Cannot find correct coolant temp sending unit

[tucsonjwt]

My 83 C20 454 needs a new coolant temp sending unit. I have been trying to get an OEM replacement but I keep getting the wrong one sent to me.

The correct part is AC Delco 213-4793/ GM 88865046. This should be a 3/8" thread but the part inside is always a 5/8" thread. AC Delco customer service is no help. Nobody will actually check the thread size prior to shipment, and no dealers stock this part.

I want to stay with an OEM part because of existing accuracy issues, but cannot find even a correct aftermarket part.

This factory sending unit in my Goodwrench engine has a 56 series style electrical connector. The Delco replacement part listed has a typical spade connector.

Does anyone have any ideas about where I can get the correct part?

[Bandit130]

Check this one out.

https://www.autozone.com/cooling-hea...149_10199_5673

[Warrens69GMC]

Your problem is- Goodwrench

You are ordering the correct part for the year of your engine, but the goodwrench motors went to 3/8 npt for the threads- this is true for 454/350/305 motors.

Buy the bigger sender, send it to have it re-threaded
https://67-72chevytrucks.com/vboard/...ghlight=sender

[bloo]

What is 5/8" thread? Did you just measure it?

These should be pipe thread. 3/8" pipe thread means 3/8" inside the pipe, so out on the threads it will measure much bigger, probably something more like 5/8". Maybe try 1/8" pipe thread? That would measure about 3/8"

[jocko]

Member brian mac has helped me in the past - not on this particular part, but on turning down an year-correct temp sender for the truck to fit on a newer engine in it to make it work with factory gauges. He doesn't post a lot, last one about a year ago, but he's always helped when I've needed something like this done. If it comes to turning down a sender, he's your guy. I'd still try to get the right part though if at all possible. Frustrating to not get what you think you're getting - especially when done by mail.

[tucsonjwt]

Thanks for all of your input.

I can get the correct part for the engine, but the part has the incorrect threads. If you research the AC Delco and GM part number I referenced it will state 3/8" thread. For some reason, ACD decided to put a 5/8" threaded part in a 3/8" part numbered box.

I don't doubt that Mr. Goodwrench is responsible for this, but I am unable to contact him (I think he retired long ago.)

If Goodwrench did a 3/8" switcheroo, then where did they get the 3/8" sending unit? Somebody in the GM or AC Delco supply chain must have furnished it. If the thread size was reduced to 3/8", wouldn't someone come up with a new part number for that size? This part must exist somewhere.

Having a 5/8" temp threaded sensor turned down to 3/8" would be my last option. I would question the change in temp values and I think there is a greater risk in cross-threading a user modified part. I know brass is more forgiving than steel, but I would like to avoid that whole issue if possible.

I might give that Autozone sensor a try, but I suspect that it will also have a 5/8" thread, even though it states a 3/8" thread, just like the other sellers. My pursuit of an OEM sensor is based on the lack of accurate reading on my current sensor, and I think an aftermarket sensor might be just as bad. My current Goodwrench sensor works, it just reads low. I replaced the connector and wire lead into the harness and the wiring seems ok to me.

[tucsonjwt]

To clarify, I have a threaded hole in the engine which appears to be about 3/8" diameter. I acknowledge that a 3/8" threaded nipple will have a much larger outside diameter, but since I have a 3/8" hole I was assuming that the sensor should fit into that 3/8" hole. I was also assuming that the part descriptions I have read online are referencing the hole diameter, and the style of thread (pipe thread), not actually a much larger hole than that 3/8" diameter.

I have been very active in the assuming arena lately.

[bloo]

EDIT: OOPS I must have been typing while you were typing.... I think 1/8" NPT is what you want. I don't know what the part number would be.

What is 5/8" thread? Water sending units are almost always pipe thread. I have never heard of 5/8 pipe thread, and I can't find any evidence online that it ever existed. I'm not trying to be obtuse here, but I have no idea what sort of threads you are talking about. What was in the box?

[tucsonjwt]

Yup. I got the whole "nominal" 3/8" vs. "actual OD 3/8" thing you reference.

I am being led down that actual 3/8" diameter hole in the engine path to take the part descriptions to literally mean a 3/8" diameter thread on the end of the sensor. Since I only have a 3/8" diameter hole, I was thinking that the part descriptions referred to the type of thread, not actually sticking a 3/8" iron pipe nipple in the engine, which would require I lot bigger hole.

This engine is actually a Goodwrench factory rebuilt engine, so who knows what mis-mash of pieces ended up on that engine. I still think somebody has the correct sensor somewhere, and given the different temperature response characteristics for the various sensors I would like to get the correct one.

I will say that the old existing sensor is still sending a signal - just an incorrect signal. I guess I could continue looking for an abnormal spike in the gauge relative to its typical setting (135-150 degrees?), but I am very anal about things like this. A big block in the 110 degree ambient desert climate makes me nervous about overheating this beast, so I keep a close eye on the temp gauge. Every part of the cooling system has been replaced, but it doesn't take much of a part failure to roast that engine.

[bloo]

Does your truck have a gauge or just a hot light?

That GM part you listed is for a light (I think). I'm only finding 1/8" for a temp gauge.

[tucsonjwt]

Gauge.

[bloo]

I think what you need is a VDO 323-057 AKA Dakota DIgital SEN-04-1. It has the connector you want.

https://www.jegs.com/i/VDO/918/323-057/10002/-1

https://www.summitracing.com/parts/dak-sen-04-1

This is supposedly the same electrical characteristics as the gazillion universal ones on Amazon that have the wrong connector, some as cheap as $5 or less.

https://www.amazon.com/huanban072-Te.../dp/B07MNLBCNN

If this graph (posted elsewhere on this site) is right on though, it is gonna read a little high, maybe 20F, but it is the best I could come up with.



VDO also make this: https://www.amazon.com/VDO-323-050-T.../dp/B001P76H3G

It doesn't hit the graph above as close, but it is off in the opposite direction, so if the other one is way off, it might be something to try. Because it reads a little too cold I might boil it in a pot with a gauge hooked up, just to make sure it isnt reading so low that the gauge doesn't alert you. It might be.

[bloo]

I will say that the old existing sensor is still sending a signal - just an incorrect signal. I guess I could continue looking for an abnormal spike in the gauge relative to its typical setting (135-150 degrees?), but I am very anal about things like this. A big block in the 110 degree ambient desert climate makes me nervous about overheating this beast, so I keep a close eye on the temp gauge. Every part of the cooling system has been replaced, but it doesn't take much of a part failure to roast that engine.

I missed that part the first time around. What does the gauge read now with the engine at normal temp? You mean it reads 135-150 at normal temp?

I have also been assuming a stock GM gauge, in the dash. Is it?

[tucsonjwt]

Thanks for that big research effort.

If I can't get anything like an OEM sensor I will have to go down that aftermarket path.

I am probably reading 20 degrees + low right now, and if the aftermarket ones read 20 degrees high, I think I would prefer the low reading sensor just for the psychological benefit.

The style you posted with the long probe end is different from the "correct" OEM part, but I don't know if that is a relevant dimension regarding proper fitment.

I will poke around the web a bit more and see if I can scare up any interest on the part of any suppliers to do a physical inventory check. Considering how many 454s Mr. Goodwrench must have rebuilt, there must be a correct replacement sensor somewhere out there. I was hoping to find a NOS part somewhere but no such luck yet.

[tucsonjwt]

I replaced the stock gauge with another "stock" gauge from LMC (only because the indicator needle broke on the original gauge - the original gauge was still functioning.) I am estimating a top reading of 150 at normal operating temperature. As you know, the stock gauge has rather general markings, so you have to interpolate the actual temperature a bit.

However, the gauge will stay quite low in the sub-140 degree range for quite a while when the engine is warming up. I would say 140-150 is the "normal operating range" for this gauge. So, it is not like I have a dead gauge.

The factory style connector (shown in the first pic) and some new wire to the sensor have been replaced. I think I have good current flow from the sensor to the gauge.

Most guys would ignore this whole issue but as I said I am anal about this.

[bloo]

It surprised me that I wasn't able to turn up something in genuine GM. I have been seeing sensors like that on everything else (Mopars, Fords), maybe with the wrong connector, for decades.

Maybe the gauge itself is hosed? Way out of calibration?

I might pull the wire off of that sender with the engine at normal operating temperature and measure ohms, sending unit terminal to ground, and see if it hits close to the Chevrolet graph (should be not to far off 195F if you are running a 195F thermostat, etc.)

Good luck!

[Pontiac1976]

Have you tried a down open plug down sizer on your block that will fit the sensor (but the open end down sizer has to let the sensor go throw so the sensor tip is in the water in the block). So it will read the temp. make sure down sizer is pipe tread(taper) if not then use Thread seal tape (also known as PTFE tape, Teflon tape, or plumber's tape) to the block only.

[akart]

Got some Summit heads,same problem. Ordered a thermostat housing w/the correct sender thread size. I can run the wire there. Also bought an Autometer temp gauge w/the correct sending unit thread size that fits the heads but that involves installing the new gauge. Haven't decided which to use as I haven't done the head swap yet. Soon though.

[Rickysnickers]

Would this one work? https://shop.advanceautoparts.com/p/...359p/5973368-P

[Warrens69GMC]

Originally Posted by Rickysnickers

Would this one work? https://shop.advanceautoparts.com/p/...359p/5973368-P

He wants the T -top not a spade terminal

[Rickysnickers]

Ah, ok sorry

[tucsonjwt]

I can modify to a spade terminal, but I don't understand why I should have to do that. As far as I can tell, the 3/8" designation on these sending units apparently refers to 3/8" pipe thread (as in a threaded hole which accepts a 3/8" iron pipe nipple), so a threaded hole much bigger than 3/8."

I guess I will just keep an eye on the gauge reading. Anything above 150 degrees and I will get nervous. The gauge has been reading this way for the past 17 years, so I guess I can continue to deal with it. No actual overheating so far.

[MJN]

Might be worth a shot contacting Joe Hudacek, he is out of Superior, Wi and deals mostly in heater valves but also carries a good number of NOS Delco swtiches. If he doesn't have it, he may be able to point you in the right direction.
www.heatervalves.net