Extending engine bay harness - solder seal or heat shrink butt connectors?

Have a swap project that requires splicing and extending some harnesses.  I was going to use the butt connectors with the heat shrink built in like these:  

https://www.amazon.com/Connectors-Eventronic-Waterproof-Automotive-Electrical/dp/B071L6VDLK/ref=sr_1_2_sspa?s=hi&ie=UTF8&qid=1515166480&sr=1-2-spons&keywords=heat+shrink+butt+connectors&psc=1

...but then googling I came across these "solder seal" wire connectors that are basically a heat to connect, which glues the wire in place, and melts the solder to give a corrosion resistant connection as well:

https://www.amazon.com/Sopoby-Connectors-Electrical-Waterproof-Automotive/dp/B01DPS8DPM/ref=sr_1_9?ie=UTF8&qid=1515166113&sr=8-9&keywords=heat+shrink+butt+connectors

I'm sure either would be fine, but those solder seal ones intrigue me.  Any experience or suggestions either way?  Should I use something else entirely?  Brand preference?  I have about 20 wires to splice for engine bay things, and light wiring harness, etc.  

Heat shrink crimp connectors. The solder ones would be annoying to work with in an engine bay from my experience using them. 

Personally, I tend to hand-solder the joints and heat shrink them (with the good adhesive lined heat shrink).  

We once coasted off the track in the late model when the ignition lost power.  Too late, we found a bad "solder" joint in a solder seal connector.  Later, I removed all of them and cut each one apart.  Of the twenty or so connectors, only one had what I considered to be adequate contact.  The rest were two wires held together by stiff shrink tube.

Whether they were done wrong, or junk, I can't say, but I can assure you I won't ever use one.

The official FM line is to use the solder seal parts, but I like a good solid mechanical crimp so that's what my cars have and what I buy for my own cars. Use a ratcheting crimper and you'll never have a failure. As noted, they are easier to install because you can crimp one end and then the other.

What you really don't want to do is get them mixed up. Try to crimp a solder seal connector and you'll have a guaranteed failure.

Hand solder vs crimping is a semi-religious debate. My take is that crimping is less brittle and less likely to suffer a vibration-related failure. It's also what the OEs use, and they hold up well over decades. Someday I need to talk to an aircraft guy and see what SOP is for the "don't let it fall out of the sky" crowd.

FYI, DelCity is a good source for quality crimp and solder seal connectors.

A good crimp is better than a soldered joint in terms of vibration resistance and such.  However, I've never had a properly done solder joint fail in a car.  And it's easier to get a good solder joint than a good crimp, especially if you're working on wiring that's still installed on the car.  

If you're really paranoid, crimp it (with an all metal crimp connector), flow solder into the joint to fill any gaps left by an imperfect crimp and then heat shrink it.  

I was a solder-splice guy until ownership of '87 Benz which suffers from corroded solder joints in the OE wiring system. Though these solder joints are exposed- not insulated with with adhesive heat shrink. That said, NASA has a great solder-splice guide PDF available: https://prod.nais.nasa.gov/eps/eps_data/145968-OTHER-002-006.pdf

I use and love the crimp/heat shrink connectors.  Using a ratcheting crimper works consistently and the built in heat shrink seals it from the elements and adds to the strength of the crimp to keep them from pulling out.

I usually use non insulated crimps and then flow a dab of solder in to it and then put a dab of dielectric grease on it and heat shrink wrap it. Never had an issue with any connections.  

I usually avoid the shrink tube crimps.  In order to properly crimp them you usually pierce the shrink part and water gets in anyway.

Never used the solder seals

The way I do it is a bit more labor intensive but its worth it to me... I use non insulated crimps and separate shrink tube.  If I really want to do it right I'll also solder the crimps, but that is a bit overkill.

dean1484 said:

I usually use non insulated crimps and then flow a dab of solder in to it and then put a dab of dielectric grease on it and heat shrink wrap it. Never had an issue with any connections.  

This is what i do minus the solder.  Never had a failure after tug test.if it fails the tug test, then....

Also easier to bundle that the all in one heat shrink crimps. Much nicer looming.

rslifkin said:

If you're really paranoid, crimp it (with an all metal crimp connector), flow solder into the joint to fill any gaps left by an imperfect crimp and then heat shrink it.  

Or you could get the connectors that are both crimp and solder. 

Curtis said:

I usually avoid the shrink tube crimps.  In order to properly crimp them you usually pierce the shrink part and water gets in anyway.

 

Depends on what heat shrink the connector has and what crimpers you are using. If you are using ones with polyolefin heat shrink and the pliers type crimpers you are almost guaranteed to cut through the heat shrink. If you are using nylon or a nylon blend heat shrink terminal and ratcheting crimpers you won't have that issue. 

I really like the 2nd ones you linked to, and used some on my engine harness extension

I'm a big fan of uninsulated crimps followed by some good marine grade heatshrink tubing.  They make a nice low profile splice so you don't end up with that huge bulge in your harness, but I still recommend that you stagger your splices.

They're also a lot cheaper than them fancy things that you linked.

Burrito said:

I'm a big fan of uninsulated crimps followed by some good marine grade heatshrink tubing.  They make a nice low profile splice so you don't end up with that huge bulge in your harness, but I still recommend that you stagger your splices.

 

They're also a lot cheaper than them fancy things that you linked.

This....  marine grade has adhesive inside the shrinktube making the joint hermetically sealed

If you're like me, you forget to slide the heat shrink over the wires before crimping approximately 30% of the time. Dangnabit. That's why I like the all-in-one And with the ratcheting crimpers and DelCity splices, I don't cut through the heat shrink.

Dusterbd13 said:

Also easier to bundle that the all in one heat shrink crimps. Much nicer looming.

That's a very good point I hadn't thought of.  I think I may go this route simply for the ease of looming/wrapping after it's all spliced up.  Thanks! 

I prefer the lineman splice, AKA the way NASA does it, with heat shrink over it.

I use splice terminals and glue lined heat shrink
http://www.cycleterminal.com/splice-terminals.html

You can get them cheaper through digikey too.

Also I have the eclipse crimp tool shown there and its not great. The dies just seem poorly formed. I have some Iwiss ones with EDM cut dies that are way nicer and didn't break the bank.  

What’s the use of the vehicle? I did quick disconnects and shrink over that. The shrink keeps them together and the water out, but it also lets me cut it off quickly and disconnect so I can verify voltage and continuity quickly, or to add voltage in to test things. Quick disconnects easily terminate with a cheap set of Amazon ratchet crimpers. 

Trackmouse said:

What’s the use of the vehicle? I did quick disconnects and shrink over that. The shrink keeps them together and the water out, but it also lets me cut it off quickly and disconnect so I can verify voltage and continuity quickly, or to add voltage in to test things. Quick disconnects easily terminate with a cheap set of Amazon ratchet crimpers. 

Limited street use and track car.  No winter use.  I ordered a case of the uninsulated butt connectors and the adhesive type shrink tube to put over them.

In reply to maschinenbau :

Obligatory full NASA manual on "how to do wires":

https://prod.nais.nasa.gov/eps/eps_data/145968-OTHER-002-006.pdf

Hi.... I would crimp but not with your standard cheap crimping tools. A pair of crimpers, like Klein 1005, uninsulated butt connectors, dielectric grease and adhesive lined shrink tube is what i would use.
Not a fan of solder in a wiring harness thats subjected to flexing and vibrations.

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