I was in a bind - had my injectors out and didn't have any heat shields lying around so I put the old ones back in. How impt. is it to have fresh ones in there? Is this an ASAP situation? Thanks in advance.

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1998 E300D, 287k, barely broken in.

Not ASAP but certainly something you should replace as soon as its practical to do so.

Sounds good, I just ordered some. So after you "crush" them for the first time and are reused, they lose their ability to protect the injector from heat? Does a reused heat shield affect the performance of the injector or just longevity? Just curious. Thanks.

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1998 E300D, 287k, barely broken in.

It looses the effectiveness of the seal. I don't claim to be an engineer but I'd say it would let the hot combustion gasses leak past the seal and heat up more nozzle surface area.

Is it possible to see where a used heat shield has crushed if you compare it to a new heat shield?

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

Yes. Compare the angles and the inner lip. I still have 2 injector prechamber washers to replace again as they leak. Car runs so its not on the top of the list.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I've reused them without catastrophic results, but they really should only be used once. The attached screen shot is the best explanation I've seen as to why they should be discarded after use. It's from this 12MB PDF file on injector servicing, page 39:

http://www.w124performance.com/docs/Bosch/Injectors.pdf

Attached Thumbnails

 

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Dave
Boise, ID
Check out my website photos, documents, and movies!

You will actually get carbon build up inside the nozzle if you reuse the heat shield. Ask me how I know.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

I frequently re-use them, but I first reform them back to original shape so that they recrush when the injector is torqued down. Seems to work.

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

How do you do that without damage?