3.0 Liter FF knocking- Should I be worried?

[reginald fairfield]

Hey ya'll, this has been worrying me for a while. i have about 135,000 on my99 ranger 4x4 with the Flex fuel 3.0. I know it it normal for a high mileage vehicles, but mine has started knocking pretty bad, usually when it it warming up or even when I am gassing it pretty good at lower rpms. I hear that the heads on the 3.0's often go, and am wondering if this is what is goanna happen. If this is the case, what should I do? Get aftermarket heads or just get my old ones reworked? Should I wait until they truly mess up or should i do it now to avoid damage? Also, what is it that goes wrong with them? They are just P'sOS or what?

 

[JohnnyO]

I used to have the same vehicle, same engine, it would knock terribly when they'd change to the oxygenated summer blend of gas we get and that was when new. Different parts of the country get different gas at different times of the year. Did you try to run 89 or 92 octane to see if that helps? I took mine to the dealer a couple times to get it adjusted (the "octane rod" they told me) and it would be okay for a few weeks then go back to knocking. I gave up and just ran 89 in the summers. Then September would roll around, they'd change the gas back, and it would be fine on 87 again.

 

[reginald fairfield]

Yeah, I have tried 89 octane and it doesn't seem to help any. In fact, I'd say it makes it worse if anything. Maybe NM just gets the dregs of the fuel, or something... Have yet to try 92 oct, but that would run me dry in about a month anyways, so... yeah... I run 89 about once every week or two, just to keep the engine a little cleaner internally. Knocking is annoying. V6s and under seem to be the worst; my mother has a toyota fourunner with an I4, and it knocks a lot too... My brother has a 350 with more miles then me and it doesn't knock at all, so I don't know what the deal is... Damn it!!

 

[Wicked_Sludge]

there is nothing wrong with the head design for the 3.0. they dont tend to blow any more often than any other motor.

spark knock, however, can cause all kinds of very serious engine damage....including, but not limited to: blown heads/gaskets, burnt valves, damaged pistons, damaged rod bearings, ect. i recommend diagnosing and repairing the problem ASAP to avoid costing yourself a motor.

if your lugging the motor (high throttle settings at low RPMS), SHIFT DOWN. the 3.0 is a revver and does not do well at low RPM. downshifting will give you more power, better fuel economy, and reduce knocking.

as always, starting with a basic tuneup is a good idea (plugs with proper gaps, PCV valve, air and fuel filters, plug wires, o2 sensors, ect). high mileage engines are prone to building up excessive carbon in the combustion chambers, which will cause knocking. you can try seafoam through the intake, this often helps. water injection is another idea, but i dont recommend trying it at home as you can easily hydrolock the motor.

 

[reginald fairfield]

there is nothing wrong with the head design for the 3.0. they dont tend to blow any more often than any other motor.

spark knock, however, can cause all kinds of very serious engine damage....including, but not limited to: blown heads/gaskets, burnt valves, damaged pistons, damaged rod bearings, ect. i recommend diagnosing and repairing the problem ASAP to avoid costing yourself a motor.

if your lugging the motor (high throttle settings at low RPMS), SHIFT DOWN. the 3.0 is a revver and does not do well at low RPM. downshifting will give you more power, better fuel economy, and reduce knocking.

as always, starting with a basic tuneup is a good idea (plugs with proper gaps, PCV valve, air and fuel filters, plug wires, o2 sensors, ect). high mileage engines are prone to building up excessive carbon in the combustion chambers, which will cause knocking. you can try seafoam through the intake, this often helps. water injection is another idea, but i dont recommend trying it at home as you can easily hydrolock the motor.

I have been slowly replacing this stuff since I bought the pickup. Got everything cept the PCV. I don't tend to lug it; I run closer to 3,000 most of the time. As to the spark issue, I don't see what could be wrong, the plugs still have half of their life till scheduled maintenance... Could the rocker arms just be loose from the previous owner lugging it? maybe I could take the valve covers off and tighten them up... What do you think?

 

[Wicked_Sludge]

if the engine is in good tune, your not lugging the motor, and it is indeed spark knock your hearing...then your problem is probably carbon build up. many of fords v-6's are somewhat notorious for it. like i said before, you can try running seafoam through the intake yourself and see if that helps. failing that, you can take it into a shop for water injection and this will usually work. only in the worst cases do the heads have to come off for physical cleaning of the combustion chambers.

valve trane noise can often be mistaken for spark knocking however, so it cant be ruled out just yet. you could always have a mechanic come for a ride with you to help confirm the noise is actually spark knock.

however, the 3.0's valve trane is pretty durable and doesnt usually cause problems. lugging the motor wont cause rocker arms to become loose, so i wouldnt worry about that.

 

[reginald fairfield]

OK... thanks... I saw some seafoam today at walmart. I will probably try it. I am certain that it is the motor knocking though, because it depends on rpm, while it it not in gear or moving, so it has to be the motor.

 

[Wicked_Sludge]

sounds good. let me know how it goes.

 

[Kdawg532]

i know this ISNT the problem its just something to check, my buddies ranger where the spark plugs plug into the electronic distributorless ignition it had a slight crack in the metal and we didnt know, so one night i was listning for where the ticking was coming i suddenly noticed a little bit of lite which was actually the spark jumping to the wire and it made a decently loud ticking sound along with the idle, and i told him to touch to see if it made it quiter and shoked the hell out of him, but any way its something to check, i know its MOST LIKELY NOT THE PROB. SO DONT YELL AT ME FOR POSTING THIS

 

[reginald fairfield]

Naw, i checked it and that ain't it... thanks though... I have decided that the knock is not coming from the pistons/carbon build up, because when I use premium that part stops knocking. It seems to have more to do with the oil, because I changed oil the other day and it always knocks way worse after fresh oil... Do ya'll think that it could be the oil pump or something? I can hear the oil churning in there a lot, it makes a weird swishing noise in addition to the knocking. Also, it sounds louder from under the motor than above, and this is with the hood open, so... Also, it smooths out only when the motor is fully warmed up.

 

[Wicked_Sludge]

noise that goes away with premium gas is spark knock...probably from carbon.

noise that goes away with the motor warming up is probably bottom end noise (pistons or rods slapping). as long as the sound isnt real bad, your probably OK for a while...but this is a sign of your motors age. you could try running a thicker grade oil to slow bottom end wear (more cushion)...but this is really a band-aid fix for what really needs to be done: rebuild.

 

[Kdawg532]

my bros 68 stang one of the hydraulic lifters in it do the same thing when its warming up, so you think running a thicker grade oil would help that 2 ??

 

[Wicked_Sludge]

no...running a motor flush during the next oil change (or next several oil changes) can sometimes free a sticky lifter.

a sticky lifter is hard to confuse with bottom end noise however, lifters make a constant "ticktickticktickticktick"...instead of a the more substantial knocking a failing bottom end will make.

 

[Kdawg532]

yeah it is more like a ticktickticktick . now i can do some stuff mechanicly but others i am oblivious to, what does an engine flush consist of? just draining all the oil out and then running some clean oil at a high pressure through it???

 

[Wicked_Sludge]

you can buy engine flush at most auto parts stores for cheap....is basically just kerosene or some other type of solvent.

when your next oil change comes up, you run the car up to temp, then dump the engine flush into the crankcase. let the engine idle for 10-15 minutes to circulate the flush and allow it to attack the sludge and varnish inside the motor. then just change the oil as per usual.

of coarse, regular oil changes are a much more effective alternative