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#1
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Out of curiosity; Injector Heat Shields
Out of curiosity, what would occur if one removed the injectors but re-used the old heat shields, I always replace them, but I see everywhere, "replace them, they are a one time seal..." What happens if you dont replace them? Just our of curiosity
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Regards, Ian White 1995 E300 Diesel w124 OM606 2014 E550 w212 M278 biturbo 2001 BMW 740i E38 M62 (past) 1981 300SD w126 OM617 (past) |
#2
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What happens is that combustion gases will go where they are not supposed to- that is along the bottom of the nozzle. I would imagine that the nozzle is cooled by fresh diesel (from inside) and can't take the extra heat.
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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 (??) |
#3
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When I fist got the Volvo I rebuilt the Injectors and reused all six Heat Shields. At the time I did not know they neede to be changed.
I drove for over 1 year like that until a Screwdriver Fell into my timing Belt and Pistons contacted Valves. The new Head Gasket came with the Heat Shields. At that point it dawned on me that they should be changed. What is interesting is that most diesels with Pre-combustion chambers or Swirl Chambers use a Copper or Aluminum Crush washer that seals on the Bottom of the Injector Nut exposing the end of the Injector Nozzle and part of the side. They also run fine.
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84 300D, 82 Volvo 244Gl Diesel |
#4
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In working through a nailing problem with my 220D, I found my injectors had no heat shields. The PO had left them out. The injectors were heavily eroded around the hole, and that part (the nozzles as the shop called them) had to be changed. So I think the shields preclude that erosion. Ron
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1971 220D, daily driver, new paint, 142K 1973 220D, low compression 1975 300D, back on the road! 166K 1971 220D, salvage, rear hit, engine excellent 1972 250, bad cam, but runs! 1971 230, engine stuck 1971 220D, low compression, rusty 1976 240D, salvage, engine excellent 1966 230SL, water in oil after rebuild |
#5
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I think they still erode around the hole, even with the heat shields working properly , after many many miles. The shields minimize it.
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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 (??) |
#6
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Correct me if I am wrong, but I think because they are also referred to as "crush washers", that when the injector is reinstalled and torqued, they deform to provide a seal between the injector and precombustion chamber. If the injectors are removed, there is no guarantee that the faces will align the exact same way before the injectors were removed and thus provide a proper seal. As well as they are a minimal investment compared to new or rebuilt injectors. Thus the mantra "replace, replace, replace...".
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1987 300SDL 2005 Ford Excursion 6.0L Powerstroke, 6" suspension lift |
#7
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What can happen is that soot will get past the washer, and then get into the threads... making the injector very hard to remove.
-Jason
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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket Tesla Model 3. 205,000 miles. Been to 48 states! Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels. 2014 Cadillac ELR 2013 Fiat 500E. |
#8
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also
I think it was mentioned, small amounts of fire and streams of hot gas.
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1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine) Raleigh NC - Home of deep fried sushi! |
#9
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Quote:
Even with new Heat Shields I put a Never-Seeze type compound on the threads. If it does nothing else it helps perevent rust from building up in that area. Having New Heat Shields is most likely most critical on the Turbo Charged Engines.
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84 300D, 82 Volvo 244Gl Diesel |
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