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  #1  
Old 07-30-2002, 11:52 AM
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Unhappy Overheating....away from home

On the way to PA (651 miles from home), I struggled with running hot. This morning I logged on and read a ton of threads on the subject. Will be returning home in two days and its hot out here.

1) My temp guage sat with the needle on the high side of 100 degrees. On inclines, it would approach 110 if I kept the air on and stayed near 73 mph. Upon coming to dead stops, twice I had to turn the heater on to bring it down.

QUESTION: If the ambient temp outside is 95-100 and humid, is this normal or a bit high?

2) My thermostat seems to be working ok as the lower hose gets hot (starting the car cold in the morning, watching the guage climb and feeling the hoses).

QUESTION: Would you guys just flush it with clean mixture?
QUESTION: Is distilled water (rather than tap water) better to mix with coolant?

3) I'm not sure I should buy new reservoir cap, hoses, thermostat, etc when I'm away from my working garage

Thanks for any advice

Don

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'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
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  #2  
Old 07-30-2002, 12:55 PM
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Do you have a fan clutch and if so have you checked to make sure it is engaging? A failing fan clutch can produce those kind of symptoms. If it is bad and you don't want to replace it on the road it might be possible to use some jumper wires and hot wire the electric fan to run constantly until you get home.
By the way, did you check to make sure the electric fan was engaging before resorting to the heater to cool it down?
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  #3  
Old 07-30-2002, 01:35 PM
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The Aux fan on the outside of the radiator seems to be functioning well. It comes on at about 80 degrees or so when idling (w/ full AC). I also noticed that it was on much of trip.

Don
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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed
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  #4  
Old 07-30-2002, 08:33 PM
MVK MVK is offline
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As per MB under severe conditions needle should not go to the red mark.
Q-1 Answer Yes if outside temp is high the heat transfer is low and engine runs at higher temp.

Q2- When you get a chance change the coolant with a good mixture. I used the red Texaco coolant and I am happy with it. Also using tap water is no good. It has salts that will deposit with time. I use distilled water or a very good quality drinking water gallon from grocery store.

Q3. I always carry xtra pair of top and bottom hoses on all my cars. Just in case.

On the thermostat issue its nothing but MB OEM also if its not broken dont replace it. I have seen horror stories with replacement thermostat.

Make sure aux fan works. Also turn off the AC occassionaly during the trip. I usually do this like once every 2-3 hours drive for 5 minutes. Check the main cooling fan clutch. Should be hard to rotate with hand when the engine is hot( but switched off LOL).

Good luck

MVK
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Last edited by MVK; 07-30-2002 at 11:38 PM.
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  #5  
Old 07-30-2002, 09:37 PM
The Least of These
 
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Location: Exton, PA
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Although these diesels do have temp climbs under load, 110+ is pushing the envelope in my book.

I am sure you do not want to get to involved far from home. If the fan clutch and aux fans are running normally you might consider 1) a bad rad. cap 2) blocked radiator 3) bad t-stat

Which of these can be tackeled out of the confort of your own garage? The cap might be the easiest to rule out - so try that first. If 2 and 3 are impossible for you to do, either bite the bullet and take it to a mechanic or top off with some synthetic, add some Water Wetter (Pep Boys in PA) and hope for the best. It might be a hot ride home.

If you are near Phily, I live in the suburbs and have a garage to which you are welcome. I also know some great Benz mechanics if a more thourough diagnosis is needed. Best of luck!!
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  #6  
Old 07-30-2002, 09:42 PM
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MVK & slowmoe:

Excellent words! I wrote down the suggestions that I haven't tried yet and will tackle them tomorrow.
Its kind of wierd working out of a parking lot and I do appreciate the invite to Philly. I'm in Lancaster and think that my problem is more annoying than drastic. I do have confidence that it'll make it home, even though it might be warm.
Tomorrow I'll flush and do the water-wetter deal.

Again, thanks for the help

Don
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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed
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  #7  
Old 07-30-2002, 10:26 PM
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High temps

Diesel Don,

My son went through this problem for months with his turbo 300 and eventuall found that the surge tank had a small crack around the neck of the tank and the radiator system never pressurized, therefore the boliing point of the system went up dramatically. Since he replaced the tank with a new and highly ribbed one, his car runs as cool as both my 300D and my daughter's 240D.

Check for cracks, now. If in doubt try removing the tank cap and putting your mouth over the neck opening and blowing into the tank, if you can't maintainthe two PSI that your mouth can produce, then the tank certainly can't maintain the 13PSI that it needs to maintain.

Ben
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  #8  
Old 07-30-2002, 11:03 PM
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Ridge: Thanks for the suggestion. The pressurized cap comes off with some serious pressure behind it when the engine is half warm so I think its holding.

MVK: One last question. I rotated the cooling fan with the engine just recently turned off (quite hot). It turned very easy. Is this how you check the main fan clutch or do you try to rotate something else.

Just wondering about a new theory. Since its been running hot, the AC has been cool but not cold like it was formerly (just had AC recharged last month). I'm wondering if the belt or something else that controls the water pump and AC condensor is weak?????

Don
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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed
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  #9  
Old 07-30-2002, 11:14 PM
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Yes, you check the fan clutch that way. It should rotate easily when cold but it should be harder to rotate when it is hot.
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  #10  
Old 07-30-2002, 11:38 PM
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I just fixed what sounds like the same problem, and I"m also in PA. Turned out that it was a faulty rad. cap, though it seemed fine to me. The first thing I'd do is get a new cap; they're only $4 and easy to change. Then, after it is warm, check to make sure there are no leaks anywhere. If that doesnt help, well, its only $4!
Oh, and if you need help on the way back, I'm in Pittsburgh, minutes from the trnpk.
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  #11  
Old 07-30-2002, 11:55 PM
MVK MVK is offline
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Kerry has the answer for you. When cold the fan clutch is supposed to let the fan slip. Or in other words the blades will rotate with a flip of the hand. This slipping allows the car to get warm quickly. Now once warm, the clutch becomes tighter and the slipping of clutch becomes minimal or in other words it should not rotate much( I mean not even from 12 o clock to 4 o clock). This means that the fan will rotate with engine almost without slippage and provide max cooling.

It sounds like you have a failing clutch. Attend to it when you go home. Get it checked from a good mechanic a lot depends on that clutch. Here in NY I have seen some cabbies using a fixed clutch in summertime to get excellent cooling on their oldmobile or chevy.( but for us its not a good idea).

Also when the engine is running hot, the AC cooling also suffers by a few degrees. Since you did some work on AC recently, make sure all belts are tight enough. If you see any of the belts with major vibration( or flapping), it might be loose.

But again the way you described hot engine and free rotating clutch, it seems like clutch.

Also, when you get the coolant replaced, its good time to flush the radiator . Some people use citric acid for this. I have never needed to do that.

Good luck. Le us know what happens. This is the way we can help other guys in future.( I am typing too fast so sorry for typo and bad spellings)

4 bucks cap idea is good too. Nothing major to loose in that

MVK
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  #12  
Old 07-31-2002, 12:18 AM
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my car ran hot today... in normal traffic (not stop-go, just normal city driving) the water temp was at 100F after 6 mi worth of driving with the A/C on. The temperature kept going up until about 105F.

That was after some highway driving. I have a feeling something is VERY wrong. The only thing I did to the cooling system was replace the '100' marked radiator reservoir cap with a '140' cap that I bought from fastlane.

I just put the 100 back on..

It was 95F outside today. I have run the car in 102F weather and the max it reached was 101F. I knew it wasn't good either. However that was after miles and miles of driving...

I'm gonna get the system flushed and refilled tomorrow. I'll probably have the shop replace the t-stat while at it. Hopefully that'll fix it. Otherwise.....

The fan clutch works though as it's hard to turn when the engine is off (the engine was hot). It also stopped turning immediately once the engine was shut off (hot engine too)

The aux fan works great..
The coolant system isn't losing any coolant..

It kinda sucked... my A/C now cools the car extremely well (even in today's hot weather). The air coming out of the vents was definitely colder than my friend's Chevy Malibu and Toyota Highlander (quite an achievement I say). However the interior wasn't quite as cold.

just had to overheat.. I'll update the results tomorrow!

wish me luck
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  #13  
Old 07-31-2002, 06:16 AM
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Quote:
The pressurized cap comes off with some serious pressure behind it when the engine is half warm so I think its holding.
This may be an indication of a need for a new head gasket - especially if the engine has not been run for very long. See if you still have pressure after the car sits overnight and cools down. If it is still pressurized then it is head gasket time.
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  #14  
Old 07-31-2002, 09:29 AM
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Wow! Big time help from all you guys. Very much appreciated.

1. Checked the pressure this morning (cold) and there wasn't any which is good news. (Cap came off easy and quiet)

2. Checked the fan clutch (cold) and it turns easily. Last night when I checked it hot I didn't rotate it far, just wiggled it a little. Am going to drive 15 miles soon and will try to move it from 12 o'clock to 4 and see what happens. I'm thinking that it might be the fan clutch.

3. The belts seem fairly tight to me. One of the double belts that runs to the water pump may be slightly weaker than its counterpart, but nothing drastic enough to adjust.

4. I just cleaned out the AC condensor a bit and straight a bunch of the fins, but again, it didn't seemed damaged enough to make much of a difference.

Thanks again,

Don
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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed
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  #15  
Old 07-31-2002, 12:00 PM
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Don, I'm not sure about 300's, but in my 190 D (2.2l-sloooowwww...) I have an electric fan clutch. it ALWAYS turns freely until the fan switch kicks in (around 110C) and then the main fan works until temp goes down to 100C. I had the same problem as yours-after about 1 hr of driving (65-70 mph) the temperature would climb to about 105C while driving. problem went away after I replaced the radiator. Also had a bad rad cap resulting (after radiator replacement) in about 101 C cruising temp. Now, in 80F + weather, the temp never goes above 95C while driving. However, after hard driving when stopped and idling, the temp goes up immediately to about 112C and then comes down after the fan clutch is engaged with the fan switch.
I hope it helps.

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