4.0 reliability vs 3.0

joshkeller · May 21, 2017

Currently own an 06 3.0 5 speed manual, 4.10 gears with 130k on it. I am averaging 17 mpg, 20 highway. I am currently shopping around to possibly get another truck.

I have found a 2008 with 4.0, manual, 3.55 gears. It has 32,000 miles. What kind of reliability, and issues does this year and motor have? Wilp gas mileage be worse, same?

I do tow an aluminum river jet boat (1800 lbs) and a 4 wheeler with trailer (1000) pounds.

Will the 4.0/3.55 gears tow better than 3.0/4.10?

Thanks guys

RonD · May 21, 2017

4.10 will have more rear wheel torque for pulling a trailer, with any engine

The 3.55 is for best fuel economy at highway speeds, not great for towing but will work with the 4.0ls power, 205HP, 3.0l has 150HP

2008 4.0l SOHC was a reliable engine, as was the 3.0l Vulcan engine(2004-2006 did have head issues)

4.0l SOHC uses 9.7:1 compression ratio, so will be "pingy" using 87 octane fuel(regular gas), Ford added a Knock Sensor which advances spark timing when pinging is detected, this reduces power of course.
So when you are going to be towing add some higher octane fuel to keep power up

4.0l will use more fuel than 3.0l, laws of physics, but there is a power to weight ratio that comes into play, running 4.0l at less throttle for same speed, pulling same weight, as 3.0l, but MPG will be less with 4.0l overall

gw33gp · May 22, 2017

I have never encountered any pinging with my 4.0 SOHC and I always use 87 octane. I tow a race car all over the country too. My Knock Sensor must work very well. BTW Ron, I think you meant to say the timing is retarded when pinging is detected.
The gas mileage of the 4.0 is not all that much worse than the 3.0 unless you have the pedal to the floor all the time. If you drive reasonably, your gas mileage can be almost as good as the 3.0. I actually get better gas mileage with my 4.0 SOHC than I did with my 1989 2.9L Ranger. That is around town and towing. The 2.9L could do just as well or a little better on the highway. I know that is comparing older technology but can still give you an idea of comparison.

RonD · May 22, 2017

Advanced so spark ignites the air/fuel mix before it can self ignite.
Higher BTDC number, and yes that could be called Retarded spark timing, but I call it Advanced

Anytime you get above 9.2:1 compression ratio 87 octane becomes dicey, EGR system really helps.

Yes, knock sensor detects pinging well before you could hear it

Loads of info out there on compression ratio and octane rating

gw33gp · May 22, 2017

That is what I call advanced timing too. I have never heard of advancing the timing to eliminate pre-ignition. I know with my race car running at almost 15:1 compression, I have to be very careful not to advance it a little too much or it blows the head gasket. However, what you are saying makes sense by igniting the air fuel mixture before it has a chance to ignite due to compression.
My 89 2.9L Ranger did not have an EGR system and I would have a pinging problem on hot/dry conditions and would need to get higher octane gas in it to calm down the pinging.

Jimmyrig · May 22, 2017

I had one in an explorer sever all years ago. It was over 200,000 when I scrapped it. I put 80,000 on it with a wrist pin making noise, went 30,000 between oil changes on ot once, because I was broke, and it got a lot of thrashing in the woods when I wasn't broke. It had an overheating issue for the last 25,000 ish miles I drove it. It still ran strong when I scrapped the car. They are tough motors by my standard, and I can attest to the durability of the other cologne engines as well. It averaged 17 mpg with 31" tires and 500 pounds of tools\ recovery gear in the back, the manual tranny helped with that though.

RonD · May 22, 2017

Spark timing is a tricky thing, not quite that straight forward because of the changing conditions

When spark happens in the cylinder it takes time for the ignition point, at the spark plug, to spread enough for the "explosive power" needed to push down the piston

The timing you want is to have this "explosive power"when piston is After TDC,
10-15deg ATDC, this gives the connecting rod the best Leverage to push down on the crank journal, adding the most power to its spin
Too early or too late and you get less power

So let say spark at 10deg BTDC gives "explosive power" at 15deg ATDC
12deg BTDC changes it to 13deg ATDC
So 25deg of travel from spark to Power

But thats at 700RPM, what about 3,000RPM,
piston is now moving from 10deg BTDC to 15deg ATDC MUCH faster
Assuming the time it takes from spark to "explosive power" stays the same then you will need to advance the spark to happen at 20deg BTDC so "explosive power" happens at 15deg ATDC.

That's what the springs and weights did in a distributor, as RPMs increased spark was advanced to give the spark enough time to get the "explosive power"

But here's the other layer, spark to "explosive power" isn't the same time length, lol, it varies by air:fuel mix.
Richer mix gets to full "explosive power" faster than leaner mix
That's where Vacuum Advance came in for distributors, idling or cruising along vacuum is high so advance was high.
When you "stepped on the gas" fuel mix gets Rich and vacuum drops so advance dropped and quicker burning Rich mix could still hit the 10-15deg ATDC window

That was the mechanical methods, computers do this now, they use coolant temp, RPM, throttle position, air:fuel mix and engine load
And they are pretty good at it, if there is an EGR system the computer will be programmed for a more "aggressive" spark timing, than a non-EGR engine.

gw33gp · May 23, 2017

I know this has drifted off topic but I would like to continue this a little. I know the issues of timing that have been explained but there is one thing about timing that has bewildered me for a long time. I don't know if this is true for street cars but in racing it has been found that at high rpm a little more power can be gained by a slight retarding of the timing above a certain rpm. This appears counter intuitive to me because it seems higher rpm could use a little advanced timing. I know that most engines also stop advancing the timing anywhere from 3,000 to 3,500 rpm. My race car has retarded timing just to start it and then it goes pretty much to full advance and stays there.

So Ron, so you have any incite as to why slight retarding of the timing at high rpm results in a little power gain?

Sorry Josh for drifting off topic. I hope you have at least gotten a satisfactory answer to your question.

RonD · May 23, 2017

It would make some sense to retard spark timing a little at very high RPMs, IF(big if) you were running aggressive(advanced) spark timing for best lower RPM timing.
When you get into the 36deg BTDC range dropping a few degs can lose horse power but gain some torque, you are moving "explosive power" closer to or just passed 15deg ATDC

Like pushing down on the pedal of a bicycle, if you wait until 15deg ATDC you will get slightly better torque when pushing down but less "horse power" than starting to push down at 10deg ATDC
Better and easier spin at 15deg, especially at high RPM

But this is more a Racing thing and above my pay grade, lol

And yes you can break stuff and blow head gaskets if spark timing is too advanced
You are dealing with an "explosion" inside the cylinder, and a powerful explosion.
If this explosion occurs before 10deg ATDC so say at 5deg ATDC then piston is MUCH harder to push down, no leverage on the crank.
Pressure of explosion is the same but now you have the old "hard place and a rock" scenario

And weakest point will show itself

85_Ranger4x4 · May 23, 2017

Going to a 4.0 you will gain power and maybe lose a tad of mileage.

Once they got the timing chain issues fixed it really helped become a decent engine. I think they still had the POS plastic thermostat housings that break/leak though. Not really a terribly expensive or a complicated fix but it is messy and annoying.

joshkeller · May 24, 2017

at what time did the 4.0 become best? Im currently shopping around, and if i can get a decent trade in, I think I'm going to pull the trigger. Id like for an extended cab vs single i have now, and power windows would be fantastic lol.

85_Ranger4x4 · May 24, 2017

joshkeller said:
at what time did the 4.0 become best? Im currently shopping around, and if i can get a decent trade in, I think I'm going to pull the trigger. Id like for an extended cab vs single i have now, and power windows would be fantastic lol.

I think it was '03 or '04 they updated the timing chains, do a quick search and it is all over the place though.

That problem was the undoing of my mom's '02 Explorer.

AllanD · May 25, 2017

I've long believed that the 3.0 Vulcan was one of the worst engines ford saddled Ranger owners with...

The engine has no specific problem it is just a gutless POS that you have to whip the snot out of until it has nothing left...

The 4.0OHV is a vastly superior engine with no real defects.
The 4.0SOHC has some issues with the timing chain guides in the earlier examples.

I've actually seen several that were bad enough that the slack chain actually chewed through the side of the cylinder head.

I am aware that the problem is basically fixed, but I choose to not own one, my Ranger has a 4.0 OHV and my Explorer is a 5.0AWD...

2002edgeplussupercab · May 27, 2017

All conditions the same, the Vulcan 3.slow will outlast the 4.0 by a long shot. Maintained like any engine should be, it is one of the most reliable engines in existence. Any master mechanic of 20+ years will agree, unless they just have an axe to grind, or just a liar.

Slammin Sam · May 27, 2017

In defense of the 3.0, my 2000 Ranger 2wd ext cab had 72K when I bought and 168K when I sold it after I found my 89 B2. Never a repair to the engine. The guy that bought it 3 1/2 years ago still drives it every day without a problem.

4.0 reliability vs 3.0

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