"New" 79-300CD with blowby - Page 2 - PeachParts Mercedes-Benz Forum

barry123400 · #16 06-01-2007, 08:41 AM

First of all North Carolina is warm enough to run straight 40 grade oil for a large portion of the year. Try it as it will reduce oil consumption to some extent maybe even substantially.
From now on I will remove the glow plugs and apply a shot of marvel mystery oil into each cylinder of my new aquisitions and let the car sit with the block heater turned on for a few days. This should soften up any carbon trapped around the rings.
It is just to eliminate any chance that there is carbon in the ring grooves. Of course if it made a major improvement I would soak it again. In most cases of worn rings or bores there will be no improvement. That is to be expected yet the marvel mystery oil is so cheap it's worth the small amount of effort involved in my opinion.
Just remember to spin the engine over before putting the glow plugs back in. This eliminates any chance of a hydrolock occuring. The marvel mystery oil will probably have gone passed the rings but why take chances.
I have just started to wonder if a few engine restorers other than the viscosity increasers are just solvents to clean out the rings basically. The engine restorers that pour out of the cans with a fairly thin viscosity may be the ones that are primarily solvents. What we generally preffer to call snake oils. That may be the reason why they help some engines and do absolutly nothing for others.
If results are favorable I have a couple of other ideals. Let's see how you make out with this approach first to see if they are worth pursuing. In the vast majority of cases the attempts to clean out stuff will probably have no effect. On some cars though it could be considerable. For the low cost involved I really would think about it.
We already have some examples of increased compression on unheated vegatable oil burners by soaking them down. They built coke or carbon in their rings fast. Even burning diesel is going to eventually accumulate carbon but at a very slow rate. The actual quantity of accumulations might be determined by how the car was used over the years. I think the jury is out in this whole area to some extent. We need feedback.
The synthetic oils may be removing carbon as well. If there is a reduction of consumption something is causing it. Certainly I do not suspect they seal any better than regular oils by themselves. If their operating viscosity is much the same that is. Also that better sealing by the synthetics themselves can be eliminated somewhat as their seems to be a gradual improvement of sealing over time in my opinion.
I just love being out on the end of tree limbs too much to stop now. You did ask for ideals. Let us know how you do and what you do as it is the only way to increase our knowledge base. Hopefully there will be some improvement.

vstech · #17 06-01-2007, 09:26 AM

Quote:

Originally Posted by dazsa

Also, there is a thick electrical wire about 3 inches long with a loop electrical connector on that is loose and the other end is attached to engine block. It is located below the front glow plug. It looks like the loose end should be attached to that close glow plug. Could it be a ground strap? It is not on my 81 300SD or the 84 300D.Any further info will be appreciated.

AAAAAAHHHHH! do not hook up that strap! it sounds like it's from the old serial plugs. it is not needed on pencil converted plugs.
John

Lonesome · #18 06-01-2007, 01:56 PM

check your motor mounts too, if they are bad you will have a terrible idle.

FlossHogg · #19 06-01-2007, 03:43 PM

Get the valves adjusted!!!!!!

Check for leaks. Change all the filters air/fuel/oil/transmission. Change all the fluids - the diesel too. Then run some seafoam or diesel purge through it. Clean out the banjo bolt line connected to the back of the intake manifold and viola.

I would say these diesels can be brought back to granduer with only a minimal amount of basic maintainence.

Bajaman · #20 06-01-2007, 03:48 PM

Quote:

Originally Posted by FlossHogg

Get the valves adjusted!!!!!!

Check for leaks. Change all the filters air/fuel/oil/transmission. Change all the fluids - the diesel too. Then run some seafoam or diesel purge through it. Clean out the banjo bolt line connected to the back of the intake manifold and viola.

I would say these diesels can be brought back to granduer with only a minimal amount of basic maintainence.

His is an NA so no banjo cleaning necessary. Check the oil fill cap gasket. If that rubber gasket is hard, it will allow oil that is splashed/slung up to escape. "Smoke" coming from the valve cover is partially burned fuel and oil vapor or blowby. As you probably know from searching, lots of blowby and a rough idle will usually point to low compression. Thats one of the first things I would check.
bb

dazsa · #21 06-09-2007, 09:42 PM

OK... I changed the fuel filters, adjusted the valves, replaced the oil cap gasket, and cleaned everything. I took pictures of the hookups on the top of the valve cover and I followed that. However, the linkage seems to be sticky... have I done something to create this?

On the good side, the idle is a little better and no oil is coming out of the oil cap! It seems like it is still missing occasionally.

I think I need to replace the motor mounts to smooth it out more. I am most concerned about the accelaration sticking.

Thanks, Don

JimmyL · #22 06-09-2007, 11:43 PM

The idle adjust knob on a non-turbo engine is on the dash, just above and to the left of the steering wheel. Turning it ccw raises the idle, and if the idle is real low it will not be very smooth. ALSO, when turning it ccw, push down on the accelerator pedal first, then turn the knob left. This will take the "load" off the plastic knob and it will last longer before it splits......

We would certainly like to see pics of the car!

vstech · #23 06-09-2007, 11:52 PM

and pics of the motor, you didn't hook up that thick electrical wire did you?
give us a pic of that too.

dazsa · #24 06-14-2007, 12:52 PM

I finished out of the intended maintenance and replacement projects as mentioned and it is running a little better. I did a diesel purge and it sounds better, but I am getting some leaking at the base of the injectors. It still idles rough and has some nailing. Oh, accelerator sticks a little.

THE BIG deal is that I did the informal compression test of covering the breather hose outlet. First, when I took off the breather hose, it smoked like a coal train! Then, when I covered the breather...it shut off the engine immediately! No five seconds or even 1.5 seconds!

Now, the guy told me that he thought that was the case and I bought it for $500 with a rust-free body, new tires, new starter, and a very good interior.

Are there any tricks I can try or just start looking for another engine?

Thanks, Don

I will post some pictures in the next few days.

P.E.Haiges · #25 06-15-2007, 12:22 AM

Here's a trick: Replace the rings.

P E H

pitansk · #26 06-15-2007, 03:51 AM

Quote:

Originally Posted by JimmyL

ALSO, when turning it ccw, push down on the accelerator pedal first, then turn the knob left. This will take the "load" off the plastic knob and it will last longer before it splits......

We would certainly like to see pics of the car!

im sure thats why mine is broken!!!