Engine tear down: uneven seal wear, scored housings *pic*
#1
Engine tear down: uneven seal wear, scored housings *pic*
I tore down my engine yesterday and found some things I expected and some that I didn't.
Background: rebuild engine and turbos 1500 miles ago. Engine made 125 psi compression on both rotors. Used Atkins master rebuild kit + a few extra parts and JHB Cermet B resurfaced rotor housings.
The problem: I didn't loctite the turbocharger nuts and my primary compressor wheel came off the shaft and shot metal down the intake.
The results: 110 psi on the rear rotor and 90 psi on the front rotor after the incident. The front eventually ended up at 75 psi and the car was impossible to start or keep running.
Tear down: I observed normal wear on the rear rotor except for medium scoring on the rotor housing from the compressor wheel parts. The rear rotor had unevenly worn apex seals and deep scoring on the rotor housing. I can't believe the engine still ran at all...
I don't have an explanation as to how the seals would wear like this. There were no lips or gouges that weren't in the same direction that the seal travels. Maybe the cermet coating acts like a file when it's damaged?
I'll take rotor housing pics later. I didn't have my camera with me when I tore it down and just brought the seals home with me to post up on here.
Background: rebuild engine and turbos 1500 miles ago. Engine made 125 psi compression on both rotors. Used Atkins master rebuild kit + a few extra parts and JHB Cermet B resurfaced rotor housings.
The problem: I didn't loctite the turbocharger nuts and my primary compressor wheel came off the shaft and shot metal down the intake.
The results: 110 psi on the rear rotor and 90 psi on the front rotor after the incident. The front eventually ended up at 75 psi and the car was impossible to start or keep running.
Tear down: I observed normal wear on the rear rotor except for medium scoring on the rotor housing from the compressor wheel parts. The rear rotor had unevenly worn apex seals and deep scoring on the rotor housing. I can't believe the engine still ran at all...
I don't have an explanation as to how the seals would wear like this. There were no lips or gouges that weren't in the same direction that the seal travels. Maybe the cermet coating acts like a file when it's damaged?
I'll take rotor housing pics later. I didn't have my camera with me when I tore it down and just brought the seals home with me to post up on here.
#3
I think the less worn side kept it in the groove. Thanks to that, my rotors came out unscathed. I'll be spec'ing out the grooves again, though.
#7
FSM procedure. It's pretty much fool-proof, since you can see the springs sitting correctly before you push the seal all the way down.
I'm 99.9% sure the springs were in properly. All three apex seals on the front rotor are worn the same way. If I improperly installed a spring, I'd expect just that one to be worn unevenly.
Last edited by alexdimen; 02-04-08 at 01:14 PM.
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#10
Also, all 3 have the polished marks from the springs being in correctly. 2 marks on the ends from the long spring and 2 in the middle step from the short one.
To add to the background:
The turbo compressor wheel came off only 300 miles into break-in. After the turbo went, i rebuilt the turbos only and continued to drive until the ~1500 mile mark when the car began to have starting problems and eventually wouldn't start or run.
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