2000 S500. While preparing to locate / repair my timing chain tensioner oil leak, I had to remove the fan and drained the coolant as per MB instructions so that I could remove the alternator and tighten timing chain tensioner which was the source of much headache and the leak. (i will post a write up with pix to aid some poor soul in the future). It took several hours mission accomplished.

However when I re-installed everything, reattached the hoses. Refilled my coolant/distilled water topoff mix in the coolant tank and turned on the engine with the heater turned to max, the engine started to smoke after 5 minutes.

I immediately turned engine off. I have not had overheating issues prior to this and no coolant leak.

I checked the coolant reservoir and noticed that there was no change in coolant level which leads me to believe that coolant was not circulating and I have air in my system. However since I did not do a coolant flush nor I release the coolant screws on the crankcase I thought there should be some coolant in the system. The fan operated as expected and the temp gauge on the dashboard did not climb above 40 before the smoke came from the engine. I turned everything off and went to bed.

The next morning checked coolant reservoir and no change, I tested engine same event (smoke, only slightly as I was ready this time) I also did not see gauge rise above 40 which is what normally happens given that the car was on for only 3 - 5 minutes.

How should I proceed.

I have searched this site and other benz sites and youtubed for bleeding coolant, overheating problems and there is such conflicting information, one could damage their engine by following all of these conflicting DIYs. Some say no need to worry about removing air as the system is self pressuring/vaccumm. Some say you need to have special equipment.

Unfortunately I am low on funds (between jobs so I have to do this myself and do not want to spend more than $50 on equipment and $40 on Coolant (my coolant was blue/greenish and clean no oil/rustiness and I do not see any leaks).

I am asking for instruction on how to determine the problem
how to correctly bleed the system and
how to re-introduce the coolant into the system.

The following is the process as I understand it, please correct where necessary.

To Bleed the system (I do not necessarily want to flush the system, but if that is necessary to get all of the air pockets out I will)

1. Have engine cool
2. Open cap at coolant reservoir
3. Release coolant bleed value (lower driver side) allow coolant to drain.
4. Unscrew coolant bleed value on Engine crankcase allow additional coolant to drain. (Is this necessary for me to get the air out of the system)

This is where I get confused
5. Start engine and turn heater up to max while running tap water through system to get all of the coolant out of the entire coolant system (however since my engine overheats – I am reluctant to do this)
6. Discontinue after all coolant is removed and only water is being released.
7. Turn off engine.
8. Reseal all bleeder screws and ensure all hoses are connected

Now what (Now that all coolant is out of the system but I have water in the system) How do I reintroduce the coolant without reintroducing air.

Do I pour in 8.5 liters of Coolant / Water mix thus displacing the water. How do I do this without introducing air into the system. Do I squeeze the top coolant hose (I did this the first time but maybe something else was missing)

Do I need to purchase that Lisle Spill flow contraption and place it on the coolant reservoir. I see people do this with the engine on but again my engine may/will over heat before the process is complete. Unless bleeding the system from the crankcase which I failed to do previously will solve the engine overheat.

 

Majorpeace, before you go through all that trouble try something very simple. The problem is most likely the water pump still has some air in it. The upper and lower hoses are very flexable. Using both hands grab the upper hose and squeeze it a number of times to force water through the system. You can do the same with the bottom hose but you may not have to. This will move water around in the system and fill the pump. Its like giving your cooling system CPR. It has worked for me in the past. Let me know how you make out.

 

One more thing, when you are running the car turn your heat on high. This will also help push water through the system.

 

Iganski

I am all for simple. I will squeeze the tubing like an amorous lover.

However do I do this with the engine running?

With the top on/off of coolant reservoir?

It just seems strange that I cant get coolant to the rear drivers side of the engine.

Thanks

 

I do it with the engine off so I can hear the air moving. I leave all the covers on. If you decide to do it with the engine running, watch out for all the moving parts.

 

With confidence I started engine. The heater came on and blew warm air as expected. After 3 minutes fan came on. But after 2 more minutes engine started to smoke on rear driver side again. I don't belive it was runoff.

I squeezed the top radiator pump hose both hands several times and the temp gauge never raised above the slow increase in temp (no redlining) my NOOB theory is no coolant is reaching the rear section of engine, but can that be if there is heat in the cabin? and would the temp gauge let me know if the engine was overheating.

I will take a pix of the next engine start after I get someone to calm me down and explain what might be causing the rear engine to not receive coolant.

 

Does anyone else have any ideas? At this point I am not sure it is a coolent problem. What does the smoke smell like? Oil, Coolent, Wires, etc? Did something get introduced into the water pump that flowed through and blocked part of your cooling system. I have never heard of localized overheating.

 

Iganski you were absolutely right. The coolant system is operating correctly.

The problem was smoke was coming from the engine! But it was run off from the oil on manifold because I was too lazy to change the driver side valve cover gasket as I did the left one because I didn't know how to disconnect several hoses that I didn't have replacements for.

I will now go to the shop and get the hoses and replace the drivers side valve cover gasket and put an end once of for all to oil leak onto the manifold that cause the engine to smoke..

And for an additional bonus. The oil sensor malfunction warning has not returned since I tightened the timing chain tensioner. But it may be a bit too early to celebrate. I will drive 15 miles and see what I see.

Thanks everyone.