Miguel Posted June 24, 2005 Share Posted June 24, 2005 There's a manual source on MKiV or bung me an email addy and ill see if i can PDF you the guide. Lets just hope you see none of this when you take it off Quote Link to comment Share on other sites More sharing options...
Kopite Posted June 24, 2005 Share Posted June 24, 2005 sorry to hear that mate! car's are nice when they work, worse than a mother-in-law when they decide to break hope you get it sorted mate, and hope it doesn't dent your wallet too much Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 24, 2005 Share Posted June 24, 2005 I'm sorry to say that i think you should get a short motor ordered up now... I'll put a fiver on detonation causing this, for what reason I don't know, but it needs to be traced so it doesn't happen again. Quote Link to comment Share on other sites More sharing options...
Gordon F Posted June 24, 2005 Share Posted June 24, 2005 Sorry to hear of your problems Jake Before you start ripping it apart, it may be worth getting someone to borescope it. It will give you a good idea of any damage without having a million pieces lying around your garage. Hope you get it sorted soon (and you CJ) Quote Link to comment Share on other sites More sharing options...
Jake Posted June 24, 2005 Author Share Posted June 24, 2005 Before you start ripping it apart, it may be worth getting someone to borescope it. I was thinking about that Gordon. If an endoscope can confirm that there is piston/bore damage (and there very likely is) the engine will have to come out so there's no point me struggling to get the head off in situ. How do I find someone with an endoscope who can come to me? I could look up "Endoscopy" in the yellow pages but I don't think I'll have much luck there. Quote Link to comment Share on other sites More sharing options...
Gordon F Posted June 24, 2005 Share Posted June 24, 2005 You should also be able to have a good look around the head as well Quote Link to comment Share on other sites More sharing options...
b_have Posted June 24, 2005 Share Posted June 24, 2005 I would say without a doubt pull the engine. I have found it way quicker to get to short block with it out (and more knuckle skin left intact!) With those compression readings and plug condition, you will almost certainly have major piston/valve damage. Feel for you mate. Quote Link to comment Share on other sites More sharing options...
BigRoy Posted June 24, 2005 Share Posted June 24, 2005 Couldnt a BHG cause 000 compression on a JZ engine? It did on an old RS2000 I had, and on 2 cylinders! Sad to hear this Jake:( Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 25, 2005 Share Posted June 25, 2005 ... If an endoscope can confirm that there is piston/bore damage (and there very likely is) the engine will have to come out so there's no point me struggling to get the head off in situ.. A leakdown test can also confirm if the block has to come out. Not too hard to do, provided that you have an air compressor and the gizmo (you can DIY it or get one from the internet, less than £80 if you look around). You can still turn the engine by hand right? Quote Link to comment Share on other sites More sharing options...
Jake Posted June 25, 2005 Author Share Posted June 25, 2005 A leakdown test can also confirm if the block has to come out. Not too hard to do, provided that you have an air compressor and the gizmo (you can DIY it or get one from the internet, less than £80 if you look around). You can still turn the engine by hand right? Correct me if I'm wrong but a leakdown test would fail if a valve was damaged/leaking, wouldn't it? I did look into how to do a leakdown test but it mentioned using 70bar pressure (seventy bar! Sod that) I do have a compressor but not a 70 bar one, who does! Where can I get this gizmo you mention? Yes, the engine turns over fine. Anyway, I did a compression test and cylinder #2 showed 0 psi. What more would a leakdown test tell me? Thanks Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 25, 2005 Share Posted June 25, 2005 Correct me if I'm wrong but a leakdown test would fail if a valve was damaged/leaking, wouldn't it? What do you mean by 'fail'? A leaky valve would have air rushing through it and you'd know immediately mate. You'd even know if it's an intake or exh valve of that cylinder. I did look into how to do a leakdown test but it mentioned using 70bar pressure (seventy bar! Sod that) I do have a compressor but not a 70 bar one, who does! Nobody, 100psi is the norm for leakdown tests. If your compressor outputs 100psi and the cylinder can only hold 90psi, then we say that you've got 10% leak. You don't even care about that, you just want to see where the air goes Where can I get this gizmo you mention? I had found one for £60odd a few months ago ("Lawson HIS" I think was the internet shop, not sure though) You could even make one yourself, I've got a guide on my website. I made one for less than £20 Yes, the engine turns over fine. You need to turn the engine bit by bit until each cylinder is at TDC (of compression). Then you pressurise that cylinder. You may need someone to hold the rachet though, as the piston might want to move downwards turning the engine. Anyway, I did a compression test and cylinder #2 showed 0 psi. What more would a leakdown test tell me? It would tell you WHY if you get bubbles in the coolant, you know if you get air from the sump, you also know hissing from the intake or exhaust --- you also know Quote Link to comment Share on other sites More sharing options...
Jake Posted June 27, 2005 Author Share Posted June 27, 2005 What do you mean by 'fail'? A leaky valve would have air rushing through it and you'd know immediately mate. You'd even know if it's an intake or exh valve of that cylinder. Nobody, 100psi is the norm for leakdown tests. If your compressor outputs 100psi and the cylinder can only hold 90psi, then we say that you've got 10% leak. You don't even care about that, you just want to see where the air goes I don't understand how I could tell *where* the escaping air is going. Isn't a leakdown test not just pressurizing the cylinder and seeing how quickly the pressure drops? How can I tell if it's leaking past a valve or a hole in the piston or whatever? Please explain. Quote Link to comment Share on other sites More sharing options...
Jake Posted June 27, 2005 Author Share Posted June 27, 2005 I borrowed an endoscope today. The two pistons with the dodgy compression appear to be intact although the one with no compression at all has two marks in the top of it. I've seen a lot worse though. Quote Link to comment Share on other sites More sharing options...
Ian C Posted June 27, 2005 Share Posted June 27, 2005 Would I be right in thinking an exploratory probe with a telescopic magnet would be an idea? If it brings out bits of piston you know you are in trouble. If it's the HG it's a head off job, if it's pistons you still need the head off, I'd crack on with taking it off It's the only way you'll know for sure. When mine let go all those years ago, the tops of the pistons looked OK but the edges had eroded away like a lollipop, might not be visible from a borescope exam. Also, my hybrids survived 100% intact, so all is not yet lost on the tubbie front. I guess you'll be taking them off to get at the head anyway, so that's Shit Job No1 on the MkIV you'll soon have under your belt. I'd start putting WD40 on the manifold bolts now Drop me a line if you want to chat about this offline mate. -Ian Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 27, 2005 Share Posted June 27, 2005 A leakdown test will show where the compression is escaping, if it's a bad leak by being audible down the exhaust if it's an exhaust valve seat problem, out the intake with the throttle wedged open if it's an intake valve leak, and up the dipstick tube or crankacase breather if it's ring or piston failure. Simple Quote Link to comment Share on other sites More sharing options...
Jake Posted June 27, 2005 Author Share Posted June 27, 2005 Would I be right in thinking an exploratory probe with a telescopic magnet would be an idea? If it brings out bits of piston you know you are in trouble. Pistons aren't made of ferrous meterial though.... are they? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 27, 2005 Share Posted June 27, 2005 Would I be right in thinking an exploratory probe with a telescopic magnet would be an idea? If it brings out bits of piston you know you are in trouble. If it's the HG it's a head off job, if it's pistons you still need the head off, I'd crack on with taking it off It's the only way you'll know for sure. When mine let go all those years ago, the tops of the pistons looked OK but the edges had eroded away like a lollipop, might not be visible from a borescope exam. Also, my hybrids survived 100% intact, so all is not yet lost on the tubbie front. I guess you'll be taking them off to get at the head anyway, so that's Shit Job No1 on the MkIV you'll soon have under your belt. I'd start putting WD40 on the manifold bolts now Drop me a line if you want to chat about this offline mate. -Ian He really will be in trouble if he's using magnetic pistons! Cast iron ones? Hewn from steel billet? Quote Link to comment Share on other sites More sharing options...
Nic Posted June 27, 2005 Share Posted June 27, 2005 Ian, your coats hung up over there mate Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 27, 2005 Share Posted June 27, 2005 Yeah, that's what I thought. Magnet for aluminum parts, WTF!? It's bad enough that many valves aren't magnetic, let alone alloys... Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 27, 2005 Share Posted June 27, 2005 A leakdown test will show where the compression is escaping, if it's a bad leak by being audible down the exhaust if it's an exhaust valve seat problem, out the intake with the throttle wedged open if it's an intake valve leak, and up the dipstick tube or crankacase breather if it's ring or piston failure. Simple yep, I thought it would be obvious enough Jake. You see bubbles up the coolant tank, or hissing from the sump or the intake or the exhaust. You get a pretty good idea what doesn't seal Quote Link to comment Share on other sites More sharing options...
Ian C Posted June 27, 2005 Share Posted June 27, 2005 He really will be in trouble if he's using magnetic pistons! Cast iron ones? Hewn from steel billet? Haha I had no idea if the stuff was magnetic or not, metallurgy isn't my bag That's why I said "would I be right..." Personally I'd have tried it and gone "hmmm, guess they aren't magnetic then". I refuse to feel foolish as I've learnt something new -Ian Quote Link to comment Share on other sites More sharing options...
LeeT Posted June 27, 2005 Share Posted June 27, 2005 gutted to hear about this jake. hope everything gets sorted at minimal cost for you. Quote Link to comment Share on other sites More sharing options...
SkyJawa Posted June 27, 2005 Share Posted June 27, 2005 Just seen this - bummer Jake Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 28, 2005 Share Posted June 28, 2005 ... I refuse to feel foolish as I've learnt something new -Ian Quite right, if we wanted to look and feel foolish they we'd have joined a comedy club, I guess. I see this as a meeting place where we exchange information and learn from each other. The only foolish thing for someone would be to avoid asking and make the wrong assumptions later. Quote Link to comment Share on other sites More sharing options...
TLicense Posted June 28, 2005 Share Posted June 28, 2005 Mig and I once had a half drunken conversation about using the head as an electromagnet and using it to create a force on the pistons.... we were chatting about it for quite a while I seem to remember, but unfortunately was lashed so can't remember much of what we were saying. As for aluminium, Everything is magnetic to some degree - even people! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.