Hello

Few questions..

1. Since I bought the car, on the highway every couple minutes it will surge to a nice increase in power, and stay that way until I hit a bump or an unknown reason. Sometimes it surges when I hit a bump also. Has nothing to do with cruise control and I cleaned out my banjo fitting and hose.. Can't figure this out. The car comes to life when this happens on the highway and I love it. (may be able to break that 107mph barrier).

2. The belly pans.. I took them off cause its a real PITA to keep taking the front one on and off every time you change your oil.. and for me that can be as often as every 2 weeks (every 3K). Any harm in leaving these off? Is this just to stop road debris or does it effect cooling or noise or what?

3. Changed my oil today and looked on my oil filter holder.. There are two rings on it that look like rubber o-rings are supposed to go there but there are none there.. could this fix my lifer noise?

4. My exhaust is rusty and becoming loud.. what do you suggest as a replacement? I was looking at timevalve (www.timevalve.com)

Thats all for now!

John

John:

o-rings on the filter shaft will fix the lifter noise.

I know what you are talking about with the "power surge" -- my 87 300DT will run away when you just tip into the throttle. Surges with the cruise control, too, but that may be the amplifier.

There is a bypass on the turbo that recycles air, supposedly to eliminate turbo lag. Maybe to reduce emissions, too, who knows. At any rate, it is a vacuum servo, electrically controlled, and I think mine isn't funtioning correctly -- huge blast of power on takeoff, but falls on its face if you let up on the throttle. Leaps forward with great power when you tip into the throttle on the highway, which is fun, but can be a pain in the butt when there is a car just in front!

Both the bypass servo supply line and the EGR supply line on mine leak vacuum. I don't know if they are supposed to -- I know they vent to atmosphere, but I'd have thought they wouldn't lose vacuum as fast as they do. I'm going to check tomorrow.

My point is that if the bypass servo or actuating system isn't working properly, you could get all or nothing turbo action -- more throttle movement than you actually need/want, telling the governor you want to go faster than you really do, then getting a blast of turbo power and overshooting the speed you want. I may disconnect the bypass servo vaccuum line and see what happens.

Great power though -- I love that surge of push at stoplights!

You might want to get a pump and suck the oil out rather than drain it -- I've heard that MB does this. That way you won't have to take the pan off. They do help with airflow and noise, and keep water off the alternator, etc.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I found my '87 300TDT almost undrivable with the bypass valve hooked up. Power would surge up and down randomly. I think it's the EDS messing around with the boost in an attempt to warm the trap oxidiser - which none of us still have. There's one sentence in the shop manual which gave me this impression, but no detailed explanation.

Try disconnecting the bypass valve and see how it drives. You can't hurt the engine - the overboost protection is still in place. If it's better, just leave it that way.

On my car, both the EGR and bypass control valves leak vacuum like crazy. To the point that the transmission doesn't shift correctly. Dunno if they're supposed to leak so rapidly, of if 15 years have taken their toll.

The belly pans are there to keep oil off your garage floor as much as anything. The one significant thing they accomplish is keeping water off the serpentine belt during a rainstorm. Enough water can cause the belt to slip on the a/c compressor and trigger the cutout circuit - you'll lose a/c until the car is restarted.

I recommend acquiring a topsider, especially if you change oil that often. Despite the protestations of one who may or may not be named Larry, I tested the topside vs. bottomside method to see which removed the greater volume of oil. The topsider won by a handy margin. It's also a helluva lot easier on my no-longer-young back and knees.

What do you do that requires 1.5K miles/week? That is a _lot_ of windshield time! I can squeeze two months out of that distance.

1- Cruise control surging: There is a recall (retrofit?) for the vacuum system that may fix this. But first make sure your throttle linkages are properly lubed, this can cause surging as well. In the W124 service manual there is a section on the vacuum retrofit, with an extra (third) switchover valve added, a restriction, and a filter. One of my 87's has this, the other doesn't. Neither surges. It's not the cruise amp - if the amp is bad, it simply won't operate, or won't stay engaged.


2- Sound encapsulation panels: They are there for a reason. They make the car quieter both at idle and on the road. They also do help keep small oil drips off your garage floor, as well as the roads (motorcyclists do NOT appreciate cars that have oil leaks.) If you really can't deal with removing 4 screws every 5kmi to change your oil, you should just buy a Topsider and then you never need to remove it. The other comments about water splashing, engine compartment airflow, etc are also good points. If you insist on removing it, save it... they are a couple hundred dollars to replace.

3- EGR and Air Recirc valve: If these aren't diconnected yet, disconnect them. If you don't have smog inspections you can remove all the plumbing and plug the vacuum source(s) at the 5-way tee above the pump. Otherwise you'll need to insert a "bb" into the line, which effectively disables the valves, but they appear normal to a visual inspection. If you have a tailpipe test (I don't know of any states that do this for diesel, yet) you may need to reconnect them if you don't pass - but I doubt they would be needed to pass any opacity test if you engine is in good shape!


Best regards,

Dave M.
1987 300D - 228kmi
1987 300D - 233kmi