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Rb25 blown?

Prof_Finesser
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Prof_Finesser Enthusiast

Prof_Finesser

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Hello again I just got my rb25 tuned yesterday made 450 forged internals and semi built head I went on a beer run and let the car warm up before I got on it and I did a small pull and then about a minute later the engine shut off. I towed it back to the house and been tearing into it today. It’s odd I cant turn the engine by hand to the right (intake to exhaust side) it has some wiggle then it stops and won’t turn any more but I can turn it to the left no problem. I did a leak down and all cylinders were in good condition. I’m so lost at this point. I checked cams in case they snapped and they are all good too. I think I’m going to pull the head off tomorrow just to see what’s going on because I don’t understand.

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GTSBoy Grand Master

GTSBoy

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Well, it's too weird to be making any guesses. I'd have the plugs out and a borescope into the cylinders before doing anything else.

When you say

  On 26/08/2024 at 12:11 AM, Prof_Finesser said:

I can turn it to the left no problem

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Do you mean to say that you can turn it over continuously? Like, it's not seized or blocked from rotation outright? Only won't turn forwards? If so, would sound perhaps like something has dropped into the timing belt area or has otherwise arranged itself like a ratchet pawl, so that it prevents rotation one way, but not the other.

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Prof_Finesser Enthusiast

Prof_Finesser

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  On 26/08/2024 at 1:05 AM, GTSBoy said:

Well, it's too weird to be making any guesses. I'd have the plugs out and a borescope into the cylinders before doing anything else.

When you say

Do you mean to say that you can turn it over continuously? Like, it's not seized or blocked from rotation outright? Only won't turn forwards? If so, would sound perhaps like something has dropped into the timing belt area or has otherwise arranged itself like a ratchet pawl, so that it prevents rotation one way, but not the other.

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Yes and that’s what I think as well and yes the rotation is continuous 

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Prof_Finesser Enthusiast

Prof_Finesser

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  On 26/08/2024 at 2:25 AM, Dose Pipe Sutututu said:

Most likely won't hold pressure, however it is still possible if the valve isn't bent

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I just realized something I’m at TDC and my intake cam is at the timing mark the horizontal mark and my exhaust cam is at like 7-8 o’clock position not even close to the timing mark. I’ve timed these engines about 5 times now and always do it the same line up the 3 marks crank and two cam. How tf have my cam spun that far off. I’m gonna check all the timing system tomorrow 

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MBS206 Grand Master

MBS206

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  On 26/08/2024 at 2:33 AM, Prof_Finesser said:

I just realized something I’m at TDC and my intake cam is at the timing mark the horizontal mark and my exhaust cam is at like 7-8 o’clock position not even close to the timing mark. I’ve timed these engines about 5 times now and always do it the same line up the 3 marks crank and two cam. How tf have my cam spun that far off. I’m gonna check all the timing system tomorrow 

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Many possibilities, like cam gears coming free of the cam shaft and spinning.

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Prof_Finesser Enthusiast

Prof_Finesser

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So good news and bad head is off. Good news engine is turning again forwards continuously and pistons have very small mark on the top where valves hit it does catch a finger nail going to still ask machinist if it’s ok to run I think they will be ok.  On to the bad I took the exhaust cam off because the exhaust valves where the only on the pistons and it seems like my first cam cap (closest to timing gear) was eating into the camshaft and end up stopping it all the valves have the marks in picture. 
 

IMG_4302.jpeg

IMG_4303.jpeg

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