Don't own a Merc, but have two VW TDIs.

The wife's Jetta recently showed a "rise" in coolant level in the expansion tank, with no other symptoms at all. The car is stock, has 160,000 miles, and has never overheated. TB and water pump were changed 1 year ago. Coolant was added then, and hasn't been touched since.

No overheating, no water or glycol in the oil on oil analysis, no white smoke, no rough running, no bubbling when reservoir cap is removed.

Nevertheless, because the pressure inside the EGR cooler is lower than the pressurized cooling system, a bad head gasket remains suspect #1.

There is no real discoloration of the pink coolant, so oil cooler seems to be out as the culprit.

Thus, I was wondering if there is a chemical test to determine whether exhaust gases (diesel) are in the coolant.

Thanks for your indulgence and any feedback would be greatly appreciated.

__________________
2000 VW Golf TDI 5M 216K mi
2000 VW Jetta TDI-A 250K mi

That test is called a "soot test" or "particulate test". Blackstone labs at one time did them.

__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

You can also remove squeeze the upper radiator hose, after the engine has cooled. There should not be any pressure on a cold engine's upper radiator hose.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

The coolant usually will become noticably darker in color because of the soot/carbon carried in the exhaust gases.

__________________
FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

Wouldn't this work on diesels as well as gas engines. It's just looking (chemically) for CO in the coolant.

http://www.etoolcart.com/index.asp?PageAction=VIEWPROD&ProdID=8195

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

That's very slick!

__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

That's cool.

Thanks a lot guys!

On edit:

Didn't I hear something about very little or no carbon monoxide in diesel exhaust? For example, one can't commit suicide by running a diesel engined vehicle in a closed garage.

Would this Combustion Leak Tester be better, since it claims the test fluid is for gas or diesel??

__________________
2000 VW Golf TDI 5M 216K mi
2000 VW Jetta TDI-A 250K mi

I've used another maker's version of that last kit, one that required seperate fluids for diesel and gas. They work REALLY well for detecting bad stuff happening in the cooling system.

I found a cracked head with one, almost instantly shifted colors in the fluid.

I'm told that some shops will use exhaust gas analyzers waved over the coolant fill port to detect it, as well.

__________________
-Josh
Testing the cheap Mercedes axiom, one bolt at a time...

I have used and exhaust gas analyzer for that purpose but only on gasoline engines. On diesel engines there is not enough carbon monoxide in the exhaust to detect with the analyzer.

Thanks for the feeback.

I'm going to purchase that kit thru Amazon and will post the results.

napa carries the block testers and block test fluid

__________________
have no worries.....President Obama swears "If you like your gun, you can keep it