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Bryan Irons photos
Stinky Jeep Teardown
Now is a good time to start removing the front accessories. Get a cheap digital camera if you dare not bring your phone into the shop. Start taking note of where the hardware comes from to avoid future headaches. A little heat or penetrating oil may be required to abstain from breaking bolts.
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Bryan Irons photos
Stinky Jeep Teardown
AMC used a unique (read: crappy) design of mounting the oil, fuel and water pumps as well as distributor in an aluminum front housing that was simply bolted to the block. If seized bolts from antifreeze and dissimilar metal corrosion were not enough, the poor wear characteristics of the cast aluminum would make Sasquatch go bald. Our water pump was in excellent shape, but as you can see the impeller of a previous pump had come in contact with the housing.
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Bryan Irons photos
Stinky Jeep Teardown
Pulling the harmonic balancer is pretty easy… with the right tools! They are normally a keyed, press fit so take your time especially if you want to reuse it.
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Bryan Irons photos
Stinky Jeep Teardown
The front cover on our AMC is like your chest cavity as almost everything the engine needs to live is linked to it. Break out your fine tooth combs and monocles.
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Bryan Irons photos
Stinky Jeep Teardown
Inside the font cover, we see where the camshaft has moved forward and scored the aluminum. Flat tappet cam lobes are ground with a slight taper to run the cam into the back of the block. We can assume that between these marks and our concave lifters, the camshaft was toast. No inspection required, just the scrap bin.
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Bryan Irons photos
Stinky Jeep Teardown
Date stamps are an important part of the break down process. How did a cover made in January of 1978 get on a 1974 engine block?
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Bryan Irons photos
Stinky Jeep Teardown
Another less then stellar design is the aluminum oil pump housing and cap. The score marks of the pump impellers are not a good sign; this motor has suffered from chronic low oil pressure, as many AMC’s do. This damage can be repaired, but the bills are starting to add up.
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Bryan Irons photos
Stinky Jeep Teardown
The steel oil pump gears look like they had been used to crush beer cans, not pump oil. Every little scratch and mar is another pathway for oil to seep from its intended path.
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Bryan Irons photos
Stinky Jeep Teardown
Only the bare bones are left. Pull the pistons and check for sloppy wrist pins, hashed bearings, and scored piston skirts. Ours looked good, felt good, and are hung on a set of relatively rare forged steel connecting rods, SCORE!
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Bryan Irons photos
Stinky Jeep Teardown
Before pulling the pistons or bearing caps, make sure to mark them, and their orientation in the block. Buy a cheap set of number or lettering stamps.
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Bryan Irons photos
Stinky Jeep Teardown
Spoiler Alert! We had just about every type of bad bearing imaginable, but what finally sealed the deal on telling us that our motor had been completely rebuilt was the date stamp in the bearings. 11-77 was on every bearing in our block. This indicates that the bearings were made in November of 1977.
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Bryan Irons photos
Stinky Jeep Teardown
Engine bearings are typically a multi layer design. These bearings are oiled from the inside out, so having the extra material wear away, like ours in this picture, means that excess oil is leaking our from around the bearing causing low oil pressure in the remainder of the engine. All the metal-to-metal contact surfaces ride on a thin layer of oil to help them glide. No or low oil pressure is a very dangerous appetite for destruction.
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Bryan Irons photos
Stinky Jeep Teardown
The thrust bearing controls how much play the crankshaft has to move back and forth. Again you can see the copper colour showing, which is never good. The good thing we did have is that all the bearings were still correctly saddled in their prospective locations. This is where the term “spun bearing” comes from.
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Bryan Irons photos
Stinky Jeep Teardown
We had already diagnosed that the camshaft was shot, and the #1 cam bearing had literally melted down, cracked, and was flaking apart. This particular bearing feeds oil to the timing chain, fuel pump eccentric, and distributor gears. This motor was decommissioned just in time before the bearing spun and caused damage to the cam-bearing bore.
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Bryan Irons photos
Stinky Jeep Teardown
We hate to end on bad news, so here is our crankshaft before machining. Run your fingernail along the bearing surfaces, they should be smooth and ours were. Also, check that the oil passages are clean and clear like ours.
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Bryan Irons photos
Stinky Jeep Teardown
So, what did we learn? Our block, crank, connecting rods, and pistons are all good for a basic rebuild, but we want to step it up a notch… as usual. The parts are starting to stack up!
By Bryan Irons
Merican Metal Menace - Stinky Jeep gets a 401: Part 2 – Deep Inside the Corpse
We set out with the intention to tear down and rebuild a motor to replace the asthmatic three-legged hamster of a motor in Stinky Jeep with something that should make us giggle like schoolgirls every time we fire it up. Our Merican Metal Menace AMC 401 V-8 is almost down to individual parts at this point. So far, we know that the motor has heads dating from around 1977 and are from a 360, but the block came out of a 1974 Jeep J-20.
The investigation continues as we further delve into the belly of the beast and start ripping into it like a pumpkin fresh off the field. The guts, oil, blood and shrapnel all tell a tale if you look close enough. Take a peek with us here and see what a little automotive archaeology can tell.
Next issue we’ll be prepping to run off to the machine shop where we turn our project over to the professionals.
Read last issue's Stinky Jeep Part 1 - 1st installment of Merican Metal Menace.
Read next issue's Machine Shop Stop - 3rd installment of Merican Metal Menace.