Horrible squealing sound at startup

[mbzgurl]

When my car starts, there is a horrible squealing sound. Then a block or more down the road, the squeak goes away. Is that caused by the belt being lose? The tensioner was replaced about 6,000 miles ago. Can I get rid of that squeal with an adjustment or just buy a new belt?

 

[gsxr]

When my car starts, there is a horrible squealing sound. Then a block or more down the road, the squeak goes away. Is that caused by the belt being lose? The tensioner was replaced about 6,000 miles ago. Can I get rid of that squeal with an adjustment or just buy a new belt?

Can you post a video of the sound at startup? It may be the smog/air pump, which will shut off shortly after you start driving.

It could also be the belt squealing but it's hard to say for sure. I assume your car is a 1992 if you had the tensioner replaced. What brand tensioner was installed? And how old is the belt, are there cracks on the ribbed portion, etc?

 

[mbzgurl]

Hey Hi, yes my car is a 92. I don't know what brand the tensioner is because it was fixed at the local Mercedes shop, but I can try to find out since now I know the mechanic. I'm trying to remember how long ago I had the belt replaced. Maybe about 10,000 miles ago, maybe less? I can't remember....I'll try to remember to video the start-up sound. Should I record it when the car is idling with the hood up? The squealing noise stops when I put it in neutral as I'm driving down the road late at night so my neighbors don't hear me. I looked at the belt and it looks ok but my eyes are getting pretty old. I sprayed the belt with the stuff that's supposed to make the squeal go away, but it didn't do diddly squat. So you might be right about the smog/air pump. Sounds awful like it's going to break apart any minute. The noise goes away after I drive it less than a mile.

 

[gsxr]

A video just after startup, with the car is idling and hood up, would be great. See if you can figure out if the noise is coming from the driver side, front/center, or passenger side... that will help identify the culprit.

If it was the belt slipping, I doubt the problem would consistently go away after a mile or two.

 

[mbzgurl]

A video just after startup, with the car is idling and hood up, would be great. See if you can figure out if the noise is coming from the driver side, front/center, or passenger side... that will help identify the culprit.

If it was the belt slipping, I doubt the problem would consistently go away after a mile or two.

I put the camera in the car so I wouldn't forget to record a sound bit. You won't believe this...I don't drive my car every day, maybe 2-3 times a week. Anyway, I started her up and it actually started right up like a normal car on the first crank and it wouldn't squeal. I didn't even notice for about 2 seconds that something unexpected just happened. That is the first time it ever did that in more than a year. How weird is that? Just talking about it fixed it. So I drove it to Home Depot and when I was leaving, it went back to the same old shit. I think when the car is completely cool it sometimes starts, and when it has warmed up won't start has something to do with the starting problem. I thought I needed a new starter, but after reading and watching YouTube I'm confused. Is it the selenoid? The relay? I think it's 2 problems. The starter brushes are worn out and the CIS injectors are leaking.

 

[gsxr]

The starter solenoid (relay) is part of the starter itself, not a separate item. The only other possibility, assuming there's no difference between having the shift lever in P or N (and, when you turn the key there is dead silence), would be maybe the ignition electrical switch. If you hear any clicking when you turn the key to "start", it's the starter itself failing.

Weird about the noise going away, but hey, if it stays gone...

 

[mbzgurl]

Not experiencing any clicking and it never goes silent. It just spins until it grabs sometimes with a clunk, then it usually starts on the next crank. Lately, I smell gas and when it restarts it stalls. Then, once it gets going the idle is rough. When I'm going down the road I feel an intermittent hesitation and it backfires baby farts when I take my foot off the gas, especially going downhill. The fuel filter isn't that old, but I bought a new one just in case (Yikes! It cost almost $100.00 ). I'll try the filter first to see what that does. The car sat outside and cooked under a heavy car cover for more than a year, which could have screwed things up. It ruined the paint. Once the car is warmed up, forget about it. It'll spin forever when the weather is super hot. I think I would rather take an Uber when I have to sit at 120º inside the car waiting for it to start. But, she always starts for me.
So what is making it spin or slip?
The screechy sound is a separate problem. The starter issue was first, then about 6 months later the squeal started. Both issues are slowly getting worse maybe because it's really hot outside. Doesn't do it as much in cold weather. I wonder...I wash the engine bay with the hose about once a year and always dry it off with towels, might that be a contributor?

The videos: Saturday 26. June & Monday 28.June

 

[TerryA]

Just my opinion but the squeal sounds like the smog pump secondly I would check the fuel pressure regulator on the fuel rail. The slight backfire might be a small hole in the exhaust system.

Just my $0.02

Keep Slugging

 

[dionphaneuf]

That sure sounds like the smog pump to me. Lower passenger side of engine compartment. Also goes away after a bit of driving. I did mine this winter, not a terrible job but not super fun either as it's a bit hard to grab the large nut that holds the pulley in place while also engaging the 6 mm (I think) allen at the center of pulley. You need to simultaneously grab both, which means you either need a special tool or a very thin walled open ended wrench (22mm?) otherwise it slips. Happy to learn of other methods. Also be sure to check which smog pump you have (6 or 8 rib) and match the replacement bearing accordingly. And should you go about doing this, you might as well replace all the smog pump hoses, or rather you'll likely need to as they are brittle as sin. I'd also advice ordering a replacement 135 deg elbow fitting, 119-990-02-78, that joins two of the hoses as that shattered when I replaced mine and I had to scramble and replace it with an AutoZone 90 deg until a replacement came. The MB part is cheaper and fits properly.

Of course, it could be something else.

 

[gsxr]

Not experiencing any clicking and it never goes silent. It just spins until it grabs sometimes with a clunk, then it usually starts on the next crank. ... Once the car is warmed up, forget about it. It'll spin forever when the weather is super hot. I think I would rather take an Uber when I have to sit at 120º inside the car waiting for it to start. But, she always starts for me. So what is making it spin or slip?

If the starter motor spins without cranking the engine, then grabs, that is the starter failing. You must replace the entire starter to fix this. Due to the parts that have to be removed to replace the starter, I'd strongly recommend also replacing the engine mounts at the same time if they are not recent, and also the lower wiring harness to the starter as well if it's original. From the video it looks like the engine mounts may be collapsed. (??)

Lately, I smell gas and when it restarts it stalls.

PLEASE DO NOT DRIVE THE CAR UNTIL YOU FIX THE FUEL LEAK! This is a serious fire hazard and can literally burn the car to the ground. This happened to a forum member years ago. If the gas smell is in the engine compartment, it may be the fuel pressure regulator (FPR) or one of the hoses. If the smell is at the rear of the car, it is likely one of the hoses near the fuel pump + filter package, likely the high-pressure hose. Everything you need to know is in this thread.

Then, once it gets going the idle is rough. When I'm going down the road I feel an intermittent hesitation and it backfires baby farts when I take my foot off the gas, especially going downhill. The fuel filter isn't that old, but I bought a new one just in case (Yikes! It cost almost $100.00 ). I'll try the filter first to see what that does.

It's definitely not the fuel filter. $100 is highway robbery, I assume that was from a local dealer - try to return it if possible. OEM aftermarket fuel filters are ~$20 or so. The filter only needs replacement every 60kmi. Stalling immediately after starting is likely related to the fuel leak. A new FPR may cure it. If the FPR is not recent, replace it on principle... it's cheap at $40 for a new Bosch FPR. Everything you need to know is in this thread. Although it shows an M104, the process is the same on the M119.

The screechy sound is a separate problem. The starter issue was first, then about 6 months later the squeal started. Both issues are slowly getting worse maybe because it's really hot outside. Doesn't do it as much in cold weather. I wonder...I wash the engine bay with the hose about once a year and always dry it off with towels, might that be a contributor?

I can't tell for certain but the smog/air pump may be causing the squeal. To test, unplug the electrical connector for the pump. Trace the wire from the pump over to the fender area. The factory location for the connector is hidden behind the passenger headlight and washer reservoir. If the pump has never been replaced, you'll need to remove the washer bottle to access the 2-pin connector and unplug it. The connector is Zip-tied in place, once you remove the Zip-tie, you can move the connector somewhere else that's easier to access. If the problem goes away with the air pump unplugged, that confirms the source of the noise. If the noise remains, it's either the pump pulley bearing, or probably another belt-driven accessory bearing (i.e., alternator).

The videos: Saturday 26. June & Monday 28.June

There's some other items of concern in your videos... the missing fan shroud will reduce cooling capacity and make the engine run hotter than normal. You can buy a used fan shroud from any 400E/E420. This is also a safety hazard, watch your fingers! And, your oil pressure gauge is not working. This could be the gauge itself, or the sending unit, or the lower wire harness to the starter. I also see the left turn signal stuck "on" and not blinking... dunno what's up there.