These problems have been around since I got this car about a year ago- however I've been able to live with them... until now -

1) the shutoff problem
When the car is idling or going very slow (<5 mph or so), it will sometimes shut off completely - the engine will shut off. THIS IS NOT A BATTERY ISSUE I AM POSITIVE! Then I thought - ah- must be a fuel issue (water in the fuel possibly)- however it has happened with diesel gas from MANY DIFFERENT gas stations - also it has still occured with additives in the gas that are supposed to absorb any water in the diesel.

I then looked under the hood. I noticed in the inline fuel filter about 1.5 inch air bubble - I thought - maybe this air bubble is causing the shutoff because at idle or slow speeds not much fuel is passing through the lines. ichanged that inline filter but on the new one theres still an air bubble, although not quite as big - anyway- long story short that didn't fix it either.

This problem is not only a shutoff problem, but it is also causing problems starting the engine right after. About 30% of the time that I start the car, the engine turns over, or turns on for a few seconds then stalls out. God this problem is annoying!

I was driving back to school today, on the way off the exit ramp (getting off the thruway), my car had problem #1 - listed above (car shutoff, steering wheel tightened), and I actually glided into the toll booth - the attendant had no idea my car was off!

2) turbo problem
this is only a recent problem, and im not sure its a 'turbo problem' specifically - but basically i am too scared to drive my car now.

It feels like the transmission is not shifting down a gear properly. Normally, the car would be around 2700rpm at 80mph. Driving back today, I was at 3000rpm at 40mph. I could hear the engine struggling - a loud spinning sound. The faster I went, the louder the spinning sound was. It felt like the turbo wanted to kick in and the transmission wanted to gear down, but just couldn't. Above 60mph I could hear a hissing sound - like air going into the turbo but not being released?? I didn't go above 65mph. I used cruise control to make sure I stayed that speed. I was at about 3250 rpm the whole trip back to school. Some interesting notes is that with cruise control on, when I was going downhill, my car was sort of "jolting" - athought staying steady at 65mph. it felt like "mini-turbos" kicking in eveyr second. Once I steadied out or started going uphill, this went away.

Also, if let go of the gas, instead of the rpm rapidly dropping like it normally would, the rpm GRADUALLY drops, and the loud spinning sound takes a while to go away.


Usualy before the car stalls out like in problem #1, I also notice the temperature rising, nearing 115C.
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I honestly have no idea what is going on with car or if it is worth fixing.

It has 290k miles but engine was rebuilt around 100k.

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1991 350SDL (Navy Blue) - 278k

Your problems sound annoying to say the least!
They're also hard to diagnose because it could be a number of things causing both, and the second problem is one of those things where I'd have to sit in the car to know what the deal was, but I'm sure someone more savvy can help you in the right direction on that one.

As far as the first problem goes, you MAY be getting air into your fuel lines. Every so often under the chassis there are these rubber pieces holding the metal fuel line to the chassis. I had a problem once where my metal fuel line literally rusted out and broke inside one of those rubber pieces holding it up. The rubber piece acted as a sort of "connector" between the broken fuel line (because it has rusted into two inside the rubber piece). There was, in turn, air getting into my fuel line. The car would take an hour to start, but it would run fine afterwards. Also, if it sat for more than an hour or so, it wouldn't start and it would take about an hour to build enough pressure in the fuel lines to get it going again. Needless to say the problem was ridiculously hard to find (because I literally couldn't tell the fuel line was broken).

You may want to check all your rubber hoses and make sure they're tight and not cracked. ALSO, check the hoses between the fuel injectors. These will often dry rot after awhile. There are also two fuel filters, and it wouldn't hurt to replace the other one since you already replaced the inline one. Its about 10 bucks, and you should do it, as it may just be a clogged filter. Sometimes the specific filter I'm talking about goes unnoticed to the average driver and will not get replaced for years, maybe even since the car was made. Also, make sure your idle is where its supposed to be (about 600 rpm I believe).

And I'm not trying to be mean, but you DID have your transmission in "D" when you were driving, didn't you? Because the symptoms you listed on your second problem kind of sounded like it just wasn't shifting into 4th gear. The "hissing" sound may clue you in to a vacuum leak as well. It may not have been the turbo, but a vacuum line, which in turn, will likely affect the transmission behaviour.

I really have just listed general things to check for that sound related to your problems. I'm sure someone else will post up and hopefully help you out a little bit more.

Good luck.

Thanks for the reply - acutally I have changed the spin on fuel filter a few months ago with a brand new Mann filter. I am curious about what you said about metal lines that have rusted too much. I really think I probably have a problem wit hthat somewhere, and also I am SURE I have rubber hoses in my car that are too old. I really wish I knew more about cars so I could fix these things myself.

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1991 350SDL (Navy Blue) - 278k

I'd be most concerned about the fact that your temperature is at 115C. That's too high. You need to inspect the components of the cooling system.
I suspect the stalling may be caused by an air leak.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

its not 115 , when im driving its between 80 and 100, i was just noting that it will sometimes start going up , nearing 115, (at which point I pull over and turn it off, or it stalls out).

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1991 350SDL (Navy Blue) - 278k

Stalling could be a number of things. Brian could probably help more but I'll try.

It could be an air leak, air leaks are tough to track down. I'd splice in some clear line behind the pre filter, run the engine and rev it a bit, see if you have any air bubbles.

It could also have something to do with the ELS. The 350's are a bit different than my 300, I'm not sure how much more computer controls there are.

As for the trans its not upshifting. When was the fluid last changed? Could be a vacuum problem as well, the FSM does detail the trouble shooting procedure, you need a Mittyvac as well.

115C is way to high, it should never run much above 105C, ever. Something is wrong with the cooling system.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200