Oil leak from rear of Injection Pump

[Kopie]

I have noticed a fairly steady drip from the lowermost allen head screw on the rear plate of my injection pump.  Tried tightening the screw, but no help there.  Does anyone have success with this?  From what I could find on other posts, this is a large o-ring seal.  It looks like the pump probably needs to come out to replace this.  Am i correct here?  Also, the leak only occurs when the engine is run and drips for little while after turning it off, but it quickly leaves quite a puddle on the floor.   I should also add that this looks like a fairly recent pump.  All of the chromate pieces are nice and shiny, and I might add exceptional compared to other components.  I've started this project with the areas that I know and love, ie. paint and interior, veneering and refinishing the wood solving minor wiring problems and such.  I'm learning and absorbing much from the collective experience here and I should add that my past experience revolves mostly around British sports cars which are very simplistic by comparison.  I can't wait to get out and actually drive.  It cranks and runs fairly well, but other problems exist.  I went through the linkage tour and I have everything adjusted so that the venturi is closed and slightly sticking, the injection pump linkage rod is measuring 220mm which is short assuming I'm doing this correctly.  Insert dowel in guide hole...make sure linkage crossover is resting against the dowel.  My fear is that someone else has done some ill-advised adjusting along the way.  I think I'm still running rich, having adjusted out the idle screw (with engine off) until it starts to feel loose and fearing to go further, it stills wants to idle around 1400.  Although I can hear hissing from the idle air screw when I turn it, doing so in either direction does not change the idle level.  I know this is a lot of info and asking, but I really am hoping for some guidance from those more experienced.  Thank you, Jim.

[wwheeler]

There are a few places the oil can be leaking from that I know of and have seen. The gaskets on the one (two) solenoids can leak although if the screws are snug, it is usually just a weep. I just replaced a solenoid that was leaking from the black plastic cap on the end of the solenoid. The idle mixture screw has an oring on it that can leak (mine did) and of course the back panel as you have suggested. Another place for leakage is on the lever shaft that is connected to the linkage. There are others, but these are the only ones I know about. All of these can leak and drain down toward the bottom of the pump.

[ctaylor738]

Extra air will make the engine idle fast and you need to find out where.  Changing the idle mixture on the pump won't have much effect, it changes the amount of fuel, not air. 

Try the Arthur Dalton trick - remove the big tube from the air cleaner and and put a sheet of paper over the throttle body inlet.  There should be no suction against it.  Then unscrew the little air cleaner from the warm-runiing device, put your finger over the hole, and make sure there's no suction (with the engine warm).

Spray some brake "klleen" around the intake manifold, especially where it joins the head, and see if you can hear the idle change.  If it does, then you have a vacuum leak (unlikely but possible).

Are you sure you're cranking down the idle air screw far enough?

[Kopie]

Thanks for the replies.  I used an inspection mirror and flashlight to observe the oil and definitely originates at the bottom of the cover.  I have felt around as well and no oil until I feel the bottom of the cover.  I'll try the idle tips first thing in the morning and report back.  I don't know why I thought I could reduce the fuel mixture, well actually I leaned it around ten or so clicks and the rpms dropped from around 1800 to 1400.  I'm glad to know that air is a possibility, as I tested the CSV and it's not leaking.  I did put my hand over the intake to see if the rpms would drop, but that sure wouldn't tell me if it was leaking slightly which I suppose is all it would take.  I'll report back tomorrow.

[Kopie]

Well, I went back today and tried the paper over the intake and there wasn't a leak there.  As far as the WRD, It sucks big time (no pun intended) when it's cold, and as it warms up it gradually subsides, but not entirely.  Even at fully warm, there is a slight suction, however covering it at this point does not change idle speed.  Does this mean something internal to the valve is leaking or that the thermostat doesn't move down far enough, ie. too many shims?  I haven't had a chance to pick up some brake Kleen, but I'll do that tomorrow.  I guess as far as the injection pump leak, I'll wait to pull it until I have the other problems sorted.  On a positive note, I managed to install the windshield with it's new gasket.  I could have used three hands for the job, but at least its done.  Any other suggestions would be most welcome.

[wwheeler]

I think most WRDs leak air just a little even when shut off. If it doesn't change the idle speed, then it shouldn't be significant. The leakage comes from the clearance between the piston and the cylinder bore. The more wear, the more leakage.   

[ctaylor738]

Did you really screw the idle air adjustment down close to all the way with no effect on idle speed?

What happens if you clamp the hose from the air cleaner to the adjuster?

[Kopie]

I really did screw it down completely.  I can also hear the hissing stop, but I haven't tried clamping the supply hose.  I'll give that a shot.  Also picked up some brakekleen today so I'll test that too.  I thought I would also disconnect the vacuum to the transmission and plug that hole as well just to rule it out. I read somewhere that having the fuel leaned out too much can raise it too although I don't know if that's true, but I am going to change it back to a richer setting.  I'll post updates as soon as I can get out to have another go.  I really appreciate all comments and suggestions.

[Kopie]

Chuck, I think maybe you have me on the right track.  I blocked supply of the air to the hose going to the idle air screw and the engine promptly stalled.  I can start the engine and partially block the air supply with my finger inside the air intake and the idle will quite down as much as i need it to.  I guess I'll be removing the idle air valve to investigate further.  Would I be wrong in assuming that screwing down that valve completely should almost shut off the air supply?

[ctaylor738]

Yes.  If you don't have air leaks elsewhere in the intake system, you should be able to kill the engine by screwing down on the valve.  Sounds like you should pull the valve out and have a look at it and the seat inside. 

[Kopie]

I picked up another idle air valve after determining that there was some rust on the inside of the pipe and the idle quiets down nicely now to 700rpm.  Thanks very much for the assistance in solving my problem.  I must say that neither valve has a seat of any kind and both will allow air to pass thru even when the screw is all the way down. I guess it's just enough to block some air from passing.  Nevertheless, I can't thank you enough.

[glenn]

The idle air screw is not meant to 'control' rpm.  The FI pump should be pumping 800 rpm(880/6 to each injector) worth of fuel at idle, NOT 801 or more worth of fuel.  If it is pumping more than 800 rpm worth of fuel and you are using the idle air screw to lower rpm, you are running too rich.  You want to adjust the idle air screw to get maximum rpm.  If it is above 800 rpm, you've got too much fuel from somewhere( that's the rub!, the CSV, your neighbors hair spray, Gulf coast spill, )

Remember, 800 rpm worth of fuel, 800 rpm worth of air.  Then cut air back to 750 rpm worth of air to get 50 rpm rich-
per the BBB. ..

That's how it left the factory.  WRD(closed) at engine temp, altitude compensation set for Stuttgart, linkage rod clamped to FI pump output shaft at 800 rpm, solenoid(s) on the back of pump adjusted.

Now the FI pump and the butterfly are ready to be opened in syn by the linkage from the throttle pedal giving the appropriate fuel rpm and air rpm from idle to max.  It's a flyweight control system.

Makes for easier starting, too.

[ctaylor738]

Glad you were able to sort it out.

My experience has been that if you start with a properly adjusted idle mix and speed (4% CO at 800 rpm), you can easily take the idle speed down to 500 or up to 1100 with the air screw.   Air is by far the bigger influence on idle speed.

You can add or take away fuel at idle with the adjustment on the pump and the idle speed won't change until you really lean it out or richen it up.

[glenn]

The Bosch FI pumps are basically metering pumps.  The 220SE pumps were 2 piston models, each piston supplying 3 injectors.  Each piston pumped about 1/2 cup(4 oz.) per minute at full load down to 0.05 cup per minute at idle(rough numbers).  The six pistons pumps made it about 1/6 cup per minute for each piston at load.  The 280 pumped a little more than 250 which pumped a little more than the 230.

When the pump left the factory it was calibrated to deliver equal amounts from each piston.  The proper air flow for combustion wasn't Bosch's bailiwick.  The knob on the FI pump(low speed fly weights) facilitated matching the fuel necessary to run each different engine at idle.  The idle air screw provided the air.  The butterfly/venturi air flow was empirically matched to the pump's flow characteristics.  The helix fuel cut on the pistons matched the air flow characteristics of the butterfly venturi combination for proper combustion.  The air flow and fuel flow are in syn up the load range.