I have a couple of engines, getting ready to do some mods and rebuild.
So what pop tester do I need, or what adapter?
I see testers for Mercedes on Ebay, does Mercedes use the same inlet fitting?
Then what to get for parts like shims? Are the injectors the same as Mercedes? Or some other injector nozzle?
Injector tester/rebuilding
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CoyoteStarfish
- Posts: 1016
- Joined: Nov 14, 2008
- Location: Miami, FL
This subject has been interesting me for some time.
The injectors LOOK like they're the same as the Mercedes-Benz OM617 (5 cyl TD) uses.
I read somewhere that the M21 injectors have a built-in heat shield whereas the OM617 has those copper washer-style heat shields you drop in before the injector. Maybe you can merge the two into a hybrid injector?
If you do the math:
M21: 2.4L/6cyl = 0.4L per injector
OM617: 3L/5cyl = 0.6L per injector
M21 with OM617 injectors = injection capacity for a 3.6L engine.
With some injection pump mods (Cummins VE internals), a intercooler and a variable nozzle turbo it could be quite an impressive car. I'll let you know when I'm done, unless someone beats me to it.
The injectors LOOK like they're the same as the Mercedes-Benz OM617 (5 cyl TD) uses.
I read somewhere that the M21 injectors have a built-in heat shield whereas the OM617 has those copper washer-style heat shields you drop in before the injector. Maybe you can merge the two into a hybrid injector?
If you do the math:
M21: 2.4L/6cyl = 0.4L per injector
OM617: 3L/5cyl = 0.6L per injector
M21 with OM617 injectors = injection capacity for a 3.6L engine.
With some injection pump mods (Cummins VE internals), a intercooler and a variable nozzle turbo it could be quite an impressive car. I'll let you know when I'm done, unless someone beats me to it.
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dieseldemon
- Posts: 48
- Joined: Nov 14, 2008
- Location: Northern Cal
Injector Pressure
The injector inlet in the M21 engine is the same as the early VW I don't know about the Mercedes but I think they are the same. I have checked the injectors in my 85 524td and some poped at 1300 psi and some at the max of 2250 the lower the pressure gets the engine tends to run on after the key is turned off. The pressure should be 150 Bar or 2205 psi.
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CoyoteStarfish
- Posts: 1016
- Joined: Nov 14, 2008
- Location: Miami, FL
Do you think the injectors from a VW with an AAZ engine would fit? Two stage injectors, they fit right into a Mercedes OM617. People reported quieter combustion noise (pre-injection) and better fuel economy.
The AAZ was a 1.9L IDI engine only sold in Canada (1993-1998 I believe)
(1.9/4)*6 = 2.8L. Only 15% over. I'm just not sure if they would fit as they're larger (taller) injectors.
For reference:
Stock OM617 injectors use Bosch #240 nozzles.
Stock AAZ uses Bosch #308 nozzles, but the Mercedes guys couldn't use those as they would damage the glowplugs.
The solution was to use Bosch #265 nozzles set at 150 bar and set timing to 28*BTDC.
How this applies to our engine, I'm not sure. For what its worth, someone might be able to do more with this info than I.
All info found on a Mercedes Benz diesel forum (Super Turbo Diesel, found on google)
The AAZ was a 1.9L IDI engine only sold in Canada (1993-1998 I believe)
(1.9/4)*6 = 2.8L. Only 15% over. I'm just not sure if they would fit as they're larger (taller) injectors.
For reference:
Stock OM617 injectors use Bosch #240 nozzles.
Stock AAZ uses Bosch #308 nozzles, but the Mercedes guys couldn't use those as they would damage the glowplugs.
The solution was to use Bosch #265 nozzles set at 150 bar and set timing to 28*BTDC.
How this applies to our engine, I'm not sure. For what its worth, someone might be able to do more with this info than I.
All info found on a Mercedes Benz diesel forum (Super Turbo Diesel, found on google)
The Merc injector body is different compared to M21. You will have to dismantle the injectors and swap the nozzles if you want to use them in M21 engine (I do think they will fit but I'm not 100% sure of it). Merc injector has the nozzle sticking out of the lower end and the fire shield is a separate washer that goes into the socket. M21 nozzle is fully hidden inside the injector body and so is the heat shield.
The nozzles from an VW AAZ engine will fit perfectly...but again, you will have to dismantle the AAZ injectors and swap the nozzles into M21 injector bodies.
BTW to calibrate the pop pressure of the injectors I've used washers cut from razor blades....they are thin, stainless and a hard alloy that is perfect for adjusting the injector break pressure.
The nozzles from an VW AAZ engine will fit perfectly...but again, you will have to dismantle the AAZ injectors and swap the nozzles into M21 injector bodies.
BTW to calibrate the pop pressure of the injectors I've used washers cut from razor blades....they are thin, stainless and a hard alloy that is perfect for adjusting the injector break pressure.