Imagine a huge 5.9-liter, 550-pound iron-block V8 engine that makes less horsepower than a late-model VW Beetle engine, that regularly fails in such a way that it literally stops sending oil to critical internal components, and that’s so large and smothered with emissions equipment that servicing it — even in a gigantic engine bay — is a chore. You don’t have to imagine, because that engine is real. It’s the AMC 360, a piece of shit that defiled some of the most beautiful vehicles of all time, including the Jeep Grand Wagoneer, Jeep Gladiator, my 1979 Jeep Cherokee Golden Eagle, the Bricklin SV-1, and many more. Let’s discuss this shameful bit of American Motors Corporation history.
[Before I get started, allow me to just vent for a moment. I spent all of Sunday trying to get my 1979 Jeep Cherokee Golden Eagle’s replacement AMC V8 engine running. Should I have been editing, writing, answering emails, researching, and hiring? Yes. But instead I was elbow deep inside what has to be the most poorly designed engine I’ve ever had the misfortune of dealing with. The shittiness of the AMC V8 is severely jeopardizing The Autopian’s future outlook; that’s fitting, in some ways. Anyway, it’s not solely my frustration that’s leading me to write this article; the AMC 360 truly is a poorly-designed motor, as I will now show].
You may know American Motors Corporation as builder of the greatest Jeep engine of all time, the AMC inline-six, a motor that came primarily in 232 cubic-inc, 258 cubic-inch, and 4.0-liter displacements. This long iron-block motor, found in pretty much every Jeep between 1970 and 2000 — was absolutely unstoppable (If you want to be “in” with the Jeep crowd, just say “That foar leeter is bulletproof I tellya” anywhere near a gas station) thanks to its simple design, ease of serviceability, and plentiful low-RPM torque.
It’s surprising, then, that the same company that built that amazing off-road motor developed the AMC V8, a contraption whose only reliability was liability, and that was ubiquitous in AMC products for decades. The thing went in damn near everything as the “step-up” from the six cylinder, even though, really, it was a huge step down. Let’s take a look at some machines burdened with hauling around this iron menace.
Probably the best-known example is the Jeep Grand Wagoneer, which got the AMC V8 as an option over the inline-six:
The AMC Gremlin also offered the V8 if you didn’t want the standard six:
AMC Javelin? Yup, AMC V8 option:
Jeep CJ-5? Sure, you could get this motor instead of the trusty 258:
Jeepster Commando? Yup, 258 standard, 304 optional:
AMG Pacer: Oh yeah, standard six, 360 optional:
That huge anchor weighed down the front-end of lots of AMC products, including — sadly — my 1979 Jeep Cherokee Golden Eagle, which I worked on this past weekend:
Sadly, some non-AMC products also got this awful motor, including Malcolm Bricklin’s Canadian creation, the SV-1:
I’m fairly sure fellow AMC-lovers are going to come out of the woodwork to defend the AMC V8, which came primarily in three variants: 304, 360, and 401. “Mine has driven over 200,000 miles,” some will say. “This guy just doesn’t know how to wrench,” others will claim. “It was a torque, stout motor,” many will cry. “Some of these have been built into highly successful race motors” others will assert. And to them I say: Wake up.
I was a sheep like you once, having fallen head-over-heels for the American Motors way of life. The soulful designs; the charmingly weird blend of Ford, GM, and Chrysler parts; the generally-stout hardware; and just the bold, Smallest-Of-The-American-Automakers rough-and-tumble way of doing things. Like you, I used to see AMC vehicles, especially Jeeps, through rose colored glasses. Hell, I currently own seven AMC-era Jeeps, and I’ve owned many more in my past! I even visited Kenosha a few years ago solely to pay homage to AMC, and I recently snuck into the old American Center former headquarters in Southfield, Michigan. I’m a diehard AMC fan, believe me.
But I have no choice but to call a boat-anchor a boat-anchor, because that’s exactly what the AMC V8 is. Yes, as much as it pains me to admit it, the engine powering the beloved Jeep Grand Wagoneer and my badass 1979 Jeep Cherokee Golden Eagle is one of the worst powertrains in Jeep history. Here’s why.
The Oil Pump Literally Eats Itself
Let’s start with what’s absolutely ruined my experience with my 1979 Jeep Cherokee Golden Eagle, a beautiful machine dripping with soul, and one that I should love, but — thanks to this motor — I actually deride.
Of all the things a motor has to do to survive, right up at the top when listed in order of importance is “make sure metals don’t rub against each other.” The way engines typically make sure bearings don’t rub against journals and camshafts don’t wear against lifters is they put a little cushion of oil between moving metal parts. Oil is the lifeblood of any internal combustion engine, which is why the AMC 360’s lubrication problems are such a big deal.
I ran my engine last summer and heard a loud noise at the top end, making me think that perhaps there was some kind of oiling issue. I removed the valve covers and, sure enough: bone dry. There was no 10W-30 making it up top.
Why was this? Well, the oil pump on the AMC 360 is driven by the distributor; this is fairly common among old engines. So, to see what was going on, I bought a priming tool, chucked it up in my high-torque handheld drill, and spun that pump at 500 RPM through the hole where my distributor once was. Thirty seconds in, I saw no oil flow to the top end. A minute in: Nothing. Two minutes in: A tumbleweed rolls across my rocker arms. Sonuva bitch.
I removed my oil pump from the bottom of my motor and re-packed it with vaseline, as is the recommended procedure to ensure that it primes properly. With the oil filter off, I turned the pump and, sure enough, oil poured out of the oil filter adapter. And yet, with the filter back on, no matter how much I spun that pump, nothing got to the top end.
Worse, I noticed very little resistance on that drill when I spun it clockwise (which I’m fairly sure is the right direction). So while there appears to be some amount of oil flow, there’s very little oil pressure — the fresh 10W-30 appears to be flowing freely…somewhere… instead of to the top of the motor. Something ain’t right.
The bearing clearances on this motor looked fine the last time I checked them, and there was no sludge in the pan. Plus, the oil pickup tube looked fine. And what’s weird is that I did an oil pressure test while the engine was idling and read over 40 PSI while cold using a mechanical gauge; that’s not amazing, but not horrible, either. So I’m confused why there’s no oil getting to the top of the engine, though at the same time, deep down, I know what the issue is.
One of the most common failure points on an AMC 360 V8 is the oil pump itself. American Motors engineers found a clever way to integrate a number of items into the aluminum timing cover at the front of the engine. That cover not only fulfills its purpose of enclosing the timing chain, but it also houses the water pump, distributor, fuel pump, oil filter, and oil pump. I’d consider it clever integration if it hadn’t been so poorly executed.
As you can see in the image above, the oil pump consists of two steel gears riding in an aluminum housing. As is probably unsurprising to many, the result of this setup is that the gears wear into the aluminum housing, and over time, the distance between the oil pump gears and aluminum part of the pump increases, causing a severe reduction in oil pressure. What you end up with is my situation — pumping action is severely reduced, and while there may be oil pressure when cold, you can forget about it when hot. And lack of oil pressure when hot is a very, very bad thing — it will lead to failure of your rod and main bearings, camshaft lobes, rings and cylinders, and much more. Basically, the engine will destroy itself in short order.
Lack of oil flow is a terrible thing, and the fact that the oil pump on the AMC 360 is basically a wear item is pathetic.
And to be clear, when I say the oil pump is a wear item, I’m referring to the entire timing chain cover. That whole aluminum piece that houses the distributor, fuel pump, oil pump, and oil filter adapter. The thing whose replacement requires one to remove the crankshaft pulley using a special puller tool. Of course, you also have to take out the radiator, fan, unbolt the whole accessory drive — it’s a nightmare (more on that job in a bit). And when you’re done, you get to drop $250 on a new timing chain cover, and even then, many forum-goers complain about performance even with the new pump and cover.
Even When The Pump Works, The Rear Cylinders Still Don’t Get Enough Oil
The sad thing is, even if the AMC V8’s timing chain cover and oil pump cover haven’t worn themselves out yet, the engine still may suffer from lubrication issues. That’s because the block’s internal oil passages are designed in such a way that, when the engine is run hard, the rearmost cylinders can be starved for oil. Here, let Great Lakes 4×4 member Leanz break it down for you:
AMC V8’s are notorious for having oil system problems. The oilpump housing is the same as the timing cover so when your oil pressure starts to drop when a oilpump rebuild kit will in most cases do you no good at all. This bypass is for the lack of oil at the 7 – 8 rod and main bearings. The oil system flows the oil from front to back, and under quick acceration, leads to lack of oil in a VERY critical area.
The bypass consists of an AN fitting inside the intake valley between the lifters for number 6 and 8. Drill and tap for the fitting in to the oil passage.
The bypass, shown above, is a fairly common modification, though it’s no easy job. It requires one to remove an absurdly heavy cast iron intake manifold, along with everything that mounts to it — and that’s a lot of stuff, especially on a smog-era vehicle like my 1979 Jeep Cherokee Golden Eagle.
It’s Really Not That Easy To Work On
You might think that an old engine like the AMC 360 has a huge advantage over modern cars when it comes to serviceability, but I don’t know that that’s true. My 1979 Jeep Cherokee Golden Eagle was built right in the middle of the smog era, meaning it’s outfitted with more vacuum lines, air pumps, and other emissions-reduction equipment than you can even imagine. Add the fact that my Jeep is a high-end machine with power steering, air conditioning, and cruise control, and the rather enormous engine bay begins to shrink, yielding — as Chrysler’s packaging would often say when I worked there as an intern — “a basket of snakes” or, my favorite, “ten pounds of shit in a five pound bag.”
Even simple things aren’t that easy to service. The rearmost spark plugs, especially the one on the passenger’s side by the heater core, are a pain in the arse to access:
And like I said earlier, replacing that timing chain cover is an awful job. One that I will likely have to do soon. (Dammit). The cover is wedged between the water pump and engine block, and damn near everything is bolted to it. To remove that cover will require dismantling the whole front of the engine.
And to dismantle the front of the engine means removing the giant harmonic balancer on the crankshaft — a job that requires a special tool and, critically, space. To get that space, I’d have to remove the fan on the water pump and take out the radiator. It’s all just a huge pain in the butt.
It Makes No Power And Sucks Gas Like You Wouldn’t Believe
Here’s the thing. Many, many great engines have achilles heels. The unstoppable Buick 3800 V6 has intake manifold problems. The beloved Cummins 12-valve has the Killer Dowel Pin issue. AMC’s own inline-six — one of the greatest engines of all time — tends to crack cylinder heads if it overheats even once. But those engines generally don’t require as much work to fix their maladies, and their fixes tend to yield a lifetime of reliable service. What’s more, none of those engines are as inefficient as the AMC V8.
The 1991 Jeep Grand Wagoneer — the last vehicle to use the AMC 360 in the U.S. market– was a 4,400 pound behemoth whose AMV V8 made 144 horsepower.
144.
That’s less horsepower than this 2011 Hyundai Elantra:
That Hyundai, by the way, scores 32 MPG combined. And while you might expect it to offer better fuel economy given its relatively diminutive size, newer powertrain and transmission technology, slipperier body, etc., I bet you wouldn’t expect it to offer nearly three times the Grand Wagoneer’s combined fuel economy of 11. Three times.
Okay that’s still not fair due to the size difference, but let’s compare the new Grand Wagoneer, which literally weighs one ton more than its predecessor. It makes over three times as much horsepower at 471 HP and scores roughly 33% better fuel economy (15 MPG versus 11).
Obviously, comparing modern cars to old ones is silly, but that’s not the point. The point is that the poorly-designed AMC 360 has singlehandedly ruined my relationship with my beautiful 1979 Jeep Cherokee Golden Eagle. I should be cruising down Woodward in style, listening to that three-speed General Motors TH350 shift through those three gears, enjoying the gentle rumble of that V8, and looking over that distinctive hood. I should be living the dream, but because of the AMC 360, I’ve been dealing with the Amber Heard of automobiles — something so beautiful, and yet so troubled.
Could you do an article on what all those emissions lines are? I see those in older engines and it just blows me away that a carb’ed engine from the 70’s looks so damned complex
Do you think you could fit 48 HF Predators in that engine bay?
Just stick a Chrysler 360 in it and be done? Would the tranny quit in protest?
Has anyone ever engineered a fix for that oil pump? If not, forgo any V8 swap and do a more David Tracy worthy vintage diesel swap with a Perkins 6.354 and claim it’s a,rare export version. FWIW Dodge used Perkins diesels in the 60s and 70s.
on second thought, establish a bond with Project Krassler and install a six cylinder version of the VM diesel
.. just sell it. What an enormous waste of time and energy. The next owner is very likely to pull this engine and put in an LS or similar.
My buddy had an AMX with the 401 and it was flawless all the time he owned it- about 2 days- he had the hood painted and the shop didn’t attach the hood latch correctly it opened on the highway and beat the roof of the car to death
Powernation actually did an episode where they addressed the oiling issues on this engine. Its maybe a little less technical that some of your articles, but has the same info.
https://www.youtube.com/watch?v=wyRL4eMW0IM
David- Why didn’t you just body swap your Lexus with the Golden Eagle. Imagine that great 1UZ 4×4 chassis with the Golden Eagle body on top. Should have kept it and hacked it up.
Another way that I think of it:
The ’79 Jeep Cherokee Golden Eagle is now 43 years old. If my conversion math works out then this would be equivalent to an 86 year-old patient in human years. Geriatric but still loved by great-grand kids and the like.
If the Jeep had replacement parts like artificial knees (suspension bits), resected gall bladder & appendix (smog apparatus removal) but now needs a heart transplant (modern engine), she would still be grandma and loved just the same.
A modern functioning engine (read: Chevy heartbeat) may be the way to go…hint, hint.
AMC always had quirky and fun designs. I grew up with Gremlins, Concords, and Eagles roaming the mean streets of my rural community. We even had a few Javelins and a Rebel Machine that were hiding in old garages or in the back 40 of someone’s property. Although, my mom almost bought a Grand Wagoneer in 1991 (she passed on it, and the cool wood panel minivan for a Olds Delta 88).
But I fully agree! Outside of the straight six, their engines were…..engineered as if a fun and quirky car design company built them. I feel like I’m living out their legacy dealing with the AMC designed, Daimler Benz produced 4.7L PowerTech. It has notoriously bad heads (valve seat drops, oil guides plugging, carbon build up) that cause a generally healthy and low mile engine to fail pretty quickly. It also has a fairly complicated SOHC set up, that requires half of the engine to be torn apart to take a head off. I’ve been told by a lot of shops they won’t touch a 4.7 head gasket job or, its cheaper to replace the engine with a junkyard unit. They’re also now hella hard to find in junkyards because these failures happened years ago.
This is why LS swaps are so common. GM nailed that engine family for the most part.
LOL it sounds like even Renault was a step up in reliability :p
Hellephant swap for the Jeep? 😉
I say dig through the toyota parts bin for a nice reliable plant. The G16E-GTS gets you 300hp and 273 pound feet of torque. Did I mention that this is a 1.5 litre 3 cylinder? I’m sure that it would be tricky to mount that longitudinally when it is intended to be done transversely in the ‘yotas. Regardless, a high strung 3 in a massive animal such as the golden would make for some fun conversations at your local “jeeps not sheeps” night.
1976 Jeep Cherokee Chief, my first car in 1983. The vacuum lines drove me nuts; it ate starters and the quadratrac chain stretched so I had to convert to locking hubs. Still in the day, in my 16 year old mind, this thing was a beast. I crushed my closest high school competitor on the dirt hill in front of school. Took the back seat out for 8 feet of high school fun at the drive in. Power back window always broke.
Never change DT,everything you have ever written about in your jeep life,i love to read about because its exectly what im going through living,and dailying 3 xjs…..
Had a ’72 CJ-5 with the 304. Man I miss that thing. I won’t say the engine was bulletproof, far from it. However, it was fairly reliable considering the age and lack of previous care.
Didn’t I read that you had an extra 4.0 at home? The Golden Eagle seems like the perfect new home for it.
Man, that sucks! Do you have any machinist friends? If it were me, I would look at machining down the bearing surface where the vanes turn, and install some flat needle bearings with some shims to take up the additional play. Either that, or just dump the boat anchor and be done with it.
It should say, “shims to set the endplay”… I wish I could edit the comment directly.
I love it when David is pissed.
I had the 304 in a 1974 Matador. Motor was fine and survived me and the person I sold it to.
Carb was junk though
Swap it with something cheap and cheerful that makes 144 HP. Should be easy
About 15 years ago I borrowed my father’s ’86 Grand Wagoneer with a recently rebuilt 360 for a bit of light hauling. It ran great! Such road presence! On the highway at a steady 60 mph, however, I could actually detect the gas needle moving. When I checked mileage over a couple of tanks, I found it was getting 7.7 mpg. Yet somehow it was so gutless that climbing a 3-mile grade on the highway with no load was a mighty struggle. There’s just no excuse.
Great read!
Keep em coming.
You need to just go ahead and either put a slant 6 in or a small block Chevy.
Was the 304″ engine faced with the same problem or was it just the 360?
I vaguely remember a guy when I was in college swapping a 327 Chev. into his Gremlin, the a major stumbling block was a conflict between the distributor and the windshield wipers, everything else went as expected with off the shelf aftermarket parts.
and worse with a big HEI cap
We tend to romanticize these old lumps, but the truth is most of them were dogs with major design flaws. Someday, I will run you through the one engine that’s the WORST ever made, the 70s Benz diesel. Every possible bit of engineering stupidity is on that turd, and the fatal flaws are kind of works or art in their own right. Yes yes…2.3 million mile taxi cab. Bullshit and hype. It makes the 360 look like a good engine.