Yes. Just purchased one from fastlane. Been reading about installing. Seems simple enough. Hope this is the problem.

I tried the infrared gun on boiling water. The temps fluctuates. It's around 95c to 110c. either I'm doing something wrong or it just isn't accurate. This is the one I have http://www.harborfreight.com/infrared-thermometer-93984.html

Ya I'm a noob...

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1984 300td euro turbo

Aren't there two near here, one for the GP relay and one for the temp gauge?

They have slightly different p/n's depending on the use, at least they did when I was searching on different parts sites. You've ID'd the one for your gauge anyway.

95-110c may be okay looking into boiling water. Maybe you're getting steam.

I think the temp switch/sender on the t-stat housing has something to do with EGR. On a euro with no EGR, maybe you never had one.

I'm about to take the car for a spin. I will check to see if there's another one for the GP relay.

I just ran some tests on with the infrared on some flat surfaces and the readings were constant and solid. I will get a reading once the car hits 100c. Happens within 15mins. Yikes!

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1984 300td euro turbo

Infrared gun read between 90 - 97. Seems about right where the needle was. Here's a dumb question... what c is it when the gauge reads between 120 and the line underneath?

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1984 300td euro turbo

The line should be about 100, so between 100 and 120.

Can you use the IR gun on different spots on the radiator? Maybe see if there's a clog?

Good idea. Will do that tomorrow. Just got back It was too dark to check to see if there was a temp plug for the GP relay.

If the radiator reads ok and the new temp sender doesn't fix the problem, I might just install a 70c thermostat for now until I can figure out what the problem is.

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1984 300td euro turbo

I don't think a thermostat will have the car run cooler overall, just open earlier. It doesn't try to hold a temperature like a home thermostat, it opens to allow coolant into the radiator after the block warms up to 70 - think of it like an open/close valve.

Ack! Well I guess I'll have to figure out what else is wrong. I'll check the radiator heat tomorrow.

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1984 300td euro turbo

I recently had to boil a thermostat so had a change to compare $5 kroger meat thermometer with $15 Harbor Freight infared. They did not match. I believe the meat thermometer to be correct because the thermostat 1opened and the car ran at rated temp.

Unfortunately, there is no easy access to the SD's radiator without the infared.
In this case, infared read cool. So much for good cheap thermometers. I'll test the thermometer's battery in case that is the cause.

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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.

You know there are different thermostats don't you - designed to open at different temperatures?

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Temp guns don't work well on boiling water. Common knowledge amongst home-brewers.

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'82 300SD - Somewhere over 220k - Becoming reliable...

Just installed the new temp sender. Really easy job. BUT I have a problem!!!

Now my gauge doesn't move at all... is there a fuse somewhere that I might have blown?? What could be the problem?

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1984 300td euro turbo

How is the condition of the wire going to the sender? Mine was - shall we say crispy. Thats why I rebuilt that harness, because several of the wires were brittle and if they weren't broken yet, it was a matter of time. You could use a jumper wire from the sender to the pin the harness plugs into as a way to check.

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'82 300SD - Somewhere over 220k - Becoming reliable...