Water Temp

hdavis

hdavis

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How warm should the car be running when warm?


The temp gauge on my car started showing overheating problems yesterday, suddenly all the way up the red, so I stopped at a gas station and the car didn't really feel that warm.

There was enough coolant in the system and it felt hot but not tremendously so. I decided to take a chance and take it home. With no traffic and running at about 60 mph, the temperature gauge would not come down.

When I got home I took out the digital gauge and pointed it to the sensor and the radiator, the reading fluctuated between 83 and 91 (came up when I turned the car off obviously). Since the gauge has no markings I have no idea where the needle should be at those temperatures, but they don't seem on the high side

Thanks
 
My Bav runs about 175° on the mechanical temperature gauge, which is about half scale on the original temp gauge. The original does tend to wander around and flicker a bit, possibly because it's 40+ years old.
 
Thanks Mike

I assume the 175 is Fahrenheit? So in Celsius about 80?

I hope it's the sender and not the gauge...
 
I connected an old gauge I had lying around and the temp reading is the same (around 280 F in this gauge, all the way in the red), but again, the handheld laser digital gauge is reading about 175 F when pointed at the base of the sensor, so I guess the culprit lies in the sender.

I'm going to borrow one from a friend to be 100% sure before ordering
 
hdavis said:
I connected an old gauge I had lying around and the temp reading is the same (around 280 F in this gauge, all the way in the red),
Click to expand...

I know when the connection between the sender and gauge is open, the gauge will read full cold - not full hot. So, it sounds as if your sender is creating a direct path to ground, not an open connection. Does the temperature gauge rise gradually as the engine warms up, or does it jump to full hot as soon as you turn on the ignition?

I'm going to borrow one from a friend to be 100% sure before ordering
Click to expand...

By "one", I assume you mean a used sender. Yea, that will be a good diagnostic. Let us know what you find.
 
Temperature does rise gradually, so the gauge and sender are working (though maybe not correctly). When you first start the engine is cold as usual, and in 5 minutes it's in the red.

The bad news is that I connected the used sender I borrowed and it is doing the same thing, something is weird.

What throws me off however is that the digital (laser) gauge is showing a cold car, and they normally are pretty accurate.

It might be time to have a mechanic take a look at it.......
 
Fan clutch working? Cooling system bled correctly?

hdavis said:
Temperature does rise gradually, so the gauge and sender are working (though maybe not correctly). When you first start the engine is cold as usual, and in 5 minutes it's in the red.

The bad news is that I connected the used sender I borrowed and it is doing the same thing, something is weird.

What throws me off however is that the digital (laser) gauge is showing a cold car, and they normally are pretty accurate.

It might be time to have a mechanic take a look at it.......
Click to expand...
 
I looked into the fan clutch thing, and it seems to be OK, but not 100% sure, and bleeding might not be perfect, but this is a quasi daily driver and the temperature started shooting up yesterday mid trip without notice.

One thing I did was run it for around 10 minutes at 60 mph and the gauge didn't move. If it were the clutch fan, that should have been enough to bring the temp down.

So it might be the water pump (but no water leaks from it and the belts are tight).

Maybe a faulty thermostat not allowing water to circulate correctly?
 
i have a new setup that includes a duplicate temp gauge a new fresh electric line, duplicate sender, vdo system, accurate and unaffected by old stuff
the vdo water temp gauge in my car reads between 85 to 90 celsius depending on driving conditions
complete renewed system, including pump, sender, thermostat, radiator,...well ,...all !

but nevertheless the original gauge in the dash may read ok, or slightly higher when driving lights or highbeam lights are on, in the past the horn has something to do with this erratic behaviour

i do not trust on laser temp, but a termometer directly into the water tank will read true for sure, i did this to check 82 celsius in the middle of a red gauge reading crisis

check it, do not drive the car
 
Check wire from sender to harness next to relays, jiggle it. We had this problem today on Marks coupe, it showed very hot. I wiggled the wire on sender and it went down. The wire degrades and breaks, it is next to Alt to a regulator bundle.
 
HB Chris said:
Check wire from sender to harness next to relays, jiggle it. We had this problem today on Marks coupe, it showed very hot. I wiggled the wire on sender and it went down. The wire degrades and breaks, it is next to Alt to a regulator bundle.
Click to expand...

hdavis said:
Temperature does rise gradually, so the gauge and sender are working (though maybe not correctly). When you first start the engine is cold as usual, and in 5 minutes it's in the red.
Click to expand...

I liked the theory of a bad wire between the sender and gauge until I asked whether the gauge immediately went to "hot", or climbed gradually as the car warmed up. I think a broken or shorted wire would peg the gauge immediately - it wouldn't mimic the behavior of an overheating engine.
 
Well, the car is still not responding to anything, and I believe the problem lies with the gauge. I have a NOS gauge and will have it installed next week, let's hope that does the trick

Thanks again for all the valuable contributions
 
Henry,

why not put a jumper cable on the sender and one to ground, and hook it up to the new gauge and see what it reads.
 
I'm having the opposite difficulties, the gauge goes low as I drive around. And it jumps from "normal" (about 4:00 O'clock) to the blue zone so I know it's an electrical problem.

Where is the sender? Does anyone have a picture of it?
 
Sender is screwed into the thermostat housing area, it has one wire coming from it.

Bwana said:
I'm having the opposite difficulties, the gauge goes low as I drive around. And it jumps from "normal" (about 4:00 O'clock) to the blue zone so I know it's an electrical problem.

Where is the sender? Does anyone have a picture of it?
Click to expand...
 
deQuincey said:
+1
there are plenty of pics in my first thread about the heating problems
if your gauge is reading wrong, probably it is a resistance issue, try to check the cable , and then change the sender to check it
Click to expand...

Ding ding ding ding ding!! We have a winner!

Yes, all I did was to pull the connector off the sender spade and then wiggle it around to break thru the corrosion. Dead steady now. Looked like the connector had green corrosion in it.

I love simple, cost free repairs, thanks! :smile:
 
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