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  1. #1
    Join Date
    Oct 2020
    Location
    Kent
    Posts
    36

    RV8 SD1 3.5 engine not starting.

    Hi all,

    Apologies in advance for the long message.

    I'm have a problem with starting my car the engine tries to turn over but does not start.

    Bit of background, the car has been running and drove.


    A few weekends ago I drove it a couple of hundred meters, and it over heated. But did idle ok before overheating.

    I turned the car off immediately.

    I considered that there was an airlock. So we went about bleeding the air out started the car again after it cooled, I topped up the expansion tank with coolant, and it was spewing out like a volcano.

    I was happy with getting rid of air pockets.

    I turned the car off after a while, the engine did take a fair bit of coolant in.

    This is where I'm at a loss, after turning the car off after bleeding the air pockets, the car will not start.

    It tries to turnover but will not fire.

    Things I have done and noticed:

    Noticed- exhausts at times has very loud bangs coming from them, not all the time but when they do sounds so loud.

    Noticed- There is pressure coming out from the carb too.

    Done- changed the ignition coil as the engine bay area got wet. Which has made no change.

    Done - compression test today and the lowest was 123psi from cylinder 1 and highest was 155psi from cylinder 4.

    The rest were between 125-145.

    To be honest, not sure what this means in terms of if this sheds some light on the problem. Although it was running and ok, ever since bleeding the air lock it has not started.

    I've checked, the car has fuel coming in. Spark and compression.

    I did test the spark, on the old coil was firing intermittent but I've replaced the coil.

    I'm at an absolute end of what's happened, if anyone has got to this point, I appreciate it and if you have some ideas then I'm all ears

    Thanks again.

  2. #2
    Join Date
    May 2004
    Location
    Finchampstead, Berkshire, UK.
    Age
    55
    Posts
    3,816
    Most likely culprit would be the timing (overheating and pops/bangs/blowback suggests it’s off) - have you got a strobe light to test where it is set?

    Rgds

    Jim
    GD Mk3 Jag based
    Supercharged LS1
    GD J1M

  3. #3
    Join Date
    May 2016
    Location
    Hockley ,Essex
    Age
    58
    Posts
    382
    I don't now the state of your engine with regards to camshaft, gears and possibly hydraulic lifters.
    If your cam gears are the nylon type with a lot of mile, they could have slipped/shredded causing
    incorrect valve timing.
    Your compression figures are not the highest but are within ten percent which is ok .
    The RV8 is not a high compression unit unless it has been modified a bit .
    You will need to check compression both wet and dry to give you more idea as to what
    is going on.
    Regards
    Chris.

  4. #4
    Join Date
    Oct 2020
    Location
    Kent
    Posts
    36
    Thanks for the advice Jim.

    I don't have one, but I will look to get one.

    With regards to the timing, if the car was running, could the timing still have been off?

    Sorry for the silly question

    Cheers
    Aaron

  5. #5
    Join Date
    May 2016
    Location
    Hockley ,Essex
    Age
    58
    Posts
    382
    If you haven't got a timing light, you can do perform a static check to
    give you a basic idea .
    chris.

  6. #6
    Join Date
    Apr 2014
    Location
    Stourport on Severn
    Age
    63
    Posts
    293
    Maybe daft question but how are you checking the spark? With a plug out, earthed will prove it.
    You say you have compression, fuel and a spark so theory goes it should run provided the timing is somewhere near.
    As others have said, your popping symptoms would point to timing so needs checking.
    Double check your plug leads haven’t got crossed over.

    Back to the initial overheat - just trying to understand the engine history, aside from the popping, was the car running ok previously and how long have you had it? Does it use much water?
    Cheers
    Steve

    My missus asked me to build her a Cobra! – How good is that!

    AK Gen2 chassis arrived 12/2/15 IVA Passed 2/7/18 on road 29/7/18
    http://stevesakcobrabuild.blogspot.com

  7. #7
    Join Date
    Oct 2020
    Location
    Kent
    Posts
    36
    Thanks Chris and Steve,

    I'll look to a static check for now as I don't have one.

    I have checked the spark by earthing and checking.

    To be honest, I have not touched the distributor in terms of moving it apart from taking the cap off.

    I've checked the leads and all is in the right place.

    Yeah the car was running ok, I've had it about 6 months and have been working on it for IVA so not on the road.

    I haven't started it all that often as I've been building it up, but when it started, it was running ok.

    The only thing I have done after the overheat was bleed the air pockets and turn it off, since then no joy at all.

    Cheers
    Aaron

  8. #8
    Join Date
    May 2016
    Location
    Cheshire
    Age
    52
    Posts
    397
    Check that the bolt on the clamp securing the dizzy to the timing cover isn't loose; if it is then the dizzy could have shifted slightly. Also, check the choke is operating correctly; when my 3.5 with SU carbs is cold it won't even attempt to fire if the choke isn't on.

  9. #9
    Join Date
    May 2016
    Location
    Hockley ,Essex
    Age
    58
    Posts
    382
    Quote Originally Posted by skinnymathew View Post
    Check that the bolt on the clamp securing the dizzy to the timing cover isn't loose; if it is then the dizzy could have shifted slightly. Also, check the choke is operating correctly; when my 3.5 with SU carbs is cold it won't even attempt to fire if the choke isn't on.
    That's a good point with regards to the distributed clamp bolt, as for choke failure, if it's a Holley like
    mine I removed the choke plate a long time ago and starts fine even when proper cold.
    Chris.

  10. #10
    Join Date
    Oct 2020
    Location
    Kent
    Posts
    36
    Thanks All,

    I've done a static set and pointed the rotor arm toward cylinder 1.

    Tried to start it, and still won't go the bolt clamp is tight.

    There is still popping and bangs coming from the carb and exhausts.

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