Coolant Loss

[VerMonsterRV]

Jon, sorry not coolant related but can you take loads of before after and during photos of the spring change over.

I am very interested in this conversion

Thanks from a sweaty Rio DJ

Neil

Will try and do that. The company doing the work may limit my time in the garage due to insurance. I may try and drop the storage boxes outside of their property as they have said more than a day to do the work, and we live in the truck. The springs arrived in Houston, now just need to wait for the truck freight to get them to El Paso. Will probably be able to knock off a few smaller projects and get the cab windows tinted.

 

[VerMonsterRV]

Since we have time right now I thought I would return to the coolant problem. Still no solution though I just talked with Rob Pickering about it and we may make the 700 mile trip north to get it fixed. He checked on a 1224 he has there and of course this part of the cooling system is different (which is also different from the 1017's). Really don't want to do long term damage to the engine. So I have already replaced the radiator caps, so I doubt that is the issue. One strange thing though, when I re-filled the tank yesterday, with the truck cold, coolant came back up the silver pipe that looks to be brazed to the radiator cap neck. About an ounce. Seems strange that this pipe is pressurized. Here is a picture of the tank.


Now this is where the silver pipe enters the radiator


Anyone know how this system works? When I removed the center radiator cap with the engine cold, about an ounce of coolant came out of the silver tube and there seemed to be some pressure. What I am familiar with is the silver tube ending up in the coolant reservoir, with hot/cold fill levels. This tube seems to end up back in the radiator. Not sure where this system vents to atmosphere if over pressurized.

Here is a picture from the top, the smaller hose right next to the ribbed intercooler hose is the hose attached to the silver tube.

 

[Sitec]

Start from scratch.... You say you can occasionally smell coolant from the internal heater... That's the first port of call in my view. Firstly disconnect that and get the cooling system back to as near as standard as possible... If after this you still have coolant loss, you have eliminated any changes from factory and can then look to doing a pressure test from cold. The reason for doing this when cold is fine leaks often don't show up when things are warm as the coolant evaporates on hot surfaces before it can be seen. You should be able to do a pressure test, and it hold pressure. If the pressure drops but there's no leak, look to caps and hoses above the water line... Once it holds pressure, then look for fine leaks... Hoses, core plugs, cab heater matrix etc etc. Have the cab tipped and crawl over everything. Pretty sure you'll find something by taking your time.

Re the white smoke on start up, this is pretty normal for older direct injection diesels.. I suspect we'll loose sight of our truck on startup when it gets really cold!

 

[VerMonsterRV]

Thanks for the tips, one thing I want to say is the coolant system is (as far as I know) 100% factory. When I said the heater I mean the factory truck cab heater. When we were having the rear leaf springs replaced at the commercial truck repair shop they took a look at the coolant issue (spent 2 hours crawling around, both with the engine off and on). They also tried to do a pressure check, problem was the cap they used only had a gasket on the pressure spring, not on the cap itself. This would work fine with the typical American cooling system (small non pressurized coolant recovery tank, likely very similar to the Holdens). When they put their cap on and pressurized the system coolant shot out of the silver pipe to the right of the cap. Seems a bit odd since, I would think the system should have some vent to the atmosphere, which for the life of me I can not see (and they could not also). And I would think this pipe would be it. I am starting to think this system on our truck might have been superseded with something else. I say this because Rob Pickering, who is likely North America's most knowledgeable mechanic for these trucks did not recognize this system. Plus the 1224, that has a slightly more powerful OM366LA (which I am envious) and is a bit newer, does not have this pipe. I keep trying to figure out how this coolant system allows for expansion and contraction without losing coolant (or for that matter where it would lose coolant to), since I can not find a "recovery tank".

Oh, not sure this is on other engines. I spent a couple of hours today with the cab tipped and the EPC. There is anther coolant line going from the black "expansion tank" to the thermostat housing. It is called an "aeration line", not sure how that one is supposed to work.

 

[Sitec]

Having re read this and studied the pictures, if that silver pipe is indeed going back to the radiator, then the cap (with the chain on it) should I think just be a flat cap with seal, and not a relief cap, as the silver pipe is the bleed return pipe (which has to return to just above the water line in the header tank unrestricted).. You can use this cap to fill, and fill to the lower edge of this cap. This then means that the higher cap to the right of the pic would be the pressure relief cap. This cap should have a spring in the center and be able to release pressure if it needs to, which in turn gives plenty of expansion room above the water level.... Is there a small outlet pipe anywhere on the filler neck of the higher cap that we can't see in the pic? If so, this needs a short length of hose on it that should/could lead into an expansion bottle (old coke bottle will do). The small hose should go to the bottom of the 'expansion' coke bottle, which allows excess coolant to escape if needed, but then allows it to be siphoned back in as the system cools again... That's how I see it working.... Mine has 2 caps... The lower one is never opened, and the higher one is the pressure release cap and doubles as the fill cap... Its usually high enough that the water level never gets to it when expanding. Hope this makes sense and good luck on your water loss quest.

 

[VerMonsterRV]

Having re read this and studied the pictures, if that silver pipe is indeed going back to the radiator, then the cap (with the chain on it) should I think just be a flat cap with seal, and not a relief cap, as the silver pipe is the bleed return pipe (which has to return to just above the water line in the header tank unrestricted).. You can use this cap to fill, and fill to the lower edge of this cap. This then means that the higher cap to the right of the pic would be the pressure relief cap. This cap should have a spring in the center and be able to release pressure if it needs to, which in turn gives plenty of expansion room above the water level.... Is there a small outlet pipe anywhere on the filler neck of the higher cap that we can't see in the pic? If so, this needs a short length of hose on it that should/could lead into an expansion bottle (old coke bottle will do). The small hose should go to the bottom of the 'expansion' coke bottle, which allows excess coolant to escape if needed, but then allows it to be siphoned back in as the system cools again... That's how I see it working.... Mine has 2 caps... The lower one is never opened, and the higher one is the pressure release cap and doubles as the fill cap... Its usually high enough that the water level never gets to it when expanding. Hope this makes sense and good luck on your water loss quest.

Thanks for taking another look, and what you are saying it why I keep talking about that pipe. From the factory the center cap with the chain was a pressure cap and makes no sense to me since that pipe is connected to the radiator. So here is what I stumbled on this morning.

I have been wondering why I have been unable to get much info on our system, I now think that they did not make many like ours. It seems that MB did a design change with the expansion tank (which is the difference with the 1224 that I mentioned above). The change is they deleted the silver pipe and changed the cap with a chain (which was a 70 kpa pressure cap) to a simple plastic fill cap. The pressure cap is the one in the upper right. They took the return from the radiator (the one that went to to silver pipe) and T'd it into the return from the "aeration line" from the thermostat housing. Now I can understand how that system would work. I still can not understand how ours would ever work as the silver pipe is pressurized and vents outside of the pressure cap spring. Seems like as soon as the engine gets hot it would constantly vent to atmosphere. Thing is I trust the Mercedes engineers way more that I trust myself, and keep thinking I must be missing something. The thing is, soon after they built our truck they changed the design to one I can figure out.

There is no traditional expansion bottle on our truck. I am seriously considering making a mod to our truck to mimic the revised system. I would need to remove the hose from the end of the silver pipe and T it into the hose directly to the right of it (this is what the revised design does). Then attach a new hose to the sliver pipe that goes to a traditional expansion bottle. If I was in an area (like Europe) that has ready access to the revised parts I would just order them up and give it a shot, but not so easy here given we do not have a fixed address.

 

[VerMonsterRV]

Got an update! We ended up going to "Total German Motorworks" in Mesa AZ. It is a small auto shop that usually works on cars. Well these guys went over the cooling system, figured out how to pressurize it and low and behold after about 15 minutes the top of the radiator started to weep. Pretty excited it is only a radiator and not the head gasket. So, before I order up a new one from Europe does anyone know if there is anything I might need for the replacement.

 

[Sitec]

Brilliant job! Those rads with plastic headers are a pain in the ********! We have managed to get a few to reseal by tightening each clip slightly, but a new one is prob best!

 

[VerMonsterRV]

So I looked up the radiator part number in the EPC. I had thought that by using your VIN in the EPC it would get the specifics of your truck. For some reason there looks to be 2 different radiator part numbers. I am going to try again today, but I crawled around a bit and have yet to find the part number stamped on our current radiator. Looks like the difference between the 2 is the width of the core. I think maybe either would fit. I am sure if I pulled the radiator I could find the number but since we are on the road and the replacement needs to come from Europe that would be a bit of a pain. Looks like in order to pull the radiator I would need to first remove the intercooler to access it. Anyone know where the part number may be stamped? With all the brackets and hoses a lot of the plastic tanks are covered.

 

[VerMonsterRV]

One more thing and I am not 100% sure about this. One of the replacement radiators mentions an "integrated oil cooler". Am I correct to assume that there would be a oil line hookup to the radiator if this is the one we have? I am pretty sure we do not. Has anyone seen something like this on these trucks?

 

[luthj]

Its common for radiators to have an integral oil cooler. (Trans, power steering, occasionally engine oil). If you have this option, there would be two small oil fittings located on one side of the radiator. The cooler is integral to one of the side plastic tanks.

 

[VerMonsterRV]

Just found the part number on the radiator. Just had to jam my head in there. I do not think we have the integrated cooler. The part number is A6775000203. Now just need to find a replacement.

 

[Joe917]

Hu Jon, here is the pic you asked for, sorry it took a while. Tank was replaced at Rob Pickering's about 5 years ago. Fill to green cap when cold.

 

[VerMonsterRV]

Thanks Joe (and no worries about time, I know you are busy with the house), seems every single MB truck I see they did a bit differently. Can I ask why you replaced the expansion tank? Also, what is the coolant line that is T'd into the cab heater line? Is that your circuit for the engine pre-heater? If so where is the other end connected?

 

[Joe917]

The old expansion tank was cracked and leaking. The line from the T is for the Webasto. Without crawling around I could not tell you where the connection is at the other end!