temp sending unit loose

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Feb 7, 2018 | 04:14 PM

sunbelt57

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temp sending unit loose

I'm putting back together a project that's been sittin a while: 1977 F150 w/ 351m and the temp sending unit seems to be missing something. I screw it into the hole in the block just below the hot water inlet/outlet and the nut tightens up but the sending unit it loose.

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Feb 7, 2018 | 05:24 PM

77&79F250

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From: S/W Missouri, Polk county

Does it go to/have an aftermarket set of gauges? Does it leak, does is work? If no and yes, then go with it.

I though the 351M has a thread in temp sensor and on the outer end had a threaded stud that a 90* elbow elec connector slipped onto.

Feb 7, 2018 | 05:35 PM

NumberDummy

Ford Parts Specialist

Joined: Nov 2006

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From: Simi Valley, CA

Quote:

Originally Posted by 77&79F250

D0WY-10884-A (replaced D0ZZ-10884-A) .. Temperature Sending Unit / Stamped #258 or #260 / 3/8" -18 pipe thread (Motorcraft SW-925)

All I-6's & V8's: 1970/74 E100/300; 1970/78 F100/350; 1975/78 E100/350; 1979 E250/350 & F150/350 460 / Myriad 1970/79 FoMoCo Passenger Cars.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
D9TZ-10884-A .. Temperature Sending Unit (Motorcraft SW-1593).

1979 E100/350 300/302/351W; 1979 F100/350 300/302/351M/400 / Note: 302 in E100/150 & F100/150 only.

Feb 8, 2018 | 05:26 AM

Don Senkow

Mountain Pass

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From: Canada

There is an adaptor the sending unit bulb screws into. That screws into the port on the engine. Google mech temp gauge to see what I mean.

Feb 8, 2018 | 05:53 AM

vtpkrat2

Tuned

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From: Vermont

I don't believe the LOCK WASHER has anything to do with this application. The nut looks to be probably "pipe" thread which tightens by itself into the proper port.With the lock washer in the mix the nut cannot "bottom out" or tighten onto the bulb holding it in place.

Feb 8, 2018 | 08:23 AM

Loosescrews

Mountain Pass

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Quote:

Originally Posted by Don Senkow

There is an adaptor the sending unit bulb screws into. That screws into the port on the engine. Google mech temp gauge to see what I mean.

Yep. Missing the piece that screws into the manifold that the sender tightens against.

Feb 8, 2018 | 09:33 AM

Aaron-71

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From: Regina, Saskatchewan

Quote:

Originally Posted by Loosescrews

Yep. Missing the piece that screws into the manifold that the sender tightens against.

Manifold? No.

Block or water neck are the only two options on the 351M/400 to measure coolant temp.

There is no place on the intake manifold for a water temp gauge - no coolant flows through the 351M/400 intake. You're thinking of a different motor.

Quote:

Originally Posted by sunbelt57

Block has a 1/2" NPT threaded hole near the top (passenger) side of the timing cover.
Water neck has two sets of 3/8" NPT threads for the stock temp vacuum switches.

They are both National Pipe Thread. The fitting that you have in the pic is straight thread, not pipe thread. It's very easy to tell the difference between the two because NPT is tapered for a tight fit. Straight thread (see pic) is.. well.. straight (not tapered)...

Here's what you need: https://www.oreillyauto.com/detail/e...t/9851/4299498

Notice how your fitting is steel? It should be brass to match the temp sender probe so that you don't have dissimilar metal contact at the probe.