Album: Photos:Car:HeadGasket3
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My Old Car showed the weakness of the headgasket for the third time. I had hoped that a professional rebuild would make it last longer, but that was not true. This time, the gasket failed next to cylinder #1. However, all 6 showed deformation on the exhaust side; #1 was just the first to go this time. The real problem is the gasket itself. It is not strong enough, nor can it properly compensate for the CTE different between the aluminum and iron. The only available reliable solution is a MLS gasket.

The plan is to clean it all up, have the head checked for flatness, and use a multi-layer metal gasket. That should fix this recurring issue. I also plan to use undercut head studs, rather than bolts, as they should allow more thermal movement with an aluminum head.

As is the case with all projects like this, when I take something all apart, improvements are made during the process. It slows down the process, but makes it better for the long run.

Lest anyone question my stubborness with this car in spite of its many failures, it is my hobby car, so I expect to work on it. Plus, I just had the body worked over, so have too much invested in it to give up now. Also, over the many years I've owned it, it has been quite reliable, even considering the major work that happens from time to time.

So, the machine shop milled 0.006” off the head, primarily to clean off the brineling from the previous head gasket. The cylinder ring put a divot and burr into the head. I then took my granite plate and some 1000 grit SiC sandpaper and sanded off the mill marks. I suspect not quite another thou went away from the sanding. But, since I have a naturally-aspirated engine, a little more compression is always welcome. I will also sand down the block deck the same way. The deck has never been touched - it still has factory marks on it. Interestingly, the service manual says nothing about decking the block. In fact, it says if the deck is not in spec, replace the block.

In order to sand the block deck, I needed to remove both dowel pins in the deck. These pins locate the gasket and head, so are critical. I bought a pulling tool, but it did not work. So, I borrowed a magnetic-base drill from work to drill them out. The drill only worked for the front one. It did a decent job, but was slow. To remove the rear dowel pin, I used a die to cut threads, then used a nut and washers to pull the pin. The firewall is in the way, so neither the drill nor the puller would work. I wish I had cut threads in the front one, as the process was rather faster. (Ref pics 35-38)

Sanding the block deck is tiring and hard on my hands and shoulders. It has been working pretty well, but is slow going. I started with 1000 grit moved to 600, then to 220 because the higher grits were so slow. To make real progress, I moved to 120. The end game is near. After 15 sheets of 120 and 5 sheets of 150 I have hope I will be done someday. (Ref pics 41-46,67-68) After 4 more sheets of 120 and 10 more of 150, it's just about ready.

The stock Toyota head bolts have hex socket heads. The aftermarket (and superior) studs I will use have 14mm 12-point nuts. In all but 2 places, a deep socket fit. In the 2 that the socket didn't fit, a little filing was all that was needed. Now I can use this socket to torque the head studs. (Ref pics 47-50)

The MLS gasket has these rivets holding the layers together while you handle it. All but one misses everything. The Web talks about people removing the rivet, but I decided instead to make a divot in the head for that rivet. (Ref pics 51-54)

My throttle-position sensor harness connector broke beyond usability this time. The only replacement anyone has isn't 100% correct. Making a compromise, I shaved 2 keys off the TPS itself and cut one slot in the connector; that way the connector is still keyed. Artistry with a utility knife! (Ref pics 55-57) To splice on the new wires, I used my usual method of soldering and heat-shrink tubing. I thought extra rosin flux was in order for the old wires. Finish off with some self-fusing tape to make a new connector boot. (Ref pics 58-64)

Start the disassembly Mayo in the breather hose Front timing cover isn't the issue Naked head, ready to remove
More naked head #1 is right Clearly a failure 4,3,2 also show deformation
6,5 deformed Deformation is clear So many parts! Unsticking the old gasket
cyl 2,1 cyl 4,3,2 cyl 6,5 Transport rig!
Cleaning the head Underside view cyl 1,2 cyl 2,3,4
cyl 4,5,6 Measuring the valve shims Mill marks on the head Sanding in process with oil
Using my flat plate So much smoother! New alternator connector intake valve
old valve stem seal no seal removing valves exhaust valve
installing the cams seal packing drilling out the front dowel pin half left
pull the rest removed the rear dowel pin a different way mark and cut 0.05mm shim stock 2 extras here
deck before sand it down like the head progress! between cyl 3 and 4
more progress progressing well socket fits here doesn't fit here
file it a little now it fits rivet sticks up make a dimple
dimpled! rivet fits in the dimple TPS connector is dead slice 2 keys off the TPS
cut a slot in the connector ready for replacement cut and strip twist and solder
used extra flux on the old wires heat-shrink tubing shrink tubing over all wires self-fusing tape to finish
exhaust manifold needs help not perfect, but way better before (top) and aft..0 sheets of 120 grit before (top) and aft..20 grit and 5 of 150
after more sanding
All photos Copyright Brian A. Whaley. All rights reserved.
Powered by album generator from David's MarginalHacks on Sat Jun 5 18:26:59 2021