Fuel Injectors
This component is part of the Fuel System. For a comprehensive look at how this all works together, see Engine Starting Aid Tour.
Definition
- Its technical name & common name(s)
- part # - start year & end year
- which area it belongs to - engine, transmission, body, injection etc, link back to the relevant section
Components
Function
Describe, in general terms the function of this component. Meaning what is it there for and what role it plays. Describe how it works, the inside mechanism. Use diagrams to explain.
Injectors
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My engine has a miss in 2 of the cylinders. Moving the injectors around, the mechanic traced the problem to 2 of the injectors. He took them to a place with a high pressure connection and discovered that 2 were bad, 2 so-so and 2 good meaning they sprayed a fine spray. My question is about the 2 so-so ones... he said they are not worth replacing since the spray while not fine is still OK for normal combustion. Does this sound right to you guys? Is there some good way to clean the injectors so that they spray evenly? Do replacement injectors really cost $100/each?
You can probably have them rebuilt for a reasonable price. I have not done it personally but have heard numbers up to $50 each for rebuilds. I think that was high end. There may be better prices out there. Pacific Fuel Injection is one source, advertise in the (MBCA) Star magazine among other places. You can do it yourself, but will be a painstaking endeavour in which you will spend $100 or more for a tester, then learn the art of shimming injectors and very very finely grinding surfaces to get moderate results.
On the question of price - I replaced all of my injectors last year, which cost $400 (although this is in the Netherlands which may be cheaper)
For what it is worth, my mechanic says to add (Chevron) Techron to a tank of gas. He claims it does a wonderful job of cleaning the injectors. I don't know if anyone has had experience with "serious" cleaning.
I replaced my injectors-not because of a problem but because I had the injector lines off for cad plating. After 30 years, it just seemed like it made sense to go ahead and replace them. I recall paying about $70 each.
Injectors are still available. I think I paid $75 each. Do keep the old injectors. Once you get them cleaned, you can swap them with the new ones way down the road when they inevitably need a good cleaning. And yes, I think you can send them to Pacific Fuel Injection for a cleaning.
Will Samples says: I am not aware of W 113-style injectors being rebuildable. I have never heard of it. Diesel injectors are designed to be rebuilt and that cost is about $50 each. The Bosch injector tester I bought 10 years ago cost about $700. To my knowledge, injectors are still available for the 113. I will supply only new. Please note that any small flec of rust or dirt will plug the injector. So, if you have dirty or rusty fuel lines from the fuel filter to the injector and it clogs up a new injector, Bosch will not give you another for free.
Pete Lesler: Will is correct as the older mechanical injectors, which are still available as MB part number 000-078-1123, are not rebuildable. The are cleanable under high pressure to a degree. The last current list price I had quoted was $103. They could be available through various sources for less. If your car is a 230 or early 250 SL, it uses a slightly different injector. They will be marked as DC8C45R1. The later 250 and 280's used DC8C45R2. The Bosch part number for this later style, which is the only one still available is 0 437 004 002.
Bernt Damm: the injection is not into the manifold but into the head before the valve in this case. There is no doubt about that. The only direct injection system they ever made was on the 300SL gullwing and roadster. It was discontinued because of problems then. The timing of the injection pump does not appreciable affect the engine performance.
This isn't Joe, It's Pete Lesler, and I wish to clarify a misconception here. The injectors spray a fine atomized pattern just before the intake valve. I believe the injection timing is important, otherwise, why would a camshaft inside the pump push the fuel out through the injectors at a certain point in the cycle? I have heard of pumps being off a few degrees and the cars ran very poorly. You must follow procedure as outline in the large blue manual.
I'm with you....If the timing doesn't matter, and the gas just lies there to be sucked in then why not pour the gas directly into the manifold? If that's the case why use injectors? The gas fumes could be sucked out from over a pool of gas.... I'm carrying this to the extreme, and do not have the technical knowledge I need to argue this intelligently, but my gut feeling is that something is missing here....
Is it OK to use a fuel injector cleaner in a 230 SL? Does anyone have a recommendation as to which cleaner works best? The car is running fine; I'm thinking this may help prevent deposits from building up.
Tom Hanson: Techron works great in any engine. It's a Chevron product.
Rodd: I've heard it said many times that you should not use any fuel additives or cleaners in a Mercedes. Don't forget, our cars run fine on high octane unleadded fuel, so don't add lead either.
Pete Lesler: I still have my originals on my 1967 250SL. I believe they will last for many years, provided you ensure they get clean, filtered fuel, and never let the car sit for too long. I have never used any sort of fuel injection cleaner whatsoever. It may be urban legend, but Hans at H&R likes the earler cone-seat fuel injectors, Bosch Part Number DC8C45R1. They seem to keep their spay pattern longer than the replacement DC8C45R2, which are Ball Seat and are still available from MB. The earlier style was used on all 230SL and 250SL up to chassis number 001364 for Auto trans and 00772 for Manuall trans. Also used on 250SE up to 0020967 for std, and 017627 for Auto trans. How you test them: find someone with a Bosch diesel fuel injector spray pattern tester. This is a unit that is used to test the spray patterns of diesel injectors, but willl work fine with the gas mechnical injectors as well. Be there when he tests them to see for yourself how they look and sound. Once you see the pattern for yourself, you will know what is a good spay pattern and a bad one. They also emit a rather high pitch squeal when they are pressurized and spraying correctly. I have actually tested them myself by unscrewing them from each cylinder and turning the engine over, making certain you do not have any sparks near the spraying fuel, this takes a while and will run your battery down, but if they are not clogged you will observe a nice wide, highly atomized pattern. You will need someone to turn the ignition key on as you observe. Do one at a time as it may be difficult to start the engine after you complete your test if all are disconnected at once.
Maintenance
Describe common maintenance procedures, and common faults that may occur. Describe how these may be diagnosed and resolved. Again, include diagrams, photographs and explanations. Where possible, include measures, tolerances, weights etc.
- Symptoms when it faults
- How to test if it is faulty - what tools to use
- How to fix / change
