Quick question about 1990 300SEL - PeachParts Mercedes-Benz Forum

nickofoxford · #1 06-07-2009, 02:07 PM

Hey guys (and gals

) Quick question, does the 1990 300SEL use vacuum and a Bowden cable to control shifting? I found a nice one on CL for dirt cheap because they're saying the transmission isn't shifting correctly and should be replaced. What are the odds that it's a vacuum problem? Does it use vacuum at all? The essential questions of mercedes life..

Hit Man X · #2 06-07-2009, 03:48 PM

Quote:

Originally Posted by nickofoxford

Hey guys (and gals

) Quick question, does the 1990 300SEL use vacuum and a Bowden cable to control shifting? I found a nice one on CL for dirt cheap because they're saying the transmission isn't shifting correctly and should be replaced. What are the odds that it's a vacuum problem? Does it use vacuum at all? The essential questions of mercedes life..

Yes it does, but be warned... the car is very slow with A/C on and with a few passengers. First gear start is too low and second is too tall, it's geared wrong for US traffic. Should have come with a 2500rpm stall converter and a 2.88:1 rear diff with first gear start... oh wait, that's what I'm doing to mine.

Unless it's super cheap and super clean (mine was, had a locked A/C comp), I'd shy away and wait for a 420sel or 500sel. The nearly extra 40lb-ft 1000rpm sooner is a huge difference, and nearly 60lb-ft with the US 500sel... the US 560 is nearly 100lb-ft more! This difference is massive in daily driving and not so much different if you cruise freeway lots.

Fuel economy difference is a wash as the car has to lug all the time to get around. The best I got on the freeway with my 300sel was 21.5mpg @ 65mph. I got just shy of 19 out of my 560sel @ 65mph (both get mid/low teens averaged out). The 420 or 500 are the best for the balance of power/economy... just have to decide if you're okay with the first generation interior/body... I am.

Had I driven the car prior to purchase, I'd not have purchased it. This isn't to say the M103 is a poor motor, it's a great one... but better suited to lighter cars (such as the 300E or 300SE) and/or with a five speed behind it.

But if you're hell bent, the trans uses vac for line pressure and the TV cable for the timing. All simple to adjust. Also verify the trans is full and has been serviced. Once around 200k, the 722.3 can be hit or miss... figure a reman to be in the $900-1200 area.

Plus the M103 will go through head gaskets, figure this around 120-170k. It's cheap and can be done on the weekend, but just keep it in mind. V8 top ends go far longer for some reason, probably stronger valve guides and 1000rpm less cruise speeds on the freeway, and I'd venture to guess stronger head gaskets.

PM or post up and I'll help the best I can.

2¢

nickofoxford · #3 06-08-2009, 12:43 AM

Thanks Hitman,

Great, a gas powered 240D!

The guy says it needs the transmission rebuilt, but I was thinking something along the lines of adjusting the vacuum and cable, because I've done both countless times between the 240D and my friends 300D.

..BUT, now I have my eyes on a beautiful 420SEL to flat out trade the 240D for! (well maybe 500 on top of it, who knows) My main goal is to get something that can handle taking me to collage every day for the next two years on the hilliest damn roads possible without lugging like crazy like good 'ol Betsy does. I mean it gets great mileage until you're climbing hill after hill with a parade of mad cow disease office workers. Not to mention passing amish horse drawn parephenalia left and right ..uphill

I wanted to do the whole biodiesel thing, but will collage, work, homework, and SWMBO.. time's going to be limited. Biodiesel can wait until after collage.. And I gotta say these w126's are pretty slick

.

Collectively I've figured out that the timing chain is the "achiles heel" of the w126, especially the V8's. The 420SEL has 260,000 or so miles so should I be concerned? What other major problems or little petpeeves should I look out for in a 126? Anyone feel free to chime in.

Hit Man X · #4 06-08-2009, 01:08 AM

Quote:

Originally Posted by nickofoxford

Thanks Hitman,

Great, a gas powered 240D!

The guy says it needs the transmission rebuilt, but I was thinking something along the lines of adjusting the vacuum and cable, because I've done both countless times between the 240D and my friends 300D.

..BUT, now I have my eyes on a beautiful 420SEL to flat out trade the 240D for! (well maybe 500 on top of it, who knows) My main goal is to get something that can handle taking me to collage every day for the next two years on the hilliest damn roads possible without lugging like crazy like good 'ol Betsy does. I mean it gets great mileage until you're climbing hill after hill with a parade of mad cow disease office workers. Not to mention passing amish horse drawn parephenalia left and right ..uphill

I wanted to do the whole biodiesel thing, but will collage, work, homework, and SWMBO.. time's going to be limited. Biodiesel can wait until after collage.. And I gotta say these w126's are pretty slick

.

Collectively I've figured out that the timing chain is the "achiles heel" of the w126, especially the V8's. The 420SEL has 260,000 or so miles so should I be concerned? What other major problems or little petpeeves should I look out for in a 126? Anyone feel free to chime in.

Never drove the 240D I bought, just lost interest. At least you know what to expect with it and has more torque at 2000rpm than the M103 does. AND in a much lighter car. The 300sel is just a turd for the US market as delivered, with a five speed it'd be great and better yet in the SWB. Should have been 300se or 300e only here. The damned thing @ 70mph is around 3500-3600rpm buzzing along to keep the car going.

Bottom end on the V8s pretty much lasts and lasts, well the top end does too if maintained. From what I gather not until into the 300k area do you have oil consumption issues. I'd roll a chain into it and swap the guides, that's the key as OE guides get brittle with age. MEYLE makes aluminum backed guides for the M116s so they never fail again and of course the chain will be stretched by this point in time... chain failure is due to guide failure. Also do the cam oiler plastic retainer stuff. Peek the front main, if it leaks swap it when you have time. Oil leaks are just a pain and can/do create vac leaks.

V8s need specific plugs, non Resistor. BP5ES NGK or W8DC Bosch from memory. And of course quality cap/rotor.

V8s like to leak oil from the oil level sender, $2 for the o-rings on the next oil change as you have to drop the lower pan. They like a heavier oil too like a 5/50, 15/50, whatever.

They start in second gear, but for a few hundred you can get a box to be rid of that nonsense. Trans is the same autos as the others, 722.3 Just service it on a regular basis and make sure it shifts crisply but not harsh.

They don't get 100% WOT stock, the rod in the back has some spring in it to prevent it. Just squish it in a vice for 100%.

1985+ cars have more efficient A/C condensers already which is good and bigger aux fan for better cooling, the '89+ cars had dual fans and updated interiors.

The auto climate can be a pain until you fix it, it's easy. Usually the car needs a new climate head (just get a Programma reman used from ebay) and you usually have three pods that'll leak. They're behind the glove box and take maybe an hour your first time... these are the dual diaphragm units.

The CIS injected cars do not like vac leaks (well what cars do?), as much of the rubber is very brittle after 20 years or more. To check easily, see if the ECONOMY gauge is pegged left at hot idle in P/N... it should be. Also, put it in B and FLOOR it from a dead stop. It should just take off without hesitation.

W126 LWB cars love rear sag, this is due to tired springs, old shocks, old rubber. Just do it all at once and motor on. Brakes are the same as on your W123 basically (style/function just bigger/more efficient on 126). Front end is the same setup, hard to align if rear sags and front is old.

The 300sel/420sel/560sel are all about the same in economy as pointed out. The 300sel buzzes and lugs, the 560 has enough torque to stay under 2k most of the time, and the 420 is like the 560 but about 50lb-ft less... plus less crap to fail.

All I got for now.

nickofoxford · #5 06-08-2009, 02:16 AM

Quote:

Originally Posted by Hit Man X

Never drove the 240D I bought, just lost interest. At least you know what to expect with it and has more torque at 2000rpm than the M103 does. AND in a much lighter car. The 300sel is just a turd for the US market as delivered, with a five speed it'd be great and better yet in the SWB. Should have been 300se or 300e only here. The damned thing @ 70mph is around 3500-3600rpm buzzing along to keep the car going.

Bottom end on the V8s pretty much lasts and lasts, well the top end does too if maintained. From what I gather not until into the 300k area do you have oil consumption issues. I'd roll a chain into it and swap the guides, that's the key as OE guides get brittle with age. MEYLE makes aluminum backed guides for the M116s so they never fail again and of course the chain will be stretched by this point in time... chain failure is due to guide failure. Also do the cam oiler plastic retainer stuff. Peek the front main, if it leaks swap it when you have time. Oil leaks are just a pain and can/do create vac leaks.

V8s need specific plugs, non Resistor. BP5ES NGK or W8DC Bosch from memory. And of course quality cap/rotor.

V8s like to leak oil from the oil level sender, $2 for the o-rings on the next oil change as you have to drop the lower pan. They like a heavier oil too like a 5/50, 15/50, whatever.

They start in second gear, but for a few hundred you can get a box to be rid of that nonsense. Trans is the same autos as the others, 722.3 Just service it on a regular basis and make sure it shifts crisply but not harsh.

They don't get 100% WOT stock, the rod in the back has some spring in it to prevent it. Just squish it in a vice for 100%.

1985+ cars have more efficient A/C condensers already which is good and bigger aux fan for better cooling, the '89+ cars had dual fans and updated interiors.

The auto climate can be a pain until you fix it, it's easy. Usually the car needs a new climate head (just get a Programma reman used from ebay) and you usually have three pods that'll leak. They're behind the glove box and take maybe an hour your first time... these are the dual diaphragm units.

The CIS injected cars do not like vac leaks (well what cars do?), as much of the rubber is very brittle after 20 years or more. To check easily, see if the ECONOMY gauge is pegged left at hot idle in P/N... it should be. Also, put it in B and FLOOR it from a dead stop. It should just take off without hesitation.

W126 LWB cars love rear sag, this is due to tired springs, old shocks, old rubber. Just do it all at once and motor on. Brakes are the same as on your W123 basically (style/function just bigger/more efficient on 126). Front end is the same setup, hard to align if rear sags and front is old.

The 300sel/420sel/560sel are all about the same in economy as pointed out. The 300sel buzzes and lugs, the 560 has enough torque to stay under 2k most of the time, and the 420 is like the 560 but about 50lb-ft less... plus less crap to fail.

All I got for now.

Shopping list so far: non resistor plugs, fluids, timing chain and guides, more R-12 (just in case).

What does this majestic tranny box do? A few hundred bucks can be bypassed if it's electronic im good with that stuff

86560SEL · #6 06-10-2009, 01:23 AM

Quote:

Originally Posted by Hit Man X

W126 LWB cars love rear sag, this is due to tired springs, old shocks, old rubber...

I have noticed this too on alot of the W126s, even the SWB models. My '85 380SE sagged a little and I am not sure, but my '88 300SEL looks like it does too... especially a certain way its parked. It dont look as saggy in this photo, but it does appear to be sagging dont it?

Mid May

Mid April

86560SEL · #7 06-10-2009, 01:07 AM

Well, its strange (as I am), because I find my 300SEL adequate for me, but I ALWAYS drive this car on my day off and never in a hurry. I drive my V8 Lexus on days I work. Also, my last Mercedes was a '84 190D (diesel and automatic), so I know what SLOW is.

Seriously, I dont mind the lower power of my 300SEL... the smoothness makes up for it as far as I am concerned. My car is nearly 160K and the tranny still shifts smooth as silk and my car dont leak or burn any oil. Possibly the headgasket/valve seals were changed before. I also like the fact that the M103 dont have the timing chain/tensioner/rails/guides issues like the V8 Mercedes have. The I6 seems to go much longer without worries. My '85 380 (V8) had 275K and the last time the chain/guides, etc were unknown and it worried me to no end. That car was no quicker than my 300SEL and it was a a shorter wheelbase and V8, but it was probably worn out.

I am amazed at your low MPG, or should I be suprised at my high MPG? I get 21 mpg in city driving with my 300SEL and about 26 mpg on the highway. I drove the car almost 200 miles and it only held 9 gallons on refill. Pretty impressive I think, but again, I drive my car lightly and dont dog it. I dont think I have ever had it over 3000 rpms.

The only beefs I have with mine is that the odometer recently stopped working at 156K, trunk seal is leaking, antenna seal is leaking and my CEL will occasionally illuminate after the car has been on for about 60 seconds, then goes off within another 60 seconds and dont come back on again. Oh, my EHA? valve is seeping a bit, which I plan to have that and my odometer repaired by a Mercedes shop real soon.

Quote:

Originally Posted by Hit Man X

Yes it does, but be warned... the car is very slow with A/C on and with a few passengers.

Fuel economy difference is a wash as the car has to lug all the time to get around. The best I got on the freeway with my 300sel was 21.5mpg @ 65mph. I got just shy of 19 out of my 560sel @ 65mph (both get mid/low teens averaged out).

Had I driven the car prior to purchase, I'd not have purchased it. This isn't to say the M103 is a poor motor, it's a great one... but better suited to lighter cars (such as the 300E or 300SE) and/or with a five speed behind it.

But if you're hell bent, the trans uses vac for line pressure and the TV cable for the timing. All simple to adjust. Also verify the trans is full and has been serviced. Once around 200k, the 722.3 can be hit or miss... figure a reman to be in the $900-1200 area.

Plus the M103 will go through head gaskets, figure this around 120-170k. It's cheap and can be done on the weekend, but just keep it in mind. V8 top ends go far longer for some reason, probably stronger valve guides and 1000rpm less cruise speeds on the freeway, and I'd venture to guess stronger head gaskets.

2¢

pawoSD · #8 06-08-2009, 12:57 AM

A V8 W126 with an original chain at those miles should have it replaced immediately, along with the guides. Its a time bomb at those miles. Ideally they should be replaced every 100-120k.

On hilly roads you'd get annoyed by the M103 in a W126.....its a revving engine....not big on torque....up in the 3000-6000rpm range its a blast, and can move the car very quickly.....but on takeoff and around town it does lug a bit. In the 300E its not an issue as its quite a bit lighter....but the W126 is heavy, torque is needed.

nickofoxford · #9 06-08-2009, 02:07 AM

Quote:

Originally Posted by pawoSD

A V8 W126 with an original chain at those miles should have it replaced immediately, along with the guides. Its a time bomb at those miles. Ideally they should be replaced every 100-120k.

On hilly roads you'd get annoyed by the M103 in a W126.....its a revving engine....not big on torque....up in the 3000-6000rpm range its a blast, and can move the car very quickly.....but on takeoff and around town it does lug a bit. In the 300E its not an issue as its quite a bit lighter....but the W126 is heavy, torque is needed.

I sure hope it's not on the original chain then.. Stupid question, but the V8 uses one chain for both heads? Or does it require two chains? I've done the chain on my 240D, it was intimidating but I got the job done, how much of a PITA is it going to be on the 420?

Looks like i'd really want the M116, Im about done with the constant struggle and downshifting thanks to Betsy. I mean she's a great car to toy around in, but it's just not my style to always be turning down my tunes so I know when to drop it back into D

Thanks for your input pawoSD!

pawoSD · #10 06-08-2009, 10:17 AM

Quote:

Originally Posted by nickofoxford

I sure hope it's not on the original chain then.. Stupid question, but the V8 uses one chain for both heads? Or does it require two chains? I've done the chain on my 240D, it was intimidating but I got the job done, how much of a PITA is it going to be on the 420?

Looks like i'd really want the M116, Im about done with the constant struggle and downshifting thanks to Betsy. I mean she's a great car to toy around in, but it's just not my style to always be turning down my tunes so I know when to drop it back into D

Thanks for your input pawoSD!

Yes they use one chain, it runs up and down and across between the heads....it is a pretty long chain and there are a number of sliders/guides....which is why its so important that it all be in perfect shape, if a guide breaks off.....

I'm thinking it'd be a lot more of a pain than on the 240.....might be best left to a dealer.

Hit Man X · #11 06-08-2009, 01:55 PM

Chain failure itself isn't the issue, it simply stretches over time. This hurts performance as cam timing is off. Not a huge deal, but the guides are the key and the driver side ones are the ones that fail causing the big boom. There are three main ones at the heads on the M116 and one for the tensioner arm (you can replace just the sleeve on the arm to save a few bux), the lower guides really don't have issues. I would change them if you have the front cover off but not until then as it'll disturb the head gaskets.

V8 chain is easy to put in, I have the MB chain guide tool and chain crimper if you need to bum it.

The trans thing just senses ABS pulses to make it start in first gear, I'm not smart enough with electronics yet to give more in-depth information. I'm in process of teaching myself the intermediate stuff... I mean I can rewire, find drains, know the principals of alternators, etc, etc, etc.

nickofoxford · #12 06-10-2009, 12:41 AM

Quote:

Originally Posted by Hit Man X

Chain failure itself isn't the issue, it simply stretches over time. This hurts performance as cam timing is off. Not a huge deal, but the guides are the key and the driver side ones are the ones that fail causing the big boom. There are three main ones at the heads on the M116 and one for the tensioner arm (you can replace just the sleeve on the arm to save a few bux), the lower guides really don't have issues. I would change them if you have the front cover off but not until then as it'll disturb the head gaskets.

V8 chain is easy to put in, I have the MB chain guide tool and chain crimper if you need to bum it.

The trans thing just senses ABS pulses to make it start in first gear, I'm not smart enough with electronics yet to give more in-depth information. I'm in process of teaching myself the intermediate stuff... I mean I can rewire, find drains, know the principals of alternators, etc, etc, etc.

Sweet thanks for the offer! I might have to take you up on that, It would be my luck that I'd get the trade done with and a week down the road the chain goes. I don't know for sure yet if I really want to tackle the chain or leave it to a dealer.. At the same time I've seen some real dumba$$es working at dealerships. I'll sleep on it.

Electronics is nothing to be proud of knowing

I've been in votech schools for electronics for 3 years now (finally graduated this year). I mean if you're learning for automotive stuff it's great stuff to know, just don't take it up as a career choice

. It makes me want to be an Amish

nickofoxford · #13 06-10-2009, 12:32 AM

Quote:

Originally Posted by pawoSD

Yes they use one chain, it runs up and down and across between the heads....it is a pretty long chain and there are a number of sliders/guides....which is why its so important that it all be in perfect shape, if a guide breaks off.....

I'm thinking it'd be a lot more of a pain than on the 240.....might be best left to a dealer.

Agreed, Im not scared of doing it it's just more the "what if"..