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  #1  
Old 05-21-2009, 11:56 PM
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'85 300dt loss of power, shifting hard

Bought an '85 300DT. Drove it 65 miles home with a notice of a little lack of power going up hill on interstate. I changed fuel filters, oil filter, and air filter and drove it and it shifts hard and will not pull a hill, big loss of power. I'm going to change transmission fluid tommorrow.
1.What kind of transmission fluid does it take?
2.Any ideas what else might cause lack of power?
3.Low compression?

Any Ideas?

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  #2  
Old 05-22-2009, 12:58 AM
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Quote:
Originally Posted by TN TRACTOR View Post
Bought an '85 300DT.
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'05 Acura TL 6MT
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Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
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'80 240D 230K "The Squash"
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  #3  
Old 05-22-2009, 06:40 AM
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sounds more like you might have popped a vacuum line out. i did this the last two times i changed my oil and fuel filters. check all the connections near the filter housings and lines and see if one came out in the process.

don't know about lack of power before you changed the filters though, but my car isn't exactly peppy going up a hill anyway.
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  #4  
Old 05-22-2009, 08:29 AM
helpplease
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Have you done a Diesel purge? Valve adjustment? Checked to make sure your turbo is working? Does it run okay on a level stretch of road or is the take off sluggish? Might be a loose linkage as well. Hope this helped.
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  #5  
Old 05-22-2009, 01:35 PM
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Quote:
Originally Posted by JimmyL View Post
OH NO!!! You have the wrath of JIMMYL on you .

Oh wait, Jimmy he said DT not TDT.

Another thing to check is the boost line coming out of the back of the intake manifold. runs over to a black switch over valve on the firewall next to the brake booster. then over to the ALDA.

unscrew the banjo fitting at the intake manifold and clean out the soot and gunk with some spray brake clean. the line to the Switch over valve and the valve itself could be gunked also. Brake Clean and compressed air should work. place a rag to catch the mess blowing out.

There are 2 small washer on either side of the banjo fitting, careful not to drop them.

Charlie
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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  #6  
Old 05-22-2009, 10:22 PM
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I'm not worried about Jimmy and his 12 year old remarks, I need info from someone whose been under the hood, not someone who still gets their money from their daddy.
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  #7  
Old 05-22-2009, 10:29 PM
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Thanx for the info Charlie, I have found a couple of problems. Someone previously bypassed the vac amp and I guess thats causing it to shift hard. Possibly fuel leak in fuel primer pump causing lack of power the longer I drive it, air in the system maybe.
By the way JimmyL, I will eventually figure it out with or without smart ass remarks,I work on MD11s, DC-8s, and 757, ..............and you?
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  #8  
Old 05-23-2009, 12:28 AM
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Quote:
Originally Posted by TN TRACTOR View Post
I'm not worried about Jimmy and his 12 year old remarks, I need info from someone whose been under the hood, not someone who still gets their money from their daddy.
That would be difficult since my father died in '85.

Quote:
Originally Posted by TN TRACTOR View Post
Thanx for the info Charlie, I have found a couple of problems. Someone previously bypassed the vac amp and I guess thats causing it to shift hard. Possibly fuel leak in fuel primer pump causing lack of power the longer I drive it, air in the system maybe.
By the way JimmyL, I will eventually figure it out with or without smart ass remarks,I work on MD11s, DC-8s, and 757, ..............and you?
Wow TN, you sure appear to have a severe need to validate yourself amongst others. Maybe when you get over 10 posts you will realize that we have a little levity on this site also.
I didn't respond to your very common problem as it is so easy to find if you can figure out the search function. I don't work on airplanes [nor drop their names for status] but I can work the search function........



You know, something just popped into my mostly empty head. Exactly what remarks did I make? {See above items bolded in blue} Did my picture early in the thread confuse you?
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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John
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  #9  
Old 05-23-2009, 12:40 AM
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If you can't take a little light hearted poking, you don't belong here.

You're the one coming off as childish with your response. What else would you like to brag about? Obviously working on airplanes has no bearing with these cars, based on your completely inept initial diagnoses.

I suggest you lighten up. Jimmy is one of our most prominent and respected members (a grown man with grown children of his own) and clearly lightyears ahead in maturity and mechanical knowledge with these cars than you.

Fixing the primer pump is a start, but probably not the main problem. Most people bypass a whole bunch of vacuum elements in these cars (especially 1985 models) because they create similar issues to your problem. Going back to the stock configuration will probably not fix it.
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  #10  
Old 05-23-2009, 12:47 AM
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You might also check and see if your intake and return lines weren't swapped for some reason. Rotchester, a 1985 300TD I recently sold had the same problem going up hill below half a tank because of this.
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1985 500SL Euro w/ AMG bits 130k
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2001 CLK55 AMG 101k
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  #11  
Old 05-23-2009, 12:51 AM
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Quote:
Originally Posted by TN TRACTOR View Post
Bought an '85 300DT. Drove it 65 miles home with a notice of a little lack of power going up hill on interstate. I changed fuel filters, oil filter, and air filter and drove it and it shifts hard and will not pull a hill, big loss of power. I'm going to change transmission fluid tommorrow.
1.What kind of transmission fluid does it take?
2.Any ideas what else might cause lack of power?
3.Low compression?

Any Ideas?
Uses standard Dexron/Mercon transmission fluid (GM kind, not Ford). Mercedes has their own fluid, preferred by purists but not necessary. Remember to drain the torque converter as well as the transmission, will take about 6 quarts. Turn the engine by hand (clockwise from front) until the drain plug in the torque converter can be seen, then remove to drain. Pull the pan, there's a filter to replace, most foreign car parts places will be able to get it or a Mercedes dealer for sure (for more money, of course). Remember to put plugs back in and don't strip the aluminum threads.

Hard shifting probably due to incorrect vacuum level going to transmission, especially if the blue flying saucer has been bypassed. There's a vacuum control valve (VCV) on the fuel injection pump (IP) that changes vacuum level in response to the footfeed at the IP. The blue flying saucer combines vacuum with boost from the intake manifold (IM) to produce the vacuum signal that the transmission needs to shift smoothly. There's also a Bowden cable from the throttle assembly on top of the valve cover (VC) that tells the transmission when to shift.

Poor power can be caused by a turbocharger not working properly but is most often caused by clogging of the line that leads from the IM through the over-boost protection solenoid to the ALDA, which is a disk-shaped thing on the IP. ALDA looks at the boost (pressure from turbo) in the IM; if allowed by ALDA, the IP gives more fuel when there is boost (more air to burn the more fuel). If the boost line is plugged (with oil/soot from EGR) or disconnected or if the overboost solenoid isn't working, ALDA won't know to have the IP give more fuel, hence you end up with about 85 HP max instead of 123 HP.

The boost signal also goes to the blue flying saucer and will affect shifting times (but not as much as it affects power). Without boost, the transmission will shift at lower RPMs and you will feel as if the car is lugging (which it is).

There are lots of ALDA-related threads on this forum. If you will use the search function, you'll find a whole weekend's worth of reading.

Don't worry about low compression until you have made sure the ALDA and the vacuum system are all working correctly. Think about getting a service manual. Haynes is OK although often panned here. Factory manuals hard to find and expensive; factory CD-ROM version may still be available ($20--cheap), check Mercedes web site, look for "classic" section.

Jeremy
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  #12  
Old 05-23-2009, 12:58 AM
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Here is the "blue flying saucer" that Jeremy is speaking of on '85 W123's.


My wife helped me get the hood open......
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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John
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  #13  
Old 05-23-2009, 01:04 AM
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The blue flying saucer on my '85 300D was bypassed, along with just about everything else cluttering up my driver's side, and my car shifts and accelerates perfectly.
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  #14  
Old 05-23-2009, 01:06 AM
ForcedInduction
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Quote:
Originally Posted by JimmyL View Post
I didn't respond to your very common problem as it is so easy to find if you can figure out the search function. I don't work on airplanes [nor drop their names for status] but I can work the search function........
Quote:
Originally Posted by TylerH860 View Post
You're the one coming off as childish with your response. What else would you like to brag about? Obviously working on airplanes has no bearing with these cars, based on your completely inept initial diagnoses.
I agree completely with both of you on this issue. My opinion of Mr. TN TRACTOR is pretty low after his 3rd and 4th posts.

There is a sticky on the first page and a whole DIY subfourm filled with links for this common problem and much more. In fact, after your very first post, I gave you the link to the resource you needed for this problem!
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  #15  
Old 05-23-2009, 06:54 PM
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Thanx for the info Jeremy. I changed the x-mission fluid and filter, also the torque converter. It seems to be more of a power problem than a x-mission problem. I know I've had to induce the problem.When I changed the fuel filters and primed it, I got leakage bypass back thru the primer pump. Maybe I have air in the fuel system? Gonna change it, adjust valves, check EGR valve, chech the intake manifold and see how that effects it.
Meant to thank you earlier, but I spend most of my time in the garage and not on the computer.

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