'89 Heads Look Bad- Maybe Too Bad
11-30-2015, 03:01 PM
#31
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Thread Starter
Regardless, I am going to have it fixed correctly. I want to do it right the first time, so that It "should" last my lifetime at least. LOL. Big issue is STILL trying to find someone local to do the required repairs. There ought to be someone given the proliferation of aluminum heads/blocks on modern vehicles, as well as the amount of circle track and drag cars in the area. Still searching.......
11-30-2015, 04:15 PM
#32
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I'm not saying this is the case, but it may be a case of galvanic corrosion. Like materials can have unlike galvanic numbers. My experience being with passivated and non passivated stainless steels. When connected in the same electrolyte the non passivated would become anodic and corrode. I have also seen where iron contamination of stainless steel caused spot corrosion that created an anodic cell that continued to corrode, long after the iron had corroded away.
If the corrosion causes a change in the metal around the corrosion, highly possible with alloys, and this change results in a change in galvanic order, again highly possible with a change in metal, and, most importantly, the coolant has passed its best buy date and become an electrolyte it is likely that the corrosion would occur first at the site of the previous corrosion.
After writing this the first question that comes to mind is it possible for some isolated pockets of coolant, say in a previous pit, that have a fair bit of surface area, and no real circulation, to deteriorate faster than the bulk of the coolant, allowing the corrosion to start again at the pit more quickly.
For sure regular changes with quality antifreeze are a good thing that should reduce corrosion regardless of the situation.
Interestingly the act of bead blasting could change galvanic order as well, for the better or the worse I don't knoe.
If the corrosion causes a change in the metal around the corrosion, highly possible with alloys, and this change results in a change in galvanic order, again highly possible with a change in metal, and, most importantly, the coolant has passed its best buy date and become an electrolyte it is likely that the corrosion would occur first at the site of the previous corrosion.
After writing this the first question that comes to mind is it possible for some isolated pockets of coolant, say in a previous pit, that have a fair bit of surface area, and no real circulation, to deteriorate faster than the bulk of the coolant, allowing the corrosion to start again at the pit more quickly.
For sure regular changes with quality antifreeze are a good thing that should reduce corrosion regardless of the situation.
Interestingly the act of bead blasting could change galvanic order as well, for the better or the worse I don't knoe.
Last edited by wpgshark; 11-30-2015 at 04:17 PM. Reason: typo
11-30-2015, 05:04 PM
#33
Captain Obvious
Super User
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Any decent automotive machine shop can skim the heads. No need to over think this. These are standard DOHC aluminium heads that are used and repaired everywhere.
12-01-2015, 12:43 PM
#34
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Thread Starter
Yes, but the grinding, welding, and then a skim coat are the problem areas. Not to mention the 3 main automotive machine shops in the area have BAD reps from some of the local clubs. BMW group especially.
12-01-2015, 12:53 PM
#35
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Get some plywood and 2x2 wood and build a nice sturdy box to hold the two heads with a piece of plywood separating the two. stuff it with cardboard and screw on the lid. Insure for $2,000 and ship them to Greg.....
Proceed with all the other tasks your car might need ......
Proceed with all the other tasks your car might need ......
12-01-2015, 01:07 PM
#36
Rennlist Member
Thread Starter
Get some plywood and 2x2 wood and build a nice sturdy box to hold the two heads with a piece of plywood separating the two. stuff it with cardboard and screw on the lid. Insure for $2,000 and ship them to Greg.....
Proceed with all the other tasks your car might need ......
Proceed with all the other tasks your car might need ......
12-01-2015, 01:19 PM
#37
Chronic Tool Dropper
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Chris-
The effort expended to get all your pictures and posts up here is 0.8813 x the effort needed to box and ship the heads to Greg. There are a few sad stories about heads packed improperly that were damaged in shipment, so heed Jim Bailey's advice on packing them well. He's seen more than three sets of heads packed and shipped safely.
In my experience, shipping heads deserves a piece of plywood sandwiched between the faces of the heads, bigger than the face of the heads by a few inches on each side, with lengths of all-thread holding the sandwich together through the head bolt holes, with washers and lockwashers. Do that 4x minimum, 8 is better, and leave enough all-thread at either end to add some more nuts and washers to serve as clamps for end panels. Cut the sides to fit between the end panels, tighten the nuts to hold it all together, add wood screws as needed. --- Put a handle or two on the long edge face of the center panel---. Carriers will use those instead of throwing the crate, giving your heads a much bette chance of surviving the shipping ordeal.
Contact Greg and find out where you will fit on his calendar. Stake out a spot, and if it's after the Christmas holidays, hold off on shipping until then. Most of the shippers are swamped for the season, with temp help doing a lot of the work. Those folks may not be as careful as the "regulars". I happen to like Fedex, if for no other reason than shipments have less time in their care and therefore less time to be damaged or lost. Find someone with a commercial account, and avoid some of the steeper retail fees. (PM me if I can help on this).
The effort expended to get all your pictures and posts up here is 0.8813 x the effort needed to box and ship the heads to Greg. There are a few sad stories about heads packed improperly that were damaged in shipment, so heed Jim Bailey's advice on packing them well. He's seen more than three sets of heads packed and shipped safely.
In my experience, shipping heads deserves a piece of plywood sandwiched between the faces of the heads, bigger than the face of the heads by a few inches on each side, with lengths of all-thread holding the sandwich together through the head bolt holes, with washers and lockwashers. Do that 4x minimum, 8 is better, and leave enough all-thread at either end to add some more nuts and washers to serve as clamps for end panels. Cut the sides to fit between the end panels, tighten the nuts to hold it all together, add wood screws as needed. --- Put a handle or two on the long edge face of the center panel---. Carriers will use those instead of throwing the crate, giving your heads a much bette chance of surviving the shipping ordeal.
Contact Greg and find out where you will fit on his calendar. Stake out a spot, and if it's after the Christmas holidays, hold off on shipping until then. Most of the shippers are swamped for the season, with temp help doing a lot of the work. Those folks may not be as careful as the "regulars". I happen to like Fedex, if for no other reason than shipments have less time in their care and therefore less time to be damaged or lost. Find someone with a commercial account, and avoid some of the steeper retail fees. (PM me if I can help on this).
12-01-2015, 01:25 PM
#38
Pro
For whatever reason, coolant has crept between the gasket and head, where, over time, the corrosion inhibitor in that tiny amount of coolant has been consumed, leaving water in contact with the alloy, leading to corrosion.
Heating and cooling cycles would see progressively larger amounts of coolant entering the ever increasing cavity volume, where the above process would continue.
So, IMO, I don't think it's any form of unusual corrosion, but the same old untreated-water-on-alloy stuff we all know about.
First up, check the head surface is true (must be a reason that coolant seeped between the gasket and head. tired gasket even?). If head is true, grind out and weld the cavities, and file down welds. Otherwise if the head need only a minimal skim, let that take care of the welds.
Heating and cooling cycles would see progressively larger amounts of coolant entering the ever increasing cavity volume, where the above process would continue.
So, IMO, I don't think it's any form of unusual corrosion, but the same old untreated-water-on-alloy stuff we all know about.
First up, check the head surface is true (must be a reason that coolant seeped between the gasket and head. tired gasket even?). If head is true, grind out and weld the cavities, and file down welds. Otherwise if the head need only a minimal skim, let that take care of the welds.
12-01-2015, 05:56 PM
#40
Pine boxes work great. Measure out the heads (remove the studs for a smaller box design) and ship (insured).
12-02-2015, 05:25 AM
#41
Pro
Good question.
Let's say the head is true (no distortion), and it is re-fitted with a new gasket.
Thinking out loud:
Theoretically the cavities would be completely sealed off c/- compression between the gasket and the head surface. But ... an air pocket would remain, subject to pressure/vacuum forces c/- heating cooling. But, over time, heated, compressed air will find it's way somewhere, which may be the combustion chamber, the coolant gallery and so on, forming a leakage pathway to any of those places.
So as I think about it, the cavities should be filled/welded, and the heads re-faced if needed. Otherwise just file back the alloy weld mounds and check with a straight edge.
As others have said, hard to imagine there isn't a competent machine shop inside a hundred miles that could do this simple task.
Upfixen.
Let's say the head is true (no distortion), and it is re-fitted with a new gasket.
Thinking out loud:
Theoretically the cavities would be completely sealed off c/- compression between the gasket and the head surface. But ... an air pocket would remain, subject to pressure/vacuum forces c/- heating cooling. But, over time, heated, compressed air will find it's way somewhere, which may be the combustion chamber, the coolant gallery and so on, forming a leakage pathway to any of those places.
So as I think about it, the cavities should be filled/welded, and the heads re-faced if needed. Otherwise just file back the alloy weld mounds and check with a straight edge.
As others have said, hard to imagine there isn't a competent machine shop inside a hundred miles that could do this simple task.
Upfixen.
12-02-2015, 09:43 PM
#42
Rennlist Member
Good question.
Let's say the head is true (no distortion), and it is re-fitted with a new gasket.
Thinking out loud:
Theoretically the cavities would be completely sealed off c/- compression between the gasket and the head surface. But ... an air pocket would remain, subject to pressure/vacuum forces c/- heating cooling. But, over time, heated, compressed air will find it's way somewhere, which may be the combustion chamber, the coolant gallery and so on, forming a leakage pathway to any of those places.
So as I think about it, the cavities should be filled/welded, and the heads re-faced if needed. Otherwise just file back the alloy weld mounds and check with a straight edge.
As others have said, hard to imagine there isn't a competent machine shop inside a hundred miles that could do this simple task.
Upfixen.
Let's say the head is true (no distortion), and it is re-fitted with a new gasket.
Thinking out loud:
Theoretically the cavities would be completely sealed off c/- compression between the gasket and the head surface. But ... an air pocket would remain, subject to pressure/vacuum forces c/- heating cooling. But, over time, heated, compressed air will find it's way somewhere, which may be the combustion chamber, the coolant gallery and so on, forming a leakage pathway to any of those places.
So as I think about it, the cavities should be filled/welded, and the heads re-faced if needed. Otherwise just file back the alloy weld mounds and check with a straight edge.
As others have said, hard to imagine there isn't a competent machine shop inside a hundred miles that could do this simple task.
Upfixen.
otherwise have them sent out to be welded up and then decked again.
12-03-2015, 12:10 PM
#43
Captain Obvious
Super User
Super User
12-03-2015, 01:31 PM
#44
Rennlist Member
but it sounds like this might work if someome is careful and scrapes off the excess .. ...has anyone done this?how hard is it to weld the decay'ed area? does it hurt the heads.. thought that heat might make things get out of wack too, and then you would to machine the surface to make sure all is straight, no?
12-03-2015, 01:50 PM
#45
Rennlist Member
Would it be enough to dremel out the pits to clean bare metal and coat it with some epoxy type? Perhaps JB weld (I have no experience with this) without the desire to fill the pit?