Z32 Breaking in a rebuilt engine

Discussion in 'Technical' started by Chesutiko, Apr 29, 2021.

  1. Chesutiko

    Chesutiko Member


    I've had my VG30DETT rebuilt and just finished putting it back into the car, connecting all the hoses, wires, piping etc and was wondering if anyone on the forum could steer me in the right direction as to the best process for breaking in a rebuilt engine? Is this something I can do myself, or will I need to take the car to a shop to be run on a dyno?

    If anyone has gone through the process before I'd be happy to hear what you did and what you didn't do or regret not having done etc. This is my first time doing this with any sort of engine, so any advice would be greatly appreciated.

    Having a look on the net has given me a great deal of mixed results, some places saying to break it in without boost, some saying to break it in hard, some say gentle.. It's pretty confusing and I don't want to screw up many hours and $$$ worth of hard work I've put in.
  2. EvZ

    EvZ 1BAD300

    My two cents worth which is probably only worth one cent.

    I ran in a new Nissan long block. Used non synthetic oil every 2k for the first 10k. Alternated between hard and soft.

    Seems to have worked out ok.

    Wait for more knowledgeable responses before considering mine o_O
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  3. rob260

    rob260 Administrator Staff Member

    Ask whoever did the assembly - even if just for the sake of your warranty
  4. Chesutiko

    Chesutiko Member

    Thank you, that makes sense.

    I'll have to check to see if the warranty still applies, it's taken me at least a few years between having the engine rebuilt and putting it back in the car.
  5. ivan129

    ivan129 Active Member

    Here's some ideas, not advice. I have run in many engines over the years from Holden Grey's to big banga small block chevs, a few ford V8's Toyota engines but no Nissans. A few things to look at:- I have always used a light weight mineral oil for break ins. Change after the first 2 - 500Ks. Check to make sure you have no oil leaks or coolant leaks. Make sure the engine holds good oil pressure at idle when hot. No noises or rattles that can't be explained. Make your valve clearance are to spec. Make sure the cooling system is working fine. Cook a new engine and you risk glazing the bores. The engine tune should be good too. Don't want to be driving a new engine if its go a miss or not performing as it should. Bedding the rings to the bores is the most important which can be done by driving the car at varying speeds and load. We used to have a favorite hilly trail we would drive up and down. Go racing after 500Ks, the engine should be run in.
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  6. MickW

    MickW Carntry member...

    What not to do - don't idle it for long periods while running it in.
    i.e. don't be letting it idle up from cold to operating temperature repeatedly, while you keep nervously double checking things before finally driving it.
    Apparently that can hinder the rings-to-cylinder bedding process in some cases.
    And revving it in the shed with no load doesn't count as " not idling it. "
    How many years did the rebuilt engine sit for mate? Have you had it running yet?
  7. MickW

    MickW Carntry member...

    I think that boat might have sailed Rob -
  8. Chesutiko

    Chesutiko Member

    It's been sitting for at least 4 years (I think?) since it was rebuilt. Due to living in Melbourne, with the car based in Mildura I've only been able to work on it in short spurts when taking annual leave to visit the family up that way. This is obviously far from ideal, as there's likely considerations to take into account with having the engine sitting around for so long..
  9. ivan129

    ivan129 Active Member

    If its been sitting there for that long, might be a good idea to remove the plugs squirt some upper cylinder lube in the bores and crank the engine over. See if you can raise oil pressure. Then if all the do's and don't check out fine. Start and drive. Most important is to get oil pressure, don't over heat or detonate when driving.
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  10. MickW

    MickW Carntry member...

    Was it properly wrapped and sealed, or just had a blanket draped over it?
    Mildura is normally dry and hot, with frequent periods of dryer and hotter. Not much humidity or frost to cause rust from condensation. Dust incursion would be the main worry.

    Another thing to look out for -
    Make sure you don't connect the hose from the windscreen washer reservoir to any of the vacuum ports on the manifold. It's been years since you pulled the engine out, you probably labeled those little black hoses really well but the labels might be faded or fallen off by now. Don't suck water from the windscreen washer bottle into your engine. Don't.
    Yep. First remove the fuel pump relay fuse, it's under the rectangular black cover near the brake booster. Wind the engine over until you see the oil pressure gauge start to move. Maybe 20 - 30 seconds, sometimes longer depending on the battery health. I saw cranking speeds around 250 - 270 RPM ( via EcuTalk ) @ 11.5 volts from a good battery.

    Good luck with it mate!
  11. beaver

    beaver southern zeds

    When its drivable, find some down hill runs, get up to the speed limit going down hill, then take your foot of the gas, let it decelerate down to 60k from 100k say, do that when ever you can during the break-in period . It helps bed the rings in.

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