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Join Date: Dec 2001
Location: Off grid in Eastern ONtario
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Engine/Gearbox rebuild 84 3.2 Carrera Diagnostic help request
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel Last edited by bdonally; 06-11-2018 at 12:54 PM.. |
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Member 911 Anonymous
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Break a Leg Brother!
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'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
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Counterclockwise?
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Looks like fun!
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Rod 1986 Carrera 2001 996TT A bunch of stuff with spark plugs |
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Hey Rod, where did you get the machine work done when you did your 3.4 build?
Looks like I need some head work - send me a PM if you want. Bob
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Looking for diagnostic help
Got the engine dismantled without too much drama.
From the looks of the intermediate shaft gear, I am pretty sure it is the source of the shiny bits in the oil filter. ![]() The gear tooth edges are burred, and the contact surfaces are pitted. I wonder if there is a root cause for this. The IM bearings are worn but not a crazy amount: ![]() The crank bearings are in good shape except for the thrust bearing. The crank has 0.008" of end play, which is the wear limit. The mating gear on the crank looks good. Possibly the crank end float is beating up on the IM gear? Its easy enough to replace the gear and bearings. Fortunately the existing gear is a code 0, which appears to be the only one available. Any feedback about anything else that might cause this failure is appreciated
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Bearing Dilemma
The crank looks great and measures at the center of the book tolerances.
The rod and main bearings are in nice condition. Bearing clearances measured by micrometer and by plastigauge are as follows: Mains: 0.05/0.06mm Rods: 0.05mm Standard practice would be to replace the bearings, but I hear quite a few issues with aftermarket bearings and I wonder about the chances of winding up with worse clearances. Here are a couple of photos of the bearings. Can anyone identify the symbol? ![]() ![]() ![]() ![]()
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Quote:
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
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Looks like a detonation pattern on that main bearing, no?
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Join Date: Dec 2001
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What about the pattern leads you to that conclusion?
It is entirely possible - My first rebuild was to replace broken compression rings. The breakage was attributed to a lean condition at middle engine speed that likely caused detonation, leading to the broken rings. I didn't split the case at that time. New bearings it is. Question is whether the available Glyco are acceptable or to spend the serious money on the Porsche parts?
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Schleprock
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I'd go with the OEM Porsche boxed bearings. There's a definite quality control difference between Porsche boxed bearings and the aftermarket Glyco
This is a good thread that covered a lot of people's observations and comments on bearing quality. I think ultimately the bad batch of 3.2/3.3/3.6 rod bearings was identified as aftermarket Glyco made in South Africa? I could be mistaken about that, as i'm going by memory here. Rod Bearing Controversy Even though I mention the rod bearings being the problem, we have also encountered main bearings that don't measure up well. I myself had some aftermarket Glyco mains and wasn't pleased with how they measured up when placed in the case, bolted together and checked with a bore gauge. The quality has slipped a lot in the aftermarket bearings and it's a real roll of the dice. You're better off just sucking it up and spending the money to get the known good bearings.
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Kevin L Present: '86 Carrera, '79 911SC widebody conversion rolling racecar shell Past: '87 Carrera |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
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Quote:
I could be wrong, but that pattern is very suspect |
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Crankshaft
Cleaned up the crank and measured everything 3 or 4 times.
Mains are consistently 59.985, and rods are consistently 54.975. By consistent, I mean within +/- 0.002mm. That puts the mains near the center of spec, and the rods near the low end. There is nothing I can feel with a fingernail. The few specs in the photos are some dust or lint. To my eye, the surfaces look reusable, but I'd appreciate input. I plan on getting coated bearings so perhaps that will keep the rod clearance in an acceptable range. ![]() ![]() ![]() ![]()
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Rod Bushings
I am bit confused with the wrist pin bushings.
As shown in the photos, the surface appears worn, partly bronze color and partly grey. I have searched and haven't found any photos to compare. The bushings measure within spec, 23.010 mm across the rod and 23.020 along it. This results in 0.02mm clearance to the pins ( which are all 23.00), at the low end of the Porsche spec. Seems to me if I have new bushing installed, the resulting clearance will be the same as I have now. What should these bushings look like? Is the mottled appearance wear or a result of honing to size? Any thoughts will be appreciated ![]() ![]() ![]()
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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The wear patter on the rod bearing is somewhat typical of a bearing shell that has little eccentricity. The bearings used in these engines have none or little form memory. However, it should be mirrored on the opposite shell, so check. Otherwise it can be indicative of several other issues.
Check the BE size as this type of pattern is often from excessive bearing crush. It usually shows further down towards the mid point, but it is worth checking. It would also be a good idea to check that the rod is not bent. Bearings show up the problems within the engine rotating assy, so don't leave anything to chance. Check everything. The pin bushings look typical of pin bushings in these engines. If the clearance measured is 0.020mm (0.0008") this is on the low or tight side. Nothing wrong here, but expect to see some wear as you have less clearance for an oil film. It is only the oil film that keeps the pin off the bushing when running. Just make sure there is not flaking and the pin bushing is round. You could have them honed which will give a good finish and open up the clearance. By adding a few tenths, here will not hurt. Some engines that show hard wearing can have as much as 0.002" clearance. |
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So the mottled appearance is normal? Is it the bronze coating being removed exposing the grey material or vice versa.?
Will honing expose more of the grey or more of the bronze? I assume that the grey material is not the steel packing. These small end bushings have been in the engine about 60000 miles. Thanks for the comments about the mains and big end bearings. I am going to replace them but it seems weird that the clearances check out with the 60000 mile bearings.
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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Bearings should last a long time if there is nothing wrong. The shells are tin coated and a very hard surface. They are made to last. As long s you have an oil film holding the crank off the bearing, there should be no wear. Its only on start up that the crank may touch the bearing. Hopefully if the clearances are no big, oil is retained when the engine stops and holds the crank off the bearing on start up.
Wear patterns on the pin bushings is typically from the pin being pounded against the bushing when the piston is trying to jerk itself out through the top of the cylinder. All very typical. Signs of wear on the cap side of the bushing is from the pin being pushed against the bushing under compression. 0.02mm clearance is tight, ok but it has to be expected that the oil film is thinner and some pin to bushing contact will happen. 60K miles and this is the only war, you are in good shape. |
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Interesting find in the valve guides:
![]() I am told that once upon a time when the original 3.2 guides wore one technique was to sleeve them using copper. The intakes are in pretty nice shape but the exhausts are thin enough at the ends that the lining peels away easily. These have been in service for about 60000 miles. So whaddya think....new guides or try to find a sleeving expert😁 Last edited by bdonally; 06-20-2018 at 05:45 PM.. Reason: Misspelling |
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I'm a believer in Swepco gear oil . The blue for the road and red for the track.
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Join Date: Dec 2001
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Oil Squirter dilemma
Finally got the cases adequately clean.
IN one case, the three squirters function properly - open at a few PSI, and a fairly uniform spray pattern. In the other case, one is stuck open, allowing backflow and not requiring any pressure to start flowing. Another one seems blocked, at least partially, and the third flows but the spray pattern isn't very good - likely also partially blocked. So far I have soaked them in carb cleaner, Seafoam, and overnight with Liquid Wrench. Nothing seems to make any difference. I was shocked at the price of the things, so am trying to decide whether one should change them all or just the malfunctioning ones. As a side note, it is interesting that the three bad squirters are on the same cylinder bank that had broken rings at the last rebuild. I wonder if the malfunctioning squirters lead to higher piston temperatures and detonation on that bank. Are there any alternatives to either the Porsche squirters, or the rebuildable ones mentioned on this BB?
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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An unpleasant finding
I was pretty sure the pistons and cylinders were good.
The pre-teardown leakdown test was good - all less than 3%. The rings look great, and the piston grooves are well inside the wear limit. Measurements of the bores shoed a bit of taper and ovality, but well within spec. Piston to bore clearances showed some wear but clearances are all 0.06 to 0.08mm. Based on that I decided that while new would be nice, I could get another few years out of the parts. Then I found this in one of the cylinders: Blown up it looks like this: Looks like some platingcame loose and left a little island in the middle. its about 2mm across. And the scratch can be felt using a fingernail. Also, while the original crosshatching is evident, only the deepest parts remain - the rest of the surface is very smooth. Sorry about the photos - its hard to get inside the bore So now it seems my options are to
I like the way my engine works. I'd be interested in comments about the 3.4 conversion, using stock cams, but updating the chip. With my current setup, I was showing about 215 rear wheel HP , so I suspect I'd get a bit more. I don't really want to change cams because I like the torque profile I have now. What would you do??
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Bob D. '84 Carrera - MAF, Wong chip, RSR flywheel, ER bushings and other bits, CTR fiberglass F/R bumpers, 7/9 Fuchs, 22/27 TB, 22/21 SB, bunch of other little stuff '69 Lotus 7 Series 3; '74 Fiat X1/9 '14 X5 diesel |
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