Several questions about my 108

[deafen]

So here's the thread where I post all of the questions that came up over four days of sitting by myself. Again, the car is a 1972 280SEL 4.5.

1. Vibration. The car has a speed-related vibration that starts at about 70 mph. It comes and goes, cycling over 30-60 seconds, sometimes longer. It is dependent on the road surface (!) -- very little vibration on concrete, bad vibration over new tarmac. There seems to be a mode at about 80-82 mph where it is worst, although it continues to be present up over 100 mph. It is *not* related to tire wear/wheel balance, as the tires are brand new Bridgestones; nor is it flex disc, as that was replaced at the dealer (and yes, it vibrated before the replacement as well). The vibration is in the vertical plane, which says to me either driveline or major suspension. It seems to be telegraphed most strongly through the steering column, but that may just be because that's a nice long lever.

2. Steering. The car has almost no ability to self-center -- that is, it requires input to bring it back to straight after turning the wheel at highway speed. The tire folks said I needed new kingpins; that's possible, but I know that I probably also need new subframe bushings, and will be attempting that first. Is this non-centering behavior typical for this chassis?

3. Fuel injection hoses. One of the connections between the main fuel rail and the injector (passenger side, front cylinder) has a leak at the rail end when cold. The clamp is tightened to its limit. Therefore, I want to renew all of the FI hoses. Can I use regular FI hose from the local auto parts store, cut to length, or is there some magic about the MB FI hose?

4. Transmission leaks. There's a drip of ATF which appears to be coming from the torque converter; haven't had a chance to track it down specifically. However, the ATF level is well above the top mark (1.5 cm?) -- would this cause such a leak? Any easy way to remove some ATF without opening up the pan? How about transmission stop-leak -- anyone used that on these cars?

5. Steering column bushings. The PO disconnected the horn because the contact for the switch was being grounded by something in the steering column, causing the horn to sound continuously. He mentioned that there were some bushings that need to be replaced. The column shifter is also fairly loose. The service manual lists a whole disassembly process, but I can't easily see from the diagram what parts he meant. Anyone have any experience with taking the column apart?

I've got a ton more, but I figure I need to save some of the fun for later. Thanks for any help you can offer!

[300SDog]

Non-centering steering wheel can be overtightened gear box... the allen bolt with 19mm nut as collar. Clockwise will loosen it, try 1/8 turn intervals from paint marked original position.

I think subframe bushings will clear up road noise and alot of the vibration. Maybe tranny mounts too.

American auto parts nylon core rubber hoses are better than original fabric wrapped MB fuel lines. There's lots of them underneath the car too en route to fuel tank. Should improve mileage to eliminate leaky lines.

If it's like the 111 horn, pull the center pad off with your hands - but be careful to preserve ribbed plastic dowel/pins holding the pad in place. A brass circular track and spring loaded bushing will be seen. Used to be you just had to clean em up to make em work.

And you can drain tranny fluid by cracking open a tranny coolant line at the tranny casing. Working with radiator core cooling line attachment is dicey, you can destroy the fragile coupling. Is there a breather on top that might be pushing fluid?

[autozen]

Vibration: It could be coming from the transmission. It did happen in those days.

Fuel hoses: If you have any leaks in the engine compartment, replace every fuel hose in the engine compartment to save yourself an engine fire. This was very common on the 4.5s. Buy bulk 7.5 mm ID hose for the fuel lines and order the little kits for the injectors. You will need 4 kits. They are not very expensive and make the job easier. There are two possible kit styles. Some injector sets had barbs to just slide the hose on to, and some used hose clamps at the base. You need to use the proper kits for your car.

Peter

[autozen]

I just checked Fast Lane prices on those hoe kits. You're lookin at $80. That's rediculous. Lokkks like ypu're going to be choppin up bulk hose.


Peter

[deafen]

Okay, thanks for the advice. The FI hoses are on my short list, for sure.

[Tomguy]

Just buy FI fuel hose (MAKE SURE it says for fuel injection on it so it can handle the pressure!) and cut it to length. This is what I did. You'll then need an extra clamp per injector to hold it on the bottom. I don't care for how the original hose/design is sealed, and I think the kits come with 2 clamps per hose as well. Should be under $5 at an auto parts store for 2' of the hose and a box of clamps! Be careful not to crack the injectors when taking the old hose off.

I replaced every fuel line under my hood. Unfortunaley I had a fire under my hood but, luckily, not due to gas. My tranny coolant line burst open on the highway and caught on fire when I stopped, as tranny fluid had spewed all over my header pipes. Buy yourself 2 new tranny coolant hoses now if yours are the original braided lines. The newer style is rubber with a spring outside to protect the hose from being worn away by the sway bar.

[Tomguy]

It looks like it says 7.5mm on the hose on FastLane for the injector repair kits. I used 5/16" hose which is the equivalent of 8.0mm. That should work fine. The half a millimeter probably doesn't matter much at all. I know mine don't leak one bit!

[autozen]

Deafen,

Like I sayed there are two styles of injectors. It doesn't matter which style you have as long as they are BLUE. The yellow injectors are for the 3.5 liter engine. One style has barbs on the nipple. This style only requires a metal ring and a hose clamp at the top to connect to the fuel rail. The other style has no barbs and requires a hose clamp at the bottom as well as the top. You can use the old hose clamps if they are fuel hose clamps. Fuel hose clamps have rolled edges so they don't cut into the hose. Also don't tighten the clamps all the way. Leave 3 to 4 mm gap between the tangs.

Peter

[deafen]

Okay, I'm renewing my FI hoses now. Now that the injectors are out, I've noticed that a couple of the "protective sleeves" (the blue plastic dome that covers the injector tip) are cracked. I assume that these must be replaced.

Are these MB-specific, or can I pick them up from any import shop?

[psfred]

You will need to replace the front subframe bushings (a nice rainy saturday job, not really terribly diffucult but time consuming). It will drive MUCH better afterwards.

Your vibration is very likely drive train related, but I would guess tires in spite of them being new, simply because you report different vibration on different road surfaces. Note that stiff front suspension parts can do goofy things, as can a bad steering damper (replace that, too).

You defintely need to check the kingpins -- jack the front wheels off the ground and see how hard it is to turn the front wheels by hand at the tire. If it's not smooth and easy, knock the tie rods off and see which side is stiff. Check the tie rods while you are at it, likely you need tie rods, drag link, and damper.

Find all 14 grease fittings and give them a good three or four squirts of synthetic grease. Repeat at least every 3000 miles or three months. This may cure the stiff steering. Could also be the box, in which case the wheels will pivot easily with the tie rods off.

Peter

[wbain5280]

Don't forget the grease nipples on the driveshaft and the two on the swing axle joint of the rear suspension.

[deafen]

This morning I finished refreshing all the FI hoses and seals. Kinda a ***** to find all the right parts; I had to special-order the seals from an independent, since MB would only sell them as part of an injector repair kit at $35 apiece! The seals (116 078 04 73) were $1.70 ea. from a local independent. Yeah, I could have gotten them cheaper online, but it would have taken longer.

I did order the protective caps from MB, though. These are the bits listed in the Engine Workshop Manual as "protective sleeves", and now called "locking caps" by MB. Part 000 987 53 45. One thing to note for future reference is that the new caps are designed for the new-style injector tip (with the thin groove near the tip, rather than the wide one a little further down.) I had one of each to recap. It snapped right in on the new-style, but took some persuasion on the old-style, and bulged out slightly. Not a problem with brand new seals.

The new-style and old-style injectors have the same embossed part number, btw, so it's impossible to tell until the cap comes off which one you're looking at. (All of mine had dual barbs.)

Grand total of about $24 in parts (4 caps, 8 seals, 4' of FI hose, and a couple clamps), and about three hours of work over several days. I'm a careful guy, what can I say?

On to the chassis.

psfred, you say "three or four squirts" -- are there any seals I need to worry about blowing when I do this? I accidentally blew a couple grease seals on my Jeep early on, and it's been a real hassle since then, having to lube up about every 1500 miles. Don't want that to happen! On the VW, the MO is "keep pumping until you see new grease oozing out" -- is that more like it?

[psfred]

Just like the VW, these are grease retainers, not seals in the strict sense. They allow dirt at water to migrate in, and you really need to push the old grease out as a result. I've never seen any grease come out anywhere on the steering knuckle fitting, but all the rest have blown out some grease.

Peter

[deafen]

To follow up, greasing the heck out of the front end does seem to have loosened up the steering a bit. It still doesn't self-center perfectly, but it's certainly not as bad as it was.

I was going to try stopleak for my tranny leak, but the PS pump is leaking way more ATF than the tranny (although both are leaking!) Guess I'll do both -- reseal the PS pump and try some stopleak in the tranny. I can't park in the driveway right now; it's brick, and my wife gets very mad when my cars drip stuff.