Coolant leak. Root cause??
04-10-2020, 04:50 PM
#31
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Thread Starter
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. 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.
Unfortunately these type of engine are becoming rather scarce in Europe. Lots of 4.5L engines but not the 4.7L S-engine....And when you find one, they always have 1 or 2 cilinders damaged...
But I never give up. I searched for about 2 years for this engine. Now my search starts again if I cannot repair this damage.
04-10-2020, 05:10 PM
#32
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Thread Starter
Could JB Weld be a solution to close the crack ? I heared some good feedback from people that used it....but can it also be used on our big V8 block ?
04-10-2020, 05:19 PM
#33
Rennlist Member
Funny you should ask about JB Weld. One of the machinists that I work with tells a story about a cracked block that he fixed with that material. According to him, the car ran for 2 years after that fix, up until he sold it. My impression from talking to him was that it was in a much more dangerous/precarious place than what you're describing.
It's a single point of anecdata but I don't think you have much to lose.
It's a single point of anecdata but I don't think you have much to lose.
04-10-2020, 05:28 PM
#34
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Thread Starter
Funny you should ask about JB Weld. One of the machinists that I work with tells a story about a cracked block that he fixed with that material. According to him, the car ran for 2 years after that fix, up until he sold it. My impression from talking to him was that it was in a much more dangerous/precarious place than what you're describing.
It's a single point of anecdata but I don't think you have much to lose.
It's a single point of anecdata but I don't think you have much to lose.
And since maximum pressure of coolant is 15 PSI, there is not much pressure on the crack itself.
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Zirconocene (04-10-2020)
04-10-2020, 07:48 PM
#37
Advanced
JB Weld will do the job. Clean the surface and abraid with a bit of coarse aluminium oxide paper. Degrease the area then apply the JB weld. Apply a bit of heat with a hot air gun till the JB weld goes a bit runny. Devcon will do the job too but is more expensive. The lugs for the air compressor on my car are held on with Devcon and after 22 years is holding up well.
04-10-2020, 08:03 PM
#38
Pro
Depending on your climate and driving habits, you may get by with a lower pressure coolant cap after the fix. It could help prevent the JB Weld from blowing out of the crack. In my younger and poorer student days, I drove several years with no radiator cap due to radiator damage. Car never overheated so long as I topped up weekly. I think I used heavy duty aluminum foil with a pinhole in it to close the cap opening and held it on with a worm clamp on the radiator neck. Not the longtime answer for you but it does show that you don't have to fully pressurize the system to achieve a reasonable level of cooling.
04-10-2020, 08:19 PM
#39
Hmm. With all due respect to epoxy welding technology, etc...
Please consider simply replacing the block if possible..
I decided to replace my damaged 4.7 L block with a 5.0 L block.
I am concerned that the defect may end up being far more extensive,
and you may only be seeing the first part of that failure mode.
Best of luck !
Please consider simply replacing the block if possible..
I decided to replace my damaged 4.7 L block with a 5.0 L block.
I am concerned that the defect may end up being far more extensive,
and you may only be seeing the first part of that failure mode.
Best of luck !
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Shark2626 (04-10-2020)
04-10-2020, 09:05 PM
#40
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Thread Starter
JB Weld will do the job. Clean the surface and abraid with a bit of coarse aluminium oxide paper. Degrease the area then apply the JB weld. Apply a bit of heat with a hot air gun till the JB weld goes a bit runny. Devcon will do the job too but is more expensive. The lugs for the air compressor on my car are held on with Devcon and after 22 years is holding up well.
Would it be better to pre-heat the surface before applying JB Weld?
04-10-2020, 09:12 PM
#41
04-11-2020, 02:25 AM
#42
Advanced
The secret to success is getting the aluminium dead clean. It needs to be as clean as if you were going to tig weld.
04-11-2020, 07:15 AM
#43
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04-11-2020, 07:18 AM
#44
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And what about https://www.xtrack.nl/en/devcon-f-10...putty-500-gram ?
Could this be a solution ?
Could this be a solution ?
The problem you are facing is knowing what the extent of the damage is and thus how far to take any attempted repair. That there is a leak path is one thing but it is quite possible [more likely highly probable] that the crack line is not passing coolant along its entirety. If I were to attempt a repair using epoxy it may be prudent to open up the crack line a bit using a dremel bit and then scour the surface of the Vee for at least half and inch either side of the crack line. Degreasing thoroughly is essential as is ensuring the surfaces the stuff is applied to are not wetted so the coolant needs to be drained. I would use a hot air gun to help dry the surfaces out and carb cleaner to degrease them. As to how much to use I would be looking to apply a layer about 6mm thick. Allow plenty of distance from where you think the crack ends. If it still weeps after that you can always rework it- nothing lost and everything to gain but do not be too surprised if it does not work . Just remember once you go down this path silver soldering and welding options are probably off the table later on.
04-11-2020, 08:35 AM
#45
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The Devcon material is a professional grade repair compound similar to the stuff we used on damaged pump casings- an epoxy called Belzona- truly excellent stuff. The JB weld gets good reviews but have no access to it over here but use similar quality products from the likes of Bison.
The problem you are facing is knowing what the extent of the damage is and thus how far to take any attempted repair. That there is a leak path is one thing but it is quite possible [more likely highly probable] that the crack line is not passing coolant along its entirety. If I were to attempt a repair using epoxy it may be prudent to open up the crack line a bit using a dremel bit and then scour the surface of the Vee for at least half and inch either side of the crack line. Degreasing thoroughly is essential as is ensuring the surfaces the stuff is applied to are not wetted so the coolant needs to be drained. I would use a hot air gun to help dry the surfaces out and carb cleaner to degrease them. As to how much to use I would be looking to apply a layer about 6mm thick. Allow plenty of distance from where you think the crack ends. If it still weeps after that you can always rework it- nothing lost and everything to gain but do not be too surprised if it does not work . Just remember once you go down this path silver soldering and welding options are probably off the table later on.
The problem you are facing is knowing what the extent of the damage is and thus how far to take any attempted repair. That there is a leak path is one thing but it is quite possible [more likely highly probable] that the crack line is not passing coolant along its entirety. If I were to attempt a repair using epoxy it may be prudent to open up the crack line a bit using a dremel bit and then scour the surface of the Vee for at least half and inch either side of the crack line. Degreasing thoroughly is essential as is ensuring the surfaces the stuff is applied to are not wetted so the coolant needs to be drained. I would use a hot air gun to help dry the surfaces out and carb cleaner to degrease them. As to how much to use I would be looking to apply a layer about 6mm thick. Allow plenty of distance from where you think the crack ends. If it still weeps after that you can always rework it- nothing lost and everything to gain but do not be too surprised if it does not work . Just remember once you go down this path silver soldering and welding options are probably off the table later on.