Newbie's 250C - PeachParts Mercedes-Benz Forum

NewWilOrder · #1 09-15-2008, 12:41 AM

Hi,

I'm new to the forum & just purchased my first Mercedes, a 1970 250C.

119k, service records, original manuals. Runs, drives, & shifts well.

New fuel pump, radiator, & A/C compressor.

Typical rusty floorpans & needs some vacuum lines replaced.

I didn't pay too much so, all in all, I feel pretty good about it so far.

Any 250C owners out there have any advice for me? It'd be appreciated!

Here are some pics:

alabbasi · #2 09-15-2008, 01:47 AM

Great looking car... the biggest thing to watch out for on these old cars is the rust. It will eat everything up if you don't watch out.

I have the injected versions but I understand that the carbs can give problems and the heater if not working is a pain to fix.

Other then that, these cars are an absolute hoot to drive and me good daily drivers provided that you don't mind spending a little money on gas.

Mike D · #3 09-15-2008, 07:21 AM

Check the the front subframe mounts out very carefully. The rear buckets on the 250C's front subframes have a nasty habit of rusting. Check the power steering mounting bolts, in fact, replace them with new 10.9 hardened bolts and re-torque just for peace of mind.

Great looking car. Nice score!

pj67coll · #4 09-15-2008, 01:37 PM

Quote:

Originally Posted by Mike D

Check the the front subframe mounts out very carefully. The rear buckets on the 250C's front subframes have a nasty habit of rusting. Check the power steering mounting bolts, in fact, replace them with new 10.9 hardened bolts and re-torque just for peace of mind.

Great looking car. Nice score!

Lovely looking car. I'd agree about the rust warning though. MikeD can you elaborate on the hardened steering bolts? Does that apply to 108's as well? Mine snapped on the first Mercedes I owned and I've never heard about strengthened mounting bolts till now.

- Peter.

Mike D · #5 09-15-2008, 02:26 PM

The 10.9 designation are the proper "case hardened" bolts to be used. All too often you'll find someone has replaced them with the 8.8 "standard" (non hardened) bolts. If they dont state "10.9" on the head of the bolt then they shouldn't be trusted. ANY and I mean ANY time you find a loose steering gear box bolt on any Benz/car, remove the existing bolts and replace with NEW! Never re-use a hardened bolt! It's not only YOUR life but I just might be on the same road as you.

NewWilOrder · #6 09-16-2008, 03:02 PM

Thanks for all the advice, everyone!

I'm sure I'll be back with plenty of questions soon enough...

NewWilOrder · #7 09-16-2008, 09:38 PM

Okay, so I've had the car for 3 days & she's already given me a project:

The defrost, side, center, & floor heating vents all worked perfectly when I got her. Then, all of a sudden - nothing!

The AC still works.

If the blower motor died, would it just quit like that?

I've read all about the horror of tearing the dashboard out to replace the blower motor but I'm wondering (praying) that it's something else.

Could it be the heater switch? If so, where is it?

Could it be a fuse located somewhere other than in the main fusebox on the drivers' side in the engine compartment? If so, where would it be?

Could it be something else? If so, what could it be?

Any ideas anyone?

Thanks!

250 Coupe · #8 09-16-2008, 10:01 PM

Nice car. I just sold my 1971 250C and I do miss it.

There are two fans, the heater blower is in the exact geometric center of the universe and is a bit hard to replace. The AC fan is just behind the grill just in front of the shifter and easy to get to.

The change over switch is just above the throttle pedal and to the inboard side. It's connected to a vacuum actuator that selects the air source, fresh VS recirc.

Michael

NewWilOrder · #9 09-17-2008, 07:33 AM

"The change over switch is just above the throttle pedal and to the inboard side. It's connected to a vacuum actuator that selects the air source, fresh VS recirc."

Hi Michael,

Yeah, I found that. When I press up on it, sure enough it blows hot air. But isn't that just the AC fan blowing hot air from the wrong source?

- Wil

Mike D · #10 09-17-2008, 08:03 AM

The change over switch changes the electrical power from the central A/C recirculating fan to the heat/defrost fan located behind the center console/heat exhange box.

The heat fan will not engage unless the vacuum (controlled by your A/C control switch) is switched from A/C to heat.

JMURiz · #11 09-17-2008, 01:52 PM

Great looking car, LOVE those small bumpers, I'm still looking for a set to back-date my 280C.

I guess I should look into that bolt upgrade on my car as well.

Mike D · #12 09-17-2008, 02:27 PM

The 10.9 bolts were original on ALL MB's. It isn't an "upgrade". Over the years your bolts might have been changed to 8.8 grades simply because a former mechanic might not have known.

Yearly checking of the torque on those bolts should included in your maintenance schedule. If you keep them torqued, then you should never have to replace them. 10.9 bolts are harder than 8.8 but this also means they are more "brittle". They are not designed for any "give" or "stretch". They will snap before they bend.

If you find one with enough "give" to allow the washer to actually move then replace all of them and re-torque. It might simply be due to "give" in the frame rail (kind of a scary thought in itself) but why take the chance for $5 in cheap insurance? The loss of a few pounds of torque is common but a quarter turn is getting into the replacement zone.

250 Coupe · #13 09-17-2008, 04:33 PM

Quote:

Originally Posted by NewWilOrder

"The change over switch is just above the throttle pedal and to the inboard side. It's connected to a vacuum actuator that selects the air source, fresh VS recirc."

Hi Michael,

Yeah, I found that. When I press up on it, sure enough it blows hot air. But isn't that just the AC fan blowing hot air from the wrong source?

- Wil

You should get one fan with the switch made and the other with the switch not made.

The air flow path is different between the two blowers but I don't remember if the AC fan will blow hot air. I don't think it will which means that the vacuum hoses that you mentioned earlier might be losing enough vacuum to keep the actuator from working correctly.

Now that I think about it, I did wedge something in the switch to get the AC fan to run on my '76 280C so I would have air flow to demist the windshield but it didn't really work as the air was not heated.

Michael

NewWilOrder · #14 09-17-2008, 08:11 PM

It's sounding more & more like a vacuum problem, since I AM getting hot air when I use the changeover switch by hand.

Hopefully, I'll stumble across the right vacuum line & it'll start working again...

Thanks for all your help guys!

I'll take a look at those steering mounting bolts, too.

Thanks again!

- Wil

NewWilOrder · #15 10-22-2008, 07:22 AM

Quote:

Originally Posted by NewWilOrder

Okay, so I've had the car for 3 days & she's already given me a project:

The defrost, side, center, & floor heating vents all worked perfectly when I got her. Then, all of a sudden - nothing!

The AC still works.

If the blower motor died, would it just quit like that?

Could it be a fuse located somewhere other than in the main fusebox on the drivers' side in the engine compartment? If so, where would it be?

Turned out to be a 40 year old fuse... just goes to show you, don't over think things...

It was on the passenger side firewall.

Pulled it, replaced it, have heat/defrost again - just in time for winter, too!

Now, back to the drive shaft...

- Wil