Blown Head gasket Warped Cylinder Head Custom Solution

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Recently started working on a 1996 FZJ80 with a blown head gasket... amongst other minor issues. The cylinder head was totally warped with the apex of the damage happening between cylinders 4 and 5, with a peak of about 0.029" (29 thousandths). I'm getting the head machined down and spent some time trying to find a copper "saver shim" to put between the block and the head gasket to make up for the inevitable change in compression ratio that's going to occur when the volume of the combustion chamber is changed. To my disappointment I could not find the correct solution online so naturally I did what I enjoy doing, came up with a solution that seemed to meet the requirements of the problem.

I went ahead and took the new head gasket and drew up a 1:1 cad file of the gasket and had it water jet, below is a sample (aluminum from some scrap) from my local water jet company that seems to be a very good match to what I need. I should be picking up the copper shims tomorrow and putting the beast back together over the weekend... it needs a few flushes as the previous owner managed to rust out the rear heater lines by using a diluted coolant mix or just water. It seemed a sign that there would be sometype of excitement... well that and the water consistently dripping out of the tailpipe. Also a good time to bypass the rear heater lines while I'm at it.

Anyways, I was pretty stoked when I brought the sample cut home to have everything match up.

If anyone needs a shim to solve a similar problem I'm having three made, one at 29 thou, and two at 21. The last two mainly to have on hand, it adds no additional cutting cost to have them cut one vs three a 60000 psi blade of water and garnet doesn't care whether its one thousandth thick or 8 inches (sorta).

I'll post some photos of the finished copper shims when I pick them up.

Thanks,
Justin

IMG_0688.jpg
 
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In essence yes, you are running two gaskets. What the copper shim does is essentially building back up the material that's been removed by the machining. The copper saver shims are used in cases like this or in uses where people are moding the engine to change the compression ratio.

On a side note, the copper shim could actually be beneficial as an additional thermal brake between the aluminum head and the steel block. Something that popped up when I was thinking about this a bit
 
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Totally, break was the wrong term. My thought was in conducting the heat and dissipating/distributing more evenly by not concentrating in one spot as heavily. Though to be fair on that point, steel and aluminum are pretty good as well. I was a little too focused on that boundary layer between the two and avoiding heat build up in one spot. The head gasket being graphite is also a good conductor, which makes sense.

Thermal bridge as opposed to a thermal break

Next up a gold shim
 
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I’m not a mechanic, but it makes since that if you machine down the head enough, you would need to replace that volume. Now how much machining is needed before that becomes a problem needed to be addressed I have no idea.
 
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If the head was warped and you had the face milled flat, the camshafts are now running in misaligned bearing paths. It will work for a while but essentially the camshafts are being flexed/curved each revolution. I was in a similar situation and elected to find a flat head to start from a true base.
 
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As far as I understand anything over .01 is getting into the range of causing serious issues as btslaser mentioned. I like the cometic solution that's a good one to keep in mind.
 
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Steve, according to my machine shop that’s been doing this for longer than I’ve been alive they seem to think the machining is fine. I’m just curious why you think it’s a no go? The warping is uniform front to rear.

I’m going to order the cometic gasket, thanks for that. I didn’t quite like the idea of stacking but knew the copper shim gasket and head gasket was something that’s been done and the shop has also done a few of these, most recently on a 470 a month or so ago. I’ve got some nice shop ornaments now.
 
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Max warpage 0.15mm (0.0059 “) if warpage is greater discard head 😁
Cam journals are machined and line bored when the head was flat, your machine shop should have advise you to find a new head !
You shouldn’t machine a warped overhead cam head unless the manufacturer states a specification. The head bolt tightening sequence , middle to the ends should allow a head within the spec range to seal properly, Otherwise Toyota would give an allowable amount that could be machined off the surface. They don’t.
 
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Best is a new head in this circumstance. The overall condition of the vehicle can guide you in the decision process. If it is a beater and you have the time and like to work on it go with the
 
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For anyone interested in making their own, or having a water jet shop do it. The owner of the vehicle I made this for seems happy, cheaper solution than a new head and solved his problems. I've attached the .dxf file. If you can't wait for the Cometic gasket, this shouldn't cost more than 200$ for materials and cutting... if you cut more than one you can save on that. I went ahead and cut three to save the owner of the vehicle some cash... while keeping some in reserve for a future fix or for a nice wall piece! If anyone needs another file option I can provide that as well, ih8mud will only allow the .dxf file format.
- Justin
 

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