Are the turbos date coded
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- Start date
Anthony P
sharing knowledge with those who care to listen
- Joined
- Jan 24, 2007
Date coded turbos??? sort of but not exactly...
86-87 stock turbo is Garrett model TB0348...........GM part # 25526630.................Garrett part # 466748-1 and later 466748-4
COMPRESSOR COVER CASTINGS:
There were 3 different aluminum castings used for the compressor cover. All are interchangeable.
The earliest 86 turbo Buicks used Garrett 466748-1 and had a compressor cover like this
showing foundry info, the "A" for Air Research and a casting date (5015 for the 15th day of 1985 pictured). Notice there is no "GARRETT" wording on the cover.
At some point, the cover casting changed to only show "Garrett" either just the letters stamped into the cover or stamped on a raised boss
TURBINE HOUSINGS:
There were two variations of the turbine housing. Aside from different foundry marks at the 3-bolt flange, The wording "GARRETT" was either cast by itself or on a raised boss.
The early 466748-1 has a turbine housing with just the cast letters
while the later 466748-4 has "GARRETT" cast onto a boss
COMPRESSOR BACKPLATE - -GARRETT TAG:
All the factory turbos had a Garrett nameplate affixed into the rectangular recess on the backplate. listed the GM part #, the Garrett part # and the unit's serial #. I don't know that anyone can decipher the serial # to a date of manufacture.
BUT, that nameplate was usually lost when the turbo was rebuilt or exchanged for a rebuilt unit or the backplate replaced. it was only glued on by a smear of aviation permatex and also could just fall off.
FACTORY CAST IRON ELBOW with wastegate puck:
There is a casting date on that elbow. "### slash ##" which is the day and year.
As shown (L) is 25th day (EDIT: day not week) of 1986 while (R) is 237th day of 1987. The casting date on my elbow is 86 days before my GN went down the assembly line. The stock wastegate elbows are a dime a dozen now. There will be plenty of them at Kirban's open house, in his "bagged and tagged" bins for $5.
I would think that today the Garrett nameplate is long gone from most stock turbos because they have been rebuilt or exchanged for a rebuilt unit at some point. When returning to stock, probably the best item would be to find a stock elbow with a casting date that is 2 to 3 months before the exact manufacturing date of your '87 (from the broadcast sheets in driver side door or hog ringed to rear of upper rear seat cushion. or use the month on the door sticker.
86-87 stock turbo is Garrett model TB0348...........GM part # 25526630.................Garrett part # 466748-1 and later 466748-4
COMPRESSOR COVER CASTINGS:
There were 3 different aluminum castings used for the compressor cover. All are interchangeable.
The earliest 86 turbo Buicks used Garrett 466748-1 and had a compressor cover like this
showing foundry info, the "A" for Air Research and a casting date (5015 for the 15th day of 1985 pictured). Notice there is no "GARRETT" wording on the cover.At some point, the cover casting changed to only show "Garrett" either just the letters stamped into the cover or stamped on a raised boss
TURBINE HOUSINGS:
There were two variations of the turbine housing. Aside from different foundry marks at the 3-bolt flange, The wording "GARRETT" was either cast by itself or on a raised boss.
The early 466748-1 has a turbine housing with just the cast letters
while the later 466748-4 has "GARRETT" cast onto a boss COMPRESSOR BACKPLATE - -GARRETT TAG:
All the factory turbos had a Garrett nameplate affixed into the rectangular recess on the backplate. listed the GM part #, the Garrett part # and the unit's serial #. I don't know that anyone can decipher the serial # to a date of manufacture.
BUT, that nameplate was usually lost when the turbo was rebuilt or exchanged for a rebuilt unit or the backplate replaced. it was only glued on by a smear of aviation permatex and also could just fall off.
FACTORY CAST IRON ELBOW with wastegate puck:
There is a casting date on that elbow. "### slash ##" which is the day and year.
As shown (L) is 25th day (EDIT: day not week) of 1986 while (R) is 237th day of 1987. The casting date on my elbow is 86 days before my GN went down the assembly line. The stock wastegate elbows are a dime a dozen now. There will be plenty of them at Kirban's open house, in his "bagged and tagged" bins for $5. I would think that today the Garrett nameplate is long gone from most stock turbos because they have been rebuilt or exchanged for a rebuilt unit at some point. When returning to stock, probably the best item would be to find a stock elbow with a casting date that is 2 to 3 months before the exact manufacturing date of your '87 (from the broadcast sheets in driver side door or hog ringed to rear of upper rear seat cushion. or use the month on the door sticker.
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