Turbo Failure Modes?
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Track Day
Joined: Feb 2002
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From: GA
Turbo Failure Modes?
Question for anyone experiencing a Turbo failure-I suffered a loss of power on the track accompanied by flashing "check engine" light and black smoke from left side only. After returning to the paddock also discovered oil leaking from area around left turbo, rough running engine and (oh my god) metal on metal knocking/rapping noise. Local track experts initialy diagnosed as bad turbo bearing, some other folks thought it might be a spun rod bearing. Incident occured exiting a turn with a mid range power setting. Has anyone experienced a turbo failure with these symptoms, or does it sound like something else? https://rennlist.com/forums/misc.php...=0&forumid=62#
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From: Lexington, KY
I didn't have the ominous metallic sounds, but did experience all the other symptoms simply from a turbo hose that blew off under sustained boost at the track. All it needed was a simple reattachment and stronger Breeze CT (constant torque) clamps.
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From: Gulf of America-Pacific NW
Without seeing pictures of the engine you will have to do the investigation for me.. You mentioned oil leaking out the left turbo, then you mentioned smoke out of the left side.. Do you have straight pipes with no mufflers.. If that is not the case.. You have smoke actually coming out of your right turbocharger, and oil leaking out of you left turbocharger..
To quickly find the turbo problem, pull the left and right plastic inlet pipes to the inlet side of the turbochargers, not the pipe that goes to the intercooler.. You will be able to shine a flashlight into the compressor housing and check the status of you compressor wheel.. You definately have oil in one of the turbochargers..
You could have broken a rocker arm and or had a hydraulic lifter fail also.. Please report back what you have found and I'll suggest other actions..
To quickly find the turbo problem, pull the left and right plastic inlet pipes to the inlet side of the turbochargers, not the pipe that goes to the intercooler.. You will be able to shine a flashlight into the compressor housing and check the status of you compressor wheel.. You definately have oil in one of the turbochargers..
You could have broken a rocker arm and or had a hydraulic lifter fail also.. Please report back what you have found and I'll suggest other actions..
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Thread Starter
Track Day
Joined: Feb 2002
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From: GA
Here's the findings so-far-rocker arm on exhaust valve broke and put a 1/4" hole in the valve cover. Broken piece has gone AWOL. Leak down shows valve damage and visual inspection shows mark on cam. Engine will have to be removed and other cylinders inspected for additional damage. Now for the fun part: since we'll have the heads off-what upgrades/preventative stuff should I consider? Specific suggestions will be greatly appreciated i.e.: new valve guides-what brand/material has shown improvement over stock in resolving the premature wear problem. Cams-how aggressive can I get while still keeping the car street able-what is RUF using in their Turbo-R conversion? I would anticipate a new ECU would be needed w/cam upgrade, mine is a stock 96 which I don’t think can be reprogrammed-what is a good replacement and who is a good source for the unit plus programming? Who has a good reputation as a machinist for working on 993’s-I’m in the Southeast but would send parts out to the “right guy”. Anybody have any experience with failed rocker arms? Would you replace all of the others?
Thanks in advance for any comments!!
Thanks in advance for any comments!!
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From: Gulf of America-Pacific NW
The problem here is the Motronic programming with cams and timing.. The second that you install new camshafts you will have to get a custom tuned program for your ECU.. The stock 993TT camshafts are very similar to the "SC" grind that many 930 owner use for the street.. I have the 993TT cam maps and other maps for this area.. Changing to 963 NA cams or even 993 RS cams are very good choices for our engines.. Broken rocker arms happen, if you are living alot in the upper RPM band.. If you float the valves or miss a shift you will stuff the rocker arm.. The new guides are phosphorous bronze.
