Belinda's Midterm Report Card - PeachParts Mercedes-Benz Forum

jassz · #1 07-10-2003, 12:33 AM

Four weeks from today till we leave for our mountain vacation, and things are progressing! Here’s what we’ve done so far, starting with the easiest first ….

The service manual talked about a gasket needed for replacing the water pump (more on that later). I made a trip to the dealership to pick one up, and while I was there I was chatting him up about the temp sensor in the rec/drier. It turns out there are two types, one with the sensor on top and one with it on the side. When it's on the top you do not need to drain the
refrigerant, but when it's on the side you do. So it looks like my mechanic and leathermang were both right. :p Ours, unfortunately, is on the side so we would have to drain it. Later, I picked my hubby up from work and was relaying all this information to him, discussing the options etc. He then
dropped me off at Safeway, and as I was walking through the parking lot he nearly ran me over in his enthusiasm to catch up to me and tell me the aux. fan WAS working (he
heard it for the first time when he was walking over to the driver's side). It just started working on it's own and has been working ever since (but is only activated by the AC). I call this method of repair, "Car, heal thyself". :p Unfortunately I have no photos to go with. :p

BTW, I wanted to ask about this suggestion to leave the car idling to save the turbo. Is the car idling, or just the key turned so the aux fan is running? How is idling cooling it off when it tends to get even hotter idling?

Next, I attempted to get the cigarette lighter to work. Not that I plan to take up smoking, but I figured it might be nice to be able to plug the cellphone in and call for help when the transmission gives out half way up a summit. :p The fuse box terminals were looking a little corroded so I cleaned them with sandpaper and also replaced a number of the fuses. What I discovered in doing this was that the pattern of the fuses in no way resembled the
'map' I have for the fuse box. Not sure if it was just a random layout of red white and blue, or if the previous owner was trying to recreate the American flag. Almost nothing was right, but I guess all were bigger than required or they would have been blowing like crazy. So, fixed that all up, but the lighter still didn't work.I dismantled the ashtray and tried cleaning the lighter itself, but still nothing. Then my husband used his voltage meter to check and I guess there is no power leading to the connection in the dash. It's not the fuse though, because the light in the glove box works (and they’re on the same one). So probably a fried wire, right? We may or may not try to resolve this, since the phone probably won’t work in the mountains anyway.

I've only filled up once, but I did wipe the antenna with a bit of left over diesel. It did go down one more notch, but I noticed today it is back to 2 notches sticking up. I may get fed up and go at it with some Varsol or something.:p

I have ordered a new reservoir cap, and a set of new alternator belts (to take along, just in case).

Hubby bled the brakes and the pulling to the right is gone!

Now, on to the more difficult things. Hubby replaced the water pump with the one from the parts car, and so far so good. But, a couple of weird things. There seemed to be no place to attach the gasket that I picked up at the dealer. I HATE having parts left over! But, narry a leak so I guess it's okay. He thinks the gasket is probably for the thermostat or something. Second weird thing is that even though we replaced the green
coolant with MB coolant a month ago or so, the coolant that came out was pretty darn green! The green stuff was heavier though, and the pan it went in to had the spigot on top so it kind of worked like a gravy separator (you guys have all made gravy, right? :p ). I filtered it all through a coffee filter too before putting it back. So, all seems well.. temp usually around 90, occasionally up to 100. But, we didn’t do any ‘burping’ such as described in 123c’s thread. Should we? MORE coolant went in this time than when the coolant was replaced, so I think there must have been an airpocket then.

So, lastly, the accumulators. Oy, oy, oy. As you describe shawnster, not exactly a barrel of laughs. To start with, the parts car is so rusted it is difficult to even find a spot from which it can safely be jacked up. You can forget the holes the jack is supposed to go through, they are dust. So he used a hydralic jack and jack stands. BTW, never leave a car on jack stands on ashphalt in the hot sun for a couple of days… you get a big hole in the ashphault! We found this out when we removed the self levelling strut, so now he puts the jacks on steel plates first. We get a little smarter every day!

Anyway, the other day he gets the car jack up, but it’s still pretty claustrophobic under there. He’s got dirt and rust falling in his eyes (though he’s wearing safety glasses), and he can’t get the smaller bolt loose and he realizes he starting to round the corners so he gives up, frustrated. He comes in, cranky as a bear (he’s also catching a cold) and starts complaining about how he hates fixing cars, when are we going to get a real car, and why don’t we sell Mary and get a minivan. WHAT? Mary? What did she ever do? Since the initial repairs that were done to Mary we havent’ had to do a thing in the way of repairs. I admit Belinda is a bit of a ‘hobby’, but I hope that it wont’ go on like this forever. Does it make any sense to sell a car that isn’t needing any repairs, and replace it with something that most like WILL need repairs, because you're tired of repairs? What we could get for Mary wouldn’t buy us a ‘good’ minivan. I’m chalking it up to irrational male hormones.

But, we are open to offers on Mary. She’s a 1973 280 with 115,000 miles. Mechanically very sound, but she’s got some rust. There. I can tell him I advertised. Probably safe to tuck that away in the diesel discussions.:p

Anyway, he did have another go at it a couple of nights later and managed to get them both off (though he had to cut one line). I did read your advice on getting new ones Peter (was also what I figured to do when he was having such a hard time removing them), but by that time the ones from the parts car were off so I thought it best to keep that to myself. Given his mood, the next thing I know the dog will be up for sale. Or me! I do hope they still ‘accumulate’! :p It’s not a car we have driven that much, but the parts car did seem to have a much smoother ride. It’s not the end of the world if they don’t work, since getting them off is the hardest part, but will probably be easy to do the second time around (a week later). He did mention something about it being good practice even if they don’t work (there’s things he would do differently when he removes them from Belinda).

I can only imagine how long our "One year ago today..." list will be by the time it rolls around, when our quarterly report is this long. But, hopefully the rest of the year won't be quite so 'fun filled'.

240Demon · #2 07-10-2003, 12:43 AM

Well, I can answer one question for you, probably the most important question concerning idle down. I am assuming you have a Turbo car, and when a turbo has been running at a sustained high speed (highway driving, high revs, racing, anything like that) they build up massive amounts of heat. Now, there is a line that circulates engine oil throughout the turbo to cool it. If you turn the car off after say an hour running 70mph, the hot oil will remain in the turbo and cook the bearings. However, if you let the car run for three minutes or so, it will circulate some cooler oil through the turbo and extend the life of it by a long ways.

Hope this helps

Fisherman · #3 07-10-2003, 12:12 PM

Very entertaining update... Sitting in the Seattle airport I'll tell you we need more posts like this to while away the time...

The aux fan fix is a neat trick, say 2 hail marys and call your mechanic in the morning?

The cig lighter might just be the connector at the back. If you pull the ashtray there is a "bracket" of sorts that screws into the bottom of the ashtray space. If you remove this bracket I believe this gives you access to the flat connectors on the left hand side that supply power to the ashtray light and lighter. The lighter by the way gets it's power from the strip on the side of the ashtray mount which is one of the weirdest designs I have ever seen.

Your husband has a great attitude about doing things so that next time it's easier. Hopefully that does not include major repairs (I'd rather fo them just once in a cars lifetime)!

Sounds like she's coming along though.
Good luck and remember that summer is almost over for us...

JimSmith · #4 07-10-2003, 12:48 PM

jassz,

Like 240Demon noted, the turbo has an "expander" wheel at one end of the shaft, with bearings in the middle and a compressor at the other end. The end with the expander wheel takes hot exhaust gas and allows it to expand and cool somewhat as the gasses travel through the vaned passages in the wheel. The lower pressure and temperature at the outlet is at a lower overall energy level. The energy lost to the gas has been converted by the expander to mechanicsal energy on the shaft connected to the compressor end. This converted engergy from the gas provides the torque needed to spin the compressor wheel.

After a good run the expander wheel gets about as hot as the exhaust gas when you were driving with the throttle pretty far open. The exhaust gas at this load is much hotter than idle. Also, the compressor wheel is getting heated up by the act of compressing air while you are demanding extra power. The heat of the expander wheel is pretty intense under load, hot enough to fry the oil if it was allowed to sit in the bearing housing. Under load this is not the case, as the oil is circulated under pressure from the oil pump. When you shut down, the oil in there will hang out there, and if it is allowed to be cooked by the heat of the expander wheel, compressor wheel and the housing, it will cook.

By idling for a while, you run much cooler exhaust through the expander section and that then cools that end, the oil flow cools the bearings and bearing housing, and the compressor end is cooled by the flow of air through it that is not being compressed much or at all. After a minute or two at idle or just low power runnng the the harmful heat soaked up by the full load operation is gone, and it is safe to shut down.

The auxiliary fan only cools the water in the radiator, which is not circulated through the turbocharger so its running has no real direct benefit (I suppose it pushes some air past the turbocharger but that is minimally effective, if at all, and is not what is intended by the suggestion to idle the engine to cool the turbocharger unit down). I am not a believer in cars or any other man-made items "healing themselves" so I would be more inclined to believe some of the other fiddling may have made an electrical contact that was previously too poor to actually pass current, more effective. I do not think I would count on this as the solution to your problems. The circuit is not that hard to trace, and I would be inclined to find the connections and clean/tighten them and be more confident the problem was behind you. Those "healing" events with cars have a tendency to become undone when you can least tolerate a return to not working...its part of our relationship with Mother Nature. Some people refer to this facet of the relationship as "Murphy's Law."

I believe the cigarette lighter circuit requires the key in the starter switch to be in the "run" position. I do not know if that is the case for the glove box light or not.

The water pump has a gasket between the pump flange and the housing. The pump flange is a cast iron or steel item while the housing is aluminum. The gasket is paper like material on older units, and may be a thicker material on later units and as a replacement. There is also a gasket between the pump housing and the engine block, which I believe is similar type. When the old pump came off it should have had either the paper or other gasket or some kind of "form-a-gasket" goo in the space between the pump flange and the housing. With nothing there I would expect a leak right away, but over time it will be inevitable. Part of the problem (besides the surface finish and fit as well as contact pressure challenges of a metal to metal seal here) is the two materials are not galvanically all that compatible, and if the coolant gets old and crummy it becomes an electrolyte. This will cause pitting of the aluminum part in the sealing area.

I always carry a short, maybe 6 to 8 inch long 2x4 or 2x6 in the trunk with the jack. The jack usually has too small a flange on the bottom to avoid sinking into the ground on the shoulder of the road, where you are most likely to be when changing a tire in an emergency. Nothing worse than getting the old wheel off, and finding out the car is too low to get the good one on because the jack sunk into the soft ground. I suppose if you had jack stands with you this might not be such a problem, but they don't make the cut for stuff being carried along in the trunk. I have been known to carry an 8" long chunk of 6x6 wood for that though.

Good luck and sounds like the project is heading for a great and successful adventure in the mountains. Jim

jassz · #5 07-12-2003, 09:52 AM

Of all the repairs done thus far, replacing the accumulators has the most significant in terms of effect. No more bumping along like some Mr. Bean episode! We filled our coffee to the brim this morning, and scoffed at train tracks on the way to work!

Smooooooth and steady she goes!

Removing the old accumulators on Belinda was much easier than the parts car. I do have one concern about the fluid. I picked up a litre at the dealership (I was there anyway picking up a replacement key and figured I should get some MB fluid jic there really is a difference). I only picked up one litre as that is all I thought I'd need ($20/L!). Anyway, I went to fill up the reservoir last night, and when I started it was on the minimum line. I added half and it was still on the minimum line. I checked to make sure it wasn't pouring out underneath (it wasn't), then added the rest. It was still sitting at minimum. I had no more to add, but while I had the hood up I decided to check the oil. It was overfull, which is odd since we always have a perpetual leak (though it was hot when I checked it). Please tell me the hydraulic fluid isn't running in to the crankcase?! The car was running fine, with the exception of yesterday afternoon when it started running hot. Around 110. But, I'm thinking we may have an air pocket after changing the water pump.

Speaking of water pumps, I guess the gasket we got from the dealership was completely the wrong size and shape, so hubby used the old one that was on the pump already. So there IS a gasket in there, and so far no leaks.

Thanks for the info on the turbo. I had another question about this statement:

Quote:

After a minute or two at idle or just low power runnng the the harmful heat soaked up by the full load operation is gone, and it is safe to shut down.

Does this mean that if you are driving at highway speeds, then slow down to enter a town/city that that counts as running at low power? In my commute I have town driving, then highway, then town again. Is the town driving enough 'cooling off'? What about things like ambient temperature, adn running the airconditioning? Does that mean a longer cooling off needed?

I think my miracle aux fan repair was likely a fuse. I did the cleaning/changing after it started working, but prior to that I was poking around and wigglign things (which is when I decided a cleanign was in order).

I had a new tailpipe bent and welded at a muffler shop. So, unless we've run in to another problem I think the only big repair left is the differential leak.

So, now it comes time to 'pay the mechanic'. Looks like we're off to the Arlington airshow today (what were you thinking??). Although he was kind of concerned about the overheating so maybe we won't go. He was back to being Mr. Discouraged last night. I went to the gym and when I got home he was phoning minivan ads.

Somehow I think a trip to Arlington will be cheaper :p .

JimSmith · #6 07-12-2003, 11:27 AM

jassz,

Yes, the operation under light throttle will adequately do the cool down. The ambient temperature, and running the airconditioner will not have much of an effect on the turbo temperature with moderate in town driving. If the turbo comes "on" it is only really during acceleration spurts in city/town driving. The exhaust gas temps we are talking about range over several hundred degrees Celsius so the ambient changes of a ten or twenty degrees is not critical.

The added load of the a/c during in town driving will affect water temps but mostly due to inadequate air flow through the condensor and radiator at low speeds. The exhaust gas temperature will likely not be affected by running the a/c as the added load will not normally force the turbo into constant action. To get the turbo "hot" you have to have the throttle opened pretty good for a significant period of time. The air resistance at 70 mph is enough to do this, as is climbing a steep hill (you have them coming), but in town driving should not.

Take a good look at the condition of the air flow passages in the condensor and the radiator. the condition of the cap, and, yes, make sure the coolant volume is not being taken up with air. Twenty or more years of collecting debris and dead bug bodies, as well as having someone distort the fins between the water passages while pressure washing the car or working on the fans will further reduce air flow and cause the capacity of the system to degrade.

Good luck, Jim

psfred · #7 07-12-2003, 02:35 PM

I believe the suspension pump is driven directly off the engine no the 617, so it is possible you have a leak and the oil is going into the crankcase. If the suspension works at the minimum level, and you don't loose any, leave it alone.

Change the oil before you take a trip, though -- the hydraulic oil isn't good enough for engine lubrication!

Peter

JimSmith · #8 07-12-2003, 02:50 PM

jassz,

The potential leveling system oil leakage into the crankcase has been written up before. When the pump is mounted to the camshaft or some other engine driven shaft, it is possible as Peter noted that high pressure oil can leak along the shaft driving the pump and into the sump.

There are some seals along this shaft that can be replaced. Some look like just O-rings and others look like they are more substantial. Check the history using a search and see if the last person reporting this issue resolved it with new seals or a new pump. I think these pumps are pretty simple and robust. The seals are subject to wear and tear, and aging, so they should be viewed as potential repair parts here. If the system seems to work now, the chances are the pump is fine. Good luck, Jim