Lets generate a list of bad engines to avoid.

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JimPghPA

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Most of us know that governments and environmental groups have been and continue to force vehicle makers to improve internal combustion engines so they get more miles (KM) per gallon (or L) and also to produce less unwanted exhaust emissions.

This has forced many vehicle makers to push the limits of designing engines, and sometimes results in engines that do not last long, and even recalls. And some of these newer engines are not good for long term ownership.

Please help me put together a list of unreliable engines that are out there now that are causing problems and should be avoided. Basically engines that a well informed BITOG member probably should not be surprised if it fails.

Please include what company is / has made the engine and the specific size / name of the engine, and if possible the common problems it has.

Thanks for any information you add.
 
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JimPghPA said:
Most of us know that governments and environmental groups have been and continue to force vehicle makers to improve internal combustion engines so they get more miles (KM) per gallon (or L) and also to produce less unwanted exhaust emissions.
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Right.

It's those pesky governments and environmentalists that want good fuel economy.

All an engine has to be is reliable and customers will happily accept 15mpg as a trade-off.

Get real :rolleyes:
 
Not a bad engine but a terrible injector configuration in the Duramax from 2001 to mid-2004. They're under the rocker covers so they are expensive to have changed by a shop and when they leak you won't necessarily realize it until fuel dilution happens.
 
JimPghPA said:
The recent Toyota 3.5 L twin turbo V6 that they started making in 2022 has to be on that list.

The Nissan variable compression engine is one that may also belong on this list.
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These are both fairly new engines. Not sure how you can condemn them yet. For example the early VQ40's had timing chain guide issues. It was a quality issue not design. Once Nissan fixed the QC they became one of the most reliable engines around. Something similar could happen with either of these.

A lot of Toyota 2GR engines had timing cover leaks. Some leaked, some didn't - otherwise highly reliable. So on what list are you going to hang it?

The issue of course is by the time you determine how reliable they really are, there out of production.

I would say the two likely candidates for fairly new engines on this list are anything H/K Theta 2, and any 4 cylinder Ford Eco Boost with a slotted deck (there cross drilling them now).
 
MrHorspwer said:
Right.

It's those pesky governments and environmentalists that want good fuel economy.

All an engine has to be is reliable and customers will happily accept 15mpg as a trade-off.

Get real :rolleyes:
Click to expand...
There's some good modern engines out there, but the point of this thread is to highlight the problem ones. Manufacturers can not settle on old designs that do not comply with today's requirements. And in designing new engines they sometimes get it wrong. Let's list the ones to avoid because they will not last long and or cost a lot to own.

Ford big Diesels are known for grenadine parts getting into the fuel rails and costing thousands to replace all the compromised parts. But if not highlighted in threads like this, it can be a big unexpected bill to the unknowing.
 
Volvo's supercharged engine design is known to breach the seal after the booster and it's a fairly expensive repair if beyond warranty.

Honda certainly could have left more space between cylinders on the 1.5 T and they could have stepped it up a notch on head bolts sizing and clamping force.

My brother had a 2011 F150 that blew ignition coils so often he became good at changing them on the side of roads when he towed his rv with it. The aftercooler accumulates water from air, and when you stomp on it like on an entrance ramp it would suck that accumulated water in and wet the sparkplug over-load the ignition coil and damage it. There's a YouTube fix involving drilling a small drain hole in the bottom of the intercooler and he did that which reduced the frequency of blown coils but it still happened sometimes.
 
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W

Thread 'Modern Turbo Engine Reliability and Durability'

I'm curious what the BITOG community's experience with modern turbo engines is. Are they durable and reliable? Can they last 200K miles or more without major repairs or maintenance (other than oil and coolant changes)? To me, it's hard to visualize turbo engines lasting as long as NA engines. But maybe your experiences will prove that wrong! Turbochargers can spin at 100,000 rpm or more, and I saw a video on YouTube (hey, that alone means everything in it MUST be true, right?! ok, sarc off) in which a guy recommended that a car with a turbo engine be warmed up for a minute or so after...
 
How about the Ford Triton 4.6, 5.4 and 6.8 liter engines with the inadequate aluminum threads that result in ejection of their spark plugs? A whole cottage industry has emerged to repair those damaged cylinder heads, including the creation of unique tools designed to repair the threads with HeliCoils/TimeSerts without having to remove the heads from the block. Other than this glaring flaw, they are generally OK engines.
 
The Navistar 6.4L diesel; found in Ford SD trucks for a few years. A true low-point in the "PowerStroke" legacy. It was an updated version of the 6.0L PSD and was strictly done to meet emissions standards, as the aging 6.0L design wasn't going to be able to keep up with the regs. The problems include complexity of the twin sequential turbo system, EGR system coolers, oil coolers, first gen DPF, cracked pistons, cracked up-pipes, fuel pump failures, front cover leaks due to cavitation, etc ... And modding the engine with tuners only exacerbated the problems and made them show up even earlier.

Some might also include the 6.0L PSD, but it pales in comparison to the absolute turd that the 6.4L was. The 6.4L PSD is what caused Ford to dump Navistar and produce the in-house 6.7L PSD (an engine which has generally been well received and continues after 14 years of production and has every indication it will continue on).
 
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I also think we need to make sure we ID specific years of the engines on this list.
Many of the engines probably have a very long lifecycle, and only a few years of issues.
Often the introductory year or two are the problems, and then the engines are slightly modified by the OEM and find very beneficial service.

Examples would be:
Ford modular engines with the spark plug thread issue (as noted above), but this engine series soldiered on for decades in the 2v versions and were VERY reliable overall.
Toyota 2GR-FE engines have some oil line leaks and front cover leaks when first introduced, but these engines generally are VERY stout and reliable after those were addressed.


I also think we need to delineate what is a reliability issue versus a maintenance issue.
For example the Ford 3.5L Cyclone v-6 engine in n/a transverse applications. These engines are VERY reliable and will last quite long time, but the water pumps are expensive to replace (internal the the front cover) and if you don't pay attention to the warning signs, the leak issue could result in a ruined engine. This topic does NOT make it a bad engine. In fact, the engine has great power for its size, runs very clean, is very easy on oil and gets good fuel economy. The reality is that water pumps don't last forever; every water pump can be expected to fail at some point. But if you don't catch the impending failure, the engine is a gon'er. This doesn't make the engine a bad one; it merely means someone wasn't paying attention.
 
The hemi has a small chance of lifter failure.

Same with the gm v8's, not sure which design is more likely to give you trouble at this point.

Both these engine designs are sold in massive quantities so its hard to get a percentage/probability figure, just going by forum reports is impossible.
 
GM 3.6L V6
first series of 4 banger Equinox/Terrain were head gasket messes
5 cylinder in the Hummer H3/Canyon/Colorado same as above
the Ford 6-point-uh-oh diesel is a mess. Head bolts amongst other issues.
Chrysler 2.7L V6 was a giant turd as well
 
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dwcopple said:
GM 3.6L V6
first series of 4 banger Equinox/Terrain were head gasket messes
5 cylinder in the Hummer H3/Canyon/Colorado same as above
the Ford 6-point-uh-oh diesel is a mess. Head bolts amongst other issues.
Chrysler 2.7L V6 was a giant turd as well
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I owned two I5’s for years with no issues …
(But wished we had 6 speeds then) …
There are 10’s of thousands of the 3.6’s out there - after the chain issue was sorted they have done Ok - (family members have them)
I’d not stay away from any vehicle with one …
 
hemioiler said:
The hemi has a small chance of lifter failure.

Same with the gm v8's, not sure which design is more likely to give you trouble at this point.

Both these engine designs are sold in massive quantities so its hard to get a percentage/probability figure, just going by forum reports is impossible.
Click to expand...
Exactly - and the OP thread is pushing “avoid” …
 
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