1999Porsche911

I don't think intake, radiator or exhaust mods would affect oil consumption in any way.

No idea about whether or not you should try the oil.

thanks for the response guys!

JeTexas, im thinking those mods are adding more air in the car and its overly compensating with oil and fuel? i'am also getting less mpg than originally when i had the cars w/o modifications. im not complaining about mpg though, more oil consumption than anything else.

any feel for your 996 oil consumption over a 1000 mile period anyone?

Zero, nada, zippo oil usage, ever. But, then again, I only use Mobil 0W40 for keeping the door hinges from squeaking. Move to the Mobil 15W50 I suggested above as it has better cleaning agents than any of the other Mobil synthetics. I have yet to see an engine that burns oil using Mobil 0W40 that did not substantially reduce or eliminate oil burning.

Try filling it with Mobil EXTENDED PERFORMANCE 15W50 should drastically reduce oil consumption and provide better protection.

i know you are sure of that 1999porsche911, but what can i tell you, the fans are on low speed or off on intial check, then i get back into my car and press the ac button, come back out and the fans run high...so whatever that proves is really meaningless to me at this point. What i mean is i care about is if the fans are working, both high and low..and they are. So if my temps are still running high i have to figure out why and correct it. Sorry if this pushes a hot button for you.

If your high speed fans are turning on when the coolant temperature is below 215F, then, assuming the system is functioning as designed, your A/C fluid temperature is too hot which is the result of too much pressure which makes the air being sucked past the radiators from the condenser hotter than it should be which reduces the cooling capacity of the radiators.

I would suggest grounding the high speed fan relays and driving that way for awhile and see the difference in coolant temperatures. If you still see high temperatures, have the high pressure of the A/C checked. Running the engine compartment fan also helps reduce coolant tempertures.

okay, been having temp issues myself. I replaced the resistors last summer because the low speed fans were not coming on. Tested today with ac on the fans blow hard. But when driving on highway the temp hack get as high as 103c. Around town with ac on and thus high speed fans the temps got to 105 and probably would have gone higher if i was driving around longer in town. So at this point i'm wondering if maybe it's time to blow out the radiator fins. Thoughts?

Your high speed fans ARE NOT on just because the A/C is on. The high speed will only kick on if the pressure switch senses too high a pressure or the coolant temperature reaches 215F.

First of all, your engine never ran at 80C. If it had, your thermostat would have remained closed. The high speed radiator fans do not come on just because the A/c is on. I have heard otherwise on this board but on the more than 35 996's I have tested, NONE of them come on high just because the A/C is on. High speed fan operation is determined by pressure in the A/C and/or coolant temperature.

The targeted coolant temperature for the 996 is 90C and in reality, it will run slightly above that at highway speeds. Slower, around town driving may raise the temperature to as high as 105 -110C unless your fans are running on high.

I'm headed out to my car to turn the traction control off and see what happens.

I bet your TC won't work when you turn it off. ;)

Thanks for the replies...I removed the alt, and TB and the only thing that looks like it is missing a tube is a hose at the very rear of the engine to the right and farther back than the intake crossover tube and starter. (See pic). If this is it do you have any suggestions on how to reattach a flimsy line to a arubber tube that is almost impossible to get my hand on? Is it important? Can I just cap the platic line? Thanks again.

That's it (left pic). You seem to be missing the long hard black plastic line. Just connect that line to the electric changeover valve tube shown in your first picture. Any type of vacuum line will do.

After I changed my oil tube I foiund this hose is no longer going where it is supposed to go. Can anyone tell me where this line ends?

It connects to another black, hard plastic tube that goes to the resonance valve on the back intake crossover tube. There should be a short rubber hose that connects the two plastic lines.

Well I have good news. You need the correct size matched tires. Your car has Traction control built into the abs control unit. When the abs control unit sees a difference in speeds front to rear at speeds the abs control unit sends a signal to the dme to hold the idle high incase the clutch is reengaged. The abs/tc gets confused because it is seeing a slower wheel speed in the rear than the front so it thinks the rear end ir locking up when you back off the gas. the cheap fix is to just turn the TC off. and you will be ok other wise you will need to get correct matching tires for that car.

Unfortunately I have spent way to much time on this problem....I believe I have about 22 hours clocked onto tracing this stupid problem out that I will probably get paid 3 for but at least I have the glory of saying I figured it out :)

please repost if this works.

Thanks Tom

Porsche of North Scottsdale

The 99 C2 TC has a cable controlled throttle and the TC does not work in the way you described. I don't see how this would effect the idle.

I have been changing my AOS. Everything is going well except that I am having problems getting the vacuum hoses hooked up properly. My car is a 1999 C2. I have several hard plastic/rubber hoses however I cannot figure out where a few things are supposed to go.

From the check valve (the one above the alternator)- I have two hoses coming out- one comes out of the check valve via a rubber elbow connector, the other tube is about 1.5 feet then it connects to a + rubber connecting piece. I cannot figure out where the hoses coming from the + rubber connector are supposed to connect too.

The four points of the + rubber connector are as follows-

1.- tube going into the + connector from the check valve (the one above the alternator)

2.- One of the tubes coming off the + connector has a round white/black piece then a hard hose- I think that this connected to the front intake connector butterfly valve (I remember this from when I removed it

3.- one point on the + connector has no tube

4.- broken tube (appears to have been broken prior to my work due the dirt)

I realize that two hoses are supposed to connect to two intake connector adapters (I already have the one on the righ side of the car connected as it comes from a different location)

I am in desperate need of help. I have been searching for quite a long time and have not found any answers. I have also search my shop manuals and also didn't find any info.

Thanks,

Steve

Here you go:

Old wive's tail. The fact is, 15W50 and 0W40 oil flow to ALL engine componants at EXACTLY the same speed using the stock oil pump. Therefore, flow is of absolutetly no concern. However, 15W50 will remain on the upper parts of the engine longer than will Mobil Water, therefore protecting the engine better.

You need to seperate the marketing "facts" from the performance facts. Viscocity is a measurement of flow by gravity and not under pressure or vacuum. Higher oil pressure does not mean less flow, but it does mean that parts are seperated better.

The flow facts can easily be tested on your engine while in your car. It has been done many times.

Could you define fact please?...seems to me you have opinions (perhaps hypotheses) but NO DATA to support your claims.

read post 66

Search on Doug Hillary and you will find someone who has studied oil in Porsches and actually has data instead of being an internet jockey.

I do not state as "fact" things I read or hear about. That would have to be classified as hearsay. Personal experience and testing is what makes it a fact. I might also ask you to provide ANY data of ANY testing that has been done EVER to prove that the oil flow in the engine is inhibited when moving from a 0W40 to a 15W50. Seems to me that people prefer to accept a conscientious as fact with no proof, yet want all kind of proof from those who know differently.

The argument made by Doug in the link you supplied begins with an incorrect assumption: That the viscosity of an oil affects its flow the same under gravity as it does under pressure. Therefore, garbage in, garbage out. Viscosity IS NOT a measurement of the flow of an oil in an engine.

Is there a Mobil 1 5w-40? That would seem ideal if you want a higher cold pressure. However, both 0W-40 and 5W-40 would both yield about the same hot oil idle pressure. The 0W and 5W only come into play when the oil is cold. Also, keep in mind that the pressure indicated is the pressure at the sender, not in the oil channels. It stands to reason that the lower the overall viscosity, the higher the flow, which is just as important as pressure. However, f there is any blockage,due to dirt, metal shavings etc, I would think that the higher pressure would have a better chance of flushing it out over flow, so it may be a 6 of one, 1/2 dozen of the other situation. a 5W-50, as 1999 advocates would give you a higher pressure as hot idle, but I do not know if that is on the approved Porsche list.

0W40 and 5W40 WILL NOT deliver that same oil pressure, hot or cold. Even 2 different 0W40 oils will most likey not deliver the same pressure. The range allowed to call an oil 40 weight is HUGE.

FWIW 1999 has been bad mouthing 0W40 forever...I have read multiple reports from competent people (such as Doug Hillary who did an extensive test on oils). Remember oil is not just for lubrication, but also for cooling. I am fine sticking with Porsche recommended oils: 0W40, 5W40, 5W50 for normal use. BTW, the most critical lubrication time is a start-up. The thicker the weight the less lubrication (first number on the multi-weight oils) at start.

Old wive's tail. The fact is, 15W50 and 0W40 oil flow to ALL engine componants at EXACTLY the same speed using the stock oil pump. Therefore, flow is of absolutetly no concern. However, 15W50 will remain on the upper parts of the engine longer than will Mobil Water, therefore protecting the engine better.

You need to seperate the marketing "facts" from the performance facts. Viscocity is a measurement of flow by gravity and not under pressure or vacuum. Higher oil pressure does not mean less flow, but it does mean that parts are seperated better.

The flow facts can easily be tested on your engine while in your car. It has been done many times.

Nothing wrong with 1 bar at idle. 0w40 is Porsche recommended weight.

That would be true IF your gauge reading of 1 bar was accurate. However, it is not even close. :D

And what makes you think it's not accurate?? The specs I found for this engine are 5 bar@5000 RPM with a oil temp of 90C. I think you might be trying to fix something that isn't broken.

All you have to do is replace your electronic sensor with a mechanical pressure gauge to see the real reading. Mobil Water is not vicious enough to properly protect bearings during low pressure and high load conditions. Just like your coolant gauge, your pressure gauge is no more than an idiot light as far as accuracy goes.

Nothing wrong with 1 bar at idle. 0w40 is Porsche recommended weight.

That would be true IF your gauge reading of 1 bar was accurate. However, it is not even close. :D

When you change oil, don't replace it with Mobil 0W40. Put a better and higher vicosity oil in the engine. You never want to see less than 1.5 bar at idle. I suggest a 5W50 or 15W50 on the 3.4 engine.

If the bet is that your coolant temperature will stay below 215F while in traffic....I'll take that bet. :D

I don't think any practical mod would produce that result, actually, though I know you feel differently. But I'll be happy with any improvement, and delighted if I never saw the far side of 105C except in the very worst circumstances.

Not my belief, but a fact. Why not just do the mod and be on your way?

The rads were $425CDN each. I did both of them as a precautionary measure. They also sent the AC condensers out for reconditioning. I'm going to bet this solves it.

On the BMW cooling system topic, I was so paranoid about this that when I bought my 04 Range Rover last year, I put a significant amount of money into replacing every failure-prone cooling system component!

EDIT: Here are a couple of pics of the rotted rads.

Yeah, you can say that again. That plastic neck snapped on my 528 and cost $3k worth of engine damage...warped head, pulled block threads that had to be helicoiled, etc, etc. Until this happened to you, I'd not have though of it either, but of course those rads are just collectors for everything, as low as they are, but then I don't drive the 996 in what little snow we get, here in Richmond. I thought most all rads cooling portions are finned aluminum nowadays, so I'm surprised it doesn't happen more often up north. BTW, how much were the rads?

If the bet is that your coolant temperature will stay below 215F while in traffic....I'll take that bet. :D

Removing fuel pump fuse sounds good.

In my documentation all I can find is a fuel relay: Row C - Position 4 (25amp)

I don't think there is a fuel fuse.

I try it, Thanks.

That's the one.

Greetings.

I am preparing my car for spring 2009: C4S Coupe 2004 (10,641 mls)

I changed the oil before storage last October (2008) (Mobil 1 0-40 Syn)

Zero winter starts.

Trickle charged @ 1.5 Amps ("Smart" Charger)

I would like to isolate the spark plugs from the firing sequence prior to starting the engine the first time after 5 month storage. Turning the engine over on battery power ensures oil transits through the critical engine components prior to first engine start; 24 revolutions puts all cylinders through each of the 4 cycles.

What is an easy method of grounding/isolating the spark plugs during the ignition phase while the starter is turning the crank?

Regards,

David

Remove the fuel pump fuse.

Yes, but removing the fuse will throw a Cel, right?

No it won't. And it wouldn't matter if it did.

Greetings.

I am preparing my car for spring 2009: C4S Coupe 2004 (10,641 mls)

I changed the oil before storage last October (2008) (Mobil 1 0-40 Syn)

Zero winter starts.

Trickle charged @ 1.5 Amps ("Smart" Charger)

I would like to isolate the spark plugs from the firing sequence prior to starting the engine the first time after 5 month storage. Turning the engine over on battery power ensures oil transits through the critical engine components prior to first engine start; 24 revolutions puts all cylinders through each of the 4 cycles.

What is an easy method of grounding/isolating the spark plugs during the ignition phase while the starter is turning the crank?

Regards,

David

Remove the fuel pump fuse.

After reading this thread and seeing the mention of a relationship bewteen the changeover valve and variocam, it should be made clear that there is no relationshup to the variocam, directly ot indirectly. The resonance control adjusts intake length, whereas the variocam adjusts valve lift. Resonance flap is controled by both vacuum and electronics and is normally open,

The butterfly valve (tuning flap) in the back crossover tube is controlled by the electric changeover valve (sits right above alternater) which recieves it's vacuum supply from a reserve canister on top of the engine. There is ALWAYS vacuum to the changeover valve.

The tuning flap is normally open and operates as follows:

Open from 700 to 3120 rpm and from 5120 rpm .

Closed from 3120 to 5120 rpm , if the throttle is also more than 30 % open at the same time.

If I were you, at this point I would invest in the Durametric cable and use the actual values logging function while you drive the car. You can see if things like throttle position change in an unusual way. The Durametric is well worth the money if you already have a suitable laptop to use with it.

I've been through the Durametric. Now I'm on the PST2. Still not finding the fault.

You're not looking for a fault, but a sensor which indicates something is outside parameters.

Thanks all, a couple of points in response

to 1999Porsche911: Actually I get coolant blowout only above 91'C ie when the thermostat is open, there are no symptoms when the engine is colder.

That is exactly why I suspect it is the tank or cap. When thermostat opens pressure is introduced to those components.

Probably just a bad cap (even tho they tested it) or a crack in the reservior. When thermostat is closed, those components are not under pressure.