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On a previous 928, I had a coolant leak that would only appear after the engine cooled, and not while running. Would come home from a drive and inspect, nothing found, then the next morning, coolant in the valley. Something to consider.
An ultrasonic leak detector will also help. It can "hear" the air escaping from the leak source during the pressure test if you know you have a leak but can't visually see the source. The meter moves up and it beeps faster the closer you get to the leak source.
Mine came from amazon.
INFICON 711-202-G1 Whisper Ultrasonic Leak Detector
by Amazon.com
Learn more:
I don't think the clamp on the rear fitting is the problem. If it was, coolant would not only be in the valley, but would also fill that little crevice just outside the valley and that looks clear. The junction of that pipe with the plate or the plate sealing itself could be the source though.
An ultrasonic leak detector will also help. It can "hear" the air escaping from the leak source during the pressure test if you know you have a leak but can't visually see the source. The meter moves up and it beeps faster the closer you get to the leak source.
I don't think the clamp on the rear fitting is the problem. If it was, coolant would not only be in the valley, but would also fill that little crevice just outside the valley and that looks clear. The junction of that pipe with the plate or the plate sealing itself could be the source though.
VERY BAD NEWS : my engine block has a large crack .
Can it be successfully be repaired or it my engine block not salvable ?
VERY BAD NEWS : my engine block has a large crack .
Can it be successfully be repaired or it my engine block not salvable ?
Oh, no!
Aside from the crack where the coolant is emanating, there are some radial lines around that left top plug too, which look a little concerning to me. I don't know what's repairable from a block standpoint, but sorry to hear the bad news. How does a block crack unless frozen with regular water in it (the only thing I know of).
That crack is deeply troubling in that at face value [very sad to say] it "suggests" a structural failure of the engine.
As to whether a repair is even feasible requires an expert input [assuming there is such an expert] but given coolant is emanating from it at a major structural node suggests at the very least the crack has permeated through from the base of the water jacket and thus would have to be ground out in its entirety to prevent further propagation and structural recovery to the extent that is possible.
Given that freeze expansion would seem a logical root cause one wonders if other cracks are propagating and whether this was just the first obvious external sign of distress. Has the car any history of accident damage?
If a repair is feasible then I would expect a complete engine strip down will be required with extensive work required to prepare for welding [de-gassing?] then of course the big question would be viability of repair.
Wish I could be more optimistic for you but that is my "take" on what I see in front of me at the moment - for sure I hope I am wrong and that someone with greater knowledge can offer a more optimistic assessment.
That crack is deeply troubling in that at face value [very sad to say] it "suggests" a structural failure of the engine.
As to whether a repair is even feasible requires an expert input [assuming there is such an expert] but given coolant is emanating from it at a major structural node suggests at the very least the crack has permeated through from the base of the water jacket and thus would have to be ground out in its entirety to prevent further propagation and structural recovery to the extent that is possible.
Given that freeze expansion would seem a logical root cause one wonders if other cracks are propagating and whether this was just the first obvious external sign of distress. Has the car any history of accident damage?
If a repair is feasible then I would expect a complete engine strip down will be required with extensive work required to prepare for welding [de-gassing?] then of course the big question would be viability of repair.
Wish I could be more optimistic for you but that is my "take" on what I see in front of me at the moment - for sure I hope I am wrong and that someone with greater knowledge can offer a more optimistic assessment.
I found the exact area where coolant comes out. Apparently it is only at the bottom where thread is:
Given that freeze expansion would seem a logical root cause one wonders if other cracks are propagating and whether this was just the first obvious external sign of distress.
For ferrous hunks Magnaflux can be used to find cracks. I am not aware of anything like this for Aluminum hunks. After the last set of near-junk heads, I looked, asked folks who would know and came up dry.
As for fixing that crack: it can be fixed by someone with the skills and experience. Then I guess you pressure test and fix the next crack? Lather rinse repeat?
More cost effective to get a different cylinder block I would think.
That you can identify where the coolant is exiting from is one thing. To escape it has travelled along a "fault line" of an as yet indeterminate length/path. The water jacket itself operates at a maximum pressure of 15 psig and in practice something less than 10 psig depending on the coolant level inside the expansion vessel. Now with a crack from inside to outside chances are the block is not holding pressure- that is no problem in and of itself as the system invariably operates well below boiling point at atmospheric pressure. The wall thickness required to hold pressure at that level is next to noting but the actual wall thickness is probably in the region of at least 5mm or so which is reasonably substantial.
Now, given the leak path is at the base of the coolant chamber and you have identified several leak points in a string the question you have to realistically ask yourself is "what are the chances that crack is localised".
The photos you have posted and the inputs you have made quite reasonably suggest there is a crack line propagating along the base of the Vee. If the damage really is very localised one has to ask the question "what could possibly cause such?". If the leak path were corrosion generated would the pinholes form a line parallel to the base of the Vee?
For sure if the damage is localised a recovery type repair will be much more easy to implement. Perhaps the best thing you can do at the moment is to dye pen test the base of the Vee to verify whether there is an extended surface crack as suggested by the photos.
If all that is required is a "seal" on a localised crack all well and good.
For ferrous hunks Magnaflux can be used to find cracks. I am not aware of anything like this for Aluminum hunks. After the last set of near-junk heads, I looked, asked folks who would know and came up dry.
As for fixing that crack: it can be fixed by someone with the skills and experience. Then I guess you pressure test and fix the next crack? Lather rinse repeat?
More cost effective to get a different cylinder block I would think.
If it needs to be a numbers-matching car...
Dye pen examination will reveal the extent of cracks that have penetrated the surface but will not show what may be going on below the surface. For sure mag particle testing is a non starter.
If the problem is localised all well and good - if it only requires "sealing up" maybe a brazing type process could be used but I reckon the "rinse and repeat" scenario is the most likely outcome.
Dye pen examination will reveal the extent of cracks that have penetrated the surface but will not show what may be going on below the surface.
This is now the edge of my world. Speculation follows.
I would think that any big mass-produced casting will have surface cracks. Maybe not with Alusil? A dye test would reveal these hypothetical surface cracks but wouldn't indicate a 'through crack.' Possibly, doing 100% of the surface area and then lining up cracks on opposite sides of a surface by eye might identify possible 'through cracks.' Or, in other words, the procedure for locating cracks requiring repair is not clear to me.
One thing that is clear: paying somebody to fix the cylinder block is very likely to be in excess of the cost of a used cylinder block unless it's some sort of unicorn block.
This is now the edge of my world. Speculation follows.
I would think that any big mass-produced casting will have surface cracks. Maybe not with Alusil? A dye test would reveal these hypothetical surface cracks but wouldn't indicate a 'through crack.' Possibly, doing 100% of the surface area and then lining up cracks on opposite sides of a surface by eye might identify possible 'through cracks.' Or, in other words, the procedure for locating cracks requiring repair is not clear to me.
One thing that is clear: paying somebody to fix the cylinder block is very likely to be in excess of the cost of a used cylinder block unless it's some sort of unicorn block.
Anybody who can read a few simple instructions can carry out a dye pen test- the trick is knowing how to interpret the results and that takes experience/knowledge. Some surface cracks will probably be present but not in straight lines that mirror the contours of the motor.
For sure it is an interesting problem - not something we come across every day- hopefully we can collectively help Gerrit make good decisions to progress the issue.
sorry to see that cracked block,
I would speculate it was probably caused by an ice incident.
Since its the block thats cracked the hi silicon content may not be able to be welded to work
As an option if you have time and money put it back together and put a bottle of K seal in it see if the leak stops
My 88 had the block filled with water for two years lucky it didnt see a hard freeze it was down in NC.
This just destroyed the head gaskets and corroded the heads.
On the bright side you now have a cleaned up block ready for coffee table duty.
use the rest of your parts on a 5.0 block and make an engine with more HP
This would be a huge undertaking and it's not clear to me that the tooling and bath sizes required are available, but one of the things that we have to contend with at my work is trying to determine the presence and extent of this type of subsurface/non-visible damage. The surface stuff is relatively easy via dye penetration but, as pointed out above, tells you absolutely nothing about the the extent of propagation below what's visible.
A technique we've investigated is the use of ultrasonic void testing. The setup I'm familiar with is from Sonoscan (no affiliation, except as a service customer). The idea is to use sound waves to look for voids. It requires, however, that parts be immersed in a water bath. I don't know if there are hand held testing devices available.
I don't know how far you want to go with something like this to save your block, but there are definitely technologies out there for this kind of investigation. From a practical perspective, I think that Stan's advice is solid. Not that you asked but, should something catastrophic ever happen to my engine, I'd like to source and install a Cayenne V8. Keep it in the Porsche family, but end up with something unique. (I don't know if it's even possible, and is a wrenching level far beyond my current skill set, but I love the concept. I'm happy to experience it vicariously.)
My condolences about your findings. It's a huge bummer.
A technique we've investigated is the use of ultrasonic void testing. The setup I'm familiar with is from Sonoscan (no affiliation, except as a service customer). The idea is to use sound waves to look for voids. It requires, however, that parts be immersed in a water bath
Very interesting! How much do you know about the technology? (I'm full of questions, but don't want to pester you or this thread.)
It looks like it can be done with aluminum castings...
That you can identify where the coolant is exiting from is one thing. To escape it has travelled along a "fault line" of an as yet indeterminate length/path. The water jacket itself operates at a maximum pressure of 15 psig and in practice something less than 10 psig depending on the coolant level inside the expansion vessel. Now with a crack from inside to outside chances are the block is not holding pressure- that is no problem in and of itself as the system invariably operates well below boiling point at atmospheric pressure. The wall thickness required to hold pressure at that level is next to noting but the actual wall thickness is probably in the region of at least 5mm or so which is reasonably substantial.
Now, given the leak path is at the base of the coolant chamber and you have identified several leak points in a string the question you have to realistically ask yourself is "what are the chances that crack is localised".
The photos you have posted and the inputs you have made quite reasonably suggest there is a crack line propagating along the base of the Vee. If the damage really is very localised one has to ask the question "what could possibly cause such?". If the leak path were corrosion generated would the pinholes form a line parallel to the base of the Vee?
For sure if the damage is localised a recovery type repair will be much more easy to implement. Perhaps the best thing you can do at the moment is to dye pen test the base of the Vee to verify whether there is an extended surface crack as suggested by the photos.
If all that is required is a "seal" on a localised crack all well and good.
04-08-2020, 03:11 PM
