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Pursesnatcher
Oct 23, 2016



Grimey Drawer

The saga continues! Fuel pump and related stuff is right around the corner, but my new Löwe IACV has arrived!



On the surface, it looks to be a dead ringer for my old one.



Some very slight differences I can see on the inside:



But that might just as well be because the old one is broken. They feel slightly different as well; when shaking them the "weight" inside shifts more surely in the new unit.

Mounting it was a breeze, and I got some findings.

  • With the old one – ignoring that whole "loves being cold, hates starting up again when warm" problem which just went away for no reason – my idle was around 800 or so. It was slightly uneven, and the engine stumbled a bit when cold, especially at low speeds.
  • With the new one in, my idle was 1100, dead even. The cold-stumble at low speed was almost completely eliminated, though the misfires became a lot more evident (didn't get worse, just easier to notice) – plus the car just kept its speed better as I did not have to apply power.
  • With the power for my new unit disconnected, idle went straight back to the way it was with my old one installed.
  • Without an IACV, the car simply won't start.
  • After removing it, fiddling with some wires, and sticking it back in, I now got a smooth idle of... 1600 or so?

Those last points are on the list because my first successful test drive revealed that my temperature gauge is now all of a sudden dead. Because of my fan issues, this is a problem, so it must be fixed. I guess I must have touched some poorly connected wires while fumbling about to install the unit in the first place, so I removed it to try to gain access. Long story short I guess I need a new sender unit for my temperature gauge, but I'm preeeeeetty confused about the whole "let's increase idle speed to 1600 lol" thing that happened after I did nothing but take it out and stick it back in (with just some experimenting with "what happens without it" and "what happens if it's in but unplugged" in between).

Fingers crossed that it'll sort itself out. At least the new unit seems to work!

Ah, and another weird thing. When I removed the hoses going into the air filter housing, this happened:



That's... rust? Inside the secondary filter, which is just attached to an air pump in the bottom of the engine that isn't even running?

Here's the other side of that hole:



So that black tube with orange dust inside it is literally just part of that small, orange filter. I am once more confused.

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angryrobots
Mar 31, 2005



Oven Wrangler

If the ECU isn't getting an accurate coolant temp reading, it's going to cause all sorts of fuckery with idle speed and fueling.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Yeah, the book says the same thing. It's also suggesting incorrect fuel pressure (so fingers crossed for that new pump and filter), faulty lambda control (which could theoretically be a thing with my exhaust leak), or various air leaks. But at this point I'm actually starting to feel like I'm working my way through the issues, rather than desperately grasping, so that's awesome!

Tomarse
Mar 7, 2001

Grr

angryrobots posted:

If the ECU isn't getting an accurate coolant temp reading, it's going to cause all sorts of fuckery with idle speed and fueling.

You are thinking too modern. "mature" vehicles like this one generally have separate temperature sensors for the gauge and for the ECU so not having a working gauge might mean nothing to the engine

angryrobots
Mar 31, 2005



Oven Wrangler

Oh well yeah that's possibly true lol. I can tune a carb and I can work with OBD2... The poo poo in between is like Pandora's box IMO.

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

My Mazda of the era had three temperature sensors (although the fan one was probably just a switch). That doesn't mean that's how the Mercedes is but it's a possibility.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Mine actually only has one for everything, and it's this little fellow, sitting on top of the thermostat housing (sort of):



I was sort of worried that the wiring was shot, but decided to try a new sensor anyway. It's a cheap enough little part, and it turned out to be stupidly easy to replace. I don't think I spent more than 3-4 minutes working on it. I spent a lot more time beforehand just making sure I knew what it looked like, where it was, and so on.



One might say there's a very slight difference between old and new... For all I know the problem was just caused by a bad connection, and maybe I could have cleaned the connector on the old one up and made it work. But I replaced it, and I'm happy I did. My temp gauge is back in action, and the weird idling issues went almost completely away.

Also, I got a brand new octopus!



My plug wire kit! The cargo hold turned out to be the best place available to lay all the wires out and sort them by length, so I could match the lengths of the old ones to the new. That also let me take this picture, comparing the insides of the bit that goes on the spark plugs:



New ones are on top. That becomes a whole lot more obvious when I turn on the flash and move in for a closer look:



So yeah, it was about time to replace all of those.

Wait, what's that sound? Oh poo poo it's the misfire police! Well that's okay, they've got nothing on me anymore, and I honestly had no idea this engine was supposed to run this smoothly. It's like an entirely different car. Not just because of the wires, or the IACV, or the temp sensor, or whatever, but it's way improved from just a week or two ago. It feels insanely satisfying to finally find and eliminate actual problems, and to feel the results.

It still idles a bit higher than I think it's supposed to, and there are other... odd issues going on as well. Some weird stumbling at low speed, and a flat-out refusal to not rumble forwards unless I actively push the brake pedal. Something going on with the throttle link adjustment, I suspect, and I'm still not convinced fuel pressure is what it ought to be.

But with some luck, tomorrow will be the day I get to the bottom of the fuel pump assembly situation. I have a good feeling about that.

Charles
May 9, 2004

zoom-zoom


Toilet Rascal

👏🏻

LloydDobler
Oct 15, 2005

You shared it with a dick.



Cybernetic Crumb

Pursesnatcher posted:

It still idles a bit higher than I think it's supposed to, and there are other... odd issues going on as well. Some weird stumbling at low speed, and a flat-out refusal to not rumble forwards unless I actively push the brake pedal.

Might be a vac leak in the brake booster that goes away when you push the pedal due to a check valve or something. Try clamping off the booster vac line and see if it makes the engine run better. But be careful because after about the third pump your brake pedal effort will skyrocket.

To temporarily clamp lines I use a needle nose vise grip with rubber hose pushed on to the jaws. That way you can squish a rubber line with no damage. Good for coolant lines and vac lines and such.

sharkytm
Oct 9, 2003

Gimme Gimme Swedish Fish...

Fallen Rib

Do you have a CIS fuel pressure tester? I sold mine to someone here a while back, but it was super useful for troubleshooting my VWs. IIRC, whoever I sold it to was working on a Mercedes.

Also, I've got a dwell meter, not sure if it's worth trying to ship it from the USA, but you're welcome to it.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Vacuum leaks; yeah, I probably have a ton. I've been meaning to try cataloging the entire inventory of rubber in the car, but I also keep finding new bits of the stuff, so that's kind of an eternal project in and of itself. I also recently got confirmed that vac leaks are also a likely explanation for the rough shifting I keep getting. My gearbox, turns out, was originally made for the S-class, so I'm pretty sure it's not supposed to give the whole car a jolt every other shift. But it (like seemingly just about everything else) also "runs" on vacuum for control.

sharkytm posted:

Do you have a CIS fuel pressure tester? I sold mine to someone here a while back, but it was super useful for troubleshooting my VWs. IIRC, whoever I sold it to was working on a Mercedes.

Also, I've got a dwell meter, not sure if it's worth trying to ship it from the USA, but you're welcome to it.

That I do not! If swapping out these next fuel parts don't work, though, I think the next step is going to be a smoke test at a shop, since air leaking somewhere is becoming a more and more likely culprit according to the book. I was hoping to try the swap yesterday, but ended up being too tired after a trip to the range – and today is too cold and wet for the man with no garage! As for dwell meter, I really appreciate it, but I'm pretty sure international freight is more expensive than me just picking up one here. But thanks for the offer!

Oh, and I dared to try taking the car out on the highway, for some high speed and high RPM's. It really feels and sounds like a race car engine. Which is the weirdest sensation after two years of it feeling like (at best) a beaten old truck engine.

meltie
Nov 9, 2003

Not a sodding fridge.

Pursesnatcher posted:

Wait, what's that sound? Oh poo poo it's the misfire police! Well that's okay, they've got nothing on me anymore, and I honestly had no idea this engine was supposed to run this smoothly. It's like an entirely different car. Not just because of the wires, or the IACV, or the temp sensor, or whatever, but it's way improved from just a week or two ago. It feels insanely satisfying to finally find and eliminate actual problems, and to feel the results.

There you go! Bravo!!

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Who knew changing a fuel filter could be so much work? And I'm not even done, but I'm almost there, I hope.

The first steps were pretty simple. I'm replacing everything but the accumulator, so I needed to salvage that.



Easy enough, though someone could have warned me that this end spews a high-pressure gas-gas once you plop off the rubber hose. I thought it was supposed to hold liquid, but apparently not?



Hose disconnected, I grabbed some aluminum foil to blind off everything. Don't want insects or spores or whatever going into my fuel system.



On the other end, someone had been kind enough to mount it using blue loctite. I suppose I'll do the same when I reassemble. Alright, so that was 1/3; cool.



Next up, fuel pump. I'm going to keep it around just in case, so gently plop off another rubber tube.



Turn it around, banjo bolt comes off easily. This has been a breeze so far!

Then we get to this absolute piece of poo poo.



So I'm very happy I bought a new steel tube of the kind you see to the right there, because it's just bloody welded to the fuel filter. It is not coming off. And it's rusted enough that I kept bending it just by trying to remove it; fine, gently caress it, leave it on. But then I've got to detach the fuel line coming out to the left there, which was also drat near impossible. I spent way too long, and way too much penetrating oil, with not a lot of luck. Finally I just soaked it, wrapped a soaked rag around it, and left it overnight.



And we have victory! Partial, anyways. Using a pipe wrench to grab onto the actual filter housing, I was eventually able to force the line sort of free. However, the brass nut thing going into the filter also came off.

Keep in mind that I'm working inside a wheel well, with an eight inch long pipe doing its other thing on the other end of the filter, two loose fuel hoses and some wires for the pump all flopping around – so I decided that just getting the filter housing out of the way should be priority one. You can also see how fragile the rubber fuel line going into the steel line looks; I couldn't be too rough.



Alright. Filter out of the way.

But now the end of my fuel line looks like this:



And I guess that's some aluminum shavings from the filter housing.



So this is now. I was finally able to slap a big nice socket onto the bit I want gone, but I am just completely unable to budge it. In fact, I am partially tempted to remove this brass thing's counterpart from my new filter, and just stick it in there. Especially since I'm not super excited about getting penetrating oils inside this bit of fuel line. But I don't know.

Any thoughts?

sharkytm
Oct 9, 2003

Gimme Gimme Swedish Fish...

Fallen Rib

That brass-looking fitting is supposed to stay with the filter. That's why there's a flare fitting leading to it. You'd have to spin the filter (like you did) instead of just tightening the flare nut. You need to get the fitting out of the flare if at all possible. Penetrating oil isn't going to hurt the fuel line or the car. It's such low-volume and the car will just burn it.

And yes, fuel lines love to spray fuel. Wrap the tool in a rag next time. Gas tastes bad and burns the eyes.

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Yeah, I figured it was supposed to stay in the filter, since the new one already has one. If I can't get that fitting loose, I think the best option might actually be replacing that whole little fuel line it's stuck in as well. I'm going to want to change fuel filters again in the next 17 years, after all... All right, more oil it is!

As far as the spraying of fuel goes, it hasn't been too bad, except for that pressurized jet of gaseous, non-liquid gas (it still tasted terrible though)

Pursesnatcher
Oct 23, 2016



Grimey Drawer

Alright so this absolute unit of junk, pain and suffering:



...has after a few days of incessant freeze cycles (hence the frost on the image above), hosings with penetrating oil, rubbings with a steel brush, and even more penetrating oil, turned into this:



Yes!

I actually had a friend come over today with his whole collection of breaker bars, steel pipes, interesting pliers and even-tougher penetrating oils, and we were set up to really go to town on this little brass shitling. With the tools laid out in front of is, what transpired next was that I put a socket over the fitting and a wrench on the nut, and he was just feeling it to make sure the socket wrench was set to click the right way. And it all just suddenly came apart with no trouble at all. Kind of an anticlimax, but on the flip side, my friend might be Superman! Or maybe the soaking-in-oil trick really works, if you just do it long enough.



Anyway, with our afternoon of sweaty fun and anguish thus ruined, all that was really left was to reassemble the cradle with new parts and stuff! Great!



New filter! Sweet! Keep in mind that this, a simple fuel filter change, was what kicked off the latest chapter in this saga.



New three-way pipe thing! Cool! The reason they look nothing alike anymore is that I had to try getting poo poo loose from the old one, and poo poo did not want to get loose.



New cradle! Awesome! If you notice a conspicuous lack of screws and plastic bracket in the new one, you are more perceptive than... others.



Even new rubber rings to hang the cradle from! So nice! As a matter of fact the old ones still held an impressive amount of flex. High-quality rubber, Mercedes rubber is.



And finally, new fuel pump! Probably superfluous, or maybe not, but the new one is prettier at least. That''s got to count for something.

Alright. Time to slap everything back together. It's really pretty self-explanatory. Stick the copper rings where they used to be, remember to slather some blue Loctite on the connection to the accumulator, like it used to be...



Alright nice, then oh man shitballs there aren't any screws to actually stick the cradle back together? Great. Magical. Fine, so let's spend some time carefully restoring the old screws as best as we're able. One of them is a bit too worn, really, but whatever. We're good to go! Right?



Right?

Hang on, let's have another look at that new filter.



poo poo.



poo poo.

everdave
Nov 14, 2005

For The Record...

Am i totally missing something or is it just upside down? It even has an arrow on it that shows it goes the other way. I could be way off base.

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Pursesnatcher
Oct 23, 2016



Grimey Drawer

everdave posted:

Am i totally missing something or is it just upside down? It even has an arrow on it that shows it goes the other way. I could be way off base.

That's what I thought, initially. But no, it's just missing the banjo screw which is supposed to connect it to that steel pipe. Of much greater concern is the fact that they gave me a filter that's way smaller than the one it's supposed to be replacing!

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