Pressure in coolant system - PeachParts Mercedes-Benz Forum

Manual Life · #1 03-19-2011, 03:13 PM

This is for an 85 300D engine.

I viewed the thread posted by Dieseldan about this problem. Apparently I'm having the same issue as he was/is. I have pressure in the coolant lines after a short and long drive.

Here is the situation. The temp gage fluctuates some. Always between about 78 and 84 degrees but usually just below 80. Goes over 80 if I drive above 70mph but stays below under that speed. Given hose facts is that normal for these engines? Should I replace the thermostat?

Second, I've driven long trips and around town. Temp and pressure stay about the same. Coolant is 6 months new and flushed. No coolant is consumed. When I release the air from the over flow tank it smell like coolant and nothing else. And the pressure is gone over night.

Then, the bypass line use to weep but it no longer does. However, the overflow line weeps a tiny bit, as in very minor.

That's what's going on. I seek a solution. Any ideas? I would like to have this taken care of before the summer heat arrives.

dagObx · #2 03-19-2011, 04:39 PM

Not too familiar with the 123's, but it sound like normal engine operation to me. Others will chime in...

tbomachines · #3 03-19-2011, 05:37 PM

What exactly is the problem to which you seek a solution? Everything you described sounds completely normal

patbob · #4 03-19-2011, 05:38 PM

Any pressure should be heat related -- there when the engine is hot, not there when it isn't. That's what I've observed with my 83. I don't even see much pressure after a drive, but I've never checked after a drive in the heat of summer. To me, "seeing pressure" = resistance when I squeeze the top radiator hose.

whunter · #5 03-19-2011, 05:39 PM

Quote:

Originally Posted by Manual Life

This is for an 85 300D engine.

I viewed the thread posted by Dieseldan about this problem. Apparently I'm having the same issue as he was/is. I have pressure in the coolant lines after a short and long drive.

Here is the situation. The temp gage fluctuates some. Always between about 78 and 84 degrees but usually just below 80. Goes over 80 if I drive above 70 mph but stays below under that speed. Given hose facts is that normal for these engines? Should I replace the thermostat?

Second, I've driven long trips and around town. Temp and pressure stay about the same. Coolant is 6 months new and flushed. No coolant is consumed. When I release the air from the over flow tank it smell like coolant and nothing else. And the pressure is gone over night.

Then, the bypass line use to weep but it no longer does. However, the overflow line weeps a tiny bit, as in very minor.

That's what's going on. I seek a solution. Any ideas? I would like to have this taken care of before the summer heat arrives.

Possible issues:

#1. Plugged breather line = trapped air/water pump cavitation = replace MB# 1152000058

#2. Head gasket bad = plan two - three day for this.

Head Gasket Set, NOTE: Does not include Valve Stem Seals or Valve Cover
Gasket.
MB# 617 010 88 20

Turbocharger Mounting Kit, Contains: (1) Turbo Mount Gasket (1) Exhaust Manifold Gasket (2) Oil Line Gaskets (4) Seal Rings
MB# 617 090 06 80

seal ring, turbo oil feed, 2 per engine
MB# 007603014104

Diesel Fuel Return Hose, 3.2 X 1.9 mm (Sold by the Meter)
MB# 6050780581

Prechamber Heat Shield, At Diesel Nozzle Tip, 5 per engine
MB# 617 017 03 60

Valve Cover Gasket
MB# 617 016 01 80

Valve Stem Seal Kit, (1 Per Car)
MB# 617 050 00 67

Grommet, turbo drain tube
MB# 6171870185

seal ring
MB# 0049975348

.

Manual Life · #6 03-20-2011, 06:03 PM

Problem?... concerned about pressure in the coolant. I understand coolant systems are made to maintain a certain amount of pressure in the lines but mine seemed slightly excessive... by my standards. Nothing major just need to plan ahead in case I need to do an operation in the future.

In the past, all the cars I have owned and worked on were gassers. So that is why I am asking about these/my engine. To make sure things are normal.

And I liked everyone else's response except Wunter's b/c I was thinking small head gasket leak. However, I will go ahead and believe that is not the case. No oil is consumed in 3k miles, nor is coolant, blow by (I use this to state the condition of the engine) is almost nil.

Thanks guys.

leathermang · #7 03-20-2011, 06:06 PM

Listen, this is a physics question and you are talking about it like it is a sociology question... a ' feelings' issue... get a pressure tester and see if you are running more than the stated pressure on the radiator cap...
If so get back to us with what you find.

whunter · #8 03-20-2011, 08:43 PM

Quote:

Originally Posted by Manual Life

Problem?... concerned about pressure in the coolant. I understand coolant systems are made to maintain a certain amount of pressure in the lines but mine seemed slightly excessive... by my standards. Nothing major just need to plan ahead in case I need to do an operation in the future.

In the past, all the cars I have owned and worked on were gassers. So that is why I am asking about these/my engine. To make sure things are normal.

And I liked everyone else's response except Wunter's b/c I was thinking small head gasket leak.
However, I will go ahead and believe that is not the case.
No oil is consumed in 3k miles, nor is coolant, blow by (I use this to state the condition of the engine) is almost nil.

Thanks guys.

If it is issue #1 = replace a $14.00 part and it is fixed.

If it is issue #2 = continued driving can result in this http://www.peachparts.com/shopforum/showthread.php?t=285883

toecutter · #9 03-21-2011, 01:10 PM

...or this (toyota 2lt, cracked head then dropped pre-chamber after continued driving):

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode