Alex Sol

Preparing for a engine rebuild after throwing a connecting rod bearing. narrowed down to a few possible reasons for throwing two in two years.

i removed the oil tank and thermostat. lots of oil leaking out the oil cooler and pipes.

went to engine rebuilder and machine shop who suggested i use soap and warm water to flush the hard lines and oil cooler. i had recently removed the front bumper, oil cooler and brought in for cleaning. looks like minor weeping but no oil leaking here.

i wish to 'back flush' so would i connect to the hard pipe that closer to me or farther from me?

also, do you recommend i do this? after flushing with soap and water, do is just air dry?

when refilling with oil, should i 'prime' the oil cooler by filling with oil?

Rocket Rob

Have you inspected your oil cooler and the rubber flex lines? When I rebuilt my engine, I refreshed the hard lines and oil cooler. The rubber in the hard lines was starting to break down and the oil cooler had a few weeps starting. I was surprised at how affordable replacing them was. Plus I had the peace of mind of having new clean parts for my new engine.

Note: I rebuilt my thermostat too.

NineMeister

These failures are down to nothing more than dirt in the oil system - the key aspect that you should consider is that replacing the oil tank, oil cooler and hard lines is expensive but a lot cheaper than a(nother) new engine. Putting it simply, if you cannot guarantee the oil system parts are spotlessly clean from all debris you should buy new to not compromise the third engine build.
Personally I would not ever trust a cleaned oil cooler and furthermore given the number of 964 tanks we now see rusted through I would probably choose the same line in respect of the oil tank. The oil lines can be cleaned easily with solvents (paraffin or petrol) and a steam cleaner, the 'stat can be stripped and inspected. Rubber lines around the tank should all be replaced, as should the breather lines. Don't forget to clean the oil feed pipe from the filler neck in the chassis leg, dirt occasionally settles in this pipe after a blow up.

Be thorough!!!!!!

Steve Weiner-Rennsport Systems

Colin nailed it.

I've seen far too many people rebuild their engines several times in a row simply due to not thoroughly cleaning each & every part that touches the oil.

This means the case, crankshaft, cam housings, oil lines, thermostats, oil tank & oil cooler. The last two items should be either ultrasonically cleaned or replaced outright.

Failure to attend to the very last detail will result in an "encore performance".

tjb616

Any tips for cleaning this one Colin? I wiped out everything I could reach from both ends, but I didn't want to stuff a clean rag in there and it's the only inch of of the oil system I haven't done in anticipation of my new motor going in.

NineMeister

Feed a springy wire down from one end to the other, then hook a paper wipe around the end and pull it through. Do this several times with a solvent soaked rag and you should be good to go. Brake cleaner is a favourite for this as you can spray it in to clean out the threaded section at the top and it will wash down to the end. Obviously this needs to be done with the oil tank removed.

Alex Sol

excellent info. thanks so much for the feedback. will order in some new parts and make sure anything i keep will be properly cleaned out.

Alex Sol

Colin, i am reading your thread with the most recent engine tear down and rebuild with all the gunk in the system, all over the oil pump and blocking off oil galleries on the block and believe i may have done the same with too much sealant thus blocking one or two of the oil galleries that are part of the block!!!

great stuff... thanks for the info and well documented pics and commentary

tjb616

Awesome, thanks Colin!

One last question while I have you... is petrol safe for the soft section of the lines to rinse out the hard lines they're attached to? IE the tstat to oil cooler lines.

Alex Sol

question about the oil filter. doesn't the oil filter keep contaminants out of the system?

tjb616

In single filter 964 oil systems (IIRC, Turbos have 2), the filter is actually after the motor in the system. Makes no sense to me. Assume that is why they added a second filter to the 993. But regardless, you want to be extra careful when rebuilding the oil system for this reason.

NineMeister

Since the engine oil is contaminated with by-products of combustion as well as unburnt fuel and they survive that, I figure a quick rinse with unleaded will do no long term harm. That said, I would not leave them soaking in the stuff for a week.

NineMeister

All 911 and 964 oil systems have the filter located on the exit of the engine, hence in theory clean oil runs through the lines, thermostat, oil cooler and returns to the oil tank ready for re-use.

The problem with this set up is that when the engine is damaged, debris travels through the scavenge side and straight into the filter. Since all oil filters have a bypass valve that opens when the filter pressure is exceeded, as soon as the filter is blocked, the valve opens and proceeds to dump the excess debris into the lines, cooler and tank. And that's why if you don't clean out the system, the same thing will happen again.

kos11-12

Thanks for raising the issue
Colin thanks for all the info !!
Due for a big service , I get the system clean up