Coolant Line Elbow

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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TooManyIdeas
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Coolant Line Elbow

#1

Post by TooManyIdeas » 13 years ago

Got another thread pitch question. The elbow fitting that goes from the heater hose line to the thermostat housing, what size is it. I noticed in Phillip's The Bomb thread the fitting looks aftermarket. What I'm trying to do is install a thermostatic control for an electric fan, so I want to Tee into that port. Unless one of you ingenious fellows has a nifty McGyveresque way to piggyback off of the temperature sending unit :wink:
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

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asavage
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#2

Post by asavage » 13 years ago

"McGyveresque"

You win the "most inventive word of the day" prize. 'Course, you have to be present to win, and you weren't :twisted:

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philip
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Re: Coolant Line Elbow

#3

Post by philip » 13 years ago

TooManyIdeas wrote: What I'm trying to do is install a thermostatic control for an electric fan, so I want to Tee into that port.
Whoneeds a fan at all? The only time my truck's A/C suffered was in 100* heat at speeds below 30mph. Serious. That said, an idling diesel generates little heat. More fuel delivered makes heat.

If the sensor has a small thread, I'd be inclined to drill / tap another hole in the thermostat housing as there is room.
-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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TooManyIdeas
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#4

Post by TooManyIdeas » 13 years ago

Philip, so your trying to tell me you don't run ANY type of fan at all :shock:. All I want to do is allow the heat from the engine to control the fan. If that heat never turns the fan on, then so be it. However I'd still like to have the insurance.
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

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philip
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#5

Post by philip » 13 years ago

TooManyIdeas wrote:Phillip, so your trying to tell me you don't run ANY type of fan at all :shock:.
The "no fan" experiment I ran showed me how much cooling reserve the SD has ... and my truck has an A/C condensor blocking some of the air flow.

As I recall, some electric fan kits use a thermo-switch whose sensor fits (jambs) in between the radiator fins and is adjustable. That's pretty simple and ... it's adjustable.
-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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#6

Post by asavage » 13 years ago

I like the bulb-sensing style. The one I've been recycling through various vehicles I bought in the very early 80s. It slips into the upper (or lower) radiator hose. There tends to be a leak of coolant around bulb's tether, so I cut a couple of small strips of bicycle inner tube to make the transistion around the tether less dramatic, and also applied RTV (in addition to a std hose clamp, of course). The bulb reads the coolant directly.

I bought a thermostat housing today at the JY. Before I removed it though, I broke the heater ell loose. I can guarantee that the thread pitch is too fine to be an NPT size. Though it's a taper fitting, it's not SAE. I will try to measure it tomorrow, but it's likely metric or BSP -- probably the former.

Looking again at Galen's pics in "The Bomb" thread, the from the thermostat housing (the hot line to the heater), looks painted OEM to me. The brass-colored return line (cool line from the heater) might be something else. The JY engine I looked at today was missing the WP, so my mind is not fresh on that one.

Image Image

Anyway, if you were hoping to use a 1/2 MNPT fitting, forget it, unless you re-tap the housing.

BTW, I have a spare housing :) I am planning on putting three new 8mmx1.25 helicoils in it, and putting it on a shelf as a spare -- so many folks here seem to have problems with the OEM vertical bolts breaking off in it. But if you really want one, I could be persuaded to part with it.
Last edited by asavage 11 years ago, edited 1 time in total.
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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TooManyIdeas
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#7

Post by TooManyIdeas » 13 years ago

Be careful when using helicoils on anything around liquids or gasses. They were not designed to seal anything. There only purpose is to repair damaged threads on solid mounting points. If your plan is to thread something near liquid or gas, you need to use a solid threaded insert IE slimsert or keensert.

Anywho, tell me which dead presidents I need to resurrect and let's make a deal (no whammy)
Last edited by TooManyIdeas 13 years ago, edited 1 time in total.
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

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asavage
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#8

Post by asavage » 13 years ago

There is no sealing needed on this part, the sealing is all done at the gasket. Time-serts are what I would use in a thread-seal situation, but that's rare for the thread repair I usually do.

This housing does come with the two sensors (one for GP controller, one for temp gauge) and the ell. If you want it that way, how about $20 and I pay the shipping (which is probably half of that).

If you don't want the sensors, cut a couple bux off. I have spare sensors on the "Vashon Truck" engine, so I don't really need these. And they don't seem to go bad very often.

I can take pics before sending if you'd like. The housing, and the camera, are at work. Earliest pics probably Tues. night, as I will probably be tied up Monday night.
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.

cseger1
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#9

Post by cseger1 » 13 years ago

I helicoiled one of the bolts on mine and it didn't cause any leaks. If anyone else has a housing to sell please PM me. THX
Christian
1981 720 SD22

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philip
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#10

Post by philip » 13 years ago

asavage wrote:There is no sealing needed on this part, the sealing is all done at the gasket.
True, the thermostat cover gasket does the sealing. But that paper gasket is not a perfect seal and ... the three bolt holes are blind holes (dead end). So ... seepage past the paper gasket reaches the bolts and corrodes them as there is no drainage path. Busted bolts result.

After having the broken bolt (or was it two) melted out, I replaced the rust prone OEM bolts with stainless dipped in antisieze grease.

Image
-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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#11

Post by asavage » 13 years ago

philip wrote:True, the thermostat cover gasket does the sealing.
My statement was in response to TMI's that helicoils are not suitable for use in sealing gasses/liquids.

I advocate for steel or SS inserts wherever there is any question about the durability or longevity of a tapped hole in a non-ferrous metal.

Not only does a helicoil prevent galling & siezure (unless you run SS hardware too, in which case anit-sieze is mandatory), the threads themselves are stonger than the parent metal, and the OD of the helicoil insert has more surface area than the original hole.

I always coat the OD of the insert with Lock-Tite.

I really like helicoils. Time-serts and the like seem to work well too, and don't have the issue with gaseous/liquid leakage through the insert.
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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asavage
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Re: Coolant Line Elbow

#12

Post by asavage » 13 years ago

TooManyIdeas wrote:Got another thread pitch question. The elbow fitting that goes from the heater hose line to the thermostat housing, what size is it.
Ya got me!

Image

It isn't 18 TPI and it isn't 20 TPI.
It isn't 1.25mm pitch and it isn't 1.5mm pitch.

Somebody with more time/knowledge than me is going to have to suss this one.

Image Image Image Image Image Image Image
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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TooManyIdeas
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Location: Albuquerque NM -VEGAS BOUND

#13

Post by TooManyIdeas » 12 years ago

Ok I found out that the elbow is 3/8 NPT so that's cool. However what are the two probes wired to. One has got to be the temp guage, but I'm clueless as to the second one (and I can't find my FSM to figure it out)

Image

could some one tell me what each of those sensors are
82 Datsun 720 King Cab Diesel - FOR SALE !!!!
85 Chevy Monte Carlo CL
90 Toyota Pickup -SOLD
05 Kia Spectra 5
02 Dodge Dakota Quadcab
-OOOOOOOOHHHHHHHHH YEAH!!!!!

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philip
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Re: More stupid questions

#14

Post by philip » 12 years ago

TooManyIdeas wrote:-SNIP- Could some one tell me what each of those sensors are
You already know what the single post sensor is for.

The two-post sensor is for glow plug control. Scroll down to the Type I schematic.

Also Adaptor plug / harnass view.
Last edited by philip 12 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"

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asavage
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Re: More stupid questions

#15

Post by asavage » 12 years ago

TooManyIdeas wrote:Ok I found out that the elbow is 3/8 NPT
No, it's not. 3/8 NPT is 18 TPI, and that elbow is definitely not 18 TPI.

While I don't doubt that you can screw 3/8 NPT in, it's not the correct thread pitch.
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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