R2.8 Cummins Build

[DetroitTJ]

I'm excited for you just as much as I'm excited for my own. If you have any questions along the way feel free to ask. Out of curiosity, did you get the R2.8 kit from Axis as well?

Thx. There’s no doubt I’ll be asking you both a lot of questions. I haven’t bought the Axis kit yet but plan to. I bought the motor mounts over the winter while I was working on my frame. I can’t wait to set the motor on the frame. One step at a time.

 

[BugoutJeep]

Well ask away and if you need to see video of something, I might have it.

I'll be pulling my transmission soon. I talked with a shop and their rate is reasonable, but the more I think about it, the more I'd like to add some heat/sound deadening stuff in that area and secure my wiring better, protect the wiring and finish my straight pipe exhaust. I might touch up part of the frame with the POR 15 while the skid plate is out too. It's pretty miserably hot now, so I'm not too keen driving the Jeep a lot, though none of my vehicles have AC so it doesn't matter, but the lack of insulation is noticeable in the TJ vs my truck.

I'm trying to find out info on the 4.3 first gear for the AX-15. I've emailed Marlin Crawlers and if possible I may just have them build me a custom transmission. I guess it depends on the price really. But I'd like to have a new transmission to go with new tank, engine, and in the next year or several new Tcase and axles/diffs. I think with the 3.55s, and 4.3, I'll get about 30% reduction in speed in first gear, which should be noticeable and only slightly annoying on the street, unless I am pulling something.

When I save up for the Atlas (2) 5:1, then I'll be rocking a crawl ratio of 76:1, which isn't bad for ditches, mud, steep terrain, etc. My truck is around 60:1 and it's night and day vs my low 30s Jeep setup. I might add that as far as mud goes, unless the truck bottoms out, it gets stuck a bit less. When it gets stuck it's horrible to get free.

 

[1945GPW]

What coolant temperature are you seeing going down the road at a steady 65, then climbing hills? My fan is always running and can’t seem to keep it below 195 going 65mph. When going up a hill I’ve gotten it as high as 215 before I pull over and let it cool down. There’s no way I can pull a small camper trailer with it heating up like this.

My transmission seems to be getting really hot too. Feels like the heater is on high. Not sure what’s going on. Thoughts?

 

[BugoutJeep]

What coolant temperature are you seeing going down the road at a steady 65, then climbing hills? My fan is always running and can’t seem to keep it below 195 going 65mph. When going up a hill I’ve gotten it as high as 215 before I pull over and let it cool down. There’s no way I can pull a small camper trailer with it heating up like this.

My transmission seems to be getting really hot too. Feels like the heater is on high. Not sure what’s going on. Thoughts?

My coolant temp isn't very consistent. At 65 (maybe higher), I'm not sure I've seen over low 190s typically 180s. I've seen 200s in traffic and big hills in 4lo. I've never seen the fan run. I assume you're looking at the Murphy gauge temp?

I would imagine you've got some sort of air bubble around the EGR, if you've got the axis coolant system. I can't remember your setup though with ac. I'm pretty sure you've got a manual right? What about the bug thing?

Btw most of the time I'm looking at my Dakota digital gauge temp, but I do compare it to the Murphy and they are within about 5% or so of each other. Often in this heat cuz my trans is boiling hot too, I run my vent blower to my feet. There's really no insulation in my Jeep.

 

[BugoutJeep]

Oh I might add that Friday my temps would get into high 160s like toward the end of hills. I might add that my system naturally bled for quite some time before my actual reservoir came in.

 

[1945GPW]

Yeah I’ve got a manual transmission and I’m reading the temp off the Murphy gauge.

So your transmission gets extremely hot as well? It sure didn’t get this hot before the swap. Wonder why they heat up so much now.

Going up any kind of hill and maintaining speed approximately 60 to 65 the temp just climbs and climbs unless I slow down or the hill stops then it will settle to about 190. Outside air temp is about 85 to 90. I thought the axis system would have kept things cooler. I’ll give Kevin a call tomorrow.

 

[BugoutJeep]

My transmission has always gotten hot, but I don't have carpet either. I can't tell any temp diff since the R2.8.

Can you tell if your thermostat has opened or not? I started driving mine in October, when it was highs 70s or 80s and it took forever to heat up. The first time the thermostat opened, I drove for an hour, then up a steep hill in the woods in 4Lo for about 5 minutes or more. However it opened like exactly at 190F.

Again I might add that I drove it a lot using a really bad overflow reservoir that leaked more than it held. I still think maybe you've got some sort of air pocket or something simple. I didn't use them, but I was thinking there were some little set screw looking things in some coolant lines around the EGR you could bleed. Have you been running your heater any? I might add that every time I fill up a drained system, I jack up the vehicle, where the radiator cap is above all other points and I've got a 1" BL, so I'm a bit higher than the EGR stuff by a few inches.

What coolant did you use?

 

[BugoutJeep]

Well I'm not focusing on the Jeep in this video, but I did compile some footage where I discovered the issue and I went over some issues on my RedARC BCDC troubles I've been having.

BTW the transmission is out and I've got the replacement part. In the meantime I'm adding some sound barrier stuff near the transmission and I'm working on the exhaust, but that may get pushed off until later.

 

[BugoutJeep]

I'm back up and running. Pulling/installing the transmission wasn't too bad, but still I spent a lot of time in the garage I didn't want to spend. I also got some wiring arranged a bit better.

The exhaust work I need to do will take more time than I anticipated. I was hoping for something easy, but I need a custom angle or 2 to get everything all tidied up. I think when it cools off I'll work on some pie cuts and stuff.

 

[BugoutJeep]

What coolant temperature are you seeing going down the road at a steady 65, then climbing hills? My fan is always running and can’t seem to keep it below 195 going 65mph. When going up a hill I’ve gotten it as high as 215 before I pull over and let it cool down. There’s no way I can pull a small camper trailer with it heating up like this.

My transmission seems to be getting really hot too. Feels like the heater is on high. Not sure what’s going on. Thoughts?

Any luck with the temps?

 

[DetroitTJ]

I'm back up and running. Pulling/installing the transmission wasn't too bad, but still I spent a lot of time in the garage I didn't want to spend. I also got some wiring arranged a bit better.

The exhaust work I need to do will take more time than I anticipated. I was hoping for something easy, but I need a custom angle or 2 to get everything all tidied up. I think when it cools off I'll work on some pie cuts and stuff.

What exactly broke? Is there a problem with the transmission adapter design? I’m planning to use the Axis kit to match up an AX15.

 

[BugoutJeep]

What exactly broke? Is there a problem with the transmission adapter design? I’m planning to use the Axis kit to match up an AX15.

It was just a bad part without enough weld. I'll put up a video showing the issue. It's obvious now, that I kinda kick myself over not catching, but I guess working in the heat for 14+ hrs a day, you just don't think and just get to work rather than ask questions.

Also, the fact that I went 6+ months without a problem and there's probably 4x more weld cross section, which means that I was probably fatiguing the welds and then 4x or more of the cross section, means that you're well above the fatigue type loading for steel.

If it was welded aluminum or titanium, then fatigue will eventually be an issue, but not so much for steel.

 

[1945GPW]

Man that sucks you had to pull it all apart for insufficient welds. I hope the new ones don't break like that. I checked the pictures before I installed mine and its got the welds on both side but that makes me nervous now.

 

[1945GPW]

Any luck with the temps?

Not yet. still getting super hot going over hills. The transmission heat I thought I am having turns out to be a torn shifting boot ( I think ) there is a pretty good tear in it and I'm thinking the heat is just from the engine now.

 

[BugoutJeep]

Here's the footage for pulling the transmission and comparing the 2 adapters. It's so obvious that I could kick myself, but I actually feel better about the new adapter because I had issues with the first adapter.

 

[BugoutJeep]

Not yet. still getting super hot going over hills. The transmission heat I thought I am having turns out to be a torn shifting boot ( I think ) there is a pretty good tear in it and I'm thinking the heat is just from the engine now.

I noticed my boot was torn as well, but I'm pretty sure its been torn for awhile. I don't think just replacing that will be some incredible fix, but it'll help a little. I think a body lift helped with some of my floor heat. I know the body lift does seem to help with access.

You shouldn't be getting 215 even up a hill. I've crawled up steep hills for probably a few minutes or so and my temp hasn't gotten above 200F and as soon as I'm able to get some throttle or air movement, the temp drops. Did Axis have any suggestions?

 

[1945GPW]

The transmission boot should keep the hot air from flooding in the cab so suspect that will help that problem. The coolant temps do just fine below 30 mph, crawling up hills in 4 low it’s fine. When I’m Trying to maintain 50 or 60 up a hill the temps just climb and climb until I remove the load from the engine. It’s not bogging down or anything, has plenty of power just likes to over heat with some load on it. I’ve talked to axis and they thought all the over heating issues were fixed. They are Thinking of fitting me with a GM fan that moves 4600 cfm instead of the 3600 I’ve got now. I don’t see that fixing the cooling problem though, and I don’t think the fan should have to run going down the hwy not stop.

 

[BugoutJeep]

The transmission boot should keep the hot air from flooding in the cab so suspect that will help that problem. The coolant temps do just fine below 30 mph, crawling up hills in 4 low it’s fine. When I’m Trying to maintain 50 or 60 up a hill the temps just climb and climb until I remove the load from the engine. It’s not bogging down or anything, has plenty of power just likes to over heat with some load on it. I’ve talked to axis and they thought all the over heating issues were fixed. They are Thinking of fitting me with a GM fan that moves 4600 cfm instead of the 3600 I’ve got now. I don’t see that fixing the cooling problem though, and I don’t think the fan should have to run going down the hwy not stop.

I only have heat under load going slow and it's like 200F. Since it's been warm, I haven't seen over 200F, but early in the spring I saw it slightly above that I think. I think mine had something to do with my coolant signal to the dash. I routed some wires better and my temps are much lower and they are within 5% of my Murphy gauge and I do expect to see variance, since they're in different locations.

To be honest, I'm more afraid my Jeep runs too cool, but I get to what I consider a normal operating temp under loads up hill, but much of the time I'm running in the 170s/180s now.

I don't know what fan I have. I was told that I was the first to get that fan relay for a TJ, that before it went for a CJ. I guess to be fair, I'm easy on my throttle by nature. These engines just aren't HP monsters without tuning, so I just try to use only enough throttle to maintain speed (3.07s/33s and now with my rack and probably a couple hundred lbs more stuff in the back at all times on big hills, if I don't speed up a bit before I go into the big hill, then I'll have to shift to maintain speed).

 

[NDSpeed]

I am watching this tread now too. I just started really digging into the swap. Had everything to start back in March. But life threw a curveball I wasn’t ready for.

I will say Kevin from Axis has been a major help. I was the first one to order his 99% kit so I’m battling my way through that.

Been irritating the wife with all the, “well crap now I need this tool. Or Oh I need a flywheel from a 4.0l”.

 

[NDSpeed]

I had the entire wiring harness and front clip blown apart for the last 7 years trying to get around to the Hemi Swap I had for it. But never had the time. This kit seemed easier to accomplish.