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Amphibious HEMTT

ExWrench said:
I believe it, your rig is more rare - 1 of 1, rather than 1 of 8900+.

Also, it's arguably more interesting :smokin: :beer:
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True, but most people don’t know it’s rare. Quite honestly, I don’t know shit about military vehicles. I know a deuce and a half and a “bobbed” deuce. I know about Hummers and of course the HEMTT. That’s about it. I think most People don’t know that much. If I saw a piece of military equipment, I would stop and look, but my wife never would. I certainly wouldn’t wait for the owner to come out of a store.

As far as interesting, to guys on this forum, yes. When I see any kind of modified truck, I have to look how they did stuff. To most people, it’s all Greek. I’ve only had one guy mention the full hydro steering.
 
Your rims are 20X14; what's the backspacing?

1661452348572.png
 
I’m pissed off at the truck today. F’ing electrical gremlins.

Electrical problem #1- My AC condenser has two E-fans that are switched on by a “Trinary” switch. The switch just gives ground to a Boasch 75 amp relay. After several months, the relay sticks on. I figured it went bad and installed a new one. Now after two weeks, it sticks. WTF? I’ve measured the amp draw on the fans and they run at 22 amps each. Is 75 amps not enough to start 44 amps of fans?

Electrical problem #2- I have two fans on my radiator also. Each fan has its own relay that is fired by a separate thermostat. The first thermostat has been sticking on. I have that thermostat running a intercooler pump also. I wouldn’t think the pump hardly draws any power. Do you think it is causing the thermostat to stick?

Electrical problem #3- The other radiator thermostat is not switching on at all. It’s supposed to come on at 160 and I’ve had it up to 200 and it’s still not coming on. (The fan works fine if I bypass the thermostat.) Do these things fail that often?

Electrical problem #4- My windshield wipers will not turn off. I have a simple wiper system that has high, low and single sweep. When I installed it, I found that it wouldn’t “park” without the blades on. It needs them to slow it down enough to park. The other day it was raining and I turned them on and that was it. The only way I can stop them is switch the cerkuit breaker off. Of course, I have to do that just at the right time to get them to stop out of the way. Even if I do that, they still turn right back on if I reset the breaker.

Electrical problem #5- My starter won’t start from the key. I have a spade connector on the line that fires the selinoid. If I unplug it and tap it against the hot post, it starts right up. When I turn the key, that wire is getting 12V, but the starter just clicks. Do I need a relay to run the selinoid? I thought that’s what a selinoid is. Maybe the key switch I got has burned the contacts where they don’t transmit enough power?

I m busy with work right now, so I parked the HEMTT and I’m back in the Bronco. Good thing I didn’t sell it.
 
WaterH said:
Electrical problem #5- My starter won’t start from the key. I have a spade connector on the line that fires the selinoid. If I unplug it and tap it against the hot post, it starts right up. When I turn the key, that wire is getting 12V, but the starter just clicks. Do I need a relay to run the selinoid? I thought that’s what a selinoid is. Maybe the key switch I got has burned the contacts where they don’t transmit enough power?
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What is the voltage at the spade connector when you have the key in start position?
My guess would be that you don't have enough current available after going through the ignition switch.
I know that John Deere had that problem on many of their mowers to the point where they had an official kit to put a relay in to power the starter relay.

Aaron Z
 
aczlan said:
What is the voltage at the spade connector when you have the key in start position?
My guess would be that you don't have enough current available after going through the ignition switch.
I know that John Deere had that problem on many of their mowers to the point where they had an official kit to put a relay in to power the starter relay.

Aaron Z
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Yep, that^

A starter solenoid could draw 10 amps or more. A 12v relay draws < 1/5 amp.
Big difference if the ignition switch + wiring aren't 1960s / industrial level of burly.
 
aczlan said:
What is the voltage at the spade connector when you have the key in start position?
My guess would be that you don't have enough current available after going through the ignition switch.
I know that John Deere had that problem on many of their mowers to the point where they had an official kit to put a relay in to power the starter relay.

Aaron Z
Click to expand...
ExWrench said:
Yep, that^

A starter solenoid could draw 10 amps or more. A 12v relay draws < 1/5 amp.
Big difference if the ignition switch + wiring aren't 1960s / industrial level of burly.
Click to expand...

So; did I guess correctly, guys?:grinpimp::laughing:
 
WaterH said:
I’m pissed off at the truck today. F’ing electrical gremlins.

Electrical problem #1- My AC condenser has two E-fans that are switched on by a “Trinary” switch. The switch just gives ground to a Boasch 75 amp relay. After several months, the relay sticks on. I figured it went bad and installed a new one. Now after two weeks, it sticks. WTF? I’ve measured the amp draw on the fans and they run at 22 amps each. Is 75 amps not enough to start 44 amps of fans?

Electrical problem #2- I have two fans on my radiator also. Each fan has its own relay that is fired by a separate thermostat. The first thermostat has been sticking on. I have that thermostat running a intercooler pump also. I wouldn’t think the pump hardly draws any power. Do you think it is causing the thermostat to stick?

Electrical problem #3- The other radiator thermostat is not switching on at all. It’s supposed to come on at 160 and I’ve had it up to 200 and it’s still not coming on. (The fan works fine if I bypass the thermostat.) Do these things fail that often?

Electrical problem #4- My windshield wipers will not turn off. I have a simple wiper system that has high, low and single sweep. When I installed it, I found that it wouldn’t “park” without the blades on. It needs them to slow it down enough to park. The other day it was raining and I turned them on and that was it. The only way I can stop them is switch the cerkuit breaker off. Of course, I have to do that just at the right time to get them to stop out of the way. Even if I do that, they still turn right back on if I reset the breaker.

Electrical problem #5- My starter won’t start from the key. I have a spade connector on the line that fires the selinoid. If I unplug it and tap it against the hot post, it starts right up. When I turn the key, that wire is getting 12V, but the starter just clicks. Do I need a relay to run the selinoid? I thought that’s what a selinoid is. Maybe the key switch I got has burned the contacts where they don’t transmit enough power?

I m busy with work right now, so I parked the HEMTT and I’m back in the Bronco. Good thing I didn’t sell it.
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1- What make/model fans? They probably have a startup current spike that is well over the relay rating. Probably need to relay the fans individually.

2- Probably the same as #1, relay the fans individually and actuate the relays with the t-stat.

3- Did you test the t-stat off the truck in temperature controlled water? It could just be in a bad location that's not getting enough coolant flow.

4- What wiper system?

5- Yes, the solenoid needs a relay because it draws a ton of current. You probably fried a wire in the ignition circuit.


Overall: ADD MORE RELAYS. :flipoff2:
 
CDA 455 II said:
You have enough battery power/electric power?🤷‍♂️
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I have two fairly new group 65 batteries, so there’s lots of power on the truck. Whether it’s getting to there is another story.

aczlan said:
What is the voltage at the spade connector when you have the key in start position?
My guess would be that you don't have enough current available after going through the ignition switch.
I know that John Deere had that problem on many of their mowers to the point where they had an official kit to put a relay in to power the starter relay.

Aaron Z
Click to expand...

It gets 12 volts at the connector with no load. I haven’t measured it while it’s hooked up. Maybe the selinoid drags it down.

ExWrench said:
Yep, that^

A starter solenoid could draw 10 amps or more. A 12v relay draws < 1/5 amp.
Big difference if the ignition switch + wiring aren't 1960s / industrial level of burly.
Click to expand...

The wiring is 16 ga aircraft wire. The switch is from McMasterCarr. It’s good quality, but I don’t know what it’s rated for.

Yotota said:
1- What make/model fans? They probably have a startup current spike that is well over the relay rating. Probably need to relay the fans individually.

2- Probably the same as #1, relay the fans individually and actuate the relays with the t-stat.

3- Did you test the t-stat off the truck in temperature controlled water? It could just be in a bad location that's not getting enough coolant flow.

4- What wiper system?

5- Yes, the solenoid needs a relay because it draws a ton of current. You probably fried a wire in the ignition circuit.


Overall: ADD MORE RELAYS. :flipoff2:
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1. Fans are Spal, not sure of model. Is there a “rule of thumb“ for startup amps vs running amps?

2. That’s the way I have it.

3. No, but the stat is right in the center of a tube leaving the rad. (All the flow)

4. Ford Bronco.

5. no wire is fried, but I guess I need a relay.
 
You could have enough voltage drop to not engage the solenoid. I had that issue on a boom lift. Key switch was in basket and wire was long so it wouldn't always start from basket, but always from the ground where the wire was shorter.
 
WaterH said:
It gets 12 volts at the connector with no load. I haven’t measured it while it’s hooked up. Maybe the selinoid drags it down.
The wiring is 16 ga aircraft wire. The switch is from McMasterCarr. It’s good quality, but I don’t know what it’s rated for.
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Looking at the chart at:12 Volt Wiring: Wire Gauge to Amps | (and similar ones) at 10 amps they recommend no more than 7' of 16 gauge wire (and any resistance through your ignition switch will make that worse).
1661646555915.png


Seems like a relay is in your future, but sticking a meter on the small terminal on the starter to see what the voltage when cranking is would allow you to verify it for sure.

Aaron Z
 
I easily have more than 7’ . I would have run 12 ga if I thought it was an issue. Now it’s kind of a pain, so I guess I will install a relay. The relay would be better for the switch also. (Since I don’t know it’s rating)
 
aczlan said:
Looking at the chart at:12 Volt Wiring: Wire Gauge to Amps | (and similar ones) at 10 amps they recommend no more than 7' of 16 gauge wire (and any resistance through your ignition switch will make that worse).
1661646555915.png


Seems like a relay is in your future, but sticking a meter on the small terminal on the starter to see what the voltage when cranking is would allow you to verify it for sure.

Aaron Z
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nOOB question:
Does a relay (for electricity) act like a valve (for fluid)?
 
CDA 455 II said:
nOOB question:
Does a relay (for electricity) act like a valve (for fluid)?
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Yes, it acts like a solenoid valve would for fluid.
A small solenoid like a five pin solenoid will pull let's say half an amp and can control up to a 30 amp circuit.
So then the load that runs through his ignition switch is reduced from 10 amps to perhaps a quarter of an amp.

Aaron Z
 
WaterH said:
1. Fans are Spal, not sure of model. Is there a “rule of thumb“ for startup amps vs running amps?
Click to expand...
About 3 times the running amperage is my rule of thumb.

Aftermarket temp switches are shit. Try to trigger your fan relays off of the ECU.

You need to add relays to your shit.
 
Bebop said:
About 3 times the running amperage is my rule of thumb.

Aftermarket temp switches are shit. Try to trigger your fan relays off of the ECU.

You need to add relays to your shit.
Click to expand...

At this point I figure on…..

1. installing a 75 amp relay for each fan on the AC condenser. (Instead of one for both) Also, I might add a timer delay relay to make one fan come on a few seconds after the first.

2. Install a switch that turns the fan and intercooler pump on at the same time. (There’s already a relay for the fan) I don’t really need a thermostat switch to turn the first fan on because if I drive it at all, it’s going to be needed.

3. Install a new thermostat switch for the second fan and hope it works. (Again there’s already a relay there)

4. Not sure what to do about the wipers. Probably will buy a new one. Funny how I have a 90’ Bronco that the wipers still work from new. This motor is from a newer truck and is giving me problems.

5. I will be installing a relay for the selinoid on the starter.
 
1) just but a good, normal, 40amp bosch relay
2) wire your relay to the ign switch so you don't forget to turn it on (happens all the time)
3) why not
4) no input there
5) good idea
 
Bebop said:
1) just but a good, normal, 40amp bosch relay
2) wire your relay to the ign switch so you don't forget to turn it on (happens all the time)
3) why not
4) no input there
5) good idea
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2. My ignition switch is not like a standard car. (it only works the starter) I have separate battery switches. (One for each battery) The truck is wired like an aircraft. If the one thermostat works, it will be a back up to me forgetting. The truck appears to not overheat with just one fan on. But I shouldn’t forget because I will probably just leave the switch on so it will come on as soon as I switch either battery on. The only reason I would switch it off is if I wanted to listen to music with the truck not running.

4. Does anyone know if the “park“ system on a wiper motor is replaceable?
 
WaterH said:
2. My ignition switch is not like a standard car. (it only works the starter) I have separate battery switches. (One for each battery) The truck is wired like an aircraft.
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uhhh...

Back up a second... how is your stuff wired ?

Forgive me but I'm not familiar with aircrafts so you'll have to dumb it down for me.
 
Bebop said:
uhhh...

Back up a second... how is your stuff wired ?

Forgive me but I'm not familiar with aircrafts so you'll have to dumb it down for me.
Click to expand...

It’s pretty simple. Every component will have a fuse or breaker switch. (Mine are all breaker switches) The battery (or batteries) just switch power on to a main bus bar. (that switch(s) is fired by ground so no hot wire is in the cab when off)

The theroy is, if you smell smoke, you switch off the battery(s). That cuts all power so no electrical fire is fed by power. Aircraft wire is all Teflon, so it will not support fire on its own. Since most aircraft don’t need any power to run, you keep flying while you sort out the problem. You would do that by switching off everything else and then turn the battery back on. If there’s no more smoke, you can turn on stuff one by one until you figure out what is the problem. You could also not turn on unnecessary things. Since my truck is deisel and doesn’t need power to run, I thought it would be cool to wire it this way.
 
So every time you switch off your power you have a load dump from the fans and other inductive loads.
Would explain why you're frying relays.
 
Bebop said:
So every time you switch off your power you have a load dump from the fans and other inductive loads.
Would explain why you're frying relays.
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Please explain?

Theres only one relay that is giving me problems, the 75 amp Bosch controlling the AC fans. I’m assuming 75 amps doesn’t cover the start up of two 22 amp fans.
 
Resistive load (lights for example):

1661787971167.png


When you switch them on and off, the amperage follows the voltage.

Inductive load (fans for example):

1661788021523.png


When you switch them on and off, the amperage is offset from the voltage and will spike inversely proportional to the voltage.
 
I’m not going to say I completely understand that, but assuming it is correct, are you suggesting that wiring it like an aircraft results in more danger to relays? I don’t quite get that.
 
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