Author Topic: Basic Question for 79 450 SEL  (Read 425 times)

Sonch

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Basic Question for 79 450 SEL
« on: 19 November 2020, 07:11 PM »
Hey Folks. Thanks for responses to a basic.

Bought a great 79 450SEL last March. 62K orig miles. . now 65k. I'm insisting on using my ride as a daily driver. Rockin' on the expressway at 80-90mph. 4000rpms seems high to me. That sound about right/is this just the nature of the 3 speeds? Ok for the car or is this too much stress?


raueda1

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Re: Basic Question for 79 450 SEL
« Reply #1 on: 19 November 2020, 07:23 PM »
Welcome to the world of 3-speeds.  I'm a 6.9 guy, but that sounds about right to me.  Design goals were different in those days, to say the least. What's the redline on it?
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

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Re: Basic Question for 79 450 SEL
« Reply #2 on: 19 November 2020, 08:21 PM »
Are you 100% sure you have the 3 speed?   4 speed trans starts in 2nd unless you floor it or manually engage 1st before you start off.
Daniel
1977 450 SEL 6.9 - Astralsilber

Sonch

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Re: Basic Question for 79 450 SEL
« Reply #3 on: 19 November 2020, 09:13 PM »
Thanks guys. Yeah the redline is way higher, plenty of breathing room above 4K...and no I’m not sure it’s a 3 speed, was going on general info I’d read

rumb

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Re: Basic Question for 79 450 SEL
« Reply #4 on: 20 November 2020, 04:47 AM »
These MB engines were made to run at 4k all day long.Sounds great driving it daily.
 
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

daantjie

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Re: Basic Question for 79 450 SEL
« Reply #5 on: 20 November 2020, 07:09 AM »
Thanks guys. Yeah the redline is way higher, plenty of breathing room above 4K...and no I’m not sure it’s a 3 speed, was going on general info I’d read

Yup looks like 3 speed was standard from factory though of course a trans swap may have been done though I would say unlikely.  You can test by dropping into “L” when stopped then back to “D” before you step on gas, then count the shifts from pull away.
Daniel
1977 450 SEL 6.9 - Astralsilber

Sonch

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Re: Basic Question for 79 450 SEL
« Reply #6 on: 20 November 2020, 07:17 AM »
While I have you guys "on the line" (still counts as 'basic question', admin!  :P). . .what oil do we recommend for this car?

daantjie

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Re: Basic Question for 79 450 SEL
« Reply #7 on: 20 November 2020, 09:14 AM »
While I have you guys "on the line" (still counts as 'basic question', admin!  :P). . .what oil do we recommend for this car?

Depends very much on your ambient temps.  Looks like you are in Michigan so nice and cold in Winter.  So I personally would go for 10W Winter and then 40W summer, so a 10W-40 should be nice.  You can go 5W as well of course if really cold.  Stay away from synthetic, conventional only.  Castrol GTX is my personal choice.  You could also go 5W-30 if your summer temps are low, but I think 10W-40 will be a nice middle of the road grade.
Daniel
1977 450 SEL 6.9 - Astralsilber

adamb

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Re: Basic Question for 79 450 SEL
« Reply #8 on: 21 November 2020, 01:35 PM »
It's a 3 speed box. The 4000rpm as 80 mph for the 450 sounds right. The car has max speed of 130mph at the red line of about 6500rpm.

130mph/6.5 = 20mph per 1000rpm. 80mph/(20mph/1000rpm) = 4000rpm!

The 6.9 is geared higher via the differential. You can upgrade to 6.9 differential but I would not advise as it will spoil the experience overall.

Randys01

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Re: Basic Question for 79 450 SEL
« Reply #9 on: 21 November 2020, 05:23 PM »
Put it his way...you are not going to wear it out. !!
Whilst 130mph is a theoretical top speed at red line, i don't think anyone gets past low 120's with K jetronic 3 speed US spec.
All academic of course..today's reality is "not how fast can she go?"  but more like "how long can it idle?" ??? :(

Sonch

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Re: Basic Question for 79 450 SEL
« Reply #10 on: 21 November 2020, 05:29 PM »
Haha. Yes! Rough start and idle. Once she’s up and running and down the road, no problem coming back to the idle

TNNBENZ

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Re: Basic Question for 79 450 SEL
« Reply #11 on: 25 November 2020, 09:06 AM »
1977 rev max is around 5300 or 5800 I think, 6300 seems like a big difference in just 2 years......

TNNBENZ

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Re: Basic Question for 79 450 SEL
« Reply #12 on: 25 November 2020, 09:23 AM »
Do you have a radar detector ?  I am too scared to go that fast, I would get a ticket knowing my luck..........

Sonch

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Re: Basic Question for 79 450 SEL
« Reply #13 on: 25 November 2020, 09:54 AM »
I don’t have radar. In Michigan, everyone drives REALLY FAST on the expressways, here near the Gritty Motor City. I’ve commuted to my job 50 miles at ≈ 87mph for about 20 years. Been doing it in my new baby since March.

Gunna garage her any week now for the winter. Anything beyond fuel stabilizer and battery disconnect recommended?

PMcG

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Re: Basic Question for 79 450 SEL
« Reply #14 on: 27 November 2020, 06:12 PM »
Hi, just purchased my '76 450SE back in July, also put on a few thousand miles since!  Aren't these fun to drive?  My revs and speeds were very similar, and got the same advice-- this is what these cars do!  My mechanic also cleaned out the fuel injectors and its become a peppier car since, with 3400 rpm now giving me 80 mph, when it was about 4000 rpm before.  I can get to 70 mph with only 3000 rpm, so the engine is breathing much easier.  Good luck!
1976 450 SE
Diamond Blue Metallic / Navy Blue