Seller, who has a very good reputation says it's nothing to worry about, but then again, he is the seller...

Should this be a reason to walk away, or to investigate further? I don't want to throw away money on a ppi.

The 964 has got 185.000 km on the odometer and is in need for servicing. It's been 30K ago.

Andy Roe

Was the car very hot? Normal oil pressure at idle, at operating temp (8 o'clock on the temp guage) should be between 1 & 2 bar & increase to 4-5 bar when revs are increased. If the engine/oil was very hot, then the oil pressure will decrease slightly, but 0.8 bar at idle still sounds a little low to me.

I'm sure others will chime in with more info.

Devils_son

After a 20 min. drive very hot? No way, I didn't push the car. I drove like I would have done if it were my car.

Oil temp. was reading about 8 o'clock. So it is lower then average (before asking the question, I searched the forum), that I know. The thing is: what does it tell me? Is the engine close to a rebuild? Or does the reading imply that the sensor is probably faulty (and can they be sure that it is just that within the ppi, or does it need a lot more research)?

C4Russ

My C4 with 100k miles idles around 1 bar and pressure zooms to 5 bar upon application of full throttle.

The oil pump could be failing, the oil could be thin or low, the gauge could be failing, the engine may need a rebuild. This runs from cheap to do to OMG expensive. I'd say pass on this car unless you are a risk taker. At the very least have the oil changed to see if this changes the oil pressure.

Is the price so good that you'll consider the car knowing that you don't know what the deal is?

Indycam

Hiya Devils_son
If you hook up a known good presure gauge to the motor , you can find out if its the motor or
sender / gauge that is low . The problem could be the sender or gauge being out of calibration .

Its going to cost a bit to get the test done but its going to cost lots more to not get it done , if its oil presure is really down , it could be a few things but I 'd think of worst case , bearings . Major $ !
I'd send in a sample of oil to get it tested , for not much money , $19.95 , they can tell you something about the oil and or motor from just a little oil . On the list of sponsors is an oil test place , http://youroil.net/index.html for
http://youroil.net/why_should_you_ha...analyzed_.html

"I don't want to throw away money on a ppi."
Its not thrown away if you do it right , spending a little on a good ppi can save money and time .
I spent real good money on a real bad ppi . Be carefull . Find someone who knows 964s and who
will treat you well if you can .

Devils_son

No, but the car is an Amazon Green one, which I think is the nicest colour for a 964 and there aren't many. Apart from that, it has all the right options.

But that is also what worries me. It is so nice optically, that I may be blinded by that.

On the other hand, the seller doesn't mind a PPI. He will give a warranty. He is well known for being trustworthy. And I don't want to pass on a good car for the right price, in the right colour and with the right options.

So I don't mind spending an extra € 100 on extra tests during a PPI, but I do mind spending a lot more and then maybe finding out that this car is not in a good condition.

I've read that the pressure sender fails more often than the oil pump. Testing the oil pressure on the engine itself might be worth the money (assuming that this can be done for less than € 100). And then if the oil pressure really is too low, it might indeed be best to walk away...

Any other thoughts?

Indycam

Hiya Again
Don't walk away , use the info to get the right price , if the thing need a rebuild , get the price down so that the rebuild is ok .
All cars need repair , thats a given . If this one is what you like , think how nice it will be with a freshly rebuilt motor .
Just don't pay to much .

Dave R.

Try the easy things first -

1. check the oil level (properly - use the dipstick with engine warm and idling), if low then add oil and see how that affects the oil pressure

2. look at the last invoice for the oil change to verify grade/weight of oil that was added

adwriter

The figures you mention are similar to the ones I get on my 1990 C4, which passed a PPI by an OPC.

The fact that the seller doesn't mind a PPI, will give a warranty and is well known for being trustworthy is very important.

I'd arrange for a PPI and if the oil pressure checks out, you're home and dry.

Cheers

Chris

garrett376

Buy the car if you like it, before someone else does and you regret it!

My coupe C4, at idle, runs below the 1 bar level; my C4 cabrio, at idle, is at 1 bar; the C2 cabrio is at 1 bar at idle. All 3 cars are at 4 bar, maybe slightly higher, when the RPM's go up. If the oil pressure light doesn't go on, no worries!!! I think that car is fine.

willie964

Yes would agree with the above statement , don't let it bother you too much. Life is too short to worry too much about a wee differential in oil pressure

turtle and the hare

My C2 runs aroung 4 or slightly higher under acceleration. Mine has 124K on the clock on is fine. I had a leak down with 3-4% leak down. Car seems fine.

andy
turtle and the hare
91 C2 Cab
73 911 T
Corvette C5 100 Wet NOS
ML350 Sport Edition
MBZ 500SE
Diamo Tracer 150GSX

Devils_son

I've made the decision and the car will get a PPI on wednesday.

Thanks for the reply's.

Bates

Great decision!

Devils_son

Update: the PPI showed that the car was in very good condition. So I bought it and since yesterday I (ones again) am a proud owner of the best 911 ever made: the 964.