Today on my way to work temp gauge maxed out. I have been noticing low coolant light on and I add distilled water. This time the light wasn't on. Heater was blowing cool air. Stopped to add water at service station. Lots of pressure in overflow tank. As I was adding water I could hear it boiling inside which it wasn't doing before adding water. When I thought it was full, I turned on car without radiator cap. Water started flowing out of the overflow rapidly. I turned car off and added more water capped reservoir and continued the rest of the 2mi to work. As I was driving I could hear what sounded like boiling water coming from the passenger side fender. No steam though. When I got to work I felt the radiator hoses. Top radiator hose was very hot and hard with pressure. Hose at top of radiator to overflow was hot. Bottom hose on reservoir was cool. Reservoir itself felt lukewarm.

When I was adding water it looked like there may have been a small amount of oil but since I just bought this car recently I don't know when the last flush was. Service documentation States about 2 years ago.

I have noticed on occasion around the lower radiator hose On the passenger side on the ground there will be a small amount of coolant. I have seen a drop on the back side of the alternator too. Very small amount less than an ounce.

What could cause boiling in the reservoir? Thermostat?

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1987 300 SDL
2000 E320 Wagon

The head gasket is done for. You have all the classic symptom of HG failure. Check whether the top radiator hose is rock hard after engine completely cools down. Another check is to open expansion radiator cap and start engine when cold. If coolant rises or with a lot of bubbles then it is probably combustion gases.

Good luck.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

"Top radiator hose was very hot and hard with pressure. Hose at top of radiator to overflow was hot. Bottom hose on reservoir was cool. Reservoir itself felt lukewarm."

Have no idea where you are located, but if you are using your heater I would assume that you live in an area of cold weather. If your anti-freeze was not up to snuff, it is possible that you had an ice blockage in one of your radiator hoses that was not allowing the flow of coolant to circulate. You end up with a buildup of pressure within the rest of the system and you get an overflow condition when you relieve the pressure. If this is not the case, then the prior poster mentioned a blown head gasket, and gives the method of determining if that is the case. Good luck

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96 E300d

Hose is not rock hard in the morning but it isn't completely collapsible. When I take off radiator cap in the morning it makes a hiss as it relieves pressure and then the hose is completely soft. What was floating around in the water didn't really look like oil. More like possible Stop leak from previous owner. There is no water in the oil.

From what I've read pulling the head is an 8 hour job. I might as well pull the #22 head off the spare motor in garage and replace my #14 while it's off. Is there anything I should replace while head is off? I'm thinking head bolts are not reusable. Do I need to have the head machined? Does anyone have a service document or Diy for head removal and replacement? Are there any special tools I need?

It may have got into the low 30s last night. I'm in southern California. I have just been replacing lost coolant with water and I know there's no way it's 50% but I've been leary of adding g05 @$18/gal if it's just going to eat it up in a few days. Is there a cheaper coolant I can use temporarily until I can drain and flush system after I replace head?

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1987 300 SDL
2000 E320 Wagon

Hot upper hose and cold lower hose could be a clogged radiator, stuck thermostat or cooling system pressure overcoming the pump. The #14 head doesn't like it when the temp gauge goes beyond 120*C so that alone is reason to take action. You might try a new good quality thermostat before pulling the head. It'll still be new when you replace the head and/or gasket A new thermostat might balance temperature across the radiator but it won't fix system pressure.

If you need your car in the meantime, run it with the pressure cap loose like on the first notch. Cooling capacity is greatly diminished without the ability to pressurize but you won't boil off coolant in normal driving. If you'll address the situation shortly, run a reduced coolant mixture like 10-20% just to keep it from freezing. Top off in that proportion but you probably won't lose coolant if you keep the pressure cap loose.

Have the #22 head checked by a knowledegable machine shop. At the very least get MB brand valve stem seals. If the PO ran WVO or drove like a granny, have the injectors cleaned and pop tested. The prechambers too if you can get them out. Maybe the machine shop can pull them for you. Plan on using the injector lines from the #22 head for best alignment. There's a spec for head bolt elongation. If they're within spec, you should be okay reusing them. You'll need a couple of longer bolts that hold the head to the front cover. They're nothing special. Look how much the short bolts extend from the #14 head then look for similar hex head bolts at the hardware store that will extend the same amount from the #22 head.

The head bolts take a triple square/double hex bit. I think in 10mm size but maybe they're 8mm. I use a cheapo 4-piece bit set from the auto parts store but there's a fancy bit available as a MB special tool. The special tool allows you to pull the head with the cam in place. A klutz like me should never handle the head with the cam in place which means some valves open so there's no question to me that the cam comes off before anything else. Then I can use the cheap tool. The special tool to remove the valves probably runs into 4 figures after the 2014 MB price increases. A watercooled VW valve spring compressor might work. Otherwise, leave it to the machine shop. Don't pull the cam followers with a magnet as the FSM suggests. A later TSB says to use a small suction cup such as a hand turned valve lapping tool. A magnetized cam follower can trap ferrous bits circulating in the oil. You'll need a special splined socket and slide hammer adapter to pull the prechambers. A timing chain guide rail pin puller is invaluable IMO but you can get away with a bolt that'll thread into pins and a stack of washers. Injector heat shields work well as stackable washers.

For parts, use a head gasket set for your 3.0 engine, not a 3.5. The #22 head uses slightly shorter glow plugs. IIRC Bosch 80031 vs 80006 for the #14 head. Don't quote me on that, just remember they're different but look interchangeable. This is a good time to ensure you have a full set of injector line clips and hangers.

This is out of the W124 FSM but everything applies to your engine - http://www.startekinfo.com/StarTek/outside/12264/Program/Engine/602_603/01-5800hx.pdf . You can access the FSM online at www.startekinfo.com at no cost. Registration with a valid US credit card is required for the EPC but not for the FSM.

Sixto
87 300D

I went home and added water and coolant on my lunch. I noticed the water pump was dripping out of the weep hole on the bottom about 1 drop every 5 seconds. Does this indicate bad pump? Could bad water pump cause these symptoms? I did check again and I think there is oil in my water.

There has been an oil leak around the turbo. I thought it was the oring between turbo and intake. Waste Gate arm is completely soaked as is everything else in that area. Is blown head gasket known for leaking oil around cylinder 1-3? This morning it got much worse and there is splatter all over the smog vacuum pods, heat shield, intake tube, turbo, exhaust manifold. When I turn off car i can see oil smoke rising from around waste gate arm area by the manifold.

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1987 300 SDL
2000 E320 Wagon

It's common for the head gasket to fail near the #1 exhaust port with oil dripping on the chain tensioner and alternator, not to mention leaking into #1 and sometimes #2 cylinders. A coolant breach of the head gasket is a separate issue that seems to occur around the #4 cylinder. Oil pooling by the Garrett wastegate arm is more likely from the turbo oil supply junction atop the center section of the turbo. I don't think you can see a KKK wastegate arm so I'll assume you have a Garrett.

The trick is to determine whether the water pump failed on its own or the seal blew as a result of excessive coolant system pressure. The water pump should hold better than the system's 1.4 bar rating, though.

Sixto
87 300D

I thought that too but it seemed dry compared to the rest of the front engine. The back of the alternator is soaked as is the timing cover.

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1987 300 SDL
2000 E320 Wagon

You might have a tired front crank seal.

Sixto
87 300D