hi. my 84 300d turbo runs around 100c all of the time, traffic, highway etc. it will push 110 sitting in traffic on a hot afternoon. is this too hot for the 300D? I have checked the fans and both function, coolant is topped off...

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)

That's a bit hot.

A properly operating system should hold steady at around 80 C.

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Joe

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1980 300SD - 495k miles - 'The Ambassador'
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Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

Yes, too hot. It should be around 82*c and not go above 100*c.

Check fluid level, which I'm sure you have, and pop in a new thermostat first. One of the easiest cars to replace a thermostat on I've ever experienced.
Report back.

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

If the thermostat doesn't help, its radiator time. When I replaced mine the temps fell 10C and have stayed at a solid 80-82C no matter the outside temp or driving conditions.

Note: I never touched my thermostat, it was the filthy original radiator that caused the overheating.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I have yet to replace the one on the wagon. Boy, I need smaller hands! The hydraulic lines of the SLS system sure make things much more adventurous.

It's running 60 The 300D was a piece of cake though!

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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg

That sounds right, mine is getting to be the same way too. I think I'll toss in a new radiator in the spring and see what happens.

I wish my issues were as simple as a radiator.

With a brand new thermostat, the results are unchanged............the engine will typically run 95-99C. under decent loads. The infrared gun verifies that the output water from the thermostat is at 82C., but the cylinder head at #2 and #3 is right about 90C.

The engine temperature is unrelated to ambient..........doesn't matter whether it's 100F. or 40F. It's strictly load related.

I'm thinking that the sending unit........close to #3.........is reading the higher temps. generated by these two cylinders.

That is strange, do you think you have a flow restriction in that part of the head?

The only thing that I can conceive other than injector issues on those cylinders is trapped air. If a bit of air is remaining at the top of the head, the symptoms would be typical.

But, I've never heard of air remaining trapped in the head for months on end............

I have the same issue as the folks here in this thread. Temp goes right up to 100c, and stay right there like that's where it's supposed to be.

I am going to change the thermostat first. Then flush the system (PO has green coolant in there now). I guess I need to get an IR temp reader, any other way to verify that the temp gauge is accurate?

What else should I check along the way? I really don't want to replace the radiator...

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I doubt that air would stay in the head for no reason too. I was thinking of the flow passages being partially restricted with some kind of debris.

Remember that this was the rebuilt head by Metric and it functioned fine for nearly one year. The problem developed slowly over the past six months. I can't imagine anything within the system that partially restricts the flow that would develop on it's own............???

Furthermore, with a flow restriction, why would the center cylinders be warmer?? I'd think that most of them would be warmer........

I don't know.

I guess I would just try flushing the system and see what happens. I like to force water directly through the head with a hose. Just a guess.

Had this issue on my 81 300CD 2 years ago. 100 c in slow LA traffic. 85 c at 65 mph. I found the fan clutch never fully engaged. Once changed the temperature stabilized at 80 while driven and went to 90 on a hot day with A/C on. Well within spec. My 81 has no coolant recovery system so its very important to have the temperature stable. Also nobody ever checks their radiator cap. If it releases early, temperature will be higher and possibly erratic. I've always gone by the rule that stable temperature is more important than the temperature itself. Any engine will be more efficient at a stable 90 c than one that fluctuates between 80 and 100 c. I read alot of posts where the person is trying to lower engine temp when in fact, closer to 85, 90 c and stable is the preferred goal. Also, make sure that the A/C condenser is not plugged up with debris restricting air flow. A garden hose aimed at the engine side of the radiator will be the best way to force the crud out.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.