Fuel In Air Filter / Throttle Body

[Kevkeller]

I was referring to the pistons in the FIP varnishing up and seizing not the engine pistons.

I didn’t notice you had a 230sl. I was thinking the later check valves that are a combined assembly.

Nice pictures of the check valve parts.

[RonnieStiggs]

I was referring to the pistons in the FIP varnishing up and seizing not the engine pistons.

No worries, I understood you, I meant to say the engine was firing on most to all cylinders before because fuel was still getting to all pistons on the engine due to the CSV being stuck wide open, it only ran for a few seconds after I repaired the CSV, so residual fuel may still have been in the intake manifold, and the FIP pistons may have been inoperable this whole time.

Nice pictures of the check valve parts.

Thanks, I'm doing this for the first time, and only have a base understanding of the FIP's operation, so I figure more pictures more better, if I screw up, at least I know where I went wrong!

If you remove your check valve you will see the cylinder and a small plunger (piston) in the middle if you crank the engine the plunger/piston should move up and down

This is where I'm stuck, clearly in https://i.imgur.com/ftVuikm.jpg I have the valve pin removed but the rest of the valve still needs to come out, on a few other posts I've read about some successful tools people have created to perform this task mainly from these 2 posts https://www.sl113.org/forums/index.php?topic=15754.0 and https://www.sl113.org/forums/index.php?topic=27193.msg195202;topicseen#msg195202 as well as another that has had its pictures removed. I've been through 2 hardware stores and an auto parts store and nobody caries anything in m12x1.0 I've looked online but have found little to nothing that I believe will work in this application even after some machining.

From what I understand from this picture of the valve removed https://www.sl113.org/forums/index.php?action=dlattach;topic=27193.0;attach=63769;image;ts=1543147865 its currently held in place by friction and threading something on to the end of it helps us gain purchase on it to remove it without marring the valve. Doe any of ya'll know if a tool ever sold to perform this task? If so does anyone have a part number or name of said tool?

[Kevkeller]

If it’s the same tool as the later model I can lend you the one I made. I’m returning from a trip tonight and can mail it tomorrow.

[RonnieStiggs]

I come bearing good news and potentially bad news from the land of the 230sl Fuel Injection Pump.

Firstly, Kev, thanks for the offer, you are a true hero, but it appears that I'm able to get at the FIP pistons without removing the check valve fitting for my particular 230sl IP.

For comparison I removed the coupler, spring, and check valve stem from a neighboring IP piston that I knew was operational, removed the fuel pump fuse and observed the difference in piston motion. Cylinder one was not moving, cylinder two is pumping as I would expect.

I've been applying a regiment of carb cleaner and seafoam to the stuck IP piston for the last few days, and my brass punches came in today, so I gave it a few taps before some more cleaner, no movement. As a test I ran it with everything up to the couplers re-assembled, and re-inserted the fuel pump fuse. No change still.

Since most of what I'm doing is guesswork based on diagrams and how I assume the IP operates, I took a short video of the IP cylinders (https://www.youtube.com/watch?v=i0sW5m3ZdY0 as they currently stand, the far right one is one of the stuck cylinders, the next 2 are moving as I assume they should, and the 3 not shown are all stuck as well, though I haven't attempted to move those just yet (I wanted to get 1 working then do the same fix to the other 3).

My questions are:

1) How much force can I apply, with a brass punch, to the pistons before I damage something. I have mostly been tapping lightly with it, rapped the punch lightly with a small hammer once, but I've done nothing with appreciable force as I don't want to bend or mar anything, though from this angle I'm not sure how likely that is.

2) Other than the pistons being stuck in their positions (1,4, 5, 6) due to not having fuel ran through them for a long period of time, is there something else that could be wrong here? The two that are operational are closest to the banjo fitting for the IP oil inlet, but I don't know if this is significant. If its anything else I figure the issue would be more catastrophic and something else would be a miss.

[ja17]

There is a camshaft below the pistons which move the pistons upward. You may have to turn the engine a bit so that the camshaft lobe is no longer in contact with the stuck piston. After rotating the engine a bit, try tapping again with your brass punch.

[RonnieStiggs]

There is a camshaft below the pistons which move the pistons upward. You may have to turn the engine a bit so that the camshaft lobe is no longer in contact with the stuck piston. After rotating the engine a bit, try tapping again with your brass punch.

I cranked the engine a bit, periodically, between taps, but didn't see/feel any change when tapping with the punch. I did this via the starter, not manually, if that matters at all. I may be being too light with my taps, the time I used a hammer I didn't go much harder than I've been going with the punch alone.

[Kevkeller]

You don’t see rust do you?  I would think it would take quite a bit of force to do damage, more than needed to move it.

[RonnieStiggs]

You don’t see rust do you?  I would think it would take quite a bit of force to do damage, more than needed to move it.

Negative, pistons are a bit gasoline colored, thought they were brass the first time I saw them (including the moving ones) but the one I've treated with carb cleaner and seafoam is bright and shiny silver. I couldn't find signs of rust on the check valve cones or check valve springs either, just a slight amount darkish patina that cleaned right off.

I've been quite ginger with the brass punch as I've been afraid of causing damage, which may be why I'm getting nowhere.

[ja17]

Sounds like you may need to use a little more force.

[RonnieStiggs]

Sounds like you may need to use a little more force.

You are absolutely correct, and once I gave it a bit more guff the pistons moved, and I could tell by the sound of the punch when they hit the cam. After about an hour of; Punch Down > Cleaner > Crank > Repeat all IP Pistons moved freely when cranking the engine over. I crossed my fingers turned the engine over and after a few cranks, she ran and by my ear, on all cylinders. (200% improvement on the 2 before!) I've taken the car around my cul-de-sac and started it back up a few times. All seems well! Thanks to everyone in this thread for all of your guidance! I could not have gotten this far without your help!

Gratitude picture for payment

[ja17]

Happy Motoring!