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Broken duratec 2.3

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  • Broken duratec 2.3

    I think I over revved my engine today at the Streets going into the first hair pin. Engine goes clunk-clunk but there's no smoke, white or black, and I still show oil pressure. Got a flat bed ride home courtesy of AAA.

    Any ideas?


  • #2
    Oh dear, sorry to hear did that happen? Wrong gear?

    Is the sound clattering like from valve banging? In any case it may be wise to pull the valve and chain cover before any more attempts to crank, to see what is going on, then the head and sump if needed.


    P.S.: Sorry if I mentioned the obvious....


    • #3
      Maybe the timing belt just slipped a little? It still runs and idles. It's not spitting, etc. I was able to drive it off the track, onto the flatbed, and into my drive way.

      Scott E


      • #4
        Your ECU should have a rev limiter, unless you did it by downshifting into too low a gear for the speed you were going.

        Check the Alternator mount, Chris had some issues with his breaking and your's may be the same. (Broken mounting bolt) Otherwise look around for something not so obvious that is loose.

        Any other symptoms besides the noise, is the noise directly related to RPM?

        Contact me off list if you still have my email address. The old one at should still work. If not try the same name at

        Duratec's have a timing chain, however the drive sprockets are only held on by friction. I have not heard of any slipping.

        Put the car in neutral, remove the spark plugs and try to turn it over with a socket on the front crankshaft bolt. It should turn over fairly easily with no big clunks when the pistons change direction. If it jams hard against something don't force it. Look at the plugs when you take them out (keep in order) and see if one is wet or looks significantly different than the rest.

        Last edited by Doug Liedblad; February 4, 2007, 10:52 PM.


        • #5
          There's no timing belt on a Duratec. It uses a chain. The pulley is secured by a single bolt - if that's loosened you'll lose timing.

          Edited to add: Drain the oil & look for nasty looking metal bits. That'll be a real clue that something's gone bad, like a spun bearing.

          Does it make horrid sounds as it's running and idling?

          Otherwise, what Gert said is the right way to start.

          At least you had great weather...
          Last edited by moosetestbestanden; February 5, 2007, 08:00 AM.
          A day you don't go a hundred is a day wasted


          • #6
            details please

            Scott, Sorry to hear about your troubles. It would be most helpful if you could give us the details of your setup and what happened during the corner.


            Tom "ELV15" Jones


            • #7
              It's bad. There's glitter in the oil and filter. Cranked the engine over by hand and effort to turn was easy/hard, easy/hard.
              What's a stock rebuilt engine cost, I wonder.
              Problem I think was low oil due to the questionable calibration of the dipstick. I guess I didn't over rev and actually do have a rev limiter.
              Edit: The plugs all look the same. Burn looks just a little rich.

              Scott E
              Last edited by Scott E; February 5, 2007, 01:59 PM.


              • #8
                Take out the plugs and crank it again (or did you?)

                "glitter" = more evidence of a spun bearing at a minimum. Next step: drop the pan and have a look see. Broken rods have a way of letting their presence be known.

                Cam cover isn't likely to unveil anything, except for perhaps more glitter and proof that a cam hasn't broken. Still, it's easy enough to do so why not?

                Head off = major surgery - timing cams et. al. has to happen on re-assembly.

                Look here

                Don't know anything about them personally but I think the prices are in the range and they're not too far away. If you've got to open it up for a rebuild I suggest some nice rods & pistons & bolts and such like. It won't add too much to the cost and things will be stronger.

                Do a cost - benefit analysis when the scope of the problem is known. If it's a write-off, imo & fwiw the 2.0L is a better way to go. That long stroke truck motor ain't suited to sports car track-like action sez I.

                Edited to add: Upon further review, you may want to spend your time pulling the thing (instead of diagnosing) as it sounds like something is genuinely gone way wrong. I think you've got to pull it & open it up anyway.
                Last edited by moosetestbestanden; February 5, 2007, 12:34 PM.
                A day you don't go a hundred is a day wasted


                • #9
                  2.0 vs 2.3

                  I agree with Chris (mostly). You will need to yank it out and open it up to find out what went wrong.

                  However, I believe that the 2.3 has plenty of potential, especially if the one you have is salvageable. If you plan to rebuild it, make sure you use HD rods and pistons. The stock units are not really suited to the kind of use you will see in a seven. If money is no object and you are more likely to use it on the track than on the street a fully built out 2.0L (like the one Chris has on order) would be great! For me a 2.3L with some tweaks should be more than enough power.

                  Regarding the oil level - assuming that you are running a raceline wet sump - it requries 5 quarts. Less than that and you will have problems.
                  Tom "ELV15" Jones


                  • #10
                    Thanks for all the help, everyone. I've decided that I must pull the engine and dismantle it. Upgrading is a question of funds and, yes future durability for track days.
                    With new pistons and rods, etc. would increasing compression yeild a large difference in fuel economy? I know it sounds silly to consider economy but I liked the idea of being able to drive 200 miles on a tank of gas during normal highway driving. At this piont a lightened flywheel is in order and maybe even the removal of the balancing shaft if it doesn't contribute to more stress on the engine's structure and that of the mounts and frame. I also will look into the trans. leaks at the speedo drive and output shaft. I'd also like to modify the diff, from, what I think, is 3.92 to 3.6? and adding LSD components.
                    See? The cost is already mounting. And I'll also fix the frickin' dipstick issue. I think it leaked substantially from where it goes into the Raceline wet sump pan.
                    Back to the initial problem I think the damage is below the rings because, remember, the was no smoke from the exhaust.

                    Scott E


                    • #11
                      Yes, what Tom said about the oil & the Raceline sump, except to stop any leaking. I never even look at the cobbled together dipstick thing that's installed on my engine. 5 quarts, ya gotter dun. I have no leaks and I don't burn any oil and I change it frequently enough not to worry.

                      Check w/ Will (if he's around) to see which diff you've got. Mine is (supposed to be) a 3.62 LSD, and I think we got our cars around the same time - same container? Btw, I have a really minor leak in both the places you mention. Ha!:D

                      Higher compression pistons & fuel mileage? Don't know. Check out this little googled bit here though:

                      A research programme has been carried out to investigate the fuel economy potential of a number of engine concepts both on the testbed and in a vehicle. A 1.5 litre high compression ratio engine with a High Ratio Compact Chamber (HRCC) and a mechanically supercharged 1.3 litre engine were compared w

                      My guess: not a lot of impact. You will have to buy higher octane gas though.

                      I'm guessing you over-reved it just enough on a downshift.

                      I got a fiver that sez at least 1 spun bearing, but I bet your rods are OK because a car w/ broken rods doesn't idle.

                      Edited to say: well, the rods won't be OK, but at least they didn't break, which means your cylinders are likely to be OK.
                      Last edited by moosetestbestanden; February 6, 2007, 01:51 PM.
                      A day you don't go a hundred is a day wasted


                      • #12
                        I have done some more research, have listened to valuable input and have decided to replace my engine with a used one. In the beginning I'd made the mistake of only viewing rebuilt engines. They're typically twice the price of a used one. Now the question is about installing a lighter flywheel. What make do you suggest? How much did it cost? Will there be other parts needed in the swap? So far it seems that replacing the flywheel mounting bolts is necessary. Anything else?

                        Scott E


                        • #13
                          Check that the spring plate/clutch has the same dimensions and bolt pattern. Better safe than bat-sh*t crazy 02:30 a Sunday morning when it doesn't fit.If the flywheel is thinner/thicker than the original, you will need to offset the hydraulic slave cylinder and throwout bearing assembly so that the distance between the throwout bearing and the spring plate remains the same.

                          /Magnus F.
                          Last edited by magnusfeuer; February 16, 2007, 11:33 AM.


                          • #14

                            I would also replace the rear seal and add ARP flywheel bolts.

                            However, I recomment caution when looking at a lightened flywheel, take a browse through the blatchat archives and see what others think. I personally am using a stock flywheel and don't think I would swich to an ultralight version - I might think about the medium one just to get the revs up quicker. Also be sure to get one of the steel ones, not the aluminum ones that Cosworth sells.
                            Tom "ELV15" Jones


                            • #15

                              Why not aluminum?

                              Scott E