Loud Clattering Noise / Low Oil Pressure at Idle

[akaKJB]

Well, this is what it says on the tin - I came home the other night and heard a clattering noise from my 1987 944S that sounds like it's under the valve cover. The oil pressure gauge was really low, 1 to 2. I checked the oil and while it was below the bottom fill line, there was oil just beneath the line. I filled it with oil, started it up and it seemed to sound a little better for a few moments but then the noise came back. The noise seems to fade and the oil pressure goes up as I increase the engine revs.

Anyone have any thought? It kind of sounds like not enough oil is getting to the top end of the motor at lower and idle rev speeds. Thoughts?

[John_AZ]

Is it on the '87 944S with 16 valves?
Then maybe the chain tensioner has failed.

Or the cam belt/WP area failed and valves hitting the pistons.

A guess.

J_AZ

[mytrplseven]

How long did you run the engine after adding oil? You may not have re-pumped up the lifters. You really have to watch your oil quantity. I'd recommend letting the engine run for 10 minutes and see if it goes away.

[akaKJB]

I can't believe I forgot to mention the model & year! Its been a rough month and not getting too much better very soon.

Yes, it's the 1987 944S. The tensioner is reasonably new, within the past 1500 - 2000 miles or so. Investigating the a noise after I bought it, we pulled the valve cover and checked the tensioner, chain, etc. Everything was fine but most of the spark plugs had managed to come halfway out. According to the service records that came with the car, the cam belt was replaced around the same time. I posted a detailed list of the various service records and work it had done on it prior to my taking possession of the car right here.

Something I forgot to mention: During the recent arctic cold snap, I started the car and got a loud, high pitched squeal that went away in a minute or so. I chalked that up a frozen belt but it was also the first time that I had to really crank the starter to get the car to fire up since I've owned it. Every time I've started it since, I've gotten that squeal for various lengths of time. The engine hasn't fired up as soon as I turn the key since then. I drove the car a few times since that first difficulty it had starting. That was when I really noticed the clattering noise.

I did let the engine run for a while after adding the oil but maybe not as long as needed. I'll give that a try in the morning.

[akaKJB]

Here's a short video of the engine running and the noise. Hopefully you can tell what I'm talking about.

[devin3200]

Hi folks, I too am having a simular issue. In the past few days when i start the car up cold the oil pressue is really low. The warning light at the oil gauge is on. I just changed the oil 5 gts 20-50 last weekend. Funny i haven't changed the oil since i bought the car a few months back. ( doing repairs and weather). So before i changed the oil , when the car is warm and i would drive it for a few miles, than stop. The oil pressure would drop( light comes on a few seconds til the engine revs back up. So a changed the oil, that problem stopped. Now with starting the car cold, the oil pressure stay low for about 10 mins. You almost have to drive the car clacking up a hill than the pressure comes up. Is the a priming issue i'm missing with this. Car 87 944 N/A.

[mytrplseven]

Originally Posted by devin3200

Hi folks, I too am having a simular issue. In the past few days when i start the car up cold the oil pressue is really low. The warning light at the oil gauge is on. I just changed the oil 5 gts 20-50 last weekend. Funny i haven't changed the oil since i bought the car a few months back. ( doing repairs and weather). So before i changed the oil , when the car is warm and i would drive it for a few miles, than stop. The oil pressure would drop( light comes on a few seconds til the engine revs back up. So a changed the oil, that problem stopped. Now with starting the car cold, the oil pressure stay low for about 10 mins. You almost have to drive the car clacking up a hill than the pressure comes up. Is the a priming issue i'm missing with this. Car 87 944 N/A.

I'm wondering if the 20W50 is too thick a weight for the ambient temp.

[devin3200]

Hmm that could possible be an issue. The temp around here has gone from the below 30 degress to just below 70. In the past few days since oil was changed. What do you suggest as far a medium for oil weight. (this is DC and the weather never is the same).

[akaKJB]

I'm running the Royal Purple 5W20 weight oil in mine, having seen it recommended by several people on various forums.
Devin - your oil pressure issue sounds a little like one I had right after I bought my '87. It was sort of the reverse of yours - the light would come on and the gauge would stay at the top, moving just enough while driving to tell me that it wasn't a stuck or faulty gauge. After cleaning accumulated road gunk off the oil pressure sending unit, the gauge now works perfectly. Now I just need to figure out why my pressure at idle is so low and whether or not it has anything to do with the clattering noise.
Getting ready to fire her up and give it a good 10 minutes to see if mytrplseven's suggestion works out. I'll report back here later with the results.

[Rasta Monsta]

Originally Posted by akaKJB

I'm running the Royal Purple 5W20 weight oil in mine, having seen it recommended by several people on various forums.

I would not use RP to tar and feather my worst enemy.

Were these forums sponsored by engine rebuilders?

Originally Posted by akaKJB

Here's a short video of the engine running and the noise.

Erm, what are your fuel lines doing in this video?

[sausagehacker]

5W-20?? Drain it, add some cheap Castrol GTX 20W-50 (for now) and see if you still have now pressure at idle. The people who run xW-30 oils are already living on the edge as it is.

[djnolan]

Originally Posted by mytrplseven

I'm wondering if the 20W50 is too thick a weight for the ambient temp.

In the DC area I run a 10w30 Mobile 1 year round in my S and have not had a problem. I get a little clatter in the coldest months, but, hey that is when the car is not used much, with all of the salt on the roads. I do connect the battery tender a couple of times each winter if it is not getting driven.

[akaKJB]

Originally Posted by Rasta Monsta

I would not use RP to tar and feather my worst enemy.

Were these forums sponsored by engine rebuilders?

You know, it wouldn't surprise me. Due for a full oil change this week, anyway so I'll go ahead and replace it with some 20W-50 as suggested by sausagehacker.

I will say that the clattering noise has decreased substantially. I was also able look at the engine at work with my son pressing the gas pedal. At regular idle (it sits right at 1 on the tach), nothing visible seems to be amiss but when I had him rev the engine up to 4 on the tach I immediately noticed the belt that winds the power steering pump appeared to be loose (the belt itself in nearly new). The pump itself looks like it's moving around a bit in ways that I'm certain Porsche never intended. I'm going to try and address that issue tomorrow and see what I find.

Originally Posted by Rasta Monsta

Erm, what are your fuel lines doing in this video?

Is this a trick question? I just wanted to shoot the video so everyone could hear what I was talking about. I didn't intentionally visually target any area of the engine. Do you see something potentially amiss with the fuel lines?

[Rasta Monsta]

Originally Posted by akaKJB

Do you see something potentially amiss with the fuel lines?

Is this a trick question? They're moving!

Or, I'm losing my mind.

[akaKJB]

Originally Posted by Rasta Monsta

Is this a trick question? They're moving!

Or, I'm losing my mind.

Say WHAT?!

Okay, it took a couple of rewatches of the video but I think I see what you're talking about. I think that's an optical illusion due to the vibration slightly messing with the lens. I think I was partially leaning against the front of the car to help stabilize myself and the vibration passed through me to the lens. I've certainly never seen them do that while I'm looking at them!

[sausagehacker]

For a sanity check, a good oil pressure model for the NA 944 is:

P (bars) = 0.0232 * v (cSt) * RPM^0.288

...where 'v' is the kinematic viscosity of the oil at a given temp. According to the RP data sheet, your current oil is 48.58 cSt at 40 deg.C and 8.5 cSt at 40 deg.C.

Long story short, you can expect an oil pressure of roughly ~1.42 bar when the oil is fully up to temp and the engine is idling at 950 RPM. No bueno, switch to at LEAST a 0W-30 if you insist on a thin-ass oil. M1 0W-40 is a good choice for cold climates, I run M1 15W-50 in Texas with no qualms.

For a cold start, the oil pressure gauge should be pegged, even with the current oil (~8.1 bar). If you aren't seeing that, you have bigger problems that noisy lifters.

(derivation of that equation can be found here).

[akaKJB]

Thanks for the advice. I'd decided to run a long life synthetic after getting advice that it could help ease the ongoing wear on the engine parts that been with the car since it rolled off the line (although judging from the service records, I'm not sure there are many of those left). Even though I grew up working in my Dad's service station / garage, we never really dealt with performance cars like Porsches and synthetics didn't really exist at that point so my experience with it before now is minimal. I'll throw it out to you guys - what's the opinion on synthetic oil and if the consensus is that it's worthwhile, I'd appreciate some recommendations on brand & weight.before I change the oil tomorrow. I'm using service bay where a friend works that has a service trench so I can determine if the power steering pump is just loose of if there's something else going on.

I have to drive 3 1/2 to 4 hours one way this weekend to see my Mom & Dad before he goes in for heart surgery. I'm trying make sure I don't miss something stupid and shell my engine on the way up. Yeah, I'm being paranoid about it. Way things have gone lately, being "over cautious".probably isn't a bad idea. But until the change, the rattle does seem to have decreased considerably, oil pressure sits pretty solid at just above the 2 while idling with a warm engine. Using a stethoscope, I listened to the sounds inside the valve cover and there's still a faint noise but not a clatter. Actually, for any of you that have accompanied a pregnant wife / girlfriend to a sonogram, it kind of has that sliding, whooshing sound to it. Doesn't sound particularly bad but it doesn't quite sound right, either.

Thanks again for your help, guys. I'll make sure i get my GOOD info here from now on before I go and do something else characteristically stupid.

[John_AZ]

Oil Filter.

You must use the OEM Porsche oil filter or the Mahle. They have the anti oil backflow valve. Required.

Do not use NAPA, Prestone, Fram, or any other junk filter.

J_AZ

[sausagehacker]

There are a lot of oil threads, and the truth is that everyone has their own idea of what works best. Royal Purple is a resource conserving oil, and has the same additive composition as cheaper Valvoline, so there's some objectivity. Some people swear by it, so whatever.

There are a few things to keep in mind: run a reasonable viscosity oil, change it on time, and use the right filter like John said. As long as you meet those 3 criteria, run whatever oil suits your fancy.

Reasonable viscosity: 0W-30 is cutting it close, but that's the thinnest most people would advise you to run. Sounds like you already have some data for how 5W-20 sounds in your engine.

Reasonable interval: for a good quality synthetic (i.e. all name brands you would recognize), 3000-8000 miles is conservative. Some people go up to 15,000 but it's not like oil is that expensive that you need to push it.

Reasonable filter: Read John's post. Mahle OC-142 is OEM and is like $7 from our host.

You can search and spend hours (months?) reading the oil-war threads but I think you'll come to the same conclusion as what I typed out.

[Rasta Monsta]

I run LiquiMoly 5w40 and have excellent oil pressure and wear in my 931 (I've inspected the bores and rod bearings after about 15k miles). They also put it in virtually everything at the shop I worked at for a couple years.

As for the intervals, the extremely long intervals claimed by the oil vendors may be viable for the oil, but not for the filter. If you're committed to the car, I wouldn't go past 5k.