Temperature gauge inoperative. Adding gauges?

Dealing with all subsystems specific to the diesel powered Datsun-Nissan 720 pickup trucks.

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ocd
Posts:69
Joined:14 years ago
Location:Portland, OR
Temperature gauge inoperative. Adding gauges?

#1

Post by ocd » 14 years ago

My temperature gauge does not work. the needle is perpetually posting to the left.

What should i do? how does one go about fixing this. It has been hotter than usual in Portland lately.

I like gauges. I wish there were more on my little pickup so I could tell whats going on with the little SD22 that i want to last forever. Has anyone installed more gauges? If so what and how.

Thanks.
-Noah

i deliver blends of biodiesel -no more!.

82 datsun 720 KC w/sd22
85 volvo 760gle sedan turbo diesel
85 peugeot 505s wagon turbo diesel & parts car
83 chevy k20 suburban silverado 6.2 n/a diesel

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asavage
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#2

Post by asavage » 14 years ago

If the fuel gauge works normally: Pull off the temp sender wire, ground it with a clip lead, go inside and momentarily turn the key to ON, watch the gauge. Goes up like a rocket? Turn off key! Replace sending unit. You can measure the sending unit's resistance if you want, but I don't have a "normal" reading chart. Anybody have a table of resistances for the temperature sender?

I don't seem to have a good picture of the sending unit, but it's the unit with the single wire going to it, not the one with two wires (which feeds the GP controller)! It's on the thermostat housing, left side of the engine. I don't know what year is your rig, so I can't be more exact than that. In the 1984 FSM, it's shown on page LC-17 (thermostat picture), if that helps.

If the fuel gauge also does not work, look at the instrument cluster voltage regulator, probably located on the back of the cluster itself.

Electrically, the schematic is very simple (see the upper right of page EL-71 in the FSM).
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

ocd
Posts:69
Joined:14 years ago
Location:Portland, OR

#3

Post by ocd » 14 years ago

It was just as you said - ground the wire that goes into the sending unit, turned the key to ON, and up goes the needle. The temp sending unit will take 5 days to get :x
-Noah

i deliver blends of biodiesel -no more!.

82 datsun 720 KC w/sd22
85 volvo 760gle sedan turbo diesel
85 peugeot 505s wagon turbo diesel & parts car
83 chevy k20 suburban silverado 6.2 n/a diesel

ocd
Posts:69
Joined:14 years ago
Location:Portland, OR

#4

Post by ocd » 14 years ago

I installed the temp sending unit(started when the engine was hot -soon thought better of it and finished when it was cold) and the gauge seems to work fine. she seems to run at normal operating temp at about the first third of the gauge.

So thanks a bunch it is nice to have a little more feedback from the engine. I want more gauges/sensors like my Peugoet. How feesable is installing aftermarket gauges in this vehicle? A tach would be nice. So would engine and tranny oil temp. Coolant level warning light would be great. The engine in my 85 volvo(vw 6cyl turboD) has the coolant temp sensor around the top of the block so if there is a major leak the coolant drops below the sensor before the heat increases and because air does not transmit heat as well as coolant you will go merrily along with a normal temp reading until its all over. Something they fixed later on. The Peugoet has a coolant level warning light when the sensor works.

I wish everything worked all the time 8)
-Noah

i deliver blends of biodiesel -no more!.

82 datsun 720 KC w/sd22
85 volvo 760gle sedan turbo diesel
85 peugeot 505s wagon turbo diesel & parts car
83 chevy k20 suburban silverado 6.2 n/a diesel

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asavage
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#5

Post by asavage » 14 years ago

ocd wrote:She seems to run at normal operating temp at about the first third of the gauge.
That's a bit low, except for maybe idling. I like to see it verticle under load. Too cool = shortened oil life and excessive fuel consumption.

There are excellent thermostat picturesand explanations by Philip.
How feesable is installing aftermarket gauges in this vehicle? A tach would be nice.
See this post for info on an affordable tachometer.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

Billysgoat
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Location:Titusville, FL

#6

Post by Billysgoat » 14 years ago

Installing additional gauges is normally very easy and straightforward ocd, the only drawback is they will not be "factory". The A pillar 1-4 gauge mounts have really increased in popularity the last few years, you might be able to adapt one to your purposes or fabricate it yourself.

My daily driver is a Dodge (Cummins of course 8) ) that has been fairly heavily modified, one of the first mods was a full set of gauges that monitor items specific on my model year truck (Fuel Pressure for instance, the stock supply pump is notorious for failing). While you likely won't NEED a 100-1600 degree EGT gauge, you might decide to get one for the giggles of it.

If you do want to get some additional gauges, www.genosgarage.com is a good place for the higher end models from various manufacturers. There are less expensive models available from most of your chain type parts houses.

Anything on the vehicle you want to measure from coolant level to oil temp can be measured, be creative, ask questions and see what you can figure out.

Later,

Billy
01 Dodge, (Cummins of course) 350HP daily driver

Planned project: 1950 Willis PU with SD22

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philip
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#7

Post by philip » 14 years ago

ocd wrote: SNIP
So thanks a bunch it is nice to have a little more feedback from the engine. I want more gauges/sensors like my Peugoet. How feesable is installing aftermarket gauges in this vehicle? A tach would be nice. So would engine and tranny oil temp. Coolant level warning light would be great. The engine in my 85 volvo(vw 6cyl turboD) has the coolant temp sensor around the top of the block so if there is a major leak the coolant drops below the sensor before the heat increases and because air does not transmit heat as well as coolant you will go merrily along with a normal temp reading until its all over. Something they fixed later on. The Peugoet has a coolant level warning light when the sensor works.

I wish everything worked all the time 8)
Gauges Gauges Gauges. I retired from line haul trucking. You should see some of the dash arrays I've seen O/Os (Owner/Operators) come up with. It's insane overkill AND ... unless the meter faces are chosen to have the NORMAL range indicated by an analog needle pointing verticle, too many gauges become useless. FORGET about digital.

Temperature: Final drive, transmission oil, engine oil, engine coolant, air charge, exhaust gas after turbo.

Pressure: fuel delivery, engine oil, service brake apply, air tanks.

Flow: air filter restriction.

Electrical: Volts, amps.

Tachometer, speedometer, fuel levels for each fuel tank, resettable engine hours counter, fuel/water separator light.


What "information" is meaningful on a SD22?

Engine coolant overheat warning buzzer (225 degrees).

Engine oil pressure light is better than just a gauge BECAUSE the stock DPC/Injection Pump controller will shut OFF the engine automatically when oil pressure drops to 8 psi.

That's it.

Optionally, even though the SD has no turbocharger, an Exhaust Gas Temperature gauge could be entertaining as well as a useful diagnostic tool.

An analog tachometer could be a useful driver training tool.

Outdoor ambient temperature.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

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asavage
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#8

Post by asavage » 14 years ago

philip wrote:What "information" is meaningful on a SD22?

Engine coolant overheat warning buzzer (225 degrees).

Optionally, even though the SD has no turbocharger, an Exhaust Gas Temperature gauge could be entertaining as well as a useful diagnostic tool.

An analog tachometer could be a useful driver training tool.

Outdoor ambient temperature.
I agree completely. I would add only a voltmeter to that list. My '82 didn't have one. They are a useful barometer of impending electrical problems.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

ocd
Posts:69
Joined:14 years ago
Location:Portland, OR

#9

Post by ocd » 14 years ago

asavage wrote:
ocd wrote:She seems to run at normal operating temp at about the first third of the gauge.
That's a bit low, except for maybe idling. I like to see it verticle under load. Too cool = shortened oil life and excessive fuel consumption.
thanks -i've been watching the temp guage more and my most recent longer trip(my work has been sending me to sites fairly close to home -nice short commutes and visits from my girls :D -but never getting to operating temp -what can you do?) about 30 minutes from I-5 to I-84 to 205 all the way to west linn/oregon city, 60-75mph, the closest the needle got to strait up was around 40% that is with a lumber rack and the bed full of tools and materials. the only time i've seen it 50-55% is after some 1st and 2nd gear climbes up steep and twisty gravel roads. and i have not been getting very good fuel economy around 28mpg mixed city/highway so... how much is the lumber rack and how much is bad carrier bearing, less than optimum smoke set screw setting, less than optimum air intake placement(pulling warm air from engine compartment), or high oil consumption 3-4qts in 3k miles?

oi! i need help! too much to do not enough money/time
-Noah

i deliver blends of biodiesel -no more!.

82 datsun 720 KC w/sd22
85 volvo 760gle sedan turbo diesel
85 peugeot 505s wagon turbo diesel & parts car
83 chevy k20 suburban silverado 6.2 n/a diesel

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asavage
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#10

Post by asavage » 14 years ago

If you're running near 75 MPH, 28 is probably about normal with a load on. These trucks are geared short, for 61 HP, and the torque peak is a lot lower than what the engine will be turning, when you're moving above 60.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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philip
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Location:Southern California, USA

#11

Post by philip » 14 years ago

ocd wrote: thanks -i've been watching the temp guage more and my most recent longer trip(my work has been sending me to sites fairly close to home -nice short commutes and visits from my girls :D -but never getting to operating temp -what can you do?) about 30 minutes from I-5 to I-84 to 205 all the way to west linn/oregon city, 60-75mph, SNIP.

And i have not been getting very good fuel economy around 28mpg mixed city/highway so... how much is the lumber rack and how much is bad carrier bearing, less than optimum smoke set screw setting, less than optimum air intake placement(pulling warm air from engine compartment), or high oil consumption 3-4qts in 3k miles?

oi! i need help! too much to do not enough money/time
OCD: As Al has said but I'll be more blunt ... you are HAMMERING that poor thing by maintaining speeds above 65. Wanna break a piston or toss a rod? Keep it up. These trucks were geared for a 55 mph world and with a diesel, that is were the fuel economy, oil economy, and engine life are.

How about getting yourself a Dodge/Cummins?
Last edited by philip 14 years ago, edited 1 time in total.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

ocd
Posts:69
Joined:14 years ago
Location:Portland, OR

#12

Post by ocd » 14 years ago

sorry guys :oops: - i didn't realize it was that serious. its not a habit for me to drive that fast but at the time it was the first long trip since i replaced the temp sending unit and since it really hadn't come up to operating temp i was trying to heat it up so i was pushing it. but no more for my little SD -though it doesn't seem to labor at all and it cruises pretty smooth.
-Noah

i deliver blends of biodiesel -no more!.

82 datsun 720 KC w/sd22
85 volvo 760gle sedan turbo diesel
85 peugeot 505s wagon turbo diesel & parts car
83 chevy k20 suburban silverado 6.2 n/a diesel

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asavage
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#13

Post by asavage » 14 years ago

The SD22 isn't very efficient up at that speed range, is all. It'll run there OK, but 28 MPG is probably near the best you can expect at that speed.

60 is a reasonable cruising speed, I'd think -- (besides, it's the speed limit in Multnomah Co. ;) ). Philip has a lot more miles on his than I did on mine.

(thread drift alert)
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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philip
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Location:Southern California, USA

#14

Post by philip » 14 years ago

ocd wrote:SNIP- ....and since it really hadn't come up to operating temp i was trying to heat it up so i was pushing it.
IN the process of reaching normalized operating temperature, this engine has a lot of cast iron block that has to be heated, about 2-3/4 gallons of coolant, and about 5-1/2 qts of oil (via the oil heat exchanger).

SD's are also a very undersquare engine (stroker) with a bore of 83mm (3.27") and stroke of 100mm (3.94"). SD's have 22:1 compression and were designed back in the mid 1960's. Quite the opposit of 10:1 compression Hondas having aluminum blocks, aluminum heads, and short strokes that thrive on lots of RPM.

Patience :wink:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

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