How Much Coolant in Oil in Order to Be Visible? - Page 3 - PeachParts Mercedes-Benz Forum

tobybul · #31 12-10-2010, 04:49 PM

if u r lossing coolant and its not thru the cap or any part of the exp tank, then u may just be wasting $$$ replacing it. why not just clean it. I suggest send in your oil for analysis instead of swapping parts out. Then you'll know for sure.

I normally get test results from Blackstone the same day they receive the sample. The report is emailed to me. Since I'm in Michigan and their in Indiana, they get UPS the next day.

leathermang · #32 12-10-2010, 07:48 PM

In the old days we would withdraw the oil dip stick when the engine is hot and let it drip on the exhaust manifold...
If water was present it would ' sizzle' ...

Water is hydrogen and oxygen. oxidation of engine oil or transmission fluid causes a sharp increase in halving the lubrication of the fluid.... just as high temperatures does...for the same reason.. oxidation.... an example of accelerated oxidation due to temperature with transmissions ... rocking the trans from low to reverse to attempt to get it out of a hole... after a certain point an increase of a few degrees halves the life of the trans fluid... it can mean that after one pot hole event the trans fluid should be changed... depending on the temperature which was reached.... the charts are somewhere on the internet I am sure...
Spraying (by the piston cooling squirters ),pumping, etc, and other things the oil goes through inside the engine may not cause the water to ' evaporate' fast enough that the ill effects of it being present are avoided...

layback40 · #33 12-10-2010, 08:10 PM

Given that types of glycols are one of the the raw materials for some synthetic oils, its unlikely that a small amount in the oil is going to be of concern compared with say soot in the oil. If the coolant was finding its way into the combustion chamber I would be much more concerned, see whunter's recent thread with pics of a failed head.
If it isnt going down so much with the level a little lower, it sounds like you are loosing water vapor out the overflow.
There are probably many other things that should be of more concern.
It will be interesting to see the oil test results.

Glowplug · #34 12-11-2010, 06:28 AM

You sure you're not losing any coolant via an old cracked hose? Possibly a water-pump in it's final death throws starting to weep coolant ?

I've seen plenty of Head Gaskets go at the track, mostly Small Block Chevrolets. The amount of water contamination really is the key here. I've witnessed some pretty major leaks into the oil system, oil looks almost white/tan in color. The first signs of viscosity break down due to water contamination are in the valve train, since the camshaft/lifters are the last stop in the motor to receive oil the un-mistakable sound of the lifter eating itself and your cam-lobe should be unmistakable. However, sometimes you get lucky and the HG leak is between the water jackets and is dumping directly into the combustion chamber and out the exhaust, this allows you to limp along longer, but eventually the non-compressible H20 in the combustion chamber will cause you to throw a piston rod.

Also, your oil pressure would drop significantly due to the frothy milky mess its trying to pump to those bearings.

Being that Deisel engines run at very high compression, 16-18 to 1 compression, a compromised H.G. is more likely to cause greater harm at a faster pace.

shertex · #35 12-11-2010, 06:42 AM

Quote:

Originally Posted by Glowplug

You sure you're not losing any coolant via an old cracked hose? Possibly a water-pump in it's final death throws starting to weep coolant ?

No, not sure. In fact, I'm hoping that's the case. But I haven't seen any evidence of leaks yet (not that I'm a skilled observer, mind you).

Since it's been 36,000 miles since I've done an oil analysis, I thought it would be interesting to do that and hopefully rule out any engine issues. And I'll replace the cap, just because. If the level is still going down, I'll probably just keep a close eye on it, maybe have my tech look at it next time I have it in for something else.

shertex · #36 12-11-2010, 06:44 AM

Quote:

Originally Posted by layback40

Given that types of glycols are one of the the raw materials for some synthetic oils, its unlikely that a small amount in the oil is going to be of concern compared with say soot in the oil. If the coolant was finding its way into the combustion chamber I would be much more concerned, see whunter's recent thread with pics of a failed head.
If it isnt going down so much with the level a little lower, it sounds like you are loosing water vapor out the overflow.
There are probably many other things that should be of more concern.
It will be interesting to see the oil test results.

Yes, the decreasing rate of loss makes me continue to suspect the overflow system. But, if that's the issue, shouldn't the loss stop at some point? Or not necessarily?

Glowplug · #37 12-11-2010, 06:53 AM

As minute as your coolant loss is, i doubt it's anything more than evaporation or a tiny leak coming from a brittle hose.

I believe there is a simple test for a HG breach on the aluminum headed Diesels (and please someone correct me if i'm wrong). After normal driving, park car let it sit for a few hours, preferably overnight, then in the morning pop the hood and check for a bloated/tense/pressure filled upper radiator hose, if it is stiff after sitting this usually indicates a HG breach. However a flaccid hose that you can cave in with your hand means that all is well.

shertex · #38 12-11-2010, 06:58 AM

Quote:

Originally Posted by Glowplug

As minute as your coolant loss is, i doubt it's anything more than evaporation or a tiny leak coming from a brittle hose.

I believe there is a simple test for a HG breach on the aluminum headed Diesels (and please someone correct me if i'm wrong). After normal driving, park car let it sit for a few hours, preferably overnight, then in the morning pop the hood and check for a bloated/tense/pressure filled upper radiator hose, if it is stiff after sitting this usually indicates a HG breach. However a flaccid hose that you can cave in with your hand means that all is well.

Just checked the hose....very flaccid indeed. Car had sat for 10 hours after having been driven.

Loosened expansion tank cap and there was the TINIEST bit of expulsion of air. Almost negligible, but it was there. Should that concern me?

layback40 · #39 12-11-2010, 07:01 AM

One last suggestion.
If you have a quart bottle 1/2 full of water sitting under the hood with the overflow going into it. See if the level in the coolant tank changes.
Just read your latest. That sounds like you dont have a significant HG problem.
Time to just drive & enjoy your car !!

shertex · #40 12-11-2010, 07:07 AM

Quote:

Originally Posted by layback40

One last suggestion.
If you have a quart bottle 1/2 full of water sitting under the hood with the overflow going into it. See if the level in the coolant tank changes.
Just read your latest. That sounds like you dont have a significant HG problem.
Time to just drive & enjoy your car !!

Not sure I understand the suggestion.

But, yes, I'm beginning to relax a bit. My hope is to make it to 300K without anything MAJOR major....still in good shape, I hope.

Glowplug · #41 12-11-2010, 07:14 AM

No thats a good thing! A good tight seal is what you want on your coolant system.

As little air in the system as possible especially with a closed-loop type of coolant system.

I just wonder if your thermostat isn't starting to go bad, I.E. not popping oppen at correct temperature and it's causing the coolant to heat up more than it should which would cause steamy/boiling temps just long enough to build pressure in your overflow bottle and purge/overflow a small amount of coolant before the thermo finally pops open to allow the coolant to flow through the block then radiator?

If you've ever popped your overflow bottle while the engine was still hot, you'd know what i mean. It comes gushing out under pressure, the pressure will try to equalize itself and will literally PURGE your coolant with force directly out of your motor, maybe this is happening on a much smaller level of course, as your vehicle was designed with a hose to that empties below the engine bay just for this purpose on hot days and higher engine temps.

layback40 · #42 12-11-2010, 07:21 AM

I am suggesting that the overflow pipe from your existing tank could be put into a bottle. It may no have a long overflow pipe. It comes off the neck of where the radiator cap goes.

shertex · #43 12-11-2010, 07:33 AM

Quote:

Originally Posted by Glowplug

I just wonder if your thermostat isn't starting to go bad, I.E. not popping oppen at correct temperature and it's causing the coolant to heat up more than it should which would cause steamy/boiling temps just long enough to build pressure in your overflow bottle and purge/overflow a small amount of coolant before the thermo finally pops open to allow the coolant to flow through the block then radiator?

If you've ever popped your overflow bottle while the engine was still hot, you'd know what i mean. It comes gushing out under pressure, the pressure will try to equalize itself and will literally PURGE your coolant with force directly out of your motor, maybe this is happening on a much smaller level of course, as your vehicle was designed with a hose to that empties below the engine bay just for this purpose on hot days and higher engine temps.

Thermostat is seven years and 85,000 miles old, so I'm probably not far from needing a new one. But, temperature wise, everything seems to works fine....comes up quickly to 82C and stays there.

Keep in mind that, on my car, the overflow tube from the expansion tank goes into an overflow tank (behind right wheel well). If the system is operating properly, any overflow is sucked back into the expansion tank when the system cools down. So, at the end of the day, even if what you're describing is happening, I shouldn't lose any coolant....IF the overflow system is working as it should.

Glowplug · #44 12-11-2010, 07:40 AM

Then one fun and easy way to check with certainty is to hit your local Parts store and get florecent radiator die, add a bit to your coolant run through system, pull in garage or wait for a nice dark night and break out the UV or Black Light and start inspecting. Might be something as simple as a cracked overflow tank.

shertex · #45 12-16-2010, 04:47 PM

Got my oil analysis back. Good news: no evidence of coolant whatsoever! So that's a relief. Whatever my coolant loss is due to, it's not the head gasket.

FYI my soot level was 1.1% after 7750 miles....pleased with that too. Interestingly, they automatically flagged that as "Severe." But I'm told that all generic Mercedes get flagged at 1%. I guess I'll push on to 10,000 miles.