Jump to content
SAU Community

Help Needed To Diagnose Problem

=premo=

By =premo=,
in Engines & Forced Induction

 Share

Recommended Posts

=premo= Mentor

=premo=

Posted
Posted

I've just finished rebuilding an engine for track use after it had spun a bearing. Started it up and it sounds rough, shakes a bit (although it was on car stands so might not be an issue when its on wheels) and start's popping out the exhaust at 2000rpm so I turned it off straight away and went shopping for explosives to blow it up (getting sick of it).

I used a backing plate to setup the timing belt but its not actually on the engine. When I used the backing plate I held it up to the cam gears so I could see the marks from the back of the engine and lined up the tooth on the cam gear to the mark then looked from the front of the engine to make sure it was the right tooth that I had just lined up. I checked it at least three times to make sure the marked tooth was at the right spot. The only thing I can think of is that the marks on the backing plate are not symmetrical so when I've flipped the plate horizontally so I could see the marks against the cam gears its given a different result... Although the backing plate does look symmetrical.

Any suggestions on how I can diagnose the problem or work out which gear needs to go which way?

I still have 10 degrees of adjustment either direction on the cam gears that I haven't used so I might not need to pull it apart to fix the problem if I can work out exactly what the problem is. Its also possible that timing isn't the problem at all but its the only thing I can think of that could have stuffed up. If it wasn't for the popping I'd think there was nothing wrong and its just a bit rough.

Any good help is much appreciated.

Link to comment
https://www.sau.com.au/forums/topic/259085-help-needed-to-diagnose-problem/
Share on other sites
blind_elk Grand Master

blind_elk

Posted
Posted

Why aren't you running the backing plate? What could be so important that you would risk the valve timing being off and a valve punching a hole through your brand new pistons?

Use the backing plate - it's there for a reason.

=premo= Mentor

=premo=

Posted
  • Author
Posted

Put the backing plate on and realized that the cam timing is out a tooth on both gears because of the tensioner's. Because its an RB30 I have two tensioner's and when I've done them up its pulled the cam's around almost a full tooth. The down side is that wasn't the problem. I checked the compression to make sure no bent valves and all is good but when I started it up again it was doing the same thing. Pulled off coil pack plugs 1,2 and 4 and no difference, the fkn thing is running on 3 cylinders. All the spark plugs are black as fk and its blowing heaps of fuel and black smoke out the exhaust. The popping at 2000rpm is still there.

I'm currently running RB20det coil packs even though its a RB26 head and engine loom, are RB20 coil packs different to RB26 coil pack's and could this be causing the problem or is it more likely to be a tuning problem?

Thanks,

Daniel

blind_elk Grand Master

blind_elk

Posted
Posted

First thing to do is move coils in 1, 2 & 4 to 3, 5 & 6, see how it runs. If the coils in 1/2/4 aren't firing, then it's the igniter or loom, or maybe spark plugs; if 3/5/6, then it's the coils.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • George.
      R34 GTT AC short cycling ? Normal behaviour?

      By George. · Posted

      Hey guys, Just want some advice on r34 GTT ac system. Since I’ve owned it, the ac compressor, doesn’t matter the set temperature or ambient temperature, runs for around 10 seconds then disengages the clutch, then re-engages everywhere 30 seconds or so and keeps repeating this.    is this normal?   I had it recharged today as it was slightly low and thought it would fix it but still does it. it cools fine in summer even prior to the recharge, except for the usual warmup when stopped or in traffic (still yet to wire overheat fan to on with ac)   any thoughts would be much appreciated 
    • GTSBoy
      Factory oil temp sensor in a RS4V without gauges?

      By GTSBoy · Posted

      To plug the hole. The engine plant may not have known whether the car it was going into had a gauge or not. It was a long time ago and the integrations might not have been fully modern. Or they might not have cared because the extra inventory and processes to save a few cents on the sender might have cost more anyway. But please tell me you are not still confusing the idea of a pressure gauge sender, and an oil pressure light switch. The switch will be out there. In a separate hole. Probably with only one wire running to it. Running the light.
    • GTSBoy
      Is there a good place to learn how an engine works online?

      By GTSBoy · Posted

      Blower needs to go low on the exhaust side, displacing the AC and PS, which you have to decide whether you want to keep and how and where to relocate if you do. Electric option for PS is, at least, helpful. Sadly, there is no workable 12V electric AC of any value. Whilst the blower is the last compression step before the throttle, and so it might seem a good idea to have it near the inlet manifold (as mentioned above), you probably want it to go through an intercooler first, so, having it on the opposite side of the car facilitates that air flow path. The turbo discharges into the blower, so proximity of the turbo's compressor outlet to the blower's inlet is nice. But then you might want to intercool that too, before boosting it again....which would probably be a ball ache. Routing pipes out to the front and back could be a bit shit. If there was room for (at least) a small (but preferably larger) water to air core on that side, then that would probably be the best approach. I guess a reasonable alternative would be to locate the blower where the alternator is (more or less, associated with the inlet manifold, per Matt's thought), and somehow incorporate a water to air core into the manifold, sort of like they do for modern blown V8s. The big difference here though is that those V8s have only the one throttle (upstream the blower) and only the one compression step (the blower) and no need for too much in the way of bypass/blowoff valves. Whereas in a twin charged 6, you do need to think about one or two bypass valves associated with the 2 compressors and you would prefer to have the intercooling done before the air has to pass through the throttle. You'd like the throttle to work approx the same no matter what the compression is doing. But if it is located in hot air stream before a cooler, then sometimes the air will be real hot, sometimes it will be quite cool, and the throttle mapping/response will be quite different between those two cases. The throttle, if sized for hot air, would be too large for cold conditions. It's all a ball ache.
    • MBS206
      Is there a good place to learn how an engine works online?

      By MBS206 · Posted

      Package SC on exhaust side. Remote mount turbo. Still a fair bit of room when you get creative on the inlet side of the motor too. Especially if you can get really creative with the welding, and effectively build it into the bottom of the inlet manifold. Would definitely take some design work, and some trial and error, to make sure flow works well still! Might be easier to just start with the Nissan March though... All the work is already done for you...
    • Chi-Town
      C34 RSFour V Build in the US

      By Chi-Town · Posted

      I'll sit down and get a post together 😁
×
×
  • Create New...