617 IP Issue?
 

I think my 300D IP is acting up. I have a significant loss of power, similar to a very clogged fuel filter. Adjusting the ALDA had no affect, I can't make it smoke at all. I've checked the linkage and the IP is getting full travel. If I move the linkage by hand, in park, the engine doesn't respond untill about half throttle. On the highway, it's topping out at about 70 with the throttle on the floor. Otherwise, it's running and idling perfectly. Strange.

I'm driving it home from TX for the weekend, but I will be traveling next week too. No time to play with it, so I think I'll drop it off at the shop and let them take a look. I think I will just have them toss in a rebuilt IP and see what happens.

You've checked the boost signal line from the manifold to the ALDA through the switchover valve? How about removing the ALDA?

Does similar to a very clogged filter mean you've replaced the filters?

Sixto
87 300D

I did try replacing the filters with no affect. I did check the banjos. I would rather swap out the IP/ALDA than run without a ALDA. Maybe it's just the ALDA?

Run without the ALDA as a diagnostic step.

Configure a MityVac to blow pressure and check that the ALDA holds some pressure. I don't know if it should be pressure tight but it shouldn't leak so much that you can't build pressure. Don't pull a vacuum on the ALDA!

Sixto
87 300D

I'll give that a try, I suspect it is the ALDA leaking. If so, I'll probably just replace the ALDA.

Try a pressure gauge right at the ALDA fitting so you know it's not a boost leak.

Sixto
87 300D

In park the ALDA does not do anything, it should rev up right away even with slight throttle. I suspect an internal IP issue.

I'll try the ALDA troubleshooting first, then try swapping the IP.

The amount that the alda adjusts the IP is very little. I ran without one as a test, and all it did was slightly improve off the line acceleration, but with a lot more smoke.

Did you check/clean the tank strainer?

I think the bottle of diesel trick is in order, bypass all the filters and run off the bottle. And also check for play in the throttle linkages.

Check the timing chain stretch.

Pretty much seals the deal. No external devices or adjustments...........ALDA, timing, fuel filters.........etc............will cause that symptom to occur. Something is amiss internally on the linkages to the rack. Could be as simple as a broken spring.

Yup, it seems that way to me. I've adjusted everything enough to make it feel normal at low speed (if I use twice as much peddle), but it still runs out of power at about 70 mph and I cannot do anything to get any visible smoke. I don't think it's the tank strainer because fuel leaked out at a normal rate when I removed the pre-filter. I'm also betting that something inside the IP has changed.

I don't trust it, so I'm going to use another car and leave it at the shop next week so they can get into it. I assume they will just put in a rebuilt IP. I don't know the history of this one, it came with my used engine about 100k miles ago and has be perfect up to now.

The accelerator linkage pivot mount is on the firewall on the driver's side. Mine was broken and causing a power loss on my 82' 300TD. Turns out since it was broken and falling out of its mount, it drastically affected the moving of the other linkages=no full throttle was possible. Worth a look...

https://www.**********.com/search/product.aspx?sid=e3s2rjv0qs3mskek4cemfe55&makeid=800016@Mercedes&modelid=1194319@300TDT&year=1982&ci d=22@Fuel%20%26%20Air%20System&gid=5893@Accelerator%20Cable%20Part