It runs again...
08-14-2004, 02:06 AM
#1
Drifting
Thread Starter
It runs again...
Its been exactly 373 days since my 1986 944 NA skipped the timing belt, and completely toasted what I thought to be a great running engine(see Timing Belt Poll thread). In October 2003, I was so desperate to get my P-car fix going, I went to a local boneyard to replace the NA motor with a 1987 long block that sat idle for four years(but, only had 78k/mi!). I spent four days trying to get the lifters to stop clanging intermittently- which included three oil changes. Then, one morning- it happened. The noise smoothed-out. I was so excited I drove it proudly like a 10-year-old kid on a new bike.
Three weeks later, traveling at 80mph on the freeway- I hear what sounds like a pneumatic jackhammer powering the car. I pull over, and check for oil leaks. I cannot spot a single drop under the car. I check the dipstick..and it is full. I remove the timing cover again...and the balance shaft belt is stripped of every tooth. The new timing belt appears to be fine, though. I start the car and it barely turns over- finally seizing up. At this point- I was so frustrated at the Porsche Gods- I seriously considered cutting my losses, and just parting the car out on eBay. But, I towed the car back to the yard where the gummed-up, sludgy motor was sold, explaining to the owner what had happened. Prior to purchasing the $850 long block- the salvage yard owner gave me a 30-day warranty against failure. However, he refused to honor his written warranty, citing I should have brought the car in to him as soon as the engine made lifter noise. I argue with the owner... but give up, realizing I took a risk by trying to fix the problem myself. The diagnosis and collateral damage this time; Rusted and gummed-up(once a full crankcase of oil, all dried-up!) oil pressure relief valve failure caused total lubrication breakdown. First, the plastic-counterweighted(1987) balance shafts overheat and expand shredding plastic matter throughout the oil galleys, clogging the crank journals until the #3 rod bearing spins, shearing the connecting rod end cap off. The crankshaft strikes the conrod stump like a cat playing with a hanging toy. The stump ricochets again, gouging 1/3 of the lower #3 cylinder off. I brought the blown engine to my ASE automotive class, as we hypothesized various failure scenarios, microscopically inspecting the damage like Forensic Pathologists.
The gutted 944 sat for another month, before I jumped on an opportunity to get an 83' 2.5L motor + new Sachs Power Clutch.... for $80. After spending $130 to ship the pallete to me- this time I decided to send the short block straight to a machine shop, specializing in Porsche, MBZ, BMW engines.. A week later- the shop calls, saying my engine has the rare KS forged alloy piston/conrod set and will require a special honing process, costing an additonal $300. He also stated I cannot utilize power steering, because of the 83's shorter crankshaft snout(-2mm). The Bosch Motronic DME sensors are also not correct for the application year. Although undeterred by the news- I say, "go for it- do whatever it needs to work" and the motor resides in the machine shop, another 90 days.
When I get the 83' engine back.... it is completely rebuilt top-to-bottom, with new standard-size Goetze piston rings, and bearings. The crankshaft is align bored, polished and knife-edged, with balanced counterweights. Each crank journal now has a new perpendicular drill hole, to further aid in bearing lubrication. On system lubrication- I simply did not want to modify the oil/water intercooler with the one-piece OPRV(I heard of the price and possible risks), so I switched the old 83' piston/spring set with an 86' set that had an improved, grooved piston that prevents wiggling and sticking, with a longer spring and 30% increased spring rate. Installing the newer OPRV requires some incredible finger strength! The 83' block was completely modified to accept the later 85.5-up DME, which included the magnetic Hall-effect sensor. This also required tapping the block at the #1 cylinder to 30mm, accomodating a two-prong coolant temp sender. The rear reference sensor mounting area was altered, by grinding down the bellhousing mating surface. The head is from a 1987 NA, with new seals, springs and intake valves. The cam tower is also from a 1987- and completely resealed and electroplated with .05 microns of silver(thanx to a Jeweler friend). The finished product is viewed below this post. The engine started after three turns of the key(reference sensor adjustments), and immediately established high oil pressure.....however with a nasty oil leak, emanating from the oil pump where the upper and lower oil channels join the block. Two days later- the oil pump is sealed like a vault and the engine is completely airtight again. Previously, I almost made a grave error in choice of sealing compounds. But, I am extremely fortunate to have enough foresight, and get my work verified by an ASE-II Porsche MasterTech, as a pre-flight precaution. His findings resulted in us resealing both balance shafts, water pump, and oil pan gasket. I also mounted a heat shield under the exhaust area, to keep the oil pan gasket from melting prematurely. We finally buttoned-up the install and ran the car on a short, 2-mile victory lap. I cannot describe how healthy and robust the high-compression 83' motor sounds, with lower rotating mass and increased throttle response. Let the pictures tell the rest of the story...
Zach
Rebuild Stats:
1983 2.5L/2479cc SOHC block; KS Alusil process; KS Forged light alloy HC pistons/connecting rods; Goetze Chrome rings, Glyco Main, rod bearings
1987 944NA- head, TRW valves, springs, turbo viton seals; not shaved, 951 wide-fire ring head gasket, ported intake
1987 944NA- 115 degree/lift; 228degree dur. camshaft, cam tower, Turbo lifters, .05micron light silverplate etching, powdercoating, polish
1983 Crankshaft, knife-edged, perp-drilled rod journals, polished, counter weighted, Fidanza 9lb billet flywheel, Sachs 225mm Power Clutch,
1983 Balance shafts w/ polished journals, balanced.
Est. Assembly-Installation Time: 170hrs
Total Parts/Services Cost: $3,276.00(DIY figure)
Purpose: Non-race street/road tourer
**PIX OF ENGINE AT-HOME SOON!**
Three weeks later, traveling at 80mph on the freeway- I hear what sounds like a pneumatic jackhammer powering the car. I pull over, and check for oil leaks. I cannot spot a single drop under the car. I check the dipstick..and it is full. I remove the timing cover again...and the balance shaft belt is stripped of every tooth. The new timing belt appears to be fine, though. I start the car and it barely turns over- finally seizing up. At this point- I was so frustrated at the Porsche Gods- I seriously considered cutting my losses, and just parting the car out on eBay. But, I towed the car back to the yard where the gummed-up, sludgy motor was sold, explaining to the owner what had happened. Prior to purchasing the $850 long block- the salvage yard owner gave me a 30-day warranty against failure. However, he refused to honor his written warranty, citing I should have brought the car in to him as soon as the engine made lifter noise. I argue with the owner... but give up, realizing I took a risk by trying to fix the problem myself. The diagnosis and collateral damage this time; Rusted and gummed-up(once a full crankcase of oil, all dried-up!) oil pressure relief valve failure caused total lubrication breakdown. First, the plastic-counterweighted(1987) balance shafts overheat and expand shredding plastic matter throughout the oil galleys, clogging the crank journals until the #3 rod bearing spins, shearing the connecting rod end cap off. The crankshaft strikes the conrod stump like a cat playing with a hanging toy. The stump ricochets again, gouging 1/3 of the lower #3 cylinder off. I brought the blown engine to my ASE automotive class, as we hypothesized various failure scenarios, microscopically inspecting the damage like Forensic Pathologists.
The gutted 944 sat for another month, before I jumped on an opportunity to get an 83' 2.5L motor + new Sachs Power Clutch.... for $80. After spending $130 to ship the pallete to me- this time I decided to send the short block straight to a machine shop, specializing in Porsche, MBZ, BMW engines.. A week later- the shop calls, saying my engine has the rare KS forged alloy piston/conrod set and will require a special honing process, costing an additonal $300. He also stated I cannot utilize power steering, because of the 83's shorter crankshaft snout(-2mm). The Bosch Motronic DME sensors are also not correct for the application year. Although undeterred by the news- I say, "go for it- do whatever it needs to work" and the motor resides in the machine shop, another 90 days.
When I get the 83' engine back.... it is completely rebuilt top-to-bottom, with new standard-size Goetze piston rings, and bearings. The crankshaft is align bored, polished and knife-edged, with balanced counterweights. Each crank journal now has a new perpendicular drill hole, to further aid in bearing lubrication. On system lubrication- I simply did not want to modify the oil/water intercooler with the one-piece OPRV(I heard of the price and possible risks), so I switched the old 83' piston/spring set with an 86' set that had an improved, grooved piston that prevents wiggling and sticking, with a longer spring and 30% increased spring rate. Installing the newer OPRV requires some incredible finger strength! The 83' block was completely modified to accept the later 85.5-up DME, which included the magnetic Hall-effect sensor. This also required tapping the block at the #1 cylinder to 30mm, accomodating a two-prong coolant temp sender. The rear reference sensor mounting area was altered, by grinding down the bellhousing mating surface. The head is from a 1987 NA, with new seals, springs and intake valves. The cam tower is also from a 1987- and completely resealed and electroplated with .05 microns of silver(thanx to a Jeweler friend). The finished product is viewed below this post. The engine started after three turns of the key(reference sensor adjustments), and immediately established high oil pressure.....however with a nasty oil leak, emanating from the oil pump where the upper and lower oil channels join the block. Two days later- the oil pump is sealed like a vault and the engine is completely airtight again. Previously, I almost made a grave error in choice of sealing compounds. But, I am extremely fortunate to have enough foresight, and get my work verified by an ASE-II Porsche MasterTech, as a pre-flight precaution. His findings resulted in us resealing both balance shafts, water pump, and oil pan gasket. I also mounted a heat shield under the exhaust area, to keep the oil pan gasket from melting prematurely. We finally buttoned-up the install and ran the car on a short, 2-mile victory lap. I cannot describe how healthy and robust the high-compression 83' motor sounds, with lower rotating mass and increased throttle response. Let the pictures tell the rest of the story...
Zach
Rebuild Stats:
1983 2.5L/2479cc SOHC block; KS Alusil process; KS Forged light alloy HC pistons/connecting rods; Goetze Chrome rings, Glyco Main, rod bearings
1987 944NA- head, TRW valves, springs, turbo viton seals; not shaved, 951 wide-fire ring head gasket, ported intake
1987 944NA- 115 degree/lift; 228degree dur. camshaft, cam tower, Turbo lifters, .05micron light silverplate etching, powdercoating, polish
1983 Crankshaft, knife-edged, perp-drilled rod journals, polished, counter weighted, Fidanza 9lb billet flywheel, Sachs 225mm Power Clutch,
1983 Balance shafts w/ polished journals, balanced.
Est. Assembly-Installation Time: 170hrs
Total Parts/Services Cost: $3,276.00(DIY figure)
Purpose: Non-race street/road tourer
**PIX OF ENGINE AT-HOME SOON!**
Last edited by Dilberto; 08-15-2004 at 09:06 AM. Reason: Improper Grammar
THATS AWESOME!!! Nice job man!!!
