Motech LS Swap Gremlins

SLO

SLO

Member
Half way to Moab with the family and it’s been an interesting trip so far. This is the first long trip since getting the JK back with the Motech LS swap. I have been meaning to start a build thread as there are so many little details that I feel like are worth documenting for others to know about. A few of those have crept up on the first day of the trip.

First, for anyone with the Motech kit or looking at the Motech kit, you’ll probably know that the OEM gas pedal is cut down and the GM pedal is installed next to it. The stub of the OEM pedal remains and a metal wedge is inserted so that it’s always fully depressed. To clear the oil change reminder, you will have to pull the wedge so that you can depress the pedal 10 time. MAKE SURE TO REPLACE THE METAL WEDGE. It’s a pain in the ass to put back in but it makes things behave weird (chime at 2500 rpm, wacky computer readings for gas mileage, etc) without it in there. I’m talking with John at Overland Performance and he’s going to be designing a better widget for this.

Also, I have been having issues with overheating. I did the Camaro SS fan hoping this wouldn’t be an issue. I’m thinking that the overload breaker for the fan may be undersized and that the breaker is getting tripped under heavy load, shutting off the fan. Or, maybe my winch partially blocking the grill could be playing a part.

Wondering if anyone on here with the Motech kit and a LS3 or L94 with the Camaro SS fan is having the same issues. I’m guessing the factory vehicles that run these motors (Escalade, Yukon, etc) run much bigger radiators and have larger grills for better air flow.
 
Sorry you’re having issues. I haven’t seen how your front end is set up but sounds like the winch needs to be sitting lower. Trans cooler may be in a bad spot. Fan programming is probably all fucked up. Could also be a shitty thermostat. I recommend changing it to a Lingenfelter 160*.

Don’t worry too much about the wedge. That shit doesn’t do anything important anyways. The chime at 2500 is probably more associated with the Jeep computer looking for an rpm signal that doesn’t exist anymore.


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Thanks for the reply, Bubba. Took this picture yesterday (John asked the same thing about the front end). I may need to lower the winch. I was hoping that wouldn’t be the case.
IMG_0857.jpg
 
SLO said:
Thanks for the reply, Bubba. Took this picture yesterday (John asked the same thing about the front end). I may need to lower the winch. I was hoping that wouldn’t be the case.
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Yeah I would get a bumper that’ll allow the winch to sit lower. I program the fans here to run at 40% at 203-206 because we have decent humidity and temps in the summer are normally around 100. It’s nearly impossible to control the engine temperature in that type of environment without turning up the fan. Try adding Water Wetter or an equivalent. They have it at Autozone. It MIGHT help.


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Exodus Jeeps said:
Yeah I would get a bumper that’ll allow the winch to sit lower. I program the fans here to run at 40% at 203-206 because we have decent humidity and temps in the summer are normally around 100. It’s nearly impossible to control the engine temperature in that type of environment without turning up the fan. Try adding Water Wetter or an equivalent. They have it at Autozone. It MIGHT help.
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What Bubba said ^^^^ Your winch is blocking too much of your grill. I know it'd be a pain but remove it just for a test and you'll see that you get lower numbers.
 
A different situation but relate-able, I had the same issue with a Warn Zeon 10s mounted right where yours is on a S/C 3.8. I would hit 3/4 on the temp gauge on long hills and when it was 90+ when I was in boost for more than a few seconds. I ended up with the Genright Bumper designed to work with the Zeon winch recessed between the frame rails. I will say that it was much cheaper when I bought it a few years back.

https://genright.com/products/jk-low-profile-winch-guard-front-bumper-aluminum.html

It opened up the airflow to both the inter cooler and radiator dramatically. Thermostat needle never moves beyond half now even running AC under boost in 90+ weather.
 
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay too OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
 
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That must be a newer Jeep thing because I pulled the old pedal out of my 07 and have had zero negative effects.
Sharkey said:
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay to OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
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Sharkey said:
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay to OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
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I agree. Don’t know if I that route is really in the cards for me, but I certainly couldn’t do all of that if the stock pedal is a stub under there. Lol


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Sharkey said:
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay to OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
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Bierpower said:
That must be a newer Jeep thing because I pulled the old pedal out of my 07 and have had zero negative effects.

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RockinAZJK said:
I agree. Don’t know if I that route is really in the cards for me, but I certainly couldn’t do all of that if the stock pedal is a stub under there. Lol


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It’s not necessary to keep it in. I’ve pulled it and only plug it back in when the oil change needs to be reset.


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wayoflife said:
What Bubba said ^^^^ Your winch is blocking too much of your grill. I know it'd be a pain but remove it just for a test and you'll see that you get lower numbers.
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Exodus Jeeps said:
Yeah I would get a bumper that’ll allow the winch to sit lower. I program the fans here to run at 40% at 203-206 because we have decent humidity and temps in the summer are normally around 100. It’s nearly impossible to control the engine temperature in that type of environment without turning up the fan. Try adding Water Wetter or an equivalent. They have it at Autozone. It MIGHT help.


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Sounds like I’ll be ordering the PS Bruiser bumper. I was hoping not to have to re-do the front end but whatever it takes at this point.

I finally got a hold of Robbie today (about 20 seconds before driving the damn thing off a cliff). He thinks there may be an air bubble in the radiator which is very possible. The first run I did when I got it back, I overheated and it spit coolant everywhere. I never filled it back to the point of bubbling over while the engine is running and then filling the bottle (which apparently is very important). I’m going to give that a try in the morning.

I do think the t-stat could be bad as well.

Last thing I’m going to try is an updated tune from John at Overland. Just had someone overnight my auto cal tuner and laptop to Moab. The only thing I forgot to bring.
 
Sorry to hear about your issues. Hopefully they can get ironed out! Given the troubles you have had would you still recommend them for a V8 swap? It appears that their customer support is top notch.


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SLO said:
Sounds like I’ll be ordering the PS Bruiser bumper. I was hoping not to have to re-do the front end but whatever it takes at this point.

I finally got a hold of Robbie today (about 20 seconds before driving the damn thing off a cliff). He thinks there may be an air bubble in the radiator which is very possible. The first run I did when I got it back, I overheated and it spit coolant everywhere. I never filled it back to the point of bubbling over while the engine is running and then filling the bottle (which apparently is very important). I’m going to give that a try in the morning.

I do think the t-stat could be bad as well.

Last thing I’m going to try is an updated tune from John at Overland. Just had someone overnight my auto cal tuner and laptop to Moab. The only thing I forgot to bring.
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Yep, never leave for a trip without your programming tools! I’ve mad adjustments to mine while on Imogene Pass. Didn’t work because the shitty Pentastar fan shit the bed but at least I had the capability.

The thermostat is an easy fix on the truck motors. If you want to be sure theres no air in the system, pull the steam line off the radiator and hold it up while someone else fills the radiator. This allows air BEHIND the thermostat to get all the way out. You’ll also need to hold your finger over the hole on the radiator where you pulled the steam line off. Also be sure to push down on the upper radiator hose after this step. It tends to sit higher than the fill neck of the radiator and trap air.


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Sharkey said:
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay to OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
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I am kind of on the same boat on this one, it's just that 8L90 that keeps me on the fence on this when the time comes.
 
Sharkey said:
I actually didn't know the gas pedal was cut and a new one was placed next to it. I know it sounds stupid, but I am waaaaay too OCD for that shit. Seriously, that is the kind of detail that would make me go with a Hemi even if it weighed more and didn't have as much aftermarket support.
Click to expand...

jorgelrod said:
I am kind of on the same boat on this one, it's just that 8L90 that keeps me on the fence on this when the time comes.
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I’m super anal about things like that but having the cut pedal didn’t bother me one bit.

I do wish, however, that i would have gone with a Gen V with the 8L90. That engine is just a whole other level and the 8-speed transmission would be REALLY nice. We have a 2016 Escalade with the Gen V LT and 8L90 and I just bought my wife a JL. 8 speed is where it’s at. Makes the 6L80 and Gen IV seem so antiquated.
 
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