Oil Tank Question

Steam Driver · Steam Driver's Garage

I searched for this but didn't find the answer, although I would bet it has been addressed before.

I'm close to putting the engine back in my SC project, which has been derelict for about 15 - 20 years. (I have had it five, and I know it sat for at least 12 prior to that.)

Prior to my getting the car it sat in a (somewhat) heated basement garage. It was unpickled, they just drove it in and parked it for reasons I have yet to run across. Full of all the fluids. Most, but surprisingly not all, of the oil was in the engine by the time I got it of course. No debris or anything in the oil, no catastrophic failures or anything. So should I remove the oil tank to clean it? How hard is it to do on the 911. (Not easy on the 914-6; I know that one.)

The reason I ask is that long ago I redid a 914-6. When I was doing so I removed it's oil tank, cleaned it inside and out, and put it on the shelf until I stated reassembly; it probably sat there about six to eight months. Big mistake. When I was ready to restart the engine something told me "you need to check out that oil tank." Since it was in the car already I rigged up a test rig with some clear plastic tubing and one of those cheap drill-powered pumps, filling the tank with kerosene.

Boy and I glad I did! The amount of rust flakes that came out of it was appalling, probably close to a half cup. I had averted a disaster for sure if those had been pumped into the engine. I have no idea what made me think of flushing the tank, a little OCD maybe. I have no idea what may have promoted the rust as it was stored in a heated, dry, basement. I'm thinking I cleaned the oil residue out but perhaps that let acidic residue work on it. Anyway I learned a lesson here; never clean the oil off of anything unless you need to inspect it or just before it's to be used again. If you have to inspect the part, re-oil it before storage!

Anyway, what do you think about the tank in the SC? It's not been cleaned, so maybe oil residue inside it has protected it. Has anyone else run into this oil tank rust issue?

RedCoupe · 11-11-2018, 06:38 AM

Steam, I think you answered your own question when you described your experience with your 914/6. If it were my project I would at least flush it with solvent or kerosene or something similar. Remember, there is no filter between the tank and the oil pump, so any debris in the tank gets pumped right into the engine bearings.

Steam Driver · Steam Driver's Garage

Wel, I was hoping someone would tell me that was a special case . . .

Steve@Rennsport · 11-12-2018, 05:56 AM

Without exception, we send each and every oil tank out for ultrasonic cleaning. This saves engine bearings from damage caused by FOD in the tank.

mepstein · 11-12-2018, 05:41 PM

Quote:

Originally Posted by Steve@Rennsport

Without exception, we send each and every oil tank out for ultrasonic cleaning. This saves engine bearings from damage caused by FOD in the tank.

Cheap insurance.

I just bought a motorcycle that was a show bike until 2014. Owner put it in his shed and everything got corroded. A bike that he rode all the time looked fine. His theory was there wasn't any oily grime to protect the clean bike from corrosion.

KTL · 11-13-2018, 12:20 PM

Completely agree with the other fellas. For a tank like that sitting so long, definitely get it cleaned. You never know what you might find in there. Don't be surprised if you find an extra dipstick (or two, or three.....)

Removing the tank is quite easy. Just remove the two nuts in the engine bay that have large round washers next to them. Of course remove the oil filter and hoses in the engine bay too. Down below there is a clamp on the rocker panel support strut. Also down below you have to remove the oil line nut which can be a bit stubborn. Don't get too physical with it and don't hesitate to cut the nut off with a cutting wheel if need be. Fiber reinforced cutoff wheel on a dremel tool will slot that nut no problem. Just go slow and avoid cutting into the threads too much on the oil tank fitting.

Steam Driver · Steam Driver's Garage

OK; as long as we’re going this far, what about the front cooler and lines?

Steve@Rennsport · 11-14-2018, 05:15 AM

Quote:

Originally Posted by Steam Driver

OK; as long as we’re going this far, what about the front cooler and lines?

Send the cooler to be ultrasonically cleaned and scrub the lines out yourself using long brushes and lots of clean solvent.

KTL · 11-14-2018, 07:30 AM

You can flush the old oil out of the cooler (does it have a cooler or a cooling loop?) by disconnecting the oil lines from the thermostat. However that's easier said than done because the connections to the thermostat are typically very stubborn.

Once you get the lines disconnected from the cooler, you can flush the lines with solvent. They're brass so they're not going to rust. I flush the lines with a splash of kerosene or brake cleaner and then I fish a strong string through the line with a couple of hex nuts tied to the end. At the other end I tie a piece of cloth to the string. I make sure to tie the cloth very securely so it doesn't come off the string and get stuck in the middle of the line. The cloth swabs the line clean as you pull it through. I do it multiple times until the cloth comes out clean.