GhosT5

I had somebody do some work on my car, he pulled the engine and broke the two wires going to the oil pressure switch and just taped it, now the gauge is reading crazy high oil pressures because of increased resistance. What tape can I use to isolate the wires from heat and all for the gauge to work properly?

SSellers

You can get a new pigtail and solder it to the wires and cover with heat shrink.
http://www.summitracing.com/search/p...oil%20pressure

wssix99

iTrader: (5)

Heat and electrical tape aren't a part of the equation? Maybe he just twisted them together and then taped them? If so, the twist is the issue.

The proper fix depends on where the cut is. How far from the connector are the wires cut? Did they just pull out of the connector?

If you just need to splice the wires, you need a mechanical crimp, heat shrink connector to get a strong, reliable, water tight connection. Soldering is something to be avoided unless its combined with a mechanical crimp. (Due to the vibrations a car's wiring is exposed to.)

GhosT5

Yeah the guy is no electric so he just twisted them together and put tape on it. The wires ripped apart right next to the connector, but the problem is there is barely any space in there, unless I can manage to pull the wires to the top and fix the connection there. Still didn't take a look at it though.

wssix99

iTrader: (5)

I feel your pain: https://ls1tech.com/forums/general-m...ding-unit.html

There is no room to take any length off of that wire.

Can you post a pic?

You may need to get a new pigtail to get the extra length and use a mechanical crimp clip or a good butt splice.

VIP1

Why? Do you realize how many soldered connections are in cars and they hold up fine for decades? Just make sure you do it correctly.

wssix99

iTrader: (5)

Its because of the "paper clip" effect. If you bend a paperclip over and over it cracks and snaps. This is the same reason you won't see any solid wire on a car, boat, airplane, etc. Stranded can bend without stressing the wire as much and is needed for the vibration.

A solder splice makes the strands of the wire solid and this issue comes in to effect. So mechanical stabilization/reinforcement is required. GM's wiring repair kit has special (they work really well) mechanical crimps for splicing wires, which have a port to inject solder, but the tools to use them properly are expensive. The crimps above do the job well with regular crimpers and will also make the joint water tight.

Cars do have a lot of solder, but they are restrained (by a circuit board, etc.) so they aren't effected by vibration as much. The biggest issue is with a traditional solder splice which is unreinforced.

WhiteBird00

iTrader: (4)

I'm afraid I have to agree with VIP1 on this one. Solder and heat shrink for non-moving connections (such as a stereo harness) is not subject to metal fatigue (the "paper clip" effect you mentioned) because there is insufficient movement or vibration to cause fatigue over the normal life of the car.

Most connections that the average user will encounter fall into the same category. For example, even if you were adding an under hood light, the soldered connection would not normally be in the portion of the harness that moves when the hood opens - it would be cable tied to some stationary point under the hood.

I have used soldered connections on motorcycles for more than 30 years without a single failure and I think you'll agree that a motorcycle generally produces more vibration than cars. I'm just careful to ensure the connection is well insulated, watertight and solidly positioned on a frame member or similar support.

wssix99

iTrader: (5)

I agree. It's not a recipe for disaster and in many applications soldered splices might work out fine. Airplanes and gas-powered boats are more of an issue as any potential arcing has greater consequences.... that is until we start driving cars with electronic brakes and electronic steering and.... - well at least these cars don't have that issue.

I'd recommend a high reliability connection with this wire as its a real bitch to get to and securing it from movement/vibration would be hard. (Getting a soldering iron back there may not even be possible.) I've had to change my OPSU twice and never ever want to do it again. I can't even imagine trying to repair the connector wire with the engine in the car.

VIP1

WhiteBird00 covered my point pretty well. You won't get the "paperclip effect" on something that isn't bent/stressed in that manner in which to lead to that kind of failure.

wssix99

iTrader: (5)

So, we are talking about an OPSU sensor wire here, which is not secured from movement along its full length and has a free run in the back of the engine bay. Are you saying that vibration will not fatigue a solidified section of wire?

SparkyJJO

iTrader: (11)

I think a soldered connection isn't going to fatigue too much because it isn't a large section. The wire before and after the connection can flex and take up the vibrations and such.

Personally I've had more crimp barrel connections wiggle or pull loose than soldered connections, but they were crimped with a cheap single tooth "mash" crimp as I like to call it.

wssix99

iTrader: (5)

This is a great point. Unless a high quality crimper is used, there's probably a higher likelihood of a problem with the crimp vs. solder cracking/fatigue.

VIP1

We aren't talking about a wire that is flapping around so loose it could flex and tangle to that point. It will be fine. If it was really that bad, the wire would flex where it enters the crimp and snap at that point anyway making your concern moot. Most flex failures are not in the solder or crimp but where the wire enters the solder or crimp. So your concerns of breakage with solder also applies to crimp. Potentially moreso due to how the wires are pinched and stressed at point of entry to the crimp. A properly soldered and heat shrunk connection should survive just fine.

SSellers

It's like any other connection. Don't let the joint support the cable and vice versa and it'll be fine.