mine got to the mark after 80 degrees. is that 90 or 100?? the head I have had fixed and I have put in a new headgasket etc etc new bolts yes, turbo too. but I don't trust these 603's at all and I don't want it to break straight away...

I used to run my '86 citroen diesel with a bad radiator in spain (hot with mountains) up to 114 degrees. then the electronic display would start blinking and I would stop to let it cool off. did that 26 times on my way home to the north of France. the car still runs fine... aluminium head by the way, 2.5 turbo 5 speed. would go 195 km/h.
anyway, thus I am used to not worrying about engine temps but with mercedes it's a different story I've heard.

80C, maybe a bit more.

__________________
2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

so they just crack their heads because in the south it's hot and the antifreeze gells up the radiator so it doesn't work 100% ??

I'm selling this ****er. no more 603's for me.

The 3.5L 603's don't really have a head cracking problem. By the time they came around, MB had pretty much figured out that problem but introduced a new one with the connecting rods.

Hmm? You have to overheat the 3.5's pretty bad to crack the heads, but sometimes it just happens.

Its an old car with lots of old parts, the radiator is probably marginal. Do the electric cooling fans still work? Whats wrong with the coolant? Do you have the proper mixture? Is it the proper coolant?

Maybe you could try fixing the problem insted of complaining.

__________________
2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

FWIW I run at 84 to 85 degrees on really hot days with the AC on. Today was 100 degrees and it ran about like that. at one point it registered 105 on the outside temperature gauge.

It makes me nervous when it clears the 80 degree mark, but it seems to me if you watch it and take corrective action there should be no issues.

There is nothing wrong with any OM603 that gets to 100 degrees C on a hot day with the AC running. Completely normal.

Its those white and especially red marks 115 - 120C that one should concern themselves with.

__________________
1987 300SDL (324000)

1986 Porsche 951 (944 Turbo) (166000)

1978 Porsche 924 (99000)

1996 Nissan Pathfinder R50 (201000)

Here in Las Vegas on hot days like we're now having (105 to 110F ambient temps - dash thermometer read 118 yesterday) my 350SD often gets up to 100C when in stop & go traffic or pulling up an incline. When I get moving or hit level ground, it cools back to about 90C - where it typically runs with the A/C. From what I have read in other threads/posts here, my experience is very typical.

__________________
Autos:
1991 350SD 276,000 miles
2001 VW Beetle TDI 115,000 miles

Horns:
1955 Selmer Mark VI Alto (55,xxx)
1958 Selmer Mark VI Tenor (85,xxx)
1964 Selmer Mark VI Tenor (125,xxx)
1967 King Super-20 Tenor (430,xxx)
2002 Selmer Series III Soprano

For Jazz Saxophone enthusiasts - check out my website...
www.RustyBlevins.com

Bingo. To expect it to run at 80 to 85 C in summer w/ A/C running is not realistic. You can replace parts until the cows come home, but you will never get it to run that cool in traffic, high ambients, and A/C on.

Fantastic! That means my 300 SDL is runnin' just fine!

__________________
86 300 SDL - Vesuvius

96 SL 500

Assumption is the mother of all screw ups.

Do not go gentle into that good night. Rage, rage against the dying of the light. - Dylan Thomas

All that is necessary for the triumph of evil is that good men do nothing - Edmund Burke

that's what my indie says too... I don't have a problem so I won't try to fix it by throwing parts at the car. I'll sell it though
it has 150 k on mb warranty engine. the one with the upgraded rods...

Let us know when you're selling it or what you want for it. That was the car I desperately preferred, but I couldn't find an example I trusted... Maybe yours is/was it. Keep me posted.

Cheers, John

__________________
'98 E300TD (W210) | Sold 6/09 with 205k and counting
'04 VW Touareg V10TDI

The '86 goes up to 99C. on every decent upgrade when I hold 65 mph or more. The temperature gauge is basically a boost gauge. On downhills, it drops to 82C. The is basically independent of ambient temp. It will do it at 60F. and it will do it at 95F.....doesn't matter.

I'm hardly concerned.

You shouldn't be concerned, either.

I am new to this forum, which by the way is excellent.

I live here in Vegas, and just bought an 82 300SD. I run around 90 to 100 degrees C with 108 degree F ambient in stop and go traffic with the AC on. Thanks everyone for their feedback, because this had been bothering me.