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johnmh last won the day on March 14 2018

johnmh had the most liked content!

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  • Porsche Club
  • Present cars
    996 Cabriolet, some Italian stuff

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  1. To provide an update, I replaced all 4 shocks with Konis from Pelican (more reasonably priced than the Bilsteins), reused the original springs and changed all four control arms, drop links, front upper mounts, upper and lowed spring pads and sway bar bushings. Following an alignment, the car rides and handles far better than it ever did and no longer creaks over bumps (remarkable for a 19 year old convertible with 130,000 km). I am quite pleased with it.
  2. Those parts go around the hole on either side of the rear panel (above the rear seat and below the rear windows) where the optional air blocking screen connects to the car. I found one of those in the back of my 2001 996 cabriolet, but could not find it on the fiche or locate a part number, I need the right side one.
  3. I run Evans NPG coolant, which operates as zero pressure when hot, so it was less likely to push coolant into the engine, but, given the location of the crack between between the plug holds and the freeze plug near cylinder number 3, it was more likely to push oil into the coolant. I did notice a small amount of mixed oil and coolant in the hose between the AOS and the top of the 4-6 bank and some 'sludge' but not a milkshake substance in the bottom of my sump. The crack was hairline, initially hard to spot until I was told where to look. I can dig out a photo if helpful.
  4. Hi, now that the cylinder head crack is fixed, the engine reinstalled and the car runs well, I am going to address the 19 year old suspension. The rubber bushings and ball joints visible in the suspension links still seem in good shape (they may not be original) but the shocks, rubber boots and bumps stops appear badly worn. Replacements are coming , but should I also replace the original springs? Do they lose strength by a noticeable amount over time? The car has 19 years and 81,000 miles on it. Getting sport springs and lowering the car is not a viable option as i want to preserve a decent ride, have lots of speed bumps where I live, and being a cabriolet, I am unlikely to start tracking it. Does anyone sell stock length and rate aftermarket springs anyways? The OEM items are vastly more expensive than aftermarket. Are upper shock mounts typically shot? With the metal washers above and below the rubber inserts, it is hard to visually inspect them for cracks. The car does not make any clunking sounds over bumps, it just seems poorly damped and makes the occasional groan or squeak when going over speed bumps. Thanks for any insight.
  5. Thanks. I saw the fitting but never would have guessed that coolant belonged there. The AOS is alien technology.
  6. Anyone know what the other end of rubber hose from the top of the AOS unit connects to? I took it apart and forgot to take enough pictures. The mystery tube (circled) connects to the 12 o'clock position on the round thing on top of the AOS.
  7. Thanks to everyone who has provided assistance and guidance with my 2001 996 Cab project. The car did have a crack in the 1-3 cylinder head which was allowing oil and water to mix. I sent the heads to Hoffman Machine in GA, they were fantastic, I highly recommend them (thanks for the suggestion). Heads are back and reassembly is going smoothly, but for one curious question. Above the chain slider on the 1-3 bank is a small metal baffle plate fastened with a short 10mm bolt inside the head. You can see it above the chain slider and cam chain in this pelican parts photo immediately to the left of the left most cam journal on the intake cam (see below). My question is an odd one - is there no identical baffle to be installed on the 4-6 bank? I was quite careful storing all the bits that came off the engine and cannot find it. FWIW, the 996 parts fiche suggests that only one of these is installed in the car (heat shield 996 104 233 01). The Bentley manual suggests this part is only needed for the left side (1-3 bank), but this seems somewhat illogical for a Porsche (and I have found errors in the Bentley manual elsewhere). Is it true that only one of these is needed?
  8. I did get both heads off yesterday, pretty easy, actually. No visible cracks, but the AOS vent line to the 4-6 bank is filled with oil / water intermix. Weird. I cannot pressure test the head myself, so will see what Hoffman says. Actually, cam journals, bores, combustion chambers, etc all look really good for a 130,000 km 2001 car. No scoring, all pretty clean, not much carbon build up. Now to build those shipping boxes...
  9. Thanks, that thread is pretty hard to follow - is there an actual product there, or just a suggestion to seal an atmospheric port on the OEM AOS? I will be replacing mine in any event, along with hoses, oil cooler, etc.
  10. Thanks, I had done that job about a year ago last time the engine was out. Those sliders were really worn. I got the 1-3 bank head off this evening (no obvious cracks), 4-6 will come off tomorrow (which is full of crud, so I suspect I will find a crack there). Then to find some quality packing materials... Hoffman will get my heads too.
  11. Hi, I am taking my heads off my 3.4 to get them checked and at least one crack welded. To remove the head on 1-3, I set the crank at TDC cylinder 1 and remove the head. Easy. I can use zip ties and paint marks to check the timing does not change. To then remove the 4-6 head, I assume the crank can stay at TDC cylinder 1? I do not need to rotate it 360 degrees to set cylinder 4 at TDC? To do so would be difficult, as the cam chain and gear which bolts to the 1-3 exhaust cam would need to turn (difficult with the 1-3 chain zip tied in place on the exhaust cam sprocket). The Bentley manual is unclear on this point.
  12. OK, so replacing NPG coolant (which runs under no pressure) with straight water in an attempt to flush the cooling system proved beyond any doubt that there was a crack in the head. In short order the 4-6 valve cover developed some oil water mix. So the engine is out and I am about to remove the cylinder heads and send them to repair at Hoffman. Thanks for the tip. Along the way I will swap out the old coolant hoses which were exposed to oil. Should I replace the (1 year old) AOS and oil cooler as well? I want this oil in the coolant issue behind me.
  13. How can I diagnose the crack in a head without removing the engine, both heads, etc.? What percentage of 996 heads crack? If it hasn't yet in 19 years it may not. Even if I have them both welded, they can just crack elsewhere, no? Can I check it with a cooling system pressure check to see if it holds pressure? My current strategy is to flush the system completely until no oil can be found, drive it for a while longer and wait to see if the issue reappears.
  14. No coolant in the sump. Driving also does not seem to consume any noticeable oil. The car did have a failed oil cooler when I got it - there is no question oil got into the cooling system, I replaced it as well as all the hoses. As oil circulates at a much higher pressure than the coolant, there is no question that oil would get into the cooling system. One idea of a local technician I know is that the oil in the cooling system may be significant in amount, but residual from the time spent with the broken oil cooler. He suggested flushing it, repeatedly. I have now flushed it 7 times over 2 weekends, using 4 cans of rad flushing fluid in the process (last 2 flushes with water alone). The drained fluid has gone from red to pink to light beige, with diminishing amounts of what looks like old, dark oil in it (none in the last flush) although a small layer of white foamy scum always settles on the top of each sample. I drive it with the heater on for about an hour between flushes and unplug various hoses to push excess water out, using a compressor each time. I may just try the garden hose until it runs clear and try my luck. All else fails, I think I can pull the cylinder head myself (if I can figure out which one is cracked).
  15. My 2001 996 has been depositing oil into the coolant for some time now. After reading everything I can find on the subject, I suspect that it has developed a crack in one of the cylinder heads which allows oil to enter the cooling system. I am going to get a local shop to help diagnose which head is cracked, any suggestions other than removing and examining both? Car runs perfectly otherwise, so I suspect coolant is not getting into any combustion chamber (a test for combustion gas in the coolant was negative). While not terminal for the car, it seems like a real pain to drop the engine, remove a cylinder head and send it out for welding. Does anyone have a suggestion as to who does this repair well? Ideally, I would be able to swap heads on a core exchange basis.
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