(300SDL!) I drove 25 miles home from work stopping half way to pick up an 80 amp fuse for the glow plug relay which was in two pieces. Well, after I got home and installed the fuse I checked my upper hose and it was very hard. I slowly undid the radiator cap at the reservoir and there was quite a bit of pressure that came out. Some air came out even after I let the cap sit at the middle position. Does it sound as if my head might be cracked? I have the -14 head. I thought I had checked it before and it wasn't this stiff.

When coming back from Charlotte, NC the temp gauge rose up to around 110 but there were 4 other people in the car and the trunk was packed full. It wasn't that hot very long at all just when I stopped at a gas station. The cooling fans came on, etc. so I figured it should be ok. When I was going down the interstate the temp was at 85 so no trouble there.

What do you guys think?

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I did some searching and it was stated that I shouldn't have any pressure when the system is cold. Shoud I run it at all or will the pressure stay in the system if the head is cracked? I can go out before school and check quickly but I would think the car would have to run some to pressurize the system if the head were cracked.

Also, I have had the car for about 10k miles and it has used no coolant and starts quickly.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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Relax, what you describe is TOTALLY NORMAL. If your cooling system is OK, than the top Radiator hose WILL get rock hard when the engine is at normal operating temperature. Don't open the cap next time.

However, If the top Radiator hose is rock hard when the engine is stone cold, that's when you may have a problem.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Basically what Phil said.

Check the vehicle the next morning.

Squeeze the hose. If it feels hard, open the cap. If it now feels soft, you might have some "issues" brewing.

I don't like 110°C. one bit. The ambients are not all that warm and if it's hitting 110°C. now, you are in for some difficulty when the heat hits.

You might want to pull the radiator and backflush all the fins very carefully with foaming cleanser, pressurized air, or a light duty pressure washer. These fins get quite a bit of debris in them over the years and it severely restricts airflow.

It had a new Behr radiator put in 3 years ago and it is pretty clean. I wash it off all the time when I wash it buit I'll be sure to spray from the back next time. Is there a proper way to check the fan clutch like if it spins for so long after the car is off? Mine stops in pretty short order so I think it works and the aux. fans come on as they should. However, get this, it has green stuff in it. I have two bottles of flush I'm going to run through it but the thing is I need to wait a week or two before I do it because I'm up a creek if temps. drop around 32F. I have two bottles of zerex for when I am done with the citric flush.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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You ran the car for 25 miles on the highway I would fully expect the hoses to be hard and their to be some pressure in the system.

However 110C is not normal.

Last weekend I took my SDL camping the temps were in the mid 60's. Their were two people in the car and the trunk was packed with supplies and wood. The back seat was also full of stuff and wood. It cruised without any problems between 70-85 up and down hills and the temp guage never got any higher then between the 80c mark and 100c line, 90c I assume.

The electric fan is supposed to come on at 105c so it seems MB thought that was about as hot as they should be getting.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

hattie, the temp only rose after long freeway runs and the car was idling with the A/C, however, I do not think my temps are normal either. Other than those stops on the way back the temp has never even gone to 100 with the A/C on.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I would start be cleaning the radiator. Take it out and clean it out you will be shocked by the crap in it. Then do a flush of the system and change the coolant. Upper radiator hoses are like $13 I would change it if it is 5 years old.

Other then making sure the fan clutch has no play and doesn't spin freely I don't know of any other way to test it.

Does your electric fan kick on when the AC is on?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

If you are going to do the citric acid flush, you have quite a bit of work ahead of you in order to attempt to get all the acid out of the system, prior to the introduction of the Zerex. Since it's impossible to get more than 80% of the coolant out of the system, you probably have to flush it at least four times, driving the vehicle in between flushes to circulate all the flush water, before finally draining it and adding coolant. It's a long and arduous process, but, don't shortchange yourself and add coolant with any of the acid in there.

I understand what you mean by properly flushing it. I want to get it done and do it right so I don't leave any speculation in the future.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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If you want it done right you have to do it yourself....after researching how to do it....what most places call a "Flush" is barely more than a drain and refill.

To do it right and to do it thourough takes time...and time is money.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Yup, keep the car as cool as possible. If it's running hot on the highway, check out the radiator. If it's running hot around town, check the thermal mechanical fan clutch and electric fans. At no point should the car get over 100c, even in the most extreme conditions.. although MB's guage does not indicate red until 125c.. It is not normal.

It only rose after long highway runs at around 80mph. Once it got that hot it started cooling down immediately. So what would cause a temp spike?

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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Clogged/ineffeient radiator. You can try to have it cleaned professionally, or buy a rebuilt.. they aren't that expensive.

Well, I had the SDL running at 70 mph with the a/c on today and heading uphill at full boost. After 30 seconds or so, the temp climbed just above 100°C. Probably peaked at 102°C. I've seen it do this before and it generally stops it's climb at about 105°C. So, I'm not fully convinced that staying below 100°C. is the de-facto standard for a 603 at full boost with 86°F. ambient temps.