Low compression on CA18DET

Thread in 'Technical Questions' started by Tomaphobia, Oct 14, 2019.

  1. Tomaphobia

    Tomaphobia Member

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    So, I know this question has been asked a lot but i'd rather have my own answers and be able to ask more as we go.

    So i'm pretty new to cars and decided to do a compression test.. The car felt a bit sluggish and had a little bit of smoke coming out the exhaust but other than that no other symptoms.

    Long story short all cylinders are 110-115 from cold and about 115-120 hot and i'm trying to find time to do a wet test.

    What's the best course of action from here? I'm pretty new to cars so I wouldn't really fancy rebuilding the engine myself and from what i've ready already its not worth it for a CA.

    I know everyone will say SR20 but i'm going to get into drifting and don't really want a great deal of power to start with.

    What would a best case scenario be? Should i just run the car until it goes bang then swap in another CA or an SR?
     
  2. r3k1355

    r3k1355 Well-Known Member

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    The engine was fully upto temp and you tested with the throttle wide open and a fully charged battery?

    What were the individual test results?
    If all cylinders are within about 10% of each other then you can happily run the engine, even down at 100psi it'll still run alrite(ish) as long as the cylinders are similar compression.

    The smoke is probably the turbo, alot are old and abit worn.
    A rebuild is only a few hundred quid so it's no great problem, depending on what type of smoke it is you could always try the one-way-valve trick to see if it stops it for a while.
     
  3. Tomaphobia

    Tomaphobia Member

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    i did a cold test first, and then a test when fully up to temp and yes throttle was wide open and yep fully charged battery.

    i can't remember the exact results but i think it was something like 110 110 115 110 ish (about the same in both hot and cold test)

    it had a new turbo not long before i bought it (apparently).. one of my friends who knows a lot about cars checked it over and picked up that the turbo was new! also isn't turbo smoke blue? the smoke coming out was white which could point towards a head gasket right?

    is that a fairly average price for a rebuild cause from what i've been reading it'll cost 800+ :cry: if i could get it done for a few hundred i'd happily get it done

    i've never heard of the one way valve trick? what is it?
     
  4. r3k1355

    r3k1355 Well-Known Member

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    Yea that sounds ok, do a wet test see if it's rings or not but it should still run ok.

    Can be white or blue, does it push out white smoke on idle but not on boost? Thats usually the turbo oil seals letting oil pass into the turbo elbow

    It helps turbo's with dodgy oil seals by creating a partial vacuum in the crankcase which holds the seals together abit better.
    You get the valves from brake servos and connecting pipework, most cars in a scrapyard should have one to use. Check the valve works by blowing into it, you should be able to blow through one direction but not in the other.

    https://www.sxoc.com/vbb/showthread.php?563942-One-Way-Valve-Trick&highlight=one+way+valve
     
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  5. Tomaphobia

    Tomaphobia Member

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    Yep, gonna do it on saturday but i have a push in tester im gonna try it with in case my cheap tester was leaking (fingers crossed this works but i don't have much hope)

    it's strange.. i have a video of the smoke but it's on my phone and i wouldn't know where to start uploading it on here lol but when i start the car up and rev it it'll smoke (cold) then i'll let it warm up in case its just condensation and the same happens, and when i'm not revving it a little bit of smoke comes out, but i took it for a drive the other day and when i was actually driving it there was no smoke at all?

    thanks mate, might have to try this.. would there be i be able to see a leak or would it be leaking to the floor? cause i've never seen anything leaking out
     
  6. r3k1355

    r3k1355 Well-Known Member

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    The seals are inside the turbo, you'd never see it leaking.
     
  7. Tomaphobia

    Tomaphobia Member

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    oh okay, could that be the cause of low compression?
     
  8. r3k1355

    r3k1355 Well-Known Member

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  9. pointz

    pointz Member

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    If those figures are that consistent and it's an eBay comp tester I'd suspect it's more the tester my mate bought one and had almost the exact same results you have!

    Get a decent tester like a gunson and test it
     
  10. Tomaphobia

    Tomaphobia Member

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    i got a clarke one from one of the boys at work and it has gave different results... i got 130,125,110,125 (ish)

    i think im just gonna run it until it blows up while trying to source a new engine, then maybe try rebuilding the old one myself and a few youtube videos haha or get someone who knows about rebuilds to sort it in their spare time and sell it on or put it back in
     

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