Thoughts on 3.6 longevity

[Zandcwhite]

HP/torque was low, but so was weight when first released. YJ & XJ were 3,000-ish pounds... while the JL is at least 4,000. The 8-speed really makes a difference...

I wonder if you can mount a ZF 8HP to a 4.0

The 8 speed is huge as a direct comparison from the JK with the 3.6L, but even the JK was a rocket compared to the TJ. If I recall correctly the 4.0L/auto TJ was ~10s 0-60 and the JK 3.6L/auto was <8s. The 8 speed dropped that to 6s but that 95hp is hard to ignore. Of course the 4.0L would be better than it was with the 8 speed, but it would still be far below the 3.6L performance wise. Now the 4.0L with the 8 speed and a turbo would be one hell of a combo.

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[AnnDee4444]

The 8 speed is huge as a direct comparison from the JK with the 3.6L, but even the JK was a rocket compared to the TJ. If I recall correctly the 4.0L/auto TJ was ~10s 0-60 and the JK 3.6L/auto was <8s. The 8 speed dropped that to 6s but that 95hp is hard to ignore. Of course the 4.0L would be better than it was with the 8 speed, but it would still be far below the 3.6L performance wise. Now the 4.0L with the 8 speed and a turbo would be one hell of a combo.

I remember getting in the low 9s with my stock 1990 XJ (non HO motor). Below is a 2000 in the mid-high 8s. Maybe the XJs were faster.

 

[Zandcwhite]

I remember getting in the low 9s with my stock 1990 XJ (non HO motor). Below is a 2000 in the mid-high 8s. Maybe the XJs were faster.

There's a lot a variations on both, XJ could have been in the 3300lb range and the TJ could have been as heavy as 3850lb. Either way, both the TJ and XJ were slow compared to the JL, even my 5300lb built/ loaded on 39s version, in my experience.

 

[LukeDagny]

The 8 speed is huge as a direct comparison from the JK with the 3.6L, but even the JK was a rocket compared to the TJ. If I recall correctly the 4.0L/auto TJ was ~10s 0-60 and the JK 3.6L/auto was <8s. The 8 speed dropped that to 6s but that 95hp is hard to ignore. Of course the 4.0L would be better than it was with the 8 speed, but it would still be far below the 3.6L performance wise. Now the 4.0L with the 8 speed and a turbo would be one hell of a combo.

Agree with the 8 speed. My 2005 Jeep LJ with the 4.0 had the 4 speed minivan transmission. The 42RLE was horrible. Because of the ultra low OD (0.67), when I regeared, I went with 4.88 gear compared to 4.10, if I had a manual transmission.

 

[UncleJimmy]

I'd love to see evidence about that? Which car models and which problems are we talking about? I am under the impression that as far as german cars go, anything with a BMW B58 or a Porsche drivetrain is pretty much the most reliable stuff you'll get.

Plus unlike Stellantis, you can still get full manufacturer support for a 5-10-50 year old Porsche.

Look up "bore scoring" with Porsche. The coatings wear on the piston and abrasion wears the cylinder walls requiring short block replacement. Can occur with low miles.

Mercedes. I owned both the old straight 5 and the V6 diesels. No comparison in terms of longevity, reliability and repair cost.

Probably one of the most reliable cars as far as reputation, the Toyota Camry have problems with stuck piston rings leading to excessive oil consumption and requiring new engines. This doesn't even touch the issues with the new hybrid TTV6 engines in the Tundra. And as I have mentioned elsewhere, the older V8 Tundra had common cam tower leaks, water pump leaks, head gaskets etc. that were very expensive to repair, much more in fact, than the lifter replacement we see with the Pentastar if caught early enough.

The leading cause boils down to CAFE and emission requirements forcing manufacturers to prioritise for emissions/efficiency over reliability. Some OEMs build better than others but all are affected. Low tension piston rings, GDI, very low viscosity engine oil, 10k mi oil changes, EGR systems, "lifetime" coolant and transmission fluids as well as double the ethanol in fuels over the last 20 years all contribute to increase contaminants and lead to excessive wear and eventual failure. The focus of the OEMs is on complying with regulations, selling convenience to the customer in terms of maintenance, and making it through warranty and maybe a little beyond.

If you want maximum reliability, for passenger cars, half the recommended OCI from 10k mi to 5k mi. For Wranglers which are already cooling challenged, that see severe duty just by adding larger tires, off road gear etc., half it again and change the oil every 2500 mi. A good rule of thumb is the 3/30/30 rule (3k oil, 30k coolant, transmission and gear fluids). I would also add to that higher viscosity engine oil, top tier fuel, fuel treatments and catch cans.

 

[Swisskidd]

If you want maximum reliability, for passenger cars, half the recommended OCI from 10k mi to 5k mi. For Wranglers which are already cooling challenged, that see severe duty just by adding larger tires, off road gear etc., half it again and change the oil every 2500 mi. A good rule of thumb is the 3/30/30 rule (3k oil, 30k coolant, transmission and gear fluids). I would also add to that higher viscosity engine oil, top tier fuel, fuel treatments and catch cans.

Fully Agree!!!

 

[Willys41]

Look up "bore scoring" with Porsche. The coatings wear on the piston and abrasion wears the cylinder walls requiring short block replacement. Can occur with low miles.

Mercedes. I owned both the old straight 5 and the V6 diesels. No comparison in terms of longevity, reliability and repair cost.

Probably one of the most reliable cars as far as reputation, the Toyota Camry have problems with stuck piston rings leading to excessive oil consumption and requiring new engines. This doesn't even touch the issues with the new hybrid TTV6 engines in the Tundra. And as I have mentioned elsewhere, the older V8 Tundra had common cam tower leaks, water pump leaks, head gaskets etc. that were very expensive to repair, much more in fact, than the lifter replacement we see with the Pentastar if caught early enough.

The leading cause boils down to CAFE and emission requirements forcing manufacturers to prioritise for emissions/efficiency over reliability. Some OEMs build better than others but all are affected. Low tension piston rings, GDI, very low viscosity engine oil, 10k mi oil changes, EGR systems, "lifetime" coolant and transmission fluids as well as double the ethanol in fuels over the last 20 years all contribute to increase contaminants and lead to excessive wear and eventual failure. The focus of the OEMs is on complying with regulations, selling convenience to the customer in terms of maintenance, and making it through warranty and maybe a little beyond.

If you want maximum reliability, for passenger cars, half the recommended OCI from 10k mi to 5k mi. For Wranglers which are already cooling challenged, that see severe duty just by adding larger tires, off road gear etc., half it again and change the oil every 2500 mi. A good rule of thumb is the 3/30/30 rule (3k oil, 30k coolant, transmission and gear fluids). I would also add to that higher viscosity engine oil, top tier fuel, fuel treatments and catch cans.

I also agree.
In both my 3.6. 5w40 oil and RPM extreme JL fan controller.

 

[WI_Sarge]

3.6 was great in our town and country. When all the moms heard my pentastar screaming in the school dropoff lane, just start drooling over me and my dope van. Couldnt think of a better engine to drop in a truck…

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