excuse me for this dumb question... - PeachParts Mercedes-Benz Forum

ruchase · #1 09-30-2012, 05:48 PM

Hi folks,
I'm getting ready to replace the lower/upper oil cooler lines on my '78 300cd as I address the sources of various leaks. The times I’ve done this, they were on newer 617's so the throttle linkage is to the right of the motor (as you look in from the front). Just to be sure I don't damage anything, I typically disconnect the linkage where it attaches to the firewall since I would have to raise the motor several inches.

Well the thing is I can't figure out how the '78 linkage is set up. It looks like there is a rod running parallel the firewall, but the actual linkage comes through the intake manifold (from the left of the motor looking in from the front) and then attaches to the linkages on the valve cover. Overall it looks like a fairly convoluted setup, and the last thing I need is to bungle the throttle linkage trying to do the oil lines.

Is there any easy way to disconnect this linkage, or should I just not worry about it even though I'll be raising the motor 3-4" to gain access to the oil cooler lines?

Thanks!

junqueyardjim · #2 09-30-2012, 07:31 PM

Take a couple of pictures of it, save the pictures and take it a part. Do the same thing as you have done many times before in changing your oil lines. When finished with the oil lines, put the linkage back together. If you have difficulty remember you have the pictures.

Diesel911 · #3 09-30-2012, 07:41 PM

Is your Car a Diesel?

It is not uncommon to strip the Aluminum Nipples on the Oil Cooler due t corrosion of the Aluminum to the Steel Nipples.
There is a repair for that but there is a few threads on how to decrease the chances of it happeining.
It happend to me on one of my Nipples.
DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum

PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

vstech · #4 09-30-2012, 09:04 PM

on the 78 it should be no big issue, as the a/c compressor is on the other side. you may not even have to lift the motor. that said, if you do have to unhook it, I'd just pop it loose at the firewall. I have a 78 parts car, so I can take a pic for you if you like... and make suggestions for you.

whunter · #5 09-30-2012, 09:28 PM

I hope one of these helps.

300td no shifting, no vacuum -- pump diaphragm?

78 300D linkage and idle adjust questions

300D Turbo: Accelerator Linkage Kit?

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ruchase · #6 09-30-2012, 10:24 PM

Thanks for the usefuly info folks!

Diesel911 yes its a 300cd. I'm praying I don't strip any of the oil cooler fittings; however, I've already had trouble with several rounded bolts & a frozen trans cooler line while I was working on a leaky WP housing seal (to block) a few weeks ago, so this wouldn't be a surprise.

Just to be sure, I might take the blowtorch to each of the fittings for a few seconds then apply some liquid wrench overnight. Thankfully the 2 times I've done this before it hasn't been an issue.

whunter · #7 09-30-2012, 10:33 PM

You want to bookmark this link.
It has every possible disaster and repair covered in great detail.
Engine oil cooler and hose/line issue, link thread

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Govert · #8 10-01-2012, 04:35 AM

It is this type of linkage:

The rod runs along the firewall, connects under the intake manifold to a lever, that lever connects to the control rod for the transmission. As the IP needs to be actuated too, there are rods running over the valve cover to the IP.

It is a carry-over from the W115 setup. It is decribed in the FSM, so you can look it up there too.

ruchase · #9 10-01-2012, 10:59 PM

Thanks much!

spdrun · #10 10-01-2012, 11:02 PM

I'm replacing mine soon. I've heard of a procedure where you cut through the metal crimp bands holding the rubber lines to the metal ones. Then cut off the rubber lines. Install new rubber (rated for oil, use hydraulic line) portions and clamp them to the nipples with two stout hose clamps per end.

No removal of fragile fittings required.

Diesel911 · #11 10-04-2012, 11:46 AM

Quote:

Originally Posted by spdrun

I'm replacing mine soon. I've heard of a procedure where you cut through the metal crimp bands holding the rubber lines to the metal ones. Then cut off the rubber lines. Install new rubber (rated for oil, use hydraulic line) portions and clamp them to the nipples with two stout hose clamps per end.

No removal of fragile fittings required.

That is what I ended up doing.
I stripped 3 threads off of one Nipple on my Oil Cooler. I was new to Mercedes and the Forum and had not read about the Repair.

As you said I ground a groove in the crimpped Collar on the Hoses and pried them off with a Screwdriver. (My thread is somewhere; I don't know if the pictures show up any more.)
I use GoodYear Push or Slip Fit Hose. But, what I found is that 1/2" ID Hose is too tight and the 5/8" Hose is a sloppy fit. So, I used 2 Hose Clamps on each end of the Hose.
That was 4+ uears ago. The only issue I have had is I found one connection wet. I tightend the Clamps more and have had no other issues with the Hoses.
However, the GoodYear Hose is rather in-elastic.

I did the same thing when I replaced the Oil Cooler Hoses on my Chevy Astro Van.
What I found out is that the left over 1/2" Hose I that was too tight for the Mercedes turned out to be too sloppy for the Van. Even though the Hose on the Van is 1/2" ID.
I got some 1/2" ID Parker Hose from the local Autozone where it is sold as Power Steering Return Hose. Not only was the ID smaller than the GoodYear Hose but it is more elastic.

So if I ever have to replace the GoodYear Hose I will go with the Parker Hose.

Some people don't like the looks of the Clamps others are leery that the Hose will slip off.

And, in fact that did happen to someone who bought a Car where the Prior owner had replaced only the Hose. The Hose silpped off and the lack of Oil did in the Engine.

On the other end of it a lot of ad on Oil Coolers are installed with Hose clamps and in My case I find it hard to believe a Hose with 2 clamps holding it on is going to slip off.

Another Member bought an Air Conditioning Hose Collar Crimpping Tool and replaced the Hose and crimpped on the Collars.