Now I have the wagon for a few days and I have more observations to share and, of course, more questions to ask.

1. EGR and Air Recirculation.
This is purely on observation and I have so scientific way to back it up. After plugging these two things, the car seemed to be peppier. It almost drove like a gas car. So I measured 0 - 60 again and it was 12.1 seconds. 12.1 seconds was slower than the test I did yesterday (11.9 seconds) with them unplugged, but well with measuring uncertainty. However, it is a rainy day here in today so that might contribute to the time. Then, peppier does not necessarily mean faster 0 - 60 time. It is just more responsive. I drove about 150 miles today and my gut feeling is that with them plugged will result in a little worse diesel fuel mileage. I need more time to back this up. Anyway have any observations or comments?

2. Hydraulic fluid
Ordered 4 liters of the MB self leveling hydraulic fluid and a new filter. Will take the easy way to change the fluid and filter. The capacity of the system is 2 liters and there is 1 liter in the reservoir. So I will take out the 1 liter in the reservoir and pout in 1 liter of new fluid. Do this 4 times (after engine on, of course) will get me a system with 6.25% old fluid (50%, 25%, 12.5%, 6.25%).

3. Operating Temperature
The operating temperature is 87 deg C. I am certain of that as the 124 and 210 gas cars I have are all at that mark and they use 87 deg C thermostat. Looking at the spec sheet of the 6-03 engine, it calls for a 80 deg C thermostat. Could it be that the previous owner has a 87 deg C stat put in? What are your operating temps on the 603 engine?

4. Oil filter
The 60x oil filter housing has a center bolt. Do I remove that first, then the two other nuts for the cover or the other way around?

5. Main fuel filter
I compared mine with Diesel Don's 123 car. There are some rigid tubing around the main fuel filter on my 603 engine. Do you have to remove anything before you can remove this filter? It looks like it can be done but space is certainly tight without spilling diesel.

Thanks again. The more I drive this thing, the more I like it. My 1997 E320 is getting to be a garage queen now.

3) I'm running pretty close to 80 as indicated on the dash gauge on my '87 300D.

4) Don't turn the center bolt. In fact, it wouldn't turn for me and I rounded off the bolthead a bit. I just removed the two outer bolts. Further, to be able to pull up the cover (which has a center shaft attached to it) I had to remove both rubber gaskets behind it and a portion of the plastic barrier held by four little clips. Maybe you don't have to do this if you can loosen the center bolt - but for my part I'll always remove the plastic barrier piece. It gave me a chance to clear out all the old collected leaves.

Good confirmation, Ken300D. I think I might have a stat that is a little high.

I'll let you know if I can remove the center bolt when I changed the oil in a week or two. It does look a bit hard to remove.

Answers in turn:

1) Mine's much nicer with the air recirculating valve disconnected. During normal cruise it would just turn off all the boost. Driving along a surface street at 40MPH the engine would lose power and you'd have to toe into the throttle to maintain speed. Then it would come surging back 10 or 15 seconds later. Disconnecting the valve cured these annoying habits.

2)Here's another tip. There's fluid under pressure inside the accumulators and lines from the control valve. If you want to be moderately obsessive and flush this, do the following. Crawl under rear of car. Locate level control valve - it's silver, on passengers side near rear wheel, connected to sway bar via adjustable link. Disconnect adjustable link from arm on control valve - single 10mm nut. You can now pump fluid into and out of rear suspension at will. Start engine and move level control arm up - rear of car will begin raising. After about 2 minutes and 3" of elevation gain, valve will begin buzzing as overpressure relief triggers. Then move lever below horizontal - car will begin coming down. Congratulations - you've just flushed out the accumulators.

3) I've got an 87 thermostat. Don't see that it makes much difference between the two. No overheating problems, and I live in Texas.

4) I always remove the center bolt. You can't get the cap out from under the cowl lip without removing the center bolt (or, apparently, disassembling the cowl.) It's there to facilitate changing the filter.

5) Memory's a bit fuzzy here, but I couldn't change the fuel filter without loosening the mounting bracket - I think. I know some disassembly was required to change the fuel filter, but can't recall exactly what. Biggest problem was the injector return lines - these get real brittle with age, and mine just cracked in two. Had to replace it before I could restart the car. It should be quite soft and flexible - if not, add this to your list of little repairs.

jcyuhn:

Thanks for the answers.

1) I will leave them plugged to see the long term effects.

2) In the 124 Chassis manual I have, it talks about draining 0.5 liter of fluid from the control valve. It says there is a drain plug. I have not crawl under the car yet. Probably will take a look this weekend.

3) Then I will just leave the stat in for now.

4) So if I can remove the center bolt, I do not need to remove the cowl for filter change? A while ago, I remembered reading the washers on the center bolt are very important for idle noise.

5) The reason I asked this is because Diesel Don (123) did not have to a thing to remove the main fuel filter. I can see how easy it is on his. Just one bolt on the top. The surrounding is clear.

1) Disconnect the line will get your turbocharger kick in early (as those early 300Ds do). The 300D sedan takes about 10 second from 0-60. I think the 300TD should get the same performance.

3) The thermostat is 80 degree (to start open). Your gauge should read about 85 with the 80 degree thermostat installed.

4) It is the defective rubber o-rings at the end of the center bolt causing the engine tapping noise, not the copper washer. The defective o-rings drain oil from the oil filter housing back to the oil pan after engine stops. When the engine is restarted, the oil pump has to fill up the oil housing first before any oil going to the lifters. The lifters make noise until they got the oil.

5) To change the big fuel filter for the 603 engine, you do have to loose the vacuum hose bracket and push the radiator hose a little to got the filter out.

David

Thank you, David, for your reply.

I got the "official number" about the 0 - 62.4 mph number for the 1987 300TD, it is 11.9 seconds. So mine is good at 12 from 0 - 60

Bo:

I didn't remove the center bolt -- you just have to wriggle the cover around a bit. The 300SDL doesn't have a center bolt.

Unplug the air bypass -- it is there mostly to keep the trap oxidizer hot, and you don't have one anymore, I hope. Makes the bloody thing fall flat on it's face all the time if it is connected, and made mine surge terribly on the highway with the cruise control on.

EGR can cause oil to coke in the intake, which resticts flow and can chip off and allow hard carbon chunks to get sucked into the engine -- this bends rods. I disconnected mine, and will be checking the intake soon (I think I need a new head gasket).

The 87 300D is really a blast to drive -- should get pretty good milage, too -- mine does about 36 on the highway!

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!

Bo,

What kind of mileage you are getting? Peter's 300D gots 36 mpg. That is very very good. I can only get 28 to 29 mpg.

The official number of 11.9 second is with the Trap and the air bypass. Without the Trap and with an unplugged air bypass, I expect a 87 300D to be around 10 second from 0 to 60.

Keep in mind that the air bypass is part of the smog control system. It has been installed on 300D California model since 1984 to reduce smog emissnion (by delaying the turbo kickin). I still have my air bypass connected.

David

I do not know that exact fuel mileage as the odometer is not rolling now. But I have to say it is very high. I am used to my gas 300E and it gets 25 mpg on the highway. This 300TDT is much better than that.

I filled up the tank on Saturday near the house of the previous owner, and drove 40 miles to my hotel in Oak Brook IL. On the same day, I drove to China town round trip and that was about 80 miles by taking a long route as I needed to visit a certain place. Then the next day, I took it home to Michigan and that was a 260 mile trip. I drove around town on Sunday and Monday and probably put on another 30 miles. On Tuesday, I took my daughter to her orthodontist's office, 50 miles away, and the fuel warning light came on (I also met Diesel Don on that day). All these are good estimates.

When I left my hotel in IL, the fuel gauge was right at the 3/4 mark. After about 260 miles to home, it was just below the 1/4 mark. So I think a full tank can go over 500 miles on highway. The speed was generally 7 over the limit, which is 65 in IN and 70 in MI.

The wagon is heavier than the sedan and is less aerodynamically clean. So it'll deliver lower MPG both in town and on the highway. I usually see about 24MPG in suburban commuting use and about 29MPG on the highway (hwy =80+ MPH in Texas). I suppose 30MPG or better is possible, but I don't have the patience to drive that slow.

Your milage will go up if you slow down! Drag becomes significant as you approach 90 mph, I think, at least considerably more significant than at 65. Frontal area is all that counts at lower speeds.

Patience, they say, is a virtue -- but I'd imagine that things are a bit father apart in Texas than they are here! Hopefully you also share the road with better drivers, too!

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!

Hey, Huys:

I have never noticed such a difference with a fuel additive!

Yesterday, I filled the tank with Amaco No. 2 diesel. After about 20 miles of highway driving, the idle was rough in city driving. I quickly stopped at a gas station and got some Power Service Diesel Fuel Supplement (32 oz bottle). I dumped 8 oz into the already filled tank and I felt the difference about 5 minutes after that. The idle was much smoother. I think it is due to the cetane boost in this case. Any comments?

BTW, my idle is rather low (to me). It is arounf 550 rpm. Can this be adjusted to a slightly higher idel?

Re: air resistance and speed. The air resistance is equal to the square of the speed. In another word, if you doubled the speed, the air reistance is 4 times as much. But air resistance is only part of the total resistance a car faces.

Bo:

Increasing the cetane index is what fuel additives is all about! Usually results in better ignition, hence less shake at idle, etc.

I cannot use the local Phillips 66 -- terrible starting, bad milage, lots of smoke. The local Amoco is fine.

If you can find it, Shell diesel also seems very good, at least localy. Less smoke, at least, and maybe better running.

You will have to shop around and find a source that your 300 likes. MB diesels are a little fussy about fuel.

550 rpm is about right -- just a little above 500 on the dial. Electronic idle speed control, I don't know if it can be adjusted, probably not.

Air resistance is indeed related to the square of the speed, but I believe that is strictly frontal area (the total cross section of the car), not including aerodynamic drag -- drag isn't really large enough to make a big difference at normal highways speeds, which is why I've always gotten a kick out of the low drag coefficient cars claims -- doesn't make a bit of difference at legal speeds!

Speaking of low drag coefficients, guess what production car still has the lowest one?

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!

There are four stations selling diesel in my area:

Amoco, Mobile, BP, and Meijer. Thre is a Shell but it does not have diesel. I will sample each and find the one works. Or I just keep using the Power Service stiff. Actually I found one that boosts the cetane even more. It is called Kleen and it can raise up to 6.

Drag coefficients: At one time, I thought the Mazda Rx-7 had a real low number.