What makes a diesel motor 'peppy'?
 

At the given moment (soon to change) I have 2 300Ds, each having a different gear ratio but the difference is much more than that. My 83 had about a three second delay on taking off so I bypassed the overboost valve, it is down to about a half second. However it still doesn't have the low end pep that the 84 has, how could this be? What makes it peppy? The 84 is hard to hold back from squealing tires or throwing gravel, the 83 almost refuses to do either. Why? They both have about the same high end power, but the low ends are vastly different. The instant the accelerator is pushed on the 84 it is there, the 83 on the other hand if I hit it quick enough I can go to the floor before it really takes off. Why? What should I look for or do?

Thanks in advance,

I don't think it's related to the model year. Like your '84, my '82 will spin from a start and chirp on the 1-2 shift every time if you don't go easy. My guess is that we are lucky to have found a couple that have been well maintained and run like sewing machines; It truly is stealth power.

Don't know about the 300, but just changing little things like the linkage lengths made big differences on my 240d. As this is basically my first car ever (had the other one two weeks in '84) it's a little daunting the range of things that affect the performance, the timing chain, the IP calibration, fuel delivery, compression, air mix, and so on. Just glad I've got stick. But I think if you stick it out and do a systematic attack on it, taking notes and pics on everything you can eliminate all least the easy posibilities.



P.S. All hail the forum for making my biofueled return to driving do-able





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I'm wondering if maybe the IP's timing is a little bit slow? Odds are it is still the factory timing chain so it has probably stretched a little. Would this make the big difference? I just put a new spin on fuel filter, I'll be running some diesel purge later today hopefully.

The 84 will just roast them and slide the car sideways if I juice it in a turn. While I don't need this much bottom torque it is nice to have something there available. Truth of the matter is that I sold it yesterday and they are supposed to come pick it up today.

IP timing and valve timing will make a BIG difference in performance, so will boost pressure and ALDA setting.

Check the chain first, if stretched more than 8 degrees, replace. Set ALDA per the other posts on the forum (do a search), and I'd bet you will get similar performance if the turbo is in good shape.

Peter

In my experience messing with diesel pickups timing makes a huge difference in off-idle torque and throttle response. I like to set timing at the most advanced setting within the acceptable limits or sometimes a little more or even just setting by ear. Set the timing to factory spec. Scribe a reference line on the pump/motor union and advance 1/16" at a time and see what happens. Too much advance will cause a very harsh injector rattle. You will know it when you hear it, trust me, turn it back. The motor will sound very crisp and throttle response/ off idle torque will noticeably improve with just a little more advance. Try it, you'll like it! RT

The boost pressure seems to be about right, the ALDA cap doesn't appear to have been removed. I'm going to read up on checking chain stretch tonight and check it tomorrow. If it is say 7 degrees should I just readjust the IP timing to suit this? It sounds to me as if this may be the problem. Will the IP's timing adjust externally or will I have to remove it momentarily. I'm pretty well clueless on the timing factors at the given moment, time to get reading. :)

I don't know why you just quoted me DslBenz, perhaps you overlooked the fact that I also have a 1983 300D. That is why I want to know how to get low end power back for it, similiar to the way the 84 was.

Thanks for all the replies so far, I'll give an update tomorrow evening.

Which direction does moving the IP advance timing (Twards block or away)?

Toward engine advances.

Is IP timing similar to cam timing in 3* cam = 6.5* crank?

What makes a diesel peppy? The driver! In my salad days I learned that a 180D could really rock in dense urban traffic. Kinda levels the playing field when the speed limit is 30. Commune with your engine when you're driving alone. Or, do the short form- keep that baby in the sweet zone. Which, of course, will be sweeter if we adopt the tuning tips so graciously advanced above.

I know for a fact that SWMBOs 300D, Lilly, is running the cam right at 6deg retarded from what the factory spec is (dunno about the IP) and that thing will run circles around Marlene, whose cam timing is right on the money (I dunno about Marlene's IP timing either).

Correcting Marlene's cam events made all the difference in the world in her driveability and mileage but, she's no Lilly.

The next thing on Marlene is to adjust the IP timing. I gotta do something, the difference in these two cars is making me crazier than I already am!!!

So I've came to the conclusion that the chain stretch is only 4* (8-10* is replacement), so should I jut put it back together or get a 4* woodruff key? I'm thinking for the fuel mileage it'd be nice to just install the key. How hard was it to install the woodruff R Leo?

Remember if your off by 4 degrees-


You should set the IP timing and adjust the camshaft timing. For me(and maybe I'm strange), I can wrap a new chain in a car in much less time than setting the camshaft timing and IP. Heck I do spend an extra $40, but I've got a *new* chain which hopefully will not break anytime soon.



Michael