Straight 6 update...

[NC_Overland]

The header of the 90s 4.0 would split or crack at the collector. After-market headers used a flexible pipe on one of the pipes to allow for expansion and contraction with less stress. Seems there were other things 3rd party suppliers did. I never had one crack while on a Jeep but the engine I got for my Eagle had a cracked collector and I had a neighbor slice it off and re-weld it. Stupidly, I told him to put it back on in the same position instead of turning it to clear the front differential pinion brace! So I had to make a brace to clear my exhaust. If that head pipe ever goes bad I'll probably have to drop the engine out to replace it.

The holes marked with red lines are where the pinion brace bolts to the block for Eagle - exactly where the 4.0 exhaust points.
This is the only I6 I've owned that had any exhaust manifold issues and this doesn't count as I was pulling the engine out of a Jeep and putting it in my car so it was all apart for a complete rebuild and little bit of upgrading anyway.
This is pretty common on some years of the 4.0. This one went 100,000 miles.

Yup. Common issue, but I don’t remember it being a bad job. There was a lot of room on the left side of that engine.

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[Oilburner]

By the end of the 4.0L run, they had fixed the exhaust issue. I still have one. #shrug

 

[ShadowsPapa]

By the end of the 4.0L run, they had fixed the exhaust issue. I still have one. #shrug

Yup - had multiple later 4.0s and the last one, a 2004 with 128,000 miles, had no exhaust issues.

 

[Charliedawg]

Anyone have thoughts on whether the manual transmission will be available with the I6?

 

[j.o.y.ride]

Anyone have thoughts on whether the manual transmission will be available with the I6?

Somewhere in the lineup, but after the problems the MT has had in the JT, who knows if the JL/T get it.

 

[ShadowsPapa]

Anyone have thoughts on whether the manual transmission will be available with the I6?

They'll have to use a much better clutch system if they do.

 

[Oilburner]

They'll have to use a much better clutch system if they do.

As sad as it is to say it, I expect the manual to only be available w/ a 4 cyl, just like on the Bronco-

 

[Rubi-Zero]

still enjoying my M54 engine in my almost 20 yr old BMW Z4

BMW has and still makes great I6’s.. I love my S54 in the M3 and turbo charged N55 in the M2.

I would love a 5.7 but it’s unlikely it will come but If Jeep offers this I6 in the gladiator it would be hard not to want to switch to it. I have had many pentastars and it’s pretty damn reliable
but there is a lot to desire when it comes to torque.

 

[Blade1668]

My 90XJ manifold cracked many years ago and I replaced it with a header not that big of a deal I could probably pull it off and reuse it on another 4.0
By the time the I 6 is out I'll have modded my JT to much to change over probably and not want to buy a new vehicle for a few more years if ever again. But who knows.

 

[Wheelin98TJ]

By the end of the 4.0L run, they had fixed the exhaust issue. I still have one. #shrug

Yup - had multiple later 4.0s and the last one, a 2004 with 128,000 miles, had no exhaust issues.

The 2 piece header/manifold is what fixed it.

 

[blau iii]

still enjoying my M54 engine in my almost 20 yr old BMW Z4

I have a FBO n54 that I plan to keep forever! It's faster than 95% of the stuff on the street and a pure joy to drive. Somehow the Gladdy still gets driven more but I smile every time I take the car out. The power is so smooth. This is our 4th I6 BMW and aside from the gaskets/oil leaks, the engines themselves are bullet proof. As long as you can turn a wrench yourself, they're not a horrible mistress.

 

[saintpauljeff]

I have a FBO n54 that I plan to keep forever! It's faster than 95% of the stuff on the street and a pure joy to drive. Somehow the Gladdy still gets driven more but I smile every time I take the car out. The power is so smooth. This is our 4th I6 BMW and aside from the gaskets/oil leaks, the engines themselves are bullet proof. As long as you can turn a wrench yourself, they're not a horrible mistress.

isn't the N54 turbocharged? I guess with the M54 engine line I just like that they are naturally aspirated and less to worry about breaking, I've only changed the valve cover gasket and spark plugs, that's it, no other leaks

 

[blau iii]

isn't the N54 turbocharged? I guess with the M54 engine line I just like that they are naturally aspirated and less to worry about breaking, I've only changed the valve cover gasket and spark plugs, that's it, no other leaks

Yup, the N54 is Twin Turbo and I did replace the turbos right at 100k miles. Somehow, I was able to get BMW to cover the cost of the turbos and just had to pay labor for the replacement. I also had the dealer do the clutch at the same time and replaced it with the clutch from the 550i. All in, new turbos and clutch cost me $1500. I've done everything else myself... on my 2nd VCG and done the oil filter/cooler gasket multiple times. For a car with close to 500hp and 100k miles, it still pulls like a freight train. My wife had an x5 with the N55 engine, which replaced the N54, it was solid as well. I've also had two NA I6 from BMW, all 4 cars have made it to 100k miles with no huge issues.

 

[ShadowsPapa]

The 2 piece header/manifold is what fixed it.

Yeah, I believe I have one hanging up in my shop, with an experimental aluminum head on the shelf, and I think a performance header unless I got rid of that already. (along with spare axles, stuff for CC'ing heads, interior parts)

 

[saintpauljeff]

Yup, the N54 is Twin Turbo and I did replace the turbos right at 100k miles. Somehow, I was able to get BMW to cover the cost of the turbos and just had to pay labor for the replacement. I also had the dealer do the clutch at the same time and replaced it with the clutch from the 550i. All in, new turbos and clutch cost me $1500. I've done everything else myself... on my 2nd VCG and done the oil filter/cooler gasket multiple times. For a car with close to 500hp and 100k miles, it still pulls like a freight train. My wife had an x5 with the N55 engine, which replaced the N54, it was solid as well. I've also had two NA I6 from BMW, all 4 cars have made it to 100k miles with no huge issues.

sort of dispels a lot of rumors that BMW engines are too expensive to maintain, especially when I see real world feedback supporting their reliability (including my own)

I'd be interested in seeing the application of this Fiat I6, probably not enough to sway me to buy, but I'd certainly take one out for a spin

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