JusMX141
Moderator
- 15,152
- 1,268
- Dec 13, 2005
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Greensburg,
Pennsylvania
Everyone's been in a position where they come across a hell of a good deal on a used turbo. There are a series of things you should look at before you buy.
A few things to remember:
These are photos of a thrust plate that were taken from a Bullseye T04B V-Trim that had very low miles but came from a car that blew the engine with the turbo installed. Well, see for yourself:
The thrust plate is totally loaded with shavings.
Here is the V-Trim's thrust plate next to a new T3 thrust plate. You can clearly see that the oil passages are totally clogged. The journal bearings didn't look much better.
Thanks for reading my post, and feel free to add any info from other personal experiences!
- Shaft play. This determines how well a turbo has been lubricated. There should be NO noticeable in/out shaft play (less than .002" by measurement), and as minimal up/down shaft play as possible (less than .014" on most turbos).
On a journal bearing turbo, the bronze journal bearings ride on a film of oil so if the turbo has sat off the car for a while, the oil has drained away from the bearings. You should turn the turbo upside down and pour a small amount of motor oil into the oil drain flange and allow it to flow into the journal bearings before you get a final measurement of up/down shaft play.
- Bad oil seals. If you look at the turbine wheel and it appears WET, the turbine shaft seal is bad. It is more common that the turbine shaft seal will leak before the compressor seal because of the extreme temperatures the turbine seal sees. The most common killer of oil seals is excessive shaft play.
- Damage to the turbine or compressor wheel(s). It is more common for there to be damage to the inducer of each turbine than the exducer, so be sure to examine both wheels very well. Remember- the inducer of the turbine wheel is only visible by peering into the turbine housing inlet (the flange that mounts to the manifold.)
- Exhaust housing cracks. Most cracks appear on the interior of the exhaust housing. Usually, these cracks are from the rapid heating and cooling that the housing sees, and they generally will not effect performance of the turbo. However, if cracks are present, be sure they aren't the whole way through where the housing will leak or cause the wastegate flapper to not seal properly.
- Check all of the mounting holes for stripped threads or broken hardware. This is pretty self-explained.
- If possible, check the wastegate actuator for smooth operation and make sure the flapper seals tightly against the housing. I test the actuator of every turbo I rebuild by applying 20psi into the hose nipple with a rubber-tipped blowgun. A Mitsu actuator has about 1/3 of the travel that a Garrett actuator does, so don't be surprised when the flapper of a Mitsu turbo opens less than 1/2 inch.
A few things to remember:
- Don't bother asking mileage. Many times a turbo with high miles that was well cared-for will be in better shape than a turbo with low miles that was abused. You will know how well a turbo is cared for if you check it with the steps listed above.
- Ask the owner for the history of the car that the turbo was removed from. If the turbo has just been pulled from a car with a blown engine, STAY AWAY! The inside of that turbo is so full of metal that it won't last 20 miles.
These are photos of a thrust plate that were taken from a Bullseye T04B V-Trim that had very low miles but came from a car that blew the engine with the turbo installed. Well, see for yourself:
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The thrust plate is totally loaded with shavings.
You must be logged in to view this image or video.
Here is the V-Trim's thrust plate next to a new T3 thrust plate. You can clearly see that the oil passages are totally clogged. The journal bearings didn't look much better.
Thanks for reading my post, and feel free to add any info from other personal experiences!
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