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Gents,

Based on Green993 oil diagram the chance are that the ring got pushed out from the pump into the case, then been catched at the pump screen or in the oil filter; cannot assume all debris get there but a close examination of the pump and filter will reveal this for sure. Since debris are "rubber" they when thru the pump being compressed with minimal effort, without creating dommage. My only fear is if some debris when into the crank and blocked one if the connecting rod oil passage, I guess I need to take the connecting rod off as well and clean the crank...

Will investigate and post what I found later on.

Pat
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Old 04-03-2013, 03:20 AM
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Thats the pressure side of the pump, youre right to look to the crank.
Bruce
Old 04-03-2013, 07:53 AM
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Yep that seal should not be ingested by the pump. Scavenge screen would avoid any large chunks being sent to the thermostat and oil filter. But I agree that there's opportunity for smaller bits to be sent to the crank. Crankshaft is the first place the oil goes after leaving that pump port.

Also check your camshaft housings for debris in the spray bars. Can't take any chances there either.
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Old 04-03-2013, 08:18 AM
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Old 04-03-2013, 08:40 AM
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It would be interesting to note any differences in height between the old (i.e. if you still have them) and new seals.
Old 04-03-2013, 09:57 AM
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Of the 4,349,872 different things I worried about before being able to start my rebuild, this particular issue was one of them... Did those oil pump seals seat right? As afterburn already suggested, I used some Dow Corning silicone grease to improve the odds of them staying in place. Still, there was an element of worry until I was able to finally start the thing.

It is great that you found the issue and that there is no damage. It sounds like you are doing the appropriate next steps and making sure all narrow passages, e.g. crankshaft galleys, are clear of debris.

FWIW my oil pressure on start up is 3.5 bar at 1200 rpm (high idle for a cold 3.2). After the engine starts to warm and the idle drops to 800 rpm, the oil pressure is just slightly less, maybe 3.3 or 3.4 bar). When warm, this oil pressure is about 2.2 / 2.3 bar at idle. This is the gauge reading and I have a new oil sender. This is for a stock 3.2 build (except for Euro p's & c's and longevity upgrades like Supertec head studs and ARP rod bolts). It is obviously different than your motor, but I would not expect the idle oil pressures to be that different.

Looks like you did a thorough job and this is just a temporary delay.

Last edited by 500_19B; 04-11-2013 at 06:02 PM.. Reason: explicitly noted that first pressure readings were on a cold engine.
Old 04-03-2013, 01:45 PM
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Little update,

After removing everthing from the case ( pump and crankshaft) I found all the debris, especially the big one, but also the smaller one. I open both filters that I used and found one debris in the one of the filters. I can even rebuild the seal from all the parts I found!

My theory on what append is that the seal did not saddle properly, got pinched and when the pressure build up the seal just burst in the case. I don't think the seal quality can be questionned here, more the builder experience. However, I did kept the old seal I will compare dimensions between the new and the old one.

Next is to clean everything and assemble this engine properly, this time with the help of a friend to mate the halfs.

Pat
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Last edited by pat_thonon; 04-03-2013 at 06:15 PM..
Old 04-03-2013, 05:20 PM
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Good job Pat. Thanks for sharing the lesson.
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Old 04-03-2013, 07:21 PM
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Little update:

After a extensive week of cleaning, inspection and assembly of the engine, I got back in the car today and I start it, pressure is good, 2 bar at idle warm and 5 bar at 2250rpm. and the engine runs without leaks ( for now !), few things worth to be mentionned:

1) For the second sealing, I used the Supertec method of sealing, ( four glue), and I am really pleased with the result.
2) the New #8 bearing was 0.002" bigger then the original on the outside diameter, which made the the case's halfs not joining properly the first time at the #8 bearing area, I decide to install the old one the secound time, much nicer fit now.
3) MUCH, MUCH, MUCH easier to put the case 's half together when you are two persons, especially when it is your first time ( now my second).
4) I used good quality o-ring assembly grease, this sured help to seat the pumps sealing rings
5) finally, always investigate until the problem is resolve, I had to do the job twice, but i am really pleased that I found this problem. Low oil pressure in a Porsche engine is not a good thing.

Pat
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Last edited by pat_thonon; 04-11-2013 at 04:07 PM..
Old 04-11-2013, 04:04 PM
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Nice job sticking with it and going back in to fix it properly.
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Old 04-11-2013, 08:00 PM
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Quote:
Originally Posted by pat_thonon View Post
Little update:


4) I used good quality o-ring assembly grease, this sured help to seat the pumps sealing rings

Pat
What o-ring grease did you use?

I think I will be assembling my case at least 2 times, just to get some practice in. I will make sure to organize all the tools and all the hardware in one spot so that if I have anything left over, it should be obvious.

Have to think about sequence too. Doing a practice run or two helps sort out and develop a good and efficient sequence.

Thanks again and glad you found the problem.
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Old 04-11-2013, 08:23 PM
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AlfonsoR sorry I don't know how to quote, here your answer:

I used "MOLYKOTE® 55 O-RING GREASE" mixed with 15/50 motor oil in a 50/50 volume proportion just to make it more fluid. I used this also for the case thru bolt o-ring, this really make them slip in place, but also will make the o-ring sit properly when you tigth the bolts and the washer push on them. O-ring needs to be able to move.

Practice is a good idea, also make sure you count everything before you start, my kit came with two extra case thru bolt o-ring.

For my assembly, I had all the tools ready on the table, organized and cleaned with break cleaner. I also wrote the torque values on a post-it and had the Porsche manual at the torquing sequence page. Having a extra person to drop and position the one half and give you the hardware really helps. This part of the assembly need to be well thougth out before doing it. I am not sure how the pros are doing this, but this work for me.

Pat
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Last edited by pat_thonon; 04-12-2013 at 05:02 AM..
Old 04-12-2013, 04:58 AM
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Thanks for posting your problem Pat, hopefully it will save others (and me) from having the same issue. See you on Ottawa's horrible roads soon - we hope!
Old 04-12-2013, 07:26 AM
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I went through similar anxiety after closing up my case. I found a "bonus" oil pump seal. Rather than pull the case apart I borrowed a boroscope and ran all the orifices. I was able to see the seal positions internally, save one as I recall. I was able to scope the outside of the oil pump to look for problems as well. A boneyard engine I tore down had a a bent calcified oil pump seal which might have resulted in its failure.

A boroscope might have been able to look at this seal by going in through the pressure relief piston hole.
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Old 04-12-2013, 09:19 AM
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Pat, Great news. Glad you stuck thru to the end. Thanks for posting advice as I will be doing this shortly.
Old 04-12-2013, 10:58 AM
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Another rebuild with low oil pressure. This is and '86 3.5l, running very good pressure before rebuild. I had a ring go bad (not enough ring end gap on turbo motor) so I rebuilt the entire motor. Nickies, JE pistons, bearings, new cams eveything. I flushed EVERYTHING including oil lines to front cooler, all case galleries, rocker oiler tubes also. This is my 9th 911 rebuild and never had this problem. When oil hot (about 95C I wanted to open front cooler thermostat since it was empty after flushing) and at idle I get oil light coming on and also <1bar pressure on gage. Since both light sender and gage are showing low pressure I'm pretty sure is not the gage (but I have bought a new sender anyway). I used to get about 1.5bar prior to rebuild under same conditions. When I run without plugs on starter and cold, oil pressure momentarily (1-2secs) goes to 3 bar then drops down to ~1 bar. I've also checked both pressure relief assemblies and all looks good/free movement etc. Am running Brad Penn 30W break-in oil so expecting somewhat lower oil pressure but not to the point where the oil sender light comes on.

I used Carl Reinz gaskets and thinking either one of the greens seals did not seat properly or per some other posts some of these brand of seals was off spec interms of seal height. Does anyone know what the spec height should be on "good" ring seals for the oil pump.

Either way motor is coming apart again since I want to make sure I did not damage my new bearings during 20 min break in
Old 07-06-2018, 02:23 PM
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Don’t be so quick to assume the worst. A 3.6 has higher oil pressure at hot idle than your engine. If you consult the owners manual for older 911s they will tell you it’s not unusual to have almost zero indicated hot oil pressure. One time I spun my race car and knocked the throttle pushrod off the bell crank. The engine started but would only run at idle due to the throttle disconnect. The oil pressure was at zero as far as I could tell and it worried me. Once I connected the throttle again I found the oil pressure was fine as soon as I came off idle.

Put in the correct oil and drive the car normally. If there’s a problem you’ll find out soon enough, but I bet it’s fine.
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Old 07-06-2018, 06:33 PM
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Low oil pressure at idle

For what it's worth, from the world of NASCAR and 750 hp 358 ci 9000 rpm pushrod motors. The newer tight clearance motors that run on 0-30 racing oil see like 6 to 8 psi of oil pressure for every thousand rpms. Old school guys like me want to see 25-30 psi at idle and 50 psi at 8500 rpm and it just don't happen anymore. I realize their not Porsche flat 6's but fresh thinking and oil technology are newer and different/better. When I ran the Ford NASCAR D3 motor on the chassis dyno at Rousch-Yates the lower oil pressure scared me and they said, you'll get used to it it won't blow up that is all it needs. Excess oil pressure just raises oil temperature. That thing was at 250 oil temp all day on the mat at Daytona. That wasn't my stuff, I drove someone else's car in the ARCA 200 at Daytona in 2016. My car is older, has a Chev SB2-2 NASCAR motor that is not tight clearance. That uses VR1 20/50 and has the higher oil pressure that I was used to. I don't see oil temps over 210 and at Pocono where you hang it at 8400 for a while on 2 straightaways. When we open up the Peterson reusable mesh canister filter nothing in it so we just assume all is well. That motor will go 500 miles from rebuild and get valve springs and then another 500 miles and get rebuilt again. Max time before going back inside it will be like 1100-1200 miles to be safe.
Old 07-07-2018, 06:32 AM
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Howdy everyone,
My story is very similar to this post, just finished a 3.2 build, and I noted some clattering right after breakin when I revved the engine to 3000 RPM. This is my 9th 911 motor rebuild and follow Wayne Dempsey's guide religiously. So motor came right back out and now disassembling and carefully observing EVERYTHING. No valve interference (checked again for Dempsey's book) or evidence of anything hitting the pistons.

I am just about ready to now split the case. I did notice when pulling the large case bolts that on two of the bolts there was quite of build up loctite 574 right in the middle of the bolt where the case halves meet. This could have blocked the oil flow around bolt bores. These serve as important oil flow paths feeding the bearings. The 911 motor thread from this forum is clear on using 574 on the bearing webs but in my case I used to much causing to ooze out into the bolt bores possibly causing severe oil starvation to the crank bearings.

This is an really important consideration in my view and should be included in the engine sealing thread NOT TO USE TOO MUCH LOCTITE 574 in this application. It probably already says this but needs to be in BOLD CAPITAL font. Best case if this is the problem I will see only minor bearing damage when I finally split the cases tonight. Worst case will be crankshaft damage and off to the machine shop.

I'll update this thread. Oddly I will be relieved if this the problem as I have checked everything else and so far still scratching my head.
Andy
Old 07-18-2018, 06:49 AM
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hi there
yes another too much of 574 loctite used story...as i have mentioned in another thread here is how i do it on 911 engines on more then 30 times.Once my friend in LA did the same mistake and had an oil leak next to the inter shaft....too much of 574....
Ivan
https://www.youtube.com/watch?v=IandhtwG5no

same technique goes for assembly of camshaft housings to cylinder heads.
https://www.youtube.com/watch?v=STWf7WnC4xo
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Old 07-18-2018, 09:21 AM
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