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  #1  
Old 08-09-2003, 03:19 AM
Powerstroke
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300TD,can't get it to stop running hot.

I bought this car on E-bay and hte moment I got it the temp would go up to 120 plus when there was a heavy load put on the engine(I live in the mountains).Shortly we learned that the head gasket was bad and the dealer we bought it from agreed to buy us a salvaged motor that is supposed to have 120000 miles on it.When the mechanic finally finished putting the motor in it still did the same thing.We did everything possible to the cooling system,short of a water pump and it still did the same thing.The mechanic said that his 300TD went up to 115 degrees and he thought the car was ok as long as it didn't go into the red.We drove the car about 2 weeks and then it fially went into the red,and blew it's head gasket .We figured that the engine we got must have had a bad gasket when we got it and went ahead and got the head gasket replaced and the car was still running hot on the mechanics first test drive.The mechanic says he dosn't no what it could be and we despartly need the car fixed on Monday(my wife is driving to Ohio),Please help,thanks.

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  #2  
Old 08-09-2003, 05:16 AM
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Yikes. Here's some previous topics that might help: http://www.peachparts.com/shopforum/search.php?action=showresults&searchid=523991&sortby=lastpost&sortorder=descending

Also, check out my post in the other forum. Now that you mentioned the car is an 87, I'm almost positive that the cylinder head is cracked.
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  #3  
Old 08-09-2003, 11:54 PM
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clogged old raty radiator comes to mind.
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The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels
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  #4  
Old 08-10-2003, 12:27 AM
Powerstroke
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Everything in the cooling system is new except the water pump,brand new radiator,hoses,sensor,fan clutch and cap.The head was checked faor cracks at the machine shop and nothing was found.The mechanics that specalize in German autos don't know what to do next.We can't drive the car since we live in the mountains and it will overheat.Please help!
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  #5  
Old 08-10-2003, 01:47 AM
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flush the block??? check flow from block?

strange thing is two different engines in same car.. same thing.


Ahhhh..... is it auto tranny?

Could the auto tranny be causing the tranny cooler to somehow bring the heat up in the radiator which carries over to the engine?

oh...... and some MB's have a feature most dont even know exist and that is something like verticle blinds that shut. Supposidly only in winter to automatically block off the radiator some. If you got this maybe something is Is yours kicking on?

for a temp fix try putting a fan on the engine oil coooler. I hear a 12v fan from a computer fits rather nicely.
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by JerryBro


The Glow Plug Wait: This waiting period is a moment of silence to pay honor to Rudolph Diesel. The longer you own your diesel the more honor you will give him". by SD Blue

My normal daily life; either SNAFUed- Situation Normal... All Fouled Up, or FUBARed- Fouled Up Beyond All Repair

62 UNIMOG Camper w/617 Turbo, 85 300SD daily driver- both powered by blended UCO fuels
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  #6  
Old 08-10-2003, 02:26 AM
BobKern
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The fact that you are having a repeated problem like this would make me look at other causes of overheating. Brake drag is something that comes to mind. Are the brake calipers opening fully when you release the brake petal? Good Luck.
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  #7  
Old 08-10-2003, 09:07 AM
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I know the radiator is new, but is the condensor perfectly clean so as to enable good airflow to the radiator? I would replace the water pump, as they are cheap ans is a ikely cause of your excess heat. Also, is it the same tank of fuel for all these tests, as higher cetane could possibly have an affect under high load. The stuck brake/ bad master cylinder sounds most obvious to me. Try putting it in neutral and pushing it, or better yet, rais it in the air and try to turn the wheels.
I had a leaky master cylinder that caused brake drag and the fluid leaked into the brake booster - I sucked out about 20 ounces of brake fluid from the power brake booster!! I gues the PO had just kept filling it up when low.
Good Luck, Adam Bush

Last edited by adamb; 08-10-2003 at 09:19 AM.
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  #8  
Old 08-10-2003, 12:57 PM
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Did you check to make sure the guage is accurate?
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1985 409d 65k--sold 06
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  #9  
Old 08-10-2003, 03:36 PM
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Powerstroke,

If everything else was replaced except the water pump, try replacing that. I had a waterpump that didn't leak and appeared good but the impeller was slipping on the shaft and didn't circulate the coolant fast enough.

Then again, since the same thing happened to 2 different engines in the same carbody, it seems that something other than the engine is causing the problem. Have you had the radiator, even though new, flow tested? They should able to do it in the car at a radiator shop. They may also be of some help because their business is cooling.

Try some Evans coolant which doesn't boil until 375F. Maybe that will allow you use of the car without actually fixing the problem.

P E H
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  #10  
Old 08-10-2003, 03:46 PM
Powerstroke
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Gauge shoulod be acurate since the last time I drove it,it was defenatly overheating when I got it home.Brake drag is a possibility,but it is not noticable when driving the car.The heat seems to work fine,have not noticed any odor in the cab.The car is running on 100% biodiesel,mwhich it was not when we bought it.Thanks for the ideas,any more would be helpful.
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  #11  
Old 08-10-2003, 03:58 PM
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DO NOT run without the thermostat, you will fry the engine (again). This is a bypass system, and if the back flap on the thermostat doesn't close off the bypass flow, no water goes to the rad, it just gets hotter and hotter. This will also happen if you have an aftermarket thermostat in there without the proper plate to shut off the bypass. Behr or Whaler only, no Autozone or Pepboys generics, they are the wrong ones.

I'd replace the water pump and get a new factory thermostat and TEST IT before installing it. Installation is a *****, it's in the lower radiator hose on the side of the block beside the air intake to the turbo -- you will have to take the air intake hose off. Don't break the crankcase ventilation hose!

Make sure you have good air flow through the rad, check visco clutch operation, and make SURE the aux fan is coming on -- if either is bad, you will overheat all the time in the mountains. On steep grades, I'd expect both to run all the time. Do a search, both topics are somewhat popular.....

Peter
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  #12  
Old 08-10-2003, 04:57 PM
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I have a similar car and when I drive up hill it gets hot to the 100 degree or little more...then the fan clutch locks up and it gets colder...
there are many posts about the running hot,
IMO, you need to check:
1. If there is pressure in the upper hose of the radiator while the engine running (this is very important), check the water tank cap and if the cap base is not leaking the pressure..you could add some chemicals (water witter etc.) to lower the boiling temp and allows effecient cooling

2. if the fan clutch actually locks up (shut off the engine with the stop handle and see if the fan spins freely - assuming that it is locked the fan should stop with one revolution or less....When I installed a new fan clutch and fan (sachs)..it took me a real hot drive to start the clutch to lock...it does not lock at lower temp..also there is a modification mentioned before to make the clutch locks at lower temps...it might be required in hilly driving

3. the electric aux. fan should start spining fast at 115 degrees as a protective measure if you drive in a stop and go traffic (or lower speeds) ...this is because the fan clutch will lock slowly or in delay if the car is not fast enough, the fan clutch is activated by the hot air flow....The aux. fan also helps to lock the fan clutch by driving more hot air to it...There is also a modification (using a simple resistor) to make the aux. fan starts at lower temps.

4. if you are using AC, it is better to turn it off while driving up hill, if it is on, you need to make sure the aux. fan (low speed) is running with it.

5. Verify that the thermostat opens fully (also you can use lower temp thermostat i.e 80 degrees instead of 87

6. Use good synthetic oil (15 w 50) that lower the friction and generates less heat

7. Remove any unneccissary loads you carrying in the car

8. make sure tire pressure is optimized (I think it is 35 psi for the rear tires

If after all, you still have a noticeable problem, it is related to timing or other mechanical issues

i hope this helpful
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  #13  
Old 08-10-2003, 07:49 PM
The Least of These
 
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I would really make sure that the aux. fans are working properly. My 124 started to overheat last summer and it was the fans. A week later the radiator neck blew!!
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  #14  
Old 08-14-2003, 03:32 PM
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Over heating

I don't think anybody has mentioned checking the radiator pressure when operating. If your car has the same surge tank as the 123 turbos, they can often have hairline cracks just around the filler neck and vent pressure causing the engine to run hotter than normal.

I personally, rob older SDs of their brass surge tanks, have them resoldered and then discard the plastic tanks.

Anyway, a radiator shop can check the water system pressure.

Hope this helps,

Ben
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  #15  
Old 08-14-2003, 04:39 PM
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First, it would have helped to post the YEAR of your car, since it makes a big difference! From your profile I found it was a 1987 300TD. Given that info, you'll want to read this:

http://www.meimann.com/docs/mercedes/OM603_high_temps.pdf

http://www.meimann.com/docs/mercedes/OM603_radiator_notes.pdf

http://www.meimann.com/docs/mercedes/Citric_acid_flush.pdf


At this point I think you need to have some testing done with an infrared thermometer. You need to get the car hot then test various points on the radiator inlet & outlet, head, t-stat housing, etc to see what you find. The condenser fins must be clean. Per the three MB factory documents above, a citric acid flush is DEFINITELY in order. The electric fans are NOT intended to keep the car cool, so while it's good thing to verify that they function properly, they are not the cause of your problem. Both my 87's run at 90-95C all the time. Under load (full throttle, etc) I can make them get up to 100C but that's about it. Replace the plastic tank with the new style plastic tank ($40), which has a special anti-corrosion pack inside (there are no metal tanks made for the 124 and I don't know why you'd want one anyway).

Finally, PLEASE pull the water pump and inspect it! A friend of mine with a similar problem to yours (same car) also replaced everything and the car still ran to 120C on hot days. Check out what he found when I finally convinced him to pull the pump:

http://www.meimann.com/images/mercedes/W124_stuff/pump_impeller1.jpg
http://www.meimann.com/images/mercedes/W124_stuff/pump_impeller2.jpg

This helped his problem but hasn't totally cured it, but he hasn't done a citric acid flush yet. He did a SuperFlush with McParts cleaner and said it came out BROWN, so I told him to keep flushing with cleaner until it comes out CLEAR. He hasn't done that yet. Note that the flush procedure could possibly clog the radiator so be careful. If you have the old radiator, use that for flushing. If the radiator is more than ~2 years old, it is NOT new and may require replacement! I chased a "hot running" problem on my first '87 because the radiator was 4 years new and I thought it was fine. Nope, that was the problem, replaced that and it would rarely go above 95C in summer... keep us posted on how it's going.

BTW - with the car hot, feel the radiator surface in front of the fan & see if it's hot. It should be VERY hot (don't get burned) and should be hot over the whole radiator. Oh and don't use aftermarket t-stats (from NAPA, etc)... ONLY use an OE or OEM (Wahler, Behr) thermostat. Trust me.

Oooops, almost forgot. How do you know if the head has no cracks? They are often tiny and hairline and hard to see. If you have the old style head (603-xxx-yy-zz, where "yy" is 14 or 15) it's almost guaranteed to be cracked after a trip to the redline. You'll want a new style head from a 3.5L diesel engine ("yy" is number 17 or higher). MB redesigned the head, AND head gasket, a total of 5 times (six different part numbers). Here's photos of my cracked head:

http://www.meimann.com/images/mercedes/head_gasket/crack5.jpg
http://www.meimann.com/images/mercedes/head_gasket/crack6.jpg




HTH.

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