Cooling System Issues

[The Warden]

Hello!

I've noticed over the last few days that the engine temperature isn't warming up as usual. It'll get up to 60° Centigrade, and will fluctuate around there a bit, but won't really get up to 80°C. I'm thinking that the thermostat's sticking open.

Also...I've noticed that I'm loosing coolant fairly slowly. A week ago, I noticed that the expansion tank was almost empty, so I filled it up, and today, I noticed that the coolant level has gone down a fair amount.

Given the fact that I don't see any coolant leaking around in the engine compartment, coupled with the extremely high level of humidity that comes into the cabin whenever I set the ACC to "EC" with the heater running, I'm thinking that my heater core may be leaking.

However, while I do smell water vapor in the can whenever the heater's on in "EC" mode, I don't smell coolant, which brings me to my last (and possibly scariest) issue. While I do detect a faint trace of coolant smell from the expansion tank cap, I have a bad feeling that my cooling system's filled with water. Bad me, I haven't done a coolant flush since getting the car about a year and a half ago; lack of time and finances have prevented it. I saw orange in the expansion tank and assumed that things were okay; however, now, I'm starting to think that the orange I'm seeing is rusty water as opposed to the right coolant.

Anyone have any thuoghts on this? I am planning on doing a long-distance drive in the car on Sunday, and from there for the next couple of weeks, spending some time in an area where the temps are getting below freezing, so, while I guess I should be preparing myself for a coolant flush, is there anything I can do in preparation to confirm my fears?

And no "Bar's Stop Leak" answer regarding the heater core. :p

Any comments would be appreciated...thanks in advance!

[300SDog]

Long distance drive is excellent opportunity to flush the system using 6-8 hr radiator flush stuff..... first you gotta drain it until water runs clear, then add the radiator flush and take your trip. You can even repeat the procedure if its been long time since previous flushing.

Naturally bring some orange anti-freeze in the trunk for when you arrive at destination. Good place to purge the radiator flush out of the system might be 2 bit self-service car wash. Just make sure the engine is COLD whenever you douche the system, drain the radiator or add fresh coolant and water.

Btw, those backflush kits with inline garden hose fitting are not bad..... they can be moved around to flush the galleries in cylinder head, block, and heater core too. Another place you might be leakin coolant is at heater valve/ hose connections. And if you've got rust in the system it will probably dirty the walls on the expansion tank as well as clogging the heater core.

[sixto]

Sounds like there's a thermostat problem as well. Borrow a pressure tester from Kragen or Autozone and find the leak if there is one.

Sixto
95 S420
87 300SDL
83 300SD ... $950, see cars forum

[The Warden]

Sixto, you make a good point. I hate to ask the dumb question, but it's been a while since auto shop, and in that time, I've not needed to track down a coolant leak, so I'm rusty (no pun intended)...how can I determine where the leak is coming from with the pressure tester?

Originally posted by 240DieselDog
Long distance drive is excellent opportunity to flush the system using 6-8 hr radiator flush stuff..... first you gotta drain it until water runs clear, then add the radiator flush and take your trip. You can even repeat the procedure if its been long time since previous flushing.

Which flushing stuff should I be looking for? Also, IIRC, Prestone (or someone else; can't remember who) has a short-term flush compound; would it be worthwhile to run that through the system prior to the trip? Repeating the procedure would probably be a good thing; I have no clue when the radiator was last flushed, but it's probably been a long time.

Naturally bring some orange anti-freeze in the trunk for when you arrive at destination. Good place to purge the radiator flush out of the system might be 2 bit self-service car wash. Just make sure the engine is COLD whenever you douche the system, drain the radiator or add fresh coolant and water.

Any recommendations on coolant? Will any orange ELC do, or should I be looking for something specific? Also, will the radiator flush keep the water from freezing at 32°? If not, I'm going to have to extend a stop (dropping my girlfriend off in Bakersfield) to let the engine cool down enough to get the flush done before proceeding (because, otherwise, the car will have to sit overnight at the final destination). Also, how toxic will the water/flush be? How should I dispose of it? Lastly, I'm pretty sure that i need to replace the upper radiator hose and the hose connecting the radiator to the expansion tank (and probably the lower hose as well). When in this procedure should I do this?

Btw, those backflush kits with inline garden hose fitting are not bad.....

Where should the T-fitting be put in in the system to allow the backflush to be effective? I actually already have a kit (been planning to put it on my truck), but don't know where to put the fitting...

I know I have more questions, but can't remember them offhand...thanks!

[Ken300D]

Southern used cars are pretty famous for having weak anti-freeze. Someone who buys a car down south and takes it back north better check the anti-freeze right away with a tester!

I speak from personal recent experience. Weak anti-freeze and weak windshield cleaning fluid.

Ken300D

[The Warden]

Does anyone else by chance have anything to add?

Thanks

[gsxr]

Well, since you asked! :p

1- I'd flush with citric acid and a forced-open t-stat per the MB factory procedure. Bad you for not flushing when you bought the car! Bad, bad!

2- Given the short time allowed, I'd at least use a McParts cooling system flush if you can't locate citric acid powder on short notice before your trip.

3- If the t-stat is not recent, replace it. DO NOT use an aftermarket no-name 'stat from McParts. Use OE/OEM Behr or Wahler. Trust me.

4- If the temp still is low, try the heater. If the heater blows nice & hot, the 'stat is probably FINE. In that case, you need a new temp sender in the head for $10. As they get older, they can read low. Had the same problem on my '84.

5- Use the amber/gold colored Mercedes, or Zerex G-05, anti-freeze only. No green or bright orange junk!

6- I assume you know not to stick a cold garden hose into a warm engine when flushing. Let it cool first - shut off engine, leave heater on MAX with fan on high, and the key turned on. The electric aux pump will push coolant through the heater core and cool things down in 10-20 minutes quite nicely.

7- I'm concerned about the coolant loss. If you can't find ANY external leaks anywhere, I'm afraid it may be a head gasket...?


HTH,

[leathermang]

I am with GSXR...
The flushing is a two step process.... one is the Citric Acid ( specifically mentioned in the FSM... ( to be preferred ) I think is the way they put it... and they say you may have to use it more than once to be sure the flush can access the rust and grime buildup...
The idea is that you must get rid of any and all of the oily coating before whatever flush you use will be able to do its job correctly...

[The Warden]

Originally posted by gsxr
Well, since you asked! :p

1- I'd flush with citric acid and a forced-open t-stat per the MB factory procedure. Bad you for not flushing when you bought the car! Bad, bad!

Yes, I know I was bad for not doing it beforehand...

2- Given the short time allowed, I'd at least use a McParts cooling system flush if you can't locate citric acid powder on short notice before your trip.

I don't knwo where the citric acid can be gotten. I've tried two different dealers, and both of them gave me a blank stare when I asked them for it. I'm probably gonna have to live with a McParts flush stuff.

3- If the t-stat is not recent, replace it. DO NOT use an aftermarket no-name 'stat from McParts. Use OE/OEM Behr or Wahler. Trust me.

You don't have to tell me twice; there are problems with aftermarket thermostats for the Ford diesels as well...so I'm actually familiar with cheap t'stats not working. Where can I get an OEM one besides the dealer and Fastlane? I don't think that Fastlane could get it here quickly enough (short of paying out the nose for shipping), and I'm guessing that the dealer will want an arm, a leg, and my first-born...

4- If the temp still is low, try the heater. If the heater blows nice & hot, the 'stat is probably FINE. In that case, you need a new temp sender in the head for $10.

I need to try it again (the car may not have had a real chance to warm up last time I used the heater), but I don't think the heater's putting out as much heat now as it has in the past. In addition, this is sudden; a week ago, the gauge was reading perfectly. I know a sending unit can fail that quickly, but the odds are in favor of the t'stat...especially since I don't know its age.

5- Use the amber/gold colored Mercedes, or Zerex G-05, anti-freeze only. No green or bright orange junk!

Where can this be acquired, besides the dealer? Again, I don't think I want to know what the dealer charges for it...

6- I assume you know not to stick a cold garden hose into a warm engine when flushing. Let it cool first - shut off engine, leave heater on MAX with fan on high, and the key turned on. The electric aux pump will push coolant through the heater core and cool things down in 10-20 minutes quite nicely.

Sounds good...I presume that I should leave the heater set the same way while going through the flush, in order to ensure tha thte heater core gets flushed out as well...

7- I'm concerned about the coolant loss. If you can't find ANY external leaks anywhere, I'm afraid it may be a head gasket...?

I'm concerned about the same thing, although I'm still hoping for the heater core...especially given how humid it gets in the cab (it'll make your skin clammy, even on a dry day) whenever the ACC's set to "EC". Even still...times like this, I'm really happy for the iron-head 617...if it is a head gasket, the head should still be in good shape *knock on wood*

[leathermang]

If you have procrastinated long enough that you are really short on time you may have taken away your options other than to drive to the dealer and promise your newborn...

[sixto]

The MB part number I have for citric acid is 000 989 10 25. You can get citric acid at a nursery or garden supply place. I don't know if it's clean enough to use as a cooling system flush.

The 83 SD had a coolant leak that turned out to be a cracked reservoir. I didn't associate the persistent puddle behind the right headlight with a leak. I thought it was spillage from filling the reservoir.

Sixto
95 S420
87 300SDL
83 300SD ... $950, see cars forum

[gsxr]

Citric acid powder can be purchased from the dealer (or MB parts retailer like FastLane or Rusty), but it's cheaper to buy aftermarket. Not likely you can find it locally without a lot of calling around. I heard one person bought some from a bakery supply! You need 1Kg btw. Just use the McParts flush for now, worry about the citric acid bath later.

For an OE/OEM T-stat, the dealer is the best bet for having it in stock. Try asking for an MBCA discount and hope they don't ask to see your card, that might be good for a bonus 10% off. Or you can try every *good* local parts store, like NAPA, etc and ask them what brand it is. If you can find a Wahler or Behr, you're all set. Otherwise, yes, S&H will be as much or more than the T-stat from most other places.

MB dealers usually want between $10-$17 for the MB coolant, the high number is because some dealers (in CA anyway) charge an "environmental" fee as well. Don't ask me how or why - but I have a friend who did that ONCE. You can get Zerex G-05 at AutoZone and other McParts stores for about $9/gallon, it's allegedly the SAME stuff in a different jug. It says right on the jug that it's approved for all Daimler-Chrysler vehicles.

Oh, and yes, leave the heater on "max" during all flushing. You'll want to flush once or twice afterwards with clean water to get out all the flush agent - this is especially critical when using the more aggressive citric acid (as opposed to the generic Prestone/Zerex flushes). Use the block drain as well if applicable. I get as much out as I can (jack up the rear of the car to help), close the drains, dump in one gallon of anti-freeze, and top off with distilled water (clean tap water is ok too). Don't start the engine again until you can feel liquid in the upper radiator hose - that's how you'll know it's full.

[The Warden]

Wow, only one gallon of coolant plus water?

I'm surprised...I'd figured it'd be more

Should I be running the McParts flush over a long period of time? i.e. the first responder suggesting that I drive down to Southern California with the water/flush in the system and drain it out there (probably a 4 to 5 hour drive; if I do that, I'm going to overnight in Bakersfield and drain there in the morning instead of going all the way to my dad's and risking things freezing up).

I also presume that I should wait to install the new thermostat until I'm done flushing. Again, should I also wait to install the new hoses 'till I'm done flushing, or at what point should I put those in? I'm guessing that I'll have to get the hoses from the dealer at this point...www.partsamerica.com has the upper and lower hoses listed, but not the big hose going from the radiator to the expansion tank, and I think that one's unhappy too (I hear a crackling sound whenever I squeeze it).

I presume there's no way to take the "clear" resevior apart to clean up, so I guess I'll just remove it from the car and spray out to the best of my ability...

Yet another dumb question...where are the block drains on a 617?

Also, I read somewhere about stuff called Redline Water Wetter; suposed to increase the cooling capability of what's in the system...does anyone think it's worth trying?

Thanks again

BTW, I confirmed it tonight; after taking the car on a run that normally would have heated it up enough to get it up to operating temperature, in addition to the low gauge reading, the heater's nowhere near up to par...so the engine's definitely not heating up enough, it's not just the gauge...

[mechmagcn]

The only problem with water wetter is that it works better with pure water or very little anti-freeze. Very little effect with a 50/50 mix.

[leathermang]

Tim, The thermostat is supposed to be removed from the car during the flush procedure.
The system is definitly supposed to be completely flushed with clean water TWICE after the citric acid treatment and before adding the coolant.
You don't have your year/model listed ... but they specifically suggest AT LEAST 50 percent approved antifreeze .... and I think that is going to be a minimum of 5 liters of actual antifreeze..
They also specifically say that you are not to get below 40 percent.... and if you use only water in the system they have an anticorrosion additive you are supposed to put in....