GARRETT T3 OVERHAUL QUESTIONS

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djh61187
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Re: GARRETT T3 OVERHAUL QUESTIONS

Post by djh61187 »

.030 Clearance is way to much. I don't have the Garrett specs right now. But here are some for Borg Warner/ Schweitzer turbos. You can see regardless of turbo size they are all pretty tight. The S2B would be similar to your T3. The important part is the the ring groove edges are square. Your is probably rounded off in the inner edge if you have that much clearance. That is caused by to much thrust play. The broken carbon seal is a telltale sign of that. The most likely means the seal location on the bearing housing is trashed to. You can have the shaft remachined for a over-sized piston ring, That is usually the cheapest way. Or have it rebuild for a standard size piston ring. The best way. The same with the bearing housing seal location.

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djh61187
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Re: GARRETT T3 OVERHAUL QUESTIONS

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The turbo may have been rebuilt before. Not uncommon for turbos that old. The turbine side piston ring width should measure: Min-0.0615 to Max-0.0625. If it is bigger than that by 0.010 or 0.020 the shaft was already machined for a wider ring. Put the ring in the bearing housing up against the step and measure the gap.
Standard gap is Min-0.0080 to Max-0.0150. If it is 0.010 more the bearing housing has been bored for a larger diameter piston ring.
No need to machine the shaft for two rings. There is a Gapless ring available for the turbine side, But only in standard sizes.
The bearing housings on theses Chryslers are "Step Bore" housings. The piston ring will ride on the step when the turbo is assembled.
You should also measure the bearings to see if they are oversized to. If the turbo was rebuilt before there is a good chance the housing has been rebored and the shaft has been turned for over sized bearings.
The bearing are available in 0.005, 0.010, 0.015 and 0.020 oversized on both the I.D and the O.D of the bearing to fit a remachined shaft and housing. Standard size for the bearing is: O/D Min-0.6183 to O/D Max-0.6188. The I/D Min-0.4009 to I/D Max-0.4014. The width should measure 0.4060
djh61187
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Re: GARRETT T3 OVERHAUL QUESTIONS

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Turbine side piston rings don't normally wear the width that much unless the thrust bearing and thrust collar are lose and sloppy. There should be next to no play in the thrust bearing/Collar assembly. 0.002-0.003 clearance. If there is to much end play the shaft moving back and forth wears the ring down like yours and wears out the piston ring groove on the turbine shaft and the seal location on the housing. If the edges on the piston ring groove do not have a nice 90 degree square edge and the groove in in spec the shaft is junk. It will have to be replace or remachined for a oversized ring or the old ring area turned down and a new insert pressed/welded on and a new groove is cut for a standard ring. And 99.9999% of the time the bearing housing seal location will need to be remachined to has the ring scraping back and forth wears it down.
If your turbo has the 1 piece Encapsulated Carbon seal you will need to make a tool to get a new one in without breaking or bending it. I use a cheap socket that has a inside diameter just a little bigger than the carbon seal, but the same size has the outer retainer. In the Lathe I cut the face on the socket flat so it rests on the retainer nice and square. Most sockets nowdays are rounded on the edges on the face and it will bend the retainer and/or break the carbon seal everytime. I use a arbor press to install the seal.
djh61187
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Re: GARRETT T3 OVERHAUL QUESTIONS

Post by djh61187 »

A 360 degree thrust bearing should have been standard equipment on T3's IMO. That is the weak link in the turbo especially if you turn the boost up. I can get you a 360 thrust and a new or reman shaft if you need it. Whats the actual part number of your turbo. Probably 466298-xxxx
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