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  #1  
Old 09-30-2009, 10:45 PM
latief's Avatar
1993 300E 2.8- M104
 
Join Date: Aug 2009
Location: Gainesville, FL
Posts: 518
did something stupid today..engine cooling

I finished my headgasket install nearly 4 weeks ago. car was great, and everything went by the book. i flushed out the cooling system, new pump and new behr thermostat........

any how, i drove the car for roughly a week and then it started making a loud screeching noise...so again, took some things apart and found out a bad fan bearing bracket, and a end-of life smog pump bearing....so ordered the parts and started changing the parts...i off course had to drain most of coolant since the coolant pipe above the fan bearing bracket had to come out, and there was still some oily residue in the expansion tank despite the flush i did after the headgasket.....

any how, today, i finished the car, decided to do another system flush using the prestone stuff. i drove it around for a couple of hours to make sure all the scaling and oily residue is removed. then this evening i drained the block and the radiator, flushed with the running water hose, and put in finally some new coolant......


after i started the car once the new coolant was in. i was waiting to top off the system, with the cap off. there was a strange wining noise coming from the water pump area!!! i was very worried, and i was thinking in my head that no coolant is getting to the pump, and that the internal pump bearing will overheat and die..... so i turned off the car, and started again ..the noise came back . so i decided to take out the thermostat, just to see what is going on...it was completely dry in there......i ran it then for a couple of seconds without the thermostat and nothing improved. so i turned it off again not sure what to do...!!! i did not want to destroy the new pump. i opened it back again and installed the thermostat, and put more coolant in the expansion tank.....started the car and the noise stopped....all the sudden the auxiliary fans came on the tempreture was around 105-110 ....!!!!!i was terrified that maybe the pump was damaged complelty,,,,,i turned it off again, and waited a couple of minutes, and then all the sudden the temp went back to normal and everything seemed fine...



so, can anyone explain to me what i did wrong? did i damage the water pump? will a brief jump in temps like that cause any damage? i honestly feel like an idiot, and was commending myself earlier on a job well done on the headgasket....

so what do you guys think? everything back to normal now, should i be worried?


thanks,

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  #2  
Old 10-01-2009, 06:04 AM
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It is my understanding that the M103s & M104s take the high temperatures very well, even up close to or even briefly into the red without too much worry about engine damage. I'm not recommending it of course, but that's what I've heard more than a few times.
As far as the coolant, it sounds like you had barely enough in the block to get the thermostat to open up. When you refill the system after emptying it (particularly if you use the block drain) you're supposed to open one of the cooling system bleed plugs (located on top, front of the head along side the valve cover on the intake side) and fill until coolant comes out of it. Likewise, if you have a bleed plug on top of the thermostat housing, you should open that too, which will help you make sure that everything on the radiator side of the thermostat gets filled properly. make sure you have the heater on high so that coolant fills those portions of your cooling system.
Even after observing those steps you'll still probably have to add a little to top it off after a few drives.
The noise you heard was probably just steam whistling through the system, I doubt you hurt the water pump.

On a side note, getting all the oil residue out of the system after a head gasket failure can be very difficult. It took me about a month to get it all (almost all) out of mine. I drove my M103 for nearly a year with a blown gasket and it got pretty saturated with oil even though I siphoned it out of the coolant tank almost daily. After the new gasket I flushed it 3 times with Dawn dish detergent, with Shout laundry detergent and finally with MB citric acid flush. There was still so much sludge getting into my coolant tank that I was beginning to think it was still leaking. I was avoiding putting in my new radiator, hoses and coolant tank until it got cleaned out. But what I began to realize was that my old radiator & tank were just kind of recirculating the sludge that was finding it's way (floating) to the high points of the system (the top hose, top of the radiator and the coolant tank). The sludge also tends to coat the walls of the system after a while rather than float. So I ran it with just water for a few weeks, cleaning what I could out of the tank each day and letting all the sludge find its way to the top of the system, then I replaced the top hose (old one was just filled with goo, the radiator too), put in a new radiator, and coolant tank and flushed it once more with Prestone flush. After several days, no signs of any sludge, just a light film that should clean out with one last flush before I put in the final antifreeze solution.
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  #3  
Old 10-01-2009, 08:00 AM
pmari's Avatar
OM606.962 177hp 330nm
 
Join Date: Oct 2004
Location: L.I. N.Y.
Posts: 1,033
Bilge Oil Absorber, Single Sheet

Might want to try one of these in the expansion tank. I wouldn't run with it, just let it sit overnight when shes cooled off. Then remove it before you drive. It's only a buck
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did something stupid today..engine cooling-bilge-sheet.jpg  
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How to eliminate oil dependency through market-driven approaches.
“We could cut oil use in half by 2025, and by 2040, oil use could be zero,”

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  #4  
Old 10-01-2009, 08:59 AM
latief's Avatar
1993 300E 2.8- M104
 
Join Date: Aug 2009
Location: Gainesville, FL
Posts: 518
Quote:
Originally Posted by long-gone View Post
It is my understanding that the M103s & M104s take the high temperatures very well, even up close to or even briefly into the red without too much worry about engine damage. I'm not recommending it of course, but that's what I've heard more than a few times.
As far as the coolant, it sounds like you had barely enough in the block to get the thermostat to open up. When you refill the system after emptying it (particularly if you use the block drain) you're supposed to open one of the cooling system bleed plugs (located on top, front of the head along side the valve cover on the intake side) and fill until coolant comes out of it. Likewise, if you have a bleed plug on top of the thermostat housing, you should open that too, which will help you make sure that everything on the radiator side of the thermostat gets filled properly. make sure you have the heater on high so that coolant fills those portions of your cooling system.
Even after observing those steps you'll still probably have to add a little to top it off after a few drives.
The noise you heard was probably just steam whistling through the system, I doubt you hurt the water pump.

On a side note, getting all the oil residue out of the system after a head gasket failure can be very difficult. It took me about a month to get it all (almost all) out of mine. I drove my M103 for nearly a year with a blown gasket and it got pretty saturated with oil even though I siphoned it out of the coolant tank almost daily. After the new gasket I flushed it 3 times with Dawn dish detergent, with Shout laundry detergent and finally with MB citric acid flush. There was still so much sludge getting into my coolant tank that I was beginning to think it was still leaking. I was avoiding putting in my new radiator, hoses and coolant tank until it got cleaned out. But what I began to realize was that my old radiator & tank were just kind of recirculating the sludge that was finding it's way (floating) to the high points of the system (the top hose, top of the radiator and the coolant tank). The sludge also tends to coat the walls of the system after a while rather than float. So I ran it with just water for a few weeks, cleaning what I could out of the tank each day and letting all the sludge find its way to the top of the system, then I replaced the top hose (old one was just filled with goo, the radiator too), put in a new radiator, and coolant tank and flushed it once more with Prestone flush. After several days, no signs of any sludge, just a light film that should clean out with one last flush before I put in the final antifreeze solution.
Thanks for the detailed and helpful response......

quick questions:

other than the drain plug on cylinder 5 (in the block), i don't think my engine has any other draining/ bleeding points....where should it be?

let me understand the logic of the thermostat here. since the car is cold, the thermostat is closed. so once i pour coolant into the expansion tank, is the thermostat preventing it from getting into the block? or is it preventing it from circulating through the radiator?

how does the coolant flow in the system in the first place? the upper hose sends cold(er) coolant into the engine, and the lower hose is supposed to send the warmer coolant back into the radiator? or is it in reverse of this?

also, i have very little residue in the system, just a very thin line of oil marks in my new expansion tank....of course, it is near impossible to remove these since the tank has plastic dividers inside so you can't physically/manually clean it ... I might just live with it for a while especially since i think little more will eventually show up....i might just change the tank again in the near future.....

pmari, thanks for the tip!! where do i get that?

Your answers are much appreciated !!!
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Old 10-01-2009, 02:08 PM
pmari's Avatar
OM606.962 177hp 330nm
 
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Location: L.I. N.Y.
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Quote:
pmari, thanks for the tip!! where do i get that?

A boating supply store or on line if you have to



__________________
1999 E300DT (131,800) 154,000 Black on Black SOLD

2006 CLK 500 coupe Capri Blue on Grey (zoom,zoom)
47,000mi

04 VW TDI Passat 80,000mi
(Techno)

How to eliminate oil dependency through market-driven approaches.
“We could cut oil use in half by 2025, and by 2040, oil use could be zero,”

The Sound of Diesel Speed
Ode to MB
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  #6  
Old 10-01-2009, 03:19 PM
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1. Yes, there is only one drain on the block. On my M103, and I believe similarly on an M104, there are one or two plugs (bolts with copper or aluminum washers/seals) as mentioned in my first post:
"(located on top, front of the head along side the valve cover on the intake side)". I think they're about between the first and second injector (but tapped into the top surface of the head).

2. When you start your car cold, the thermostat is closed. The water pump is circulating coolant but only on through the block, the closed thermostat keeps it from circulating through the radiator. The underside (block side) of the t'stat has a spring that expands when it gets heated by the increasingly hot coolant (the water sitting in the radiator is still cool) and opens the valve to allow full circulation through the radiator. If there is not enough coolant in the block (or the system) the t'stat may not be getting enough immersion with the hot coolant (on the block side where the spring is) for the spring to react and open the valve properly, or when it needs to.
When you fill the coolant tank, and consequently the radiator, yes, you are filling the block to some extent via the large lower radiator hose. But as the coolant rises in the block above the level of that hose it gets backed up against trapped air at the top of the water jackets in the block, head and the top of the water pump where the t'stat is. That is why the recommendation of opening the air bleeds. There is a tiny orifice in the t'stat that allows some air to vent to the other side of it but it would still eventually run into trapped air at the top of the system. I think in many cases you would be able to fill it as normal, run it and keep topping it off until all the air eventually works it's way out, but I think bleeding the air out as mentioned is the best practice and safest for the engine. I've done it both ways, but being aware of how it works is helpful to determine if you need to bleed it.

3. When cold, as mentioned the water pump circulates coolant through the block only which heats it up and gets the car to proper operating temp quickly. Coolant circulates into the block through the water pump where it is bolted to it and returns to the pump via that real short little hose coming from the head called the bypass hose (I suppose because it bypasses the radiator when cold). Even though there is an open hose between the block and the radiator (the large lower rad hose, not to be confused with the smaller hose that comes from the coolant tank) it can't really mix with that coolant as long as the other end is closed by the t'stat. When the t'stat opens the water pump can then pull hot coolant from the block and send it through the radiator via the top hose and back into the block via the large lower hose after being cooled.
Water circulates through the heater core with the assistance of the little electric auxilliary pump located on the fender well below the coolant tank.

4. Same here, since the oil doesn't want to mix with the water, at least not readily, it tends to adhere to the walls of the system. It particularly likes to stick to plastic and rubber. When it gets to the point where it's just a very light film of cream colored or nearly white residue it will probably-maybe-sort of begin to break down and homogenize somewhat with the coolant after a few months of driving and perhaps be able to be eventually effectively flushed.

I wasn't quite true about my procedure in my last post. Actually what happened was, I found a 92 wagon at the junk yard that had a new Behr radiator in it. It too must have had a head gasket job as there was some slight sludge residue in it! But it was way cleaner than mine which still had blobs of dark gunk in it. So I bought it, and the coolant tank for $50 and installed them as interim parts till the system showed that it was pretty much cleaned out (which it already has). I may put the new radiator and tank in at that time or I may save them for my next Benz.

Last edited by long-gone; 10-01-2009 at 03:24 PM.
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  #7  
Old 10-01-2009, 08:53 PM
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Posts: 557
Air Pockets

You probably have 'air pockets' in the cooling system. Not uncommon after the work described. Cooling system needs to be properly bled after
its been evacuated. It takes about an hour to do it right... The cooling is closed loop, there can be pockets of air in this closed loop that move with the coolant and can cause the symptoms you mention. Air cools and warms much quicker than liquid, especially antifreeze. So the temp spikes due to that rapid change in coolant gauge fluxuation. That's the air pockets passing the coolant temp sensor and the sensor goes nuts cause the air is WAY HOTTER than the coolant he just measured. Then, the air pocket clears and real coolant comes into the picture, the sensor realizes that and the gauge goes down...then the air pocket comes around again and the...nevermind...
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Old 10-01-2009, 09:59 PM
latief's Avatar
1993 300E 2.8- M104
 
Join Date: Aug 2009
Location: Gainesville, FL
Posts: 518
thanks to everyone who contributed..this has been a very informative thread for me...i was very worried yesterday, but now i think everything is back to normal and the car is fine (for now)......

cliff, what you wrote makes much sense as the jump from very hot to normal was nearly instant on the temp guage........i guess it was an air pocket, albeit a big one!!!

long-gone, very detailed, informative, and accurate posts my friend, i really appreciated that !!!

I will post more questions if something else happens.....hopefully not!

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