MautoK
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| posted on 7/6/09 at 04:50 PM |
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How to check for a cracked block/head?
Is this something that a local independent garage would be able to test for?
TIA,
John.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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omega0684
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| posted on 7/6/09 at 04:54 PM |
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getting a little extreme now john 
you could x-ray the block/head, but i don't think an independant garage could do that, lol
they would have to be some pretty big cracks in the head and block and when they do go they normally go in style
[Edited on 7/6/09 by omega0684]
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mistergrumpy
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| posted on 7/6/09 at 04:56 PM |
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I took mine to an engineers who deals with engines and he pressure checked it for me. They have to have the right equipment I believe and he hummed
and ahhed at first with mine because it is a bike engine but he did it right enough.
I don't think any garage would be able to do it.
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MautoK
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| posted on 7/6/09 at 04:58 PM |
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quote:
Originally posted by omega0684
x-ray the block
 ...off to A&E then!
Engine is in the car...
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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tegwin
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| posted on 7/6/09 at 05:01 PM |
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I believe the pros would use ultrasound, there is also a special chemical that will detect cracks and make them visible to the eye if they are on the
surface....
Alternativley... you could saw the block in half and see if there are any cracks internally?
------------------------------------------------------------------------------------------------------------------------
Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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MautoK
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| posted on 7/6/09 at 05:03 PM |
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There's a couple or three competent garages in town so I'll try them - trouble is I can't go any distance cos it boils after only a
few miles 
I was hoping that some kind of leakdown test in association with a compression test might give a positive indication or otherwise.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MakeEverything
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| posted on 7/6/09 at 05:08 PM |
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Near me, there is a company called "Power Units" in Hatfield. They would be able to tell me, but id need to send it to them.
Locost way of doing it, is to take the engine out, strip it and test it with a small hammer to see if it rings or not. If a casting is cracked in any
way (as with glass) it wont ring. It will "clonk" instead.
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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MautoK
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| posted on 7/6/09 at 05:08 PM |
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If the engine were stripped then dye-penetrant and a boroscope would probably show it.
Alternatively, hang up the block and whack it then fourier transform the 'ding' (or it falls apart)
Saw sounds good, but my welding isn't good enough to stick it back together again.
quote:
Originally posted by tegwin
I believe the pros would use ultrasound, there is also a special chemical that will detect cracks and make them visible to the eye if they are on the
surface....
Alternativley... you could saw the block in half and see if there are any cracks internally?
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MautoK
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| posted on 7/6/09 at 05:11 PM |
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Pity I can't send the block as a u2u attachment!
quote:
Originally posted by MakeEverything
Near me, there is a company called "Power Units" in Hatfield. They would be able to tell me, but id need to send it to them.
Locost way of doing it, is to take the engine out, strip it and test it with a small hammer to see if it rings or not. If a casting is cracked in any
way (as with glass) it wont ring. It will "clonk" instead.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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r1_pete
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| posted on 7/6/09 at 05:13 PM |
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Reading your previous thread about overheating, are you sure the thermostat is ok? I doubt a cracked head, or failed head gasket would cause
overheating at tickover as you describe. Be worth trying a new one, or even trying the motor without one, before going to extreme expense.
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MautoK
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| posted on 7/6/09 at 05:22 PM |
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Hi Pete,
It's a brand new 87 degC 'stat, replaced it when I had the head off recently.
John.
quote:
Originally posted by r1_pete
Reading your previous thread about overheating, are you sure the thermostat is ok? I doubt a cracked head, or failed head gasket would cause
overheating at tickover as you describe. Be worth trying a new one, or even trying the motor without one, before going to extreme expense.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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r1_pete
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| posted on 7/6/09 at 05:44 PM |
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I'd still test it in a pan of boiling water, I've known new ones not work, and cos they are new get discarded as a cause of the problem.
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britishtrident
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| posted on 7/6/09 at 06:05 PM |
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(1) Asssuming you have a by-pass hose fitted ---- this is essential and covered many many times in the forum
(2) Check the ignition is advancing -- your symptoms make me suspect the ignition is not advancing with rpm.
[Edited on 7/6/09 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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02GF74
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| posted on 7/6/09 at 06:47 PM |
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compression test on block when cold and when hot ... but that may not tell the full story.
there is a dye that changes colour on contact with combustion gases - £ 30 odd - Burton Power sell it. I suspect if you shop around, ebay? may get it
for less.
long time since I did chemistry but co2 - by product of combustion will disolve in water to make it acidic - so pH paper will tell you that - a
couple of quid at most.
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Ninehigh
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| posted on 7/6/09 at 06:55 PM |
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Wouldn't a crack have liquid leaking out of it (water/oil/petrol)? I mean if it's not leaking then if there is a crack it wouldn't
be big enough to cause a problem or am I going off at the wrong end again?
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MautoK
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| posted on 7/6/09 at 08:47 PM |
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quote:
Originally posted by r1_pete
I'd still test it in a pan of boiling water, I've known new ones not work, and cos they are new get discarded as a cause of the problem.
Yes I tested it before fitting the new stat.
quote:
Originally posted by britishtrident
(1) Asssuming you have a by-pass hose fitted ---- this is essential and covered many many times in the forum
(2) Check the ignition is advancing -- your symptoms make me suspect the ignition is not advancing with rpm.
[Edited on 7/6/09 by britishtrident]
1. Bypass is a three-way 8mm ID hose connecting
a. Bleed port of the Polo rad
b. Small port on the 'stat housing
c. 'Overflow' on the (std. Sierra) header tank.
2. Need to check this in the dark - couldn't see the mark in daylight.
quote:
Originally posted by 02GF74
compression test on block when cold and when hot ... but that may not tell the full story.
there is a dye that changes colour on contact with combustion gases - £ 30 odd - Burton Power sell it. I suspect if you shop around, ebay? may get it
for less.
long time since I did chemistry but co2 - by product of combustion will disolve in water to make it acidic - so pH paper will tell you that - a
couple of quid at most.
Yet to do a hot CT.
...and 40 years since I got my Chemistry A level  
Good thinking, but not sure that pH would be far enough up the scale to register convincingly with litmus.
quote:
Originally posted by Ninehigh
Wouldn't a crack have liquid leaking out of it (water/oil/petrol)? I mean if it's not leaking then if there is a crack it wouldn't
be big enough to cause a problem or am I going off at the wrong end again?
There's no leak to the outside and there's no oil in the water, no water in the oil. I'm thinking an internal leak between
combustion chamber and water jacket that makes its presence felt more as the engine warms up...?
Thanks for all your constructive comments, guys.
Let you know how I progress.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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02GF74
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| posted on 8/6/09 at 07:14 AM |
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quote:
Originally posted by Ninehigh
Wouldn't a crack have liquid leaking out of it (water/oil/petrol)? I mean if it's not leaking then if there is a crack it wouldn't
be big enough to cause a problem or am I going off at the wrong end again?
not necessarily - the problem may occur when engine is warmed up i.e. metal has epxanded and under high pressure i.e. combustion cycle - the latter
pressures you are unlikley to achive when turning over on the starter motor.
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