Engines with legendary reliability.

[HerrStig]

Originally Posted By: TFB1
Originally Posted By: stower17
Umm Chevy 350 Diesel,

GM's 350 Diesel was a Oldsmobile abomination... The later ones were better, sometimes could make 100K mi of mostly highway operation... With only a injection pump failure and one broken head bolt(that I rep and did not change gasket), I actually ran one up to 133K mi before I sold it...

The Vega aluminum block with cast iron head motor was Chevy's own fiasco... They fixed it in '76 by using steel cylinder liners, but by that time few would touch it...
Let us not forget the Pontiac I6 OHC conversion sold for a couple of years. I had a friend whose father was a whacko car lover, he stuck the kid with an NSU (when the rest of us had VDubs we could fix) and later one of those OHC Pontiacs, then an early SAAB. At least the old man paid for them all.

 

[TFB1]

Wasn't really anything wrong with the OHC 6cyl Pontiac(block was based on 230/250 Chevy), just ahead of it's time.. Neighbor had one with no issues for approx five years before he traded it for a new NSU Prince, now that was a fiasco...

 

[HerrStig]

Another "great" motor was the Yamaha built OHC V8 which went into the Taurus "SHO". One of the neighbors kids bought a cherry one. His father (a car guy) predicted how long the engine would last and what would break if the kid drove like a moron. He was right. The cam drive parts were "unobtanium" even in junk yards. All the replacement parts had been used up. A bit of a weak point. A sane driver might have managed 100K, though. The rest of the car was pretty nice for what that was worth.

 

[HerrStig]

I remember when Car and Driver stuffed a Pontiac OHC six into an XKE and fooled a lot of Jag lovers with it.

 

[UNC017]

Originally Posted By: Miller88
Originally Posted By: GMBoy
^^^^^ You beat me to it. I 2nd the vote for the AMC/Jeep 258 (4.2L) and the later variant the 4.0L.


The fuel injection system on the later 4.0L was better than the early 4.0L, but the early 4.0L was the reliable one. The "newer" ones break pistons, crack the head and ruin the oil pump drive and seize up the oil pump.


I disagree, the early Renix 4.0s were junk. Not just the Renix injection itself, but the block lower end was too flexible, and they'd window the block with a connecting rod too easily with sustained high RPM.

Absolute best years for the 4.0 are 1997-1999.


Even then, I wouldn't put the 4.0 in the same league as the Slant-6, Ford 300, Chrysler 318 / Magnum 5.2, and several others. Close, but not quite.

I haven't seen it mentioned yet, but the GMC truck 305 CID V6 has to be ranked way up there too. It never had a big market share like the Slant 6, Ford 300, and definitely not like the Chevy 350, but alongside the 305 V6, the Chevy 350 is built like a toy.

I also gotta throw a vote in there for the International 345/392 V8's that dragged all those 1970s Loadstar 1700 and 1800 school busses and dump trucks around. They made engines like the Oldsmobile 455, Ford 460, and Chrysler 440 look a little bit lightweight. They might not have been notorious for lasting 300,000 miles, but a 345 would easily do 100,000 to 150,000 miles under sustained loads that would kill a Chevy 350 in 50k miles if not less.

 

[UNC017]

GM's 350 Diesel was a Oldsmobile abomination... The later ones were better, sometimes could make 100K mi of mostly highway operation... /quote]

Correct, and the Olds 350 was (IMO) the best and strongest of GM's gasoline v8s. It would have been way, way worse if they'd tried to convert the little Chevy smallblock to diesel with its comparatively tiny bearings and connecting rods. The Olds would have actually made a decent light-duty diesel conversion if the fuel system hadn't been such a hack. Diesels need clean fuel, and it was put in cars that simply didn't have enough filtration and water separation. And they used a really under-designed Roosa injection pump that killed a lot of engines. That's not to say it didn't also need a little beefing of the castings (which it got later), but the biggest problems weren't the mechanical core of the engine, but fuel-system related. Running a diesel with the injectors firing unequal doses of fuel because they or the fuel pump has been damaged by water/dirt can kill an otherwise good engine the same way running a gasoline engine with way too much spark advance on one or two cylinders.

According to Bill Weertman's book, if I recall correctly, Chrysler did some testing of a diesel conversion on the slant-6 with promising results but never proceeded with it (probably a very wise choice).

 

[rslifkin]

Originally Posted By: 440Magnum
I disagree, the early Renix 4.0s were junk. Not just the Renix injection itself, but the block lower end was too flexible, and they'd window the block with a connecting rod too easily with sustained high RPM.

Absolute best years for the 4.0 are 1997-1999.


The 96+ have the questionable pistons though. I can't remember whether the bottom end changed at all in 91 with the first HOs (I know the heads changed). If they fixed the bottom end issues the Renix had, then 91 - 95 would be the best of them.

And none of the 4.0s really like sustained high rpm. Spin one (of any year) past 5300 without serious work and you'll hit a really nasty harmonic that'll blow it to pieces very, very quickly.

 

[Blinker]

The engine examples i gave are not known for their legendary reliabilty, however there will always be some that outlast their counterparts. I will also add that most engines that get a bad reputation usually have a flaw or shortcoming in another system of the car that then kills the engine.

 

[Blinker]

I think most engines can achieve legendary as long as the other systems are still in working order (cooling system, fuel system, proper exhaust flow).

 

[artificialist]

VW ALH TDI
VW 2,slow gasoline engine.

Almost everything Nissan made before 1995
Practically any Nissan with 6 cylinders

 

[DoubleWasp]

Originally Posted By: 440Magnum


According to Bill Weertman's book, if I recall correctly, Chrysler did some testing of a diesel conversion on the slant-6 with promising results but never proceeded with it (probably a very wise choice).



Calling up Cummins was one of the smartest moves they ever made.

 

[3311]

Originally Posted By: GMBoy
Originally Posted By: Ramblejam
Originally Posted By: Nate1979
Originally Posted By: cptbarkey
Vortec 6000 LQ4 (6.0)


Why not the 6.0 L96? Any difference?


Agree on the LQ4; they're simple, stout, inexpensive, and can make a silly amount of power. As more and more enthusiasts discover these engines in the junkyard, their reputation and desirability will grow...

https://youtube.com/watch?v=H6Ni2gPo5Us

L96 incorporates VVT, and is too new at this point for the legendary status...


LQ4 is good but not as good as the LQ9 High output version like in my 2006 Sierra Denali. But yes - the 6.0L engines are deserving of this list.

Identical engines with the exception being the LQ9 has flat top piston vs dished on the LQ4 for higher compression and a few more ponies.

 

[UNC017]

Originally Posted By: rslifkin


The 96+ have the questionable pistons though. I can't remember whether the bottom end changed at all in 91 with the first HOs (I know the heads changed). If they fixed the bottom end issues the Renix had, then 91 - 95 would be the best of them.


The whole "questionable pistons" thing is a serious case of internet magnification. Yes, some piston skirts fail... but do they fail more after '96? More after 2000? More than other engine designs? I frankly doubt it. Every forum out there indicates that the 97-99 are by far the most "hands off" 4.0s of the lot, and so far my '99 bears that out well. I think the block stiffening happened early (~90) but they finally added the bearing cap ladder brace around 95 or 96, which (along with the better intake manifold and lack of the "331" head) is what makes the 99 so desirable.

Originally Posted By: rslifkin
And none of the 4.0s really like sustained high rpm. Spin one (of any year) past 5300 without serious work and you'll hit a really nasty harmonic that'll blow it to pieces very, very quickly.


Which is at first blush very odd, because like all inline sixes they have great balance and are smooth as glass... except at idle where they percolate like an old crusty coffee pot. But that's a combustion-related roughness. Balance-wise, they're smooth. I think it all comes down to a crank that was designed for low speeds and never given the stiffness needed for higher speeds because the top end runs out of breath around 4k RPM anyway. Just another case of how appearances can deceive. You'd think the 7-bearing Jeep 4.0 crank and bottom end would be way stronger than the 4-bearing Chrysler slant-6, but exactly the opposite is true.

 

[UNC017]

Originally Posted By: DoubleWasp
Originally Posted By: 440Magnum


According to Bill Weertman's book, if I recall correctly, Chrysler did some testing of a diesel conversion on the slant-6 with promising results but never proceeded with it (probably a very wise choice).



Calling up Cummins was one of the smartest moves they ever made.



We'll conveniently forget that they called Mitsubishi first, back when they were thinking about the slant-6 diesel. It took another 11 years for that call to Cummins...

The 77-78 half-ton trucks had a Mitsubishi (non-turbo) straight six as an option. That didn't fare too well because it was so underpowered, although it was a lot more reliable than the Oldsmodiesel in GM half-ton trucks.

 

[roadrunner1]

Originally Posted By: 440Magnum
Originally Posted By: DoubleWasp
Originally Posted By: 440Magnum


According to Bill Weertman's book, if I recall correctly, Chrysler did some testing of a diesel conversion on the slant-6 with promising results but never proceeded with it (probably a very wise choice).



Calling up Cummins was one of the smartest moves they ever made.





We'll conveniently forget that they called Mitsubishi first, back when they were thinking about the slant-6 diesel. It took another 11 years for that call to Cummins...

The 77-78 half-ton trucks had a Mitsubishi (non-turbo) straight six as an option. That didn't fare too well because it was so underpowered, although it was a lot more reliable than the Oldsmodiesel in GM half-ton trucks.


My dad bought one of those new and still owns it !!!!!!!!!!!! It was a one ton dually though and underpowered is an understatement. He did put an aftermarket turbo on it and then another 3 speed trans behind the factory 4 speed so he could tow his 5th wheel.

He never had any engine problems with it, although the rest of the truck was a mess from the start, as it turns out Dodge had the wrong bell housing for the transmission it took the dealership 7 transmissions before they found out the problem. I seem to remember Dodge also offered a Nissan diesel as an option at the same time which added to the confusion about the bell housing as they used a different transmission behind the Nissan.

I know he never replaced any injectors, injection pump, or anything else mechanical on the engine.

 

[rslifkin]

Originally Posted By: 440Magnum
Originally Posted By: rslifkin


The 96+ have the questionable pistons though. I can't remember whether the bottom end changed at all in 91 with the first HOs (I know the heads changed). If they fixed the bottom end issues the Renix had, then 91 - 95 would be the best of them.


The whole "questionable pistons" thing is a serious case of internet magnification. Yes, some piston skirts fail... but do they fail more after '96? More after 2000? More than other engine designs? I frankly doubt it. Every forum out there indicates that the 97-99 are by far the most "hands off" 4.0s of the lot, and so far my '99 bears that out well. I think the block stiffening happened early (~90) but they finally added the bearing cap ladder brace around 95 or 96, which (along with the better intake manifold and lack of the "331" head) is what makes the 99 so desirable.

Originally Posted By: rslifkin
And none of the 4.0s really like sustained high rpm. Spin one (of any year) past 5300 without serious work and you'll hit a really nasty harmonic that'll blow it to pieces very, very quickly.


Which is at first blush very odd, because like all inline sixes they have great balance and are smooth as glass... except at idle where they percolate like an old crusty coffee pot. But that's a combustion-related roughness. Balance-wise, they're smooth. I think it all comes down to a crank that was designed for low speeds and never given the stiffness needed for higher speeds because the top end runs out of breath around 4k RPM anyway. Just another case of how appearances can deceive. You'd think the 7-bearing Jeep 4.0 crank and bottom end would be way stronger than the 4-bearing Chrysler slant-6, but exactly the opposite is true.



Yeah, the harmonics are an issue of the long crank and cam. IIRC, it mostly starts in the cam and transmits from there.

As far as the pistons, the only broken skirts I've ever heard of have been on the 96+ (not that they're all that common). The 95 and older don't seem to do it at all. 96 was the year that got the extra bracing and the new pistons (and IIRC was the cutover year from the 7120 early HO head to the 0630 head).

96 - 98 4.0s should all be identical. 99 is the same as the 96 - 98 in a TJ or XJ (still has the older intake manifold, 0630 head, distributor). 99 WJs got the updates that the rest did in 2000 (updated intake manifold, coil packs, 0331 head, new exhaust manifolds).

In theory, the best combo of factory parts would be the 2000+ block/crank/rods, one of the later TUPY 0331 heads that doesn't crack (they flow a little better than the early heads), 2000+ intake and the early HO pistons.

 

[UNC017]

Originally Posted By: rslifkin

In theory, the best combo of factory parts would be the 2000+ block/crank/rods, one of the later TUPY 0331 heads that doesn't crack (they flow a little better than the early heads), 2000+ intake and the early HO pistons.


But you definitely want a 99-down tubular exhaust manifold, the 2000-up cast iron manifold was a step in the wrong direction.

 

[rslifkin]

Originally Posted By: 440Magnum
Originally Posted By: rslifkin

In theory, the best combo of factory parts would be the 2000+ block/crank/rods, one of the later TUPY 0331 heads that doesn't crack (they flow a little better than the early heads), 2000+ intake and the early HO pistons.


But you definitely want a 99-down tubular exhaust manifold, the 2000-up cast iron manifold was a step in the wrong direction.



I don't think they flow much worse, although they're 2-piece, so you need a y-pipe. But the cast iron manifolds don't crack like the early ones tend to. One of the aftermarket headers would be better than either though.

 

[UNC017]

The cast iron manifold puts a lot more radiant heat on the intake manifold and fuel rail- that's more of an issue than its flow ability. Also my 99 XJ has the "new" intake same as my 2001 had, I think only the TJ kept the 96-98 style.

 

[artificialist]

With all this talk about diesel engines derived from gasoline engine, I have to wonder something.

How durable was the Nissan LD28? It was derived from the excellent L-series gasoline engine, and was sold in the RWD Maxima for a few years.

Was it simply so uncommon that nobody noticed if they were bad?