Oil Coolers and bearing damage

[tgarnoldo]

Folks,

I think I have spun a bearing in my '87 Carrera. In the rebuild process will I need to replace both oil coolers and lines? or can I get by with just replacing the engine unit and flushing out the remainder of the system? If so, how is the best accomplished.


Thanks,

Arnie

BTW: What about the oil pump?

[ChrisBennet]

I went through this a few years ago.
Clean everything:
Remove the case plugs and clean the oil galleries.
Clean oil the oil lines
The Factory says to replace the oil coolers but you can get them ultrasonically cleaned by someplace that does them for small aircraft (FAA certified). I used Pacific Oil Cooler.
Remember, the bits of metal that are lodged in your oil coolers got there while the oil was hot and the car/engine was vibrating. Rinsing them out with solvent isn't going to cut it.
-Chris

[dwightp]

I'm going through this now also. Long process but I've got a follow up question. I understand what many say as far as cleaning everything and I'm following recomendations of professionals. BUT, as I see it, the oil returned to the tank (from the external coolers and lines) goes through the oil filter PRIOR to being held in tank and then off to engine. So why wouldn't it be enough to clean engine as you recommend, replace oil, flush lines and coolers, ultrasonic clean tank (and lines downstream) go with a 8 micron oil filter?

[ChrisBennet]

Originally posted by dwightp
I'm going through this now also. Long process but I've got a follow up question. I understand what many say as far as cleaning everything and I'm following recomendations of professionals. BUT, as I see it, the oil returned to the tank (from the external coolers and lines) goes through the oil filter PRIOR to being held in tank and then off to engine. So why wouldn't it be enough to clean engine as you recommend, replace oil, flush lines and coolers, ultrasonic clean tank (and lines downstream) go with a 8 micron oil filter?

I don't quite understand the question but I think you are asking if an oil filter will protect the motor. I suppose it would if the oil filter was a full flow type i.e. all oil had to go through the filter. This isn't the case with normal oil filter which has a pressure bypass.
When I cleaned my engine after a rod bearing turned into confetti, I only found metal in the sump so I don't have any direct evidence that would indicate how far the contamination could go. Race cars often have a full flow oil filter in the pressure to protect the oil coolers and lines from contamination.
-Chris

[dwightp]

Thanx Chris.

Yes, a full flow unit such as the Canton was what I have purchased to use on my tank filter. No bypass. A little extra insurance.

[tgarnoldo]

Just an update, I found large shards of metel on the sump drain plug, NFG. Spoke with a well respected, local Porsche Mechanic and he showed me the bill for a 3.2 l he just did, $15k+. he did put me on to a guy who might be willing to sell a 3.2 l with 45k miles. Well now it is on to a search for a motor, or figure out if I want to rebuild on my own.


Thanks,

Arnie

[911pcars]

Hmmm,
Shards of metal on your drain plug are magnetic (steel). Bearing material is non-magnetic. Excuse me for the basic question, but how did you verify a spun bearing?

Sherwood Lee
http://members.rennlist.org/911pcars

[tgarnoldo]

Sherwood,

I did not realize this. I just thought that a hardened steel Crankshaft would run in a bearing that has some steel in it? I could be wrong, it does happen on occasion (LOL). What else could it be?

Arnie

[ChrisBennet]

Contents of 3.2L after failure of #6 bearing (bearing, bits of old chain ramp and what looks like an alumimum rivet head):


Bearing from 944S2 (like new w/180K miles!):

The bearing's wear surface is quite soft (you can mark it with your fingernail) but the bearing and it's jagged pieces are definately magnetic. Less drastic wear of the bearing will show in an oil analysis as copper.
-Chris

[911pcars]

Chris,
The engine did a good job chopping up the rod bearing into uniform sizes/shapes. What caused that? Rod cap depart?

Sherwood

[Wayne 962]

You can run your old coolers, but you do so at a risk. If it were my engine, I would not do this. New coolers are probably about $1000 for the pair. I personally wouldn't trust the ultrasonic cleaning to get everything out - especially if I'm paying big bucks for new parts elsewhere in the engine.

-Wayne

[ChrisBennet]

Originally posted by 911pcars
Chris,
The engine did a good job chopping up the rod bearing into uniform sizes/shapes. What caused that? Rod cap depart?

Sherwood

The rod stayed together so the bearings got squeezed out the side and chopped up (I guess). It slices it dices...
-Chris

[ChrisBennet]

Originally posted by Wayne at Pelican Parts
You can run your old coolers, but you do so at a risk. If it were my engine, I would not do this. New coolers are probably about $1000 for the pair. I personally wouldn't trust the ultrasonic cleaning to get everything out - especially if I'm paying big bucks for new parts elsewhere in the engine.

-Wayne

I hear you Wayne. Pacific Oil cooler mostly cleans oil coolers for aircraft. The downside for an engine failure is a bit higher than for a car so it should be pretty safe. Any aircraft guys know what aircraft use for oil filters - where in and how many in the oil circuit?
-Chris

[Wayne 962]

On that note, I wouldn't use an oil cooler in my airplane that came from a failed engine. In fact, when is Pacific Oil cooler every going to clean an oil cooler that has been through catastrophic engine failure? Your reasoning has a few holes in it - if the oil coolers used on airplanes were from a catastrophic engine failure, I would predict that they would be in 1000s of pieces when they hit the ground.

Surely the coolers they clean only come from engines that have not had a catastrophic failure...

-Wayne

[steve911sc]

Hi, I am new here, just regestered...I have been an aircraft mechanic (A&P) for 25+ years..When you get an engine failure it doesn't always mean a crash. I always have the cooler cleaned and reuse.. in a lot of older aircraft there are no new coolers being made and a used one might be from the same situation. Not many aircraft have a filter like a car..most just have a screen. If they do have a filter, it is a bypass type. You do clean every thing very carefully. Also change oil after break in ~ 5 hrs. Of course aircraft owners usually change oil every 25 hours of engine run time. my $00.02 worth
Later
Later

[Skycoog]

Steve911 is correct. I've suffered two "major" problems with Continental aircraft engines (two different engines, one failing in flight) and on the rebuilds there the oil coolers were cleaned and reused. Porsche/aircraft engines are similar in many respects. A lot of GA aircraft (especially older models) utilize screens instead of oil filters. I had a piston come to pieces underneath the oil skirt on a Continental O-300 and continued to fly it from Alabama to Texas. There's nothing quite as sickening as realizing somethings wrong and taking out a screen filter and seeing large chunks of piston in it. It's remarkable how durable (and expensive) those engine are.

In taking apart my 3.2L just recently I was amazed at the craftsmanship that Porsche put into these engines. They are a remarkable piece of engineering.

In the case of a catastrophic failure of a Porsche engine, I'd have the coolers ultrasonically cleaned (as you are doing) by an aircraft shop. I'd show them the problems the engine had so that they realized the monetary seriousness of the situation. Plus it never hurts to ask them, "Knowing the problem, would you put this back into an aircraft??". Most likely they won't flinch. A good aircraft shop is accustomed to dealing with high dollar situations.

Plus, after my rebuild; I'd probably change my oil every 25 hours

[Wayne 962]

Regardless, spending $800 on new oil coolers is good insurance when you are talking about a $8000 rebuild.

-Wayne

[steve911sc]

Wayne, if you want you can send me those old "bad" coolers, I will even pay for the shipping

Steve

[dwightp]

Why stop with just the coolers? Why not buy all new lines, tank and stat?

As a pilot and aero engineer, I'm gonna have to go with the A&P here. I've seen their machine shops vs. porsche engine rebuild/repair shops. I have a hard time believing that the solution for an aircraft piston engine is not good enough for a 911 engine. I've opting for my oil tank and cooler cleaning by an avaition repair shop. Also going with a non-bypass filter. I guess time will tell if I made the right choice.

[dbryant61]

Wayne,

I think you are trying a little to hard to sell parts. Do you have any experience or verfied stories of engines being destroyed by a cooler that had been cleaned at Pacific Oil Cooler or a similar FAA/ MilSpec certified shop?

Don