Hello, I've had a head replacement and overhaul done on my 300SD due to a cracked head. Before, it ran with the temp needle slightly above the 80 mark. Now it runs maybe a quarter inch higher (see pic). I've changed the thermostat twice (once with a Stant brand, then with Mahle). I've also replaced the sending unit. Is this reading normal? If not, what's next to try? Reads this way regardless whether highway or city driving.

Attached Thumbnails

 

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-1981 300SD 242k, stock - sold @ 250k
-1994 Toyota Pickup 4x4 R150F 5 Speed, 5VZ V6 swap.
-2004 Volvo V70-R 2.5T

One of my SDs reads where yours is. The other one closer to 80*. 80* converts to 176* fehrenheight, 90* converts to 194*. Confirm with an IR thermometer. Make sure that there is no air in the system. I've done this on a 617 by filling the engine block through the upper radiator hose with the thermostat removed.

Zerex G-05 still comes full strength.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

(C X 1.8) +32 = F

(F - 32) * .5555 = C

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I'm aware that 85C in pic is around 185F. I'm wondering if this is normal or if it should be running closer to 80, given the thermostat is supposed to begin to open at 80.

For example my Toyota 5VZ, per the manual, will have a coolant temp of 87 at the sensor regardless of environmental factors should the system be working properly. I can't find anything specific regarding the temperature for the SD, other than the manual helpfully reminding me that above the red line the engine has overheated.

I do fill the coolant (50/50 Zerex & Distill water) through the upper Rad hose first to prevent bubbles. It seems to be a massive hassle otherwise to get all the air out.


EDIT: I also realize that our gauges are far from precise, and better suited to trend tracking. I'm just not sure how to explain this change in running temperature when, if anything, it should be running cooler now that the cracked head is replaced.

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-1981 300SD 242k, stock - sold @ 250k
-1994 Toyota Pickup 4x4 R150F 5 Speed, 5VZ V6 swap.
-2004 Volvo V70-R 2.5T

Both my SDL and SL run dead-centered like that. Neither one of them are overheating or otherwise "hot".

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

It's perfect

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Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

I thought running below 80 was normal for years until I changed the thermostat during a system overhaul and I thought the NEW thermostat was bad when it ran at where yours is. Some research confirmed that the higher temp is where they're supposed to be, so yours is normal.

-Rog

That's exactly where my SD runs at I'd say that's where you want to be.

Glad to hear, thanks for all the replies!

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-1981 300SD 242k, stock - sold @ 250k
-1994 Toyota Pickup 4x4 R150F 5 Speed, 5VZ V6 swap.
-2004 Volvo V70-R 2.5T

As an aside, from what I have read, Toyota senders are designed to sit in the middle of the gauge over a wide spread of temperatures. Serious 80 Series Land Cruiser owners don't like this because of head gasket problems with the engine so install a separate gauge which reads out specific temperatures in the 'normal' range.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I have heard this! When I did my 5vz swap I drove around for days with the Bluetooth OBD2 scanner and temp readout on my phone to be sure it was actually running correctly, I've heard by the time the needle reads red it's over..


QUOTE=kerry;3686406]As an aside, from what I have read, Toyota senders are designed to sit in the middle of the gauge over a wide spread of temperatures. Serious 80 Series Land Cruiser owners don't like this because of head gasket problems with the engine so install a separate gauge which reads out specific temperatures in the 'normal' range.[/QUOTE]

__________________
-1981 300SD 242k, stock - sold @ 250k
-1994 Toyota Pickup 4x4 R150F 5 Speed, 5VZ V6 swap.
-2004 Volvo V70-R 2.5T