By on September 5, 2013

Dave writes:

Hi Sajeev,

This is the second question I’ve asked on here, and while I didn’t even follow the advice I received last time and here I am again! Last time I was asking about a sporty car, and I ended up getting a 2007 Ford Ranger, 2.3L, 5 speed, with all of 35,000 miles on it. It is a regular cab with nothing extra on it, a real throw back, manual windows, no AC, a nice basic truck with nothing to go wrong right?

Wrong.

In the past two years we’ve put maybe 5,000 miles on it. It’s our second vehicle and it sits a lot except for weekends going to the to the dump, hauling kayaks, bikes, mulch, etc. Just what it was made for. In that time it has developed a serious engine knock (maybe even piston slap?). It runs fine otherwise, especially with a load and at low RPM when empty. Fuel mileage is fine, nothing in the oil except oil, doesn’t use fluids, just makes a god awful knock, especially when shifting. I first thought of detonation, but at low revs with a load in it nothing. I took it to a local shop I trust to see if they could find out what it was. The best they could come up with was it was in the #4 cylinder, they disconnected the spark lead and the knocking went away.

They suspect a wrist pin or main bearing. I suggested dropping the pan and switching the #4 piston, connecting rod and crank bearing out and maybe miking the bearing journal to see if that needs repair. They looked at me like I was nuts. Am I? Seems no one does engine repair any more, are they all throwaways now? They suggested a used or rebuilt engine and a cost of 3-4500$ for the whole job. I wonder if the truck is worth that much, but I can’t really sell it the way it is and it is useful around the house.

Any suggestions?

Sajeev answers:

Well hell…considering my daily driver is a fully optioned (i.e. carpet, A/C and power windows) version of your ride, this has me more than a little concerned. And then this YouTube video.

From what I Google, some Duratec Rangers have a problem with rod knock as they age.  Or maybe it’s a timing chain issue, like the YouTube clip above.  It might stem from neglect and over loading the truck.  Who knows, especially considering the Duratec Ranger’s crank is beefier than an ordinary Duratec I-4 unit.

And while you can easily (so to speak) fix the offending spinny-part with basic knowledge of what parts comprise the Duratec family of engines, the truth is these are throwaway motors to most folks. And most mechanics.  And that’s probably the way it should be.

My advice?  You can try one of the magic oil additives, I once used Lucas to hush-up a growly crank on a 5.0L V8.  But without a doubt, drive it until the motor pukes: don’t spend another dime trying to diagnose this. Then worry about getting a “new” throwaway motor.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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46 Comments on “Piston Slap: Gently Tapping, Tapping at My Ranger’s Door?...”


  • avatar
    jmo

    Imagine, a lightly used vehicle for sale with hardly any miles on it! Why would somebody be selling such a creampuff?

    Oh, yeh, it’s a ticking time bomb.

    • 0 avatar
      Sam P

      That truck would have still been under warranty when it was sold by the first owner; if it *really* needed a new engine, it would have received one under warranty.

      • 0 avatar
        jmo

        Good point.

        The other option is the owner knew damage had been done but without a symptom wasn’t able to get warranty work done.

        IIRC someone at TTAC wrote in about his wife driving around with the low oil pressure light on. The advice was to fill it with oil and sell it.

  • avatar

    As long as we are on the subject of replacing engines, what might be a practical yet awesome replacement mill in a Ranger? Those two, awesome and practical, may well be mutually exclusive but I thought I’d toss it out anyway.

  • avatar
    racer193

    This may just be my horsepower craving brain but if it where my truck I would jamb a 302 windsor under its hood and be done with it (it may even bolt up to the manual trans in your truck). These engines are still around in junk yards but finding a good one will be a whole bunch cheaper and it shouldnt mind the sitting around your truck does. Another bonus is frying the tires on dump road after you dump your junk.

    • 0 avatar

      ZOMG why didn’t I think of that? Plus, 5.0L Explorers are dirt cheap these days.

      I usually say LSX-FTW in times like these, but I completely overlooked it. I’m getting old.

    • 0 avatar
      mnm4ever

      That was immediately the first thing I thought of too! $3500 for a 4cyl?? Hell you can buy new 302 long blocks for what, $1500 or so?? They make swap kits and the truck sits all week anyways, might as well sit on jack stands for a few weeks while he tinkers on the swap. I used to have a Ranger like that, basic ’97 XLT reg cab 4-cyl stick and it was a great vehicle, would have been lots of fun with a five-point-oh.

  • avatar
    danio3834

    Sounds like a spun rod bearing on #4 to me. You aren’t nuts to suggest swapping out #4, although all it may need is a new bearing. Wrist pins are typically more of a diesely sound, think the sound your average K-car or Dodge Shadow engine makes.

    I’ve done sole piston swaps many times with success. Once on a 4.0L AMC I6 that actually cracked a skirt. The cylinder walls were’t bad, and that XJ served out the rest of it’s days with minimal oil consumption (considering they have that issue sorta built in anyway).

    The shop just doesn’t want to deal with the possibility of a comeback in a situation like that, and would much rather sell you an engine swap. It’s safer for them, and more profitable.

    If you can get the oil pan off with ease, pop off the con rod cap to #4 and inspect the bearing. See if it’s burnt or scored and check the crank for damage. If crank damage is minimal (doesn’t catch your finger nail) pop a new bearing in, retorque it and see how she goes.

    • 0 avatar
      NoGoYo

      I know what you mean, my sister’s Acclaim totally sounds like a diesel. It’s kind of funny how a gas engine can develop a problem and sound like a diesel engine.

      • 0 avatar
        danio3834

        Those motors notoriously developped some slop in the wrist pins and made the diesely K-car noise that is burned into my brain from my years as a mechanic. It never seemed to affect longevity, though. They’d blow a head gasket or toss a rod before the piston ever had an issue.

        • 0 avatar
          NoGoYo

          Does that make them shake like a sumbich too? Because whenever I’ve had to drive my sister’s car, the damn thing shakes like crazy when you’re not moving.

        • 0 avatar
          golden2husky

          True. I went over 250K with that idle clatter from the wrist pins. Never caused any problems. First head gasket claimed it…it does not make the engine vibrate. And yes, these engines were never the smoothest at idle….

          • 0 avatar
            NoGoYo

            My sister’s car constantly leaks oil (even when we switched to 10W40) and coolant, so it’s not long for this world anyway.

          • 0 avatar
            Sinistermisterman

            @NoGoYo
            I’ve had plenty of cars like that. Best thing to do is stick a tray underneath it every night to collect the drool and top it up every week. I only ever used to ditch such cars when a some gasket or seal really let go.

  • avatar
    -Nate

    What he said but consider polishing the bearing journal with Crocus Cloth before fitting the new bearing shells .

    Yes , there are still a few of us Journeyman Mechanics who fix or repair things .

    -Nate

    • 0 avatar
      danio3834

      Yes, this. Crocus cloth or fine emery cloth will help smooth out any burrs on the crank if there are any.

    • 0 avatar
      pragmatist

      OMG I haven’t heard the term crocus cloth used in decades.

      There is an extra fine scotchbrite that works pretty well.

      What puzzles me is that the noise is not under low speed load, this is where you expect rod/wrist pin knock to be loud. Also noise when shifting. Loose flywheel?

  • avatar
    TR4

    Repairing the bearing journal? That generally involves engine removal, disassembly, and taking the crank to a specialized machine shop for a regrind. You might get lucky and find a problem in the wrist pin area but you should be prepared for something close to a complete overhaul. In this case a used engine might be cheaper.

    • 0 avatar
      danio3834

      I’ve done it in chassis many times for people on a budget. If the damage isn’t bad, a quick polish and new bearing will usually last quite a while.

      • 0 avatar
        TR4

        “If the damage isn’t bad, a quick polish and new bearing will usually last quite a while.”

        Agreed, but since the OP said “makes a god awful knock” I figured the journal is likely trashed. Never know until you open it up though.

    • 0 avatar
      -Nate

      @ TR4 ;
      No ;

      You don’t repair the journal , you use the Crocus Cloth to remove any residue of the hammered to death babbit from the failed bearing .

      In my youth there were portable crank grinding machines that would grind one journal , crank in car .

      Also , portable boring bars that could bore one cylinder at a time .

      Danio : there are not many of us left , most don’t care to understand the job well enough .

      -Nate

      • 0 avatar
        danio3834

        ” there are not many of us left , most don’t care to understand the job well enough.”

        You’re right, and I’m not even technically in the trade any more. The cars I work on these days are my own, of acquaintances and customers who were good enough to be considered friends. I still do it on nights and weekends because I enjoy it, and there are people who need a break from being boned by certain shops that want to over-repair, or just plain throw parts at them.

      • 0 avatar
        TR4

        “In my youth there were portable crank grinding machines that would grind one journal , crank in car .”

        Yeah, I’ve heard about them too but I expect the results were comparable to making a hole with a portable drill instead of a drill press. Probably OK in the days when poured babbit bearings were scraped by hand to fit the journal but on a modern 6000 rpm engine with precision insert bearings…I doubt it.

  • avatar
    Fordson

    A lightly-used, 40k mile, 7-year-old vehicle, and the advice is to drive it until it dies? Wow.

    It’s not your everyday vehicle and if the repair becomes more involved, you can make further plans once you have the pan, end cap, etc. off and can look at the bearing and crank journal. It’s definitely worth that minimal amount of work to see if it’s just a bad bearing, the crank is fine and it can serve you for another 100k miles.

    Fifty bucks worth of parts and a hundred bucks worth of your time, not your daily driver, and that’s not worth doing? Then nothing is worth doing.

  • avatar
    mikey

    I got to go with Sajeev on this one. 5000 in two years? Why do anything,if you don’t have to? Keep the oil changed, let it warm up after a cold start, and pour the Lucas in at oil change. You may be shocked at how long that engine will last.

  • avatar
    Crabspirits

    “I suggested dropping the pan and switching the #4 piston, connecting rod and crank bearing out and maybe miking the bearing journal to see if that needs repair. They looked at me like I was nuts. ”

    Probably because you cannot change out a piston and rod from the bottom. You have to pull the head. At least in most cases, the piston will jam in the bore, or hit the crank, preventing removal. You can try a thicker oil, like 15w-40. Not a fan of Lucas, as it aerates (probably a moot point if your engine is already a write-off) and could cause problems. Another possibility since you said you hardly drive it, is a faulty lifter that leaks down after awhile. Run the engine hot at 2500rpm, and see if it goes away. If it goes away when the spark is pulled however, I would trust your mechanic’s judgement. If you can easily pull the pan, tossing in a set (or just for that rod) of rod bearings is certainly easier than swapping out a throwaway engine.

    A rod bearing swap in a SHO V6 is a 15min job for instance.

  • avatar
    highrpm

    Before you do anything, check the Ford forums. Something like ford-trucks.com maybe. They have Ranger specific sections and sections by engine group.

    Maybe the noise is something else. Tensioner? Loose bracket? I’m guessing. With my cars, I always check the forums for these type of strange noises to see if there’s some common issue with that particular car and engine. I would do this before wrenching, especially if it involves pulling the main bearings.

  • avatar
    mfgreen40

    Nate—Danio Thanks for the memories. In my career I bored many cyl. in the vehicle, but only ground one rod throw in the vehicle. I swore I would never do another one. What a mess with grinding dust falling in your face. I will agree there is no reason not to replace one rod brg. if the crank mikes OK. 400 grit is about right for polishing. There might be a .001 over size brg available. Even shim stock behind the insert works, if done properly.

  • avatar
    oldworntruck

    This problem could be as simple as carbon build up on #4 cylinder due to leaking valve seals and prolonged sitting.With a borescope it would be easy to tell.
    Or spend 10$ on a can of combustion chamber cleaner and try cleaning it out as per directions.What do you have to lose?

    • 0 avatar

      I’d try something like this too. Start w/ the cheap things. Keep the original engine, do what it takes to diagnose it accurately, and fix exactly what is the ailment. At 10 years and 150k later you’ll be laughing your ass off having only spent 19 cents / mile when…you get rear ended and the insurance company rewards you $1150 for your totaled Ranger or…you make that 17 year old neighbor kid the luckiest person ever born when he buys it for $650 and starts his own lawn mowing business and learns almost everything there is to know about vehicle repair on one of the most traditional vehicle layouts. Or…you could just sell it to him now…

  • avatar
    -Nate

    @ pragmatist : ” OMG I haven’t heard the term crocus cloth used in decades.

    There is an extra fine scotchbrite that works pretty well.

    What puzzles me is that the noise is not under low speed load, this is where you expect rod/wrist pin knock to be loud. Also noise when shifting. Loose flywheel? ”

    Rods don’t usually knock under load until you’ve hammered the crank journal ovalish . collapsed skirt or cracked pistons do .

    @ mfgreen40 ” Nate—Danio Thanks for the memories. In my career I bored many cyl. in the vehicle, but only ground one rod throw in the vehicle. I swore I would never do another one. What a mess with grinding dust falling in your face. I will agree there is no reason not to replace one rod brg. if the crank mikes OK. 400 grit is about right for polishing. There might be a .001 over size brg available. Even shim stock behind the insert works, if done properly.”

    Trust me , I get far more out of TTAC than I could _ever_ give back .

    I can’t find the 3M Crocus Cloth in rolls anymore , I used to stock it as we actually had real Mechanics who’d use it from time to time .

    I had to look hard to find it in standard sheets this time so I bought several ~ I have a beat to death Chevy/GMC 292 InLiner engine I _was_ trying to return to service but gave up ~ I may still save the crank as they’re getting a little hard to find .

    I don’t think I’d ever use 400 grit abrasive paper , I was asking some Machinists I know if I could use 1,500 grit wet/dry strips , they said to hold out for the Crocus Cloth as the abrasives there are made to polish bearing journals .

    I laughed when I read ” maybe good enough for babbit pounders ” prolly so , prolly so but he’s using it for a weekend dump hauler not a freeway flyer .

    I learned a great deal from my Generous MotorsCorp. training amongst others , also a lot by trying this typ of repair , more yet still from those WWII Veterans who took the time in the 1960′s to teach me , I’m glad they did ~ I’ll never be rich nor famous but they taught me about life , attitude and Journey Man Mechanicing , I know I made the right Life Choice in this .’

    -Nate

  • avatar
    DIYer

    Bad rod bearing. The previous owner probably ran the motor without oil/coolant in it.

    I’d try running a heavier oil, bumping it up from the standard Ford spec 5W-20 to 10W-30, and substituting 1 quart of Lucas Pure Synthetic Oil Stabilizer. This will quiet things down, but it won’t fix the problem.

    Also, take it easy during acceleration and the motor will last longer. Eventually, you’ll need a rebuild or a different motor.

  • avatar
    TybeeJim

    No help here. Don’t know if I’d spend $k for an engine when you could probably find a whole used truck for more money but with better luck.
    I have an ’04 Ranger Edge with all the goodies that I bought in ’06 with 40k miles (was on a 3 yr./36k mi. lease). It has the little v6, 150 hp. and has run like a top for another 38k miles with only front brakes at 65k, 4 new tires and oil changes every year. A good detail job and it would be almost new!

  • avatar
    Sob93

    I agree with the magic oil solution. Then drive it to a used car lot and trade it in for a V-6 1/2 ton stripper if that’s all you need or maybe a 3.0 Ranger. There’s lots out there. Make it someone else’s problem. They did it to you.

  • avatar
    nrd515

    A guy I went to school with had some old battlecruiser, a Buick 225, I think, and it made a horrible noise once it got hot. This was auto mechanics school, so we yanked the pan and the bad rod bearing was pretty easy to find, it was on the front crank throw. We pulled the cap on the rod that looked slightly “cooked” and the bearing was trashed. The crank looked all right. The teacher got his caliper and micrometer out, measured everything, went to a parts store, came back with some crocus cloth, plastiguage, two sets of rod bearings, and a can of STP. He cleaned the crank up with the crocus cloth, washed it with some carb cleaner, put the first set of bearings on, with the plastiguage, took it apart, looked at the little thread, and said, “looks good”, put some STP on the bearing shells, and put it back together. The rest of the STP went in with an oil change on it, “just to make sure the first couple of minutes it runs doesn’t do something bad”. It sounded great, and 5 years later, it was still running fine with nothing more than a water pump change out. I would give it a shot.

  • avatar
    trk2

    Check the swirl flaps in your intake manifold (similar to throttle body flappers). The shaft that supports the flaps can wear (and will typically wear at the #1 or #4 cylinder) which causes the flaps to tap against the intake manifold under certain conditions. Search for Duratec swirl flap (also called swirl plates or tumble flaps).


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