fuel injection pump seized up

[71Blue280SL]

Thanks for the link.  I agree it should not leak.

My understanding is the drain hole is inside the gasket area, and since the pictures shows it on the gear, it probably is.  Seems unlikely that it would get clogged up, but possible.

Any way to check that without pulling the pump?

Thanks.

[garymand]

True the gasket is outside, I was thinking of a gasket behind the flange with the 4 pan heads.  There should be no pressure inside if that hole is clear.

[jf308]

If the FI Injection pump is still installed on the car....how do you get solvent or access to manipulate the rack.

I have removed the 10MM bolt/cover....but can't see to spray solvent and not sure how to "manipulate" the rack.

Leaving PB Blaster sprayed into each nozzle on the FI pump, and tried to get solvent to the rack...but difficult.  Will try to spin this in the AM and see if any fuel comes thru.

John
64 230

[71Blue280SL]

I was not able to get my rack to move because all the injection pistons were stuck.  Once I got the pistons freed up, the rack started moving on its own.

To get the pistons moving I had to soak and manually tap them down after rotating the engine a few times.  Make sure you pull the fuel pump fuse.

C

[jf308]

I just removed my IP and have it on my workbench.

Removed the fittings on top and sprayed in solvent.  Can you "tap" the pistons down with the valve seals still in place?  I am not quite certain how to make the fitting to pull them, and would rather leave alone.

Comments please.

In the meantime, I am going to use air pressure to make sure all the fuel lines are clear.

[71Blue280SL]

I do not think you will be able to tap the pistons down with the check valves in place.

They are relatively easy to remove, however.  I used a quick-disconnect air nipple that had the female threaded end.  Screws right down on the check valve, then just pull it up with channel locks, pulling on the air nipple part.

[jf308]

Thanks.... any idea of the actual size of the female threaded part?  I don't think that I have anything handy.  Have to go to the hardware store.  I may drag the pump along with me.

[71Blue280SL]

Sorry, no idea on the actual size.  Seems like there was some discussion on the thread size earlier in this thread through.

[ja17]

Hello,
There is a lot of information on the procedure to free the pump. Do some searching first.  Read through this long thread. Also look up all the info you can find in the tech manual. Yes, the stuck pistons will jamb the rack. Free up the pistons and the rack will free up. just use a standard SAE brass fitting from your local hardware. You just need to grab a thread or two on the outside of the check valves to pull it out. The threads serve no other purpose.  Once the check valves are out, soak the pistons with penetrant and alcohol. Turn the pump to see what pistons do not move. Free them up by tapping them down with something not too hard, like a golf tee flattened at the pointed end.  Repeat until piston moves up and down n its own, as the pump is turned.  Try to keep the outer cylinder from moving upward, as it is keyed to go down in one position only.

[71Blue280SL]

JA17, as you were so knowledgeable through this IP thread, do you have any ideas why my IP is leaking around the inspection plate?  There is very little surface area on the sides of the plate, but I was very careful in setting the gasket and used good sealant.

It seems to me it has to be pressure related, particularly since it does not leak at idle, only above 1000rpm.  I was thinking it could be "blow-by" from one of the IP cylinders, but the engine runs great, the pump has less than 1k miles on since installation, and I do not smell any gas in the oil.

Any thoughts?

Thanks.

[ja17]

That's an unusual problem. I assume that the plate is nice and flat. Leakage should not occur even if you are leaking fuel past the pistons. The 280SL pumps should have a drain on the front of the pump allowing oil to drain back into the engine block by gravity not pressure. You might want to temporarily remove the baro compensator and check to see if the oil level is way up (above half) if so the pump drain hole is plugged or blocked. What is your pump "R" number?

[jf308]

Hello,
There is a lot of information on the procedure to free the pump. Do some searching first.  Read through this long thread. Also look up all the info you can find in the tech manual. Yes, the stuck pistons will jamb the rack. Free up the pistons and the rack will free up. just use a standard SAE brass fitting from your local hardware. You just need to grab a thread or two on the outside of the check valves to pull it out. The threads serve no other purpose.  Once the check valves are out, soak the pistons with penetrant and alcohol. Turn the pump to see what pistons do not move. Free them up by tapping them down with something not too hard, like a golf tee flattened at the pointed end.  Repeat until piston moves up and down n its own, as the pump is turned.  Try to keep the outer cylinder from moving upward, as it is keyed to go down in one position only.

SUCCESS ( I think).

FI Pump removed from the vehicle and followed the many "DIY how to's" on the forum.  THANKS ALL - especially JA17.

All pistons and rack now move.

Question:  I ALSO SEE THE ROTATIONAL MOVEMENT of the pistons within the cylinders when I manipulate the rack back and forth.  

ANYTHING ELSE TO CHECK BEFORE RE-INSTALLATION??  (THIS WILL BE THE SECOND INSTALLATION, SO I WANT TO BE 100% SURE THAT THE FI PUMP SHOULD BE OPERATIONAL).