Operation Bad Timing II: The Epilogue

Holy pepperini I’m late with this one! I’m really hoping I can get back into regular posting soon in some way as the company (which I owe now a TED Talk or Disrupt-level summit on the story of, I’m sure) becomes more defined and roles more condensed. See, if I don’t get to blog, I start almost brooding like a chicken that just has to pop an egg out and sit on it until it hatches. This is a patently unsustainable behavior in the long term. By the lack of updates, really, you can probably infer that everything worked out and I was able to move onto other things – after this post, I’m planning on a lot of back-blogging some robot and additional van work I did before the summer. If I keep saying it, it will happen, right?

We pick up the adventure again on the verge of final re-assembly as I decide to tackle the very cracked exhaust manifold before it just splits in half like something I’d see on r/JustRolledIntoTheShop. I did some light reading on cast iron welding techniques beforehand – everyone says it’s extremely difficult, so why not try since I’m not…… likely to make it worse? The method I ended up settling on is using a nickel filler rod and a TIG welder.


I wire brushed and ground out the area of the crack with some combination of a Dremel and a die grinder. The idea seems to be you have to get ahead of the crack such that it doesn’t continue propagating.

I’ve read that it’s very likely the cast iron used in manifolds is a bullshit material made of manufacturing scrap and cuttings, so the composition might not be carefully controlled, and that different manifolds will weld with different success rates because of it. Either way, it seems like a preheat is necessary – and some places even advocate post-heating. I found a simple way to pre-heat the area by virtue of just sticking the torch up the bottom.

I can say right away that these were not my proudest welds.

So I’m sure people who have repaired manifolds will giggle amongst themselves about it, but it turns out that old oil-soaked cast iron is not exactly a very cooperative material to weld. By this I mean the moment I stepped anywhere near the boundary of my cleaned/ground weld seam, it would literally explode from all the deposited junk in the surface. If it didn’t just crater the whole area, the remnant oil would actually bubble up into the weld pool and make it porous!

This meant a lot of rework and re-cleaning and re-grinding. Eventually I got the message, and simply plowed forward and just kept adding more nickel rod to fill the imperfections and porosity up, basically burning out all the oil in the area of the weld. Sadly I was only able to close the cracks on the accessible sides, and not much in the center valley, so it’s still technically leaking.

You know what, fuck it. It’s better than when I started, and nothing re-cracked yet, so it’s going in! Overall the experience in the clean, cooperative area of the weld wasn’t bad at all.


….okay, yes, but first I had to repair the studs. There was always one exhaust downpipe nut that was almost impossible to get off, and I finally found out why. In this manifold were studs of two VERY, SLIGHTLY, IRRITATINGLY different threads. Two were M10 x 1.25, a standard metric fine thread that is easy to find in the US in any disused, neglected metric parts corner.

The third was M10 x 1.0, which is apparently a parallel metric fine thread standard. Well that would certainly explain why the M10 x 1.25 nut was so difficult… this nut has never been changed or the stud inspected by itself until now, and was the one someone clearly meatheaded on long ago.

Oh, yeah, I also sheared all 3 studs off trying to get them loose, because of course they would all shear off.

The only option remaining was to drill them out down the center. Because of the awkward angles involved, I decided to not try and set them up in a drill press, but instead piloted the center of the hole  with a larger 135-degree, split-pointed drill bit, then drilled downwards with larger and larger drill bits by hand.

Manifold-kitty is pleased.

Then I slammed a M10 x 1.25 (more commonly found metric fine thread) tap through whatever remained and YOU KNOW WHAT, JUST GO DIE IN A FIRE ALREADY shipped it. Yes, I tapped right over the remains of the old studs. Who cares!?

My plan was to actually not use nuts and studs anymore and instead put some ISO large-head M10 bolts straight in from the bottom.

Very generous dollops and blobs of anti-seize lube are applied to everything in sight with respect to the exhaust manifold. The new nuts and hardware are no longer JIS standard, so they use 13mm wrenches instead of 12mm – while I was able to locate 12mm JIS series nuts, they had a regular zinc coating, whereas I could get the non-JIS ones with the yellow chrome finish. I decided to opt for maximum corrosion resistance than period hardware correctness.

Also check out the timing hardware finally installed! I’m so fast with it now! Kill me and end my suffering!

Look! I didn’t even sail right through a critical mistake-catching step this time! That is indeed the camshaft timing mark lined up with the head casting mark.


The original mistake? In the dark and without the paper manual in front of me (and boneheading through remembering the exact procedure), I missed the casting mark and instead lined it up with the top of the head.

With everything now bolted up and secure, it was time to fill it up with oil (just oil for now) and do a test fire…

Well, it didn’t explode, so…

I now had to set the distributor timing. The engine has electronic timing control, but still depends on the distributor as a crankshaft position pickup, so it has to be vaguely in the right place. To do this, I had to whip out my timing light and find the degrees-BTDC indicator on the lower timing cover, after jumping a “timing mode” connector pin located right  behind the engine on the passenger cabin firewall – this tells it to not apply any timing advance.

Wait, what? Mine didn’t look like any of the others I saw online. After a lot of head-poking and investigation, it appears this has been severely damaged at one point by an escaping pulley of some sort, or a loose/derailed belt! The “BTDC” text was visible, but all of the physical markers had been destroyed.

It took a little clever hunting for OEM parts to find an image of what the thing used to look like.

I found listings for other cars with 4G64 engines, both SOHC and DOHC since they appeared to share the same timing components besides “More of Them” for the DOHC. At the least, I wanted to check if my imagined scale – what the indicating lines would have said – was correct.

The above timing cover from the Eclipse shows the “BTDC    |” marking with a “10” near by the T and D. You can barely make out the tops of the “10” on mine, so I used this as a reference to set the distributor at the 5-7 degrees base timing it recommended. I erred closer to what I think was 5, since I’m not letting that happen again.

After setting the base timing was done, it was time to fill up fully with everything and idle until warm. Now I reconnected all of the intake and coolant hoses, as well as finally adding in the oxygen sensor (which I went ahead and replaced, since the old one at this point was a solid wad of oil minerals)

Filling a cooling system from empty means it has to purge all the air out that had been trapped. Idling until warm/hot means the thermostat valve opens, letting the coolant fully circulate and a lot of it will burp out from the radiator. After that, I could top off the radiator and close up.

Final bringup operations included organizing remaining wires/cables, spark plug wires, final check on hose clamps and tube fittings, and setting the warm idle speed by repositioning the throttle cable stop incrementally.

And we’re back online! The trip to the local gas station was really a make or break – once I got out here, it meant that any near-term catastrophic failures would have already revealed themselves….or so I’d hope.

But you know what? I was out for revenge. I had to restore my honor and dignity.  Why the hell would I do all this work just to drive 6 or 7 miles to and from the shop?

So after the 100 mile break-in oil change, the following weekend I decided to hit up….

Middle of Nowhere, Virginia. My original late May trip was going to be taking the Skyline Drive and Blue Ridge Parkway slowly down to Atlanta. Not having a random week to spare at the moment, I decided to just make a weekend (Friday evening to Sunday evening) trip out of it, on the Skyline Drive portion only. I got into the area Friday late night, spending a good chunk of Saturday wandering through and then hanging around Harrisonburg, VA before returning Sunday early afternoon.

I’d give Skyline Drive a 8/10 for sheer scenic presentation, but a 4/10 for “Hoodrat shit Charles likes to do”, which is cut up mountain roads in a nonsensical vehicle for doing so. First off, the park speed limit is 35mph and it’s very much enforced. Second, since it’s actually a national park, it’s not very technical nor tight – any schmoe has to be able to drive it without flying off the mountain. A very leisurely cruise – almost too leisurely as you are trapped behind a Winga-Dinga-class drop-top Corvette with 3 gray-haired people doing precisely 35.1 mph who REFUSE. TO TAKE. ANY. PULLOUT. At least I got to fly around a little after the second “half” south of U.S. 33 where the camper, biker, and hiker population also drops off. I think I’ll go back to U.S. 129 any day…. or hell, the Afroduck Loop if I’m that bored.

What kind of idiot goes on a 1,200 mile road trip right after rebuilding an engine? Apparently me.

Suffice to say, Operation Bad Timing II was a resounding success. I’ll be keeping an eye out on the wear and consumption levels of everything in the next few trips, but so far it’s all been super promising. After I got back, I did another wear-in oil change, and the oil consumption level has dropped to almost trivial levels. It’s after Dragon Con now (…so there’s THAT trip report), another 2,500+ mile combined trip, and I’ve topped the oil level off with about half a quart.




Operation Bad Timing II: Chinesium Rising; The Zero-Delta-Entropy Point

Last time, I had just gotten to replacing most of the seals on and cleaning up the old head before discovering a cracked exhaust valve which meant I couldn’t put everything back together before getting new ones. That delay pushed back the timeline just long enough for the Chinesium Solution to appear:

Yep, it’s cylinder head shaped alright.

– me, when I opened the box


To recap, while searching the neighboring galaxy Craigslist for old Mitsubishi truck/van parts, I discovered that there is still a lot of Chinesium aftermarket support for this engine family, the 4Gxx series. So I took a leap of faith and spent $400 on a complete cylinder head assembly, in the interest of exploring the solution space and documenting it for all other silly van enthusiasts as I tend to do for everything.

The appearance is virtually identical to my current cylinder head, minus one or two things which jut out in the corners, possibly for different accessories or mounting needs later on. However, the biggest added feature I noticed? Roller rocker arms! That’s worth at least like 1 horsepower over flat ones, which to me is a 1% gain.

The gasket-mating surface of the head is otherwise identical.

So now I’m left with a conundrum. Which head do I use!? The old one is proven and has most of its wear parts changed already, but I had new valves coming and would be changing those out, but without refinishing the valve seats. The Chinesium Option is brand new – late-2017 date code on the casting and still smelled like machining coolant – but my fundamental skepticism of Chinesium persists.

I figured that at the end of the day, all things considered, Chinese people also prefer to have working cars – so this thing probably doesn’t not work, but might have parts that have  shorter wear lifespans. However, I’m of the opinion that any new parts I can find for this thing are already Chinesium, or already will not have the expected lifespan of an original Mitsubishi OEM part, or both. For example, the head comes preloaded with valve stem seals which might wear out again at the 50-70K interval. Or they might not. Who knows?

Fact of the matter is, after doing this dive, I’m no longer uncomfortable and scared of a lot of the process, just understanding that it takes time. So what if this thing instantly and catastrophically fails – lesson learned, shove the old head back on. So for now, I’m keeping the old head around until the new one either proves itself or doesn’t.

And so we cross the point of maximum entropy, basically when your shit is the most taken apart and hopeless.

The new head even came with studs. I picked up a pack of new metric nuts to replace the hodgepodge of hardware that was on the old intake – which I still can’t figure out if it was factory-intentional or the result of some previous surgery.

This was the moment I discovered that JIS (Japanese Industrial Standard) and the rest of the world has different wrench sizes for various fasteners.

Chances are, in the U.S., if you even touch metric at all, it’s the ANSI or ISO standard. JIS is Japan’s own thing, and it has different head sizes for nuts and bolts. I finally understood why some times I found M8 nuts and screws that had 12mm hex heads and other times with 13mm ones, or more drastically, M10 nuts and screws with – get this, 14, or 15, or 17 millimeter wrench needs. I took most of these parts off with a 12mm wrench… but a 13mm is being used to re-arm them!

To be super authentic and ジェイ ディー エム, I’d have to hit up the local metric automotive supply place and get some JIS small-wrench hardware. But McMaster-Carr is just so easy.


The intake manifold now being mated to the new head. I took this opportunity to replace a few of the rubber hoses which I noticed had become sufficiently mummified, including the PCV, PCV breather, and a few vacuum lines.

Before I go too far, just double checking that it’s correct….

It took me a little while of searching to find how to re-mount the distributor. I couldn’t find where it was referenced in my USDM van manual at all, just occasionally sketched in with the intake manifold and cylinder head. I had to do some searching and found a 1990-1994 4G6 workshop manual hosted by the Canadian Delica club, where I found the instructions for the SOHC head, reproduced here for saving my ass later:


Hey, I have those locating features! The distributor will need to be fiddle with once mounted anyway, so I really just wanted to get the initial gear mate correct.  When it is correct, the rotor will face essentially straight downwards with the head in a normal upright position.

Now I flip it over and mount the exhaust studs, which are the same type.

After the head assembly was prepared, I cleaned and prepared the valve cover with a new gasket and also added the half-moon shaped plug to the back of the cylinder head with some silicone squirt-a-gasket compound.

The whole assembly was maneuvered into place with some help and put in its final location without the head gasket first – this was just to make sure it was basically in the right place to begin with and we wouldn’t be hovering over a “Don’t fuck this up or it will explode instantly”-class component trying to find the two mating locations.

After it was dropped in place, I simply had someone hold the head up a little and slid the gasket into place, then the whole assembly was dropped back down. I then sprinkled some oil into the rocker and cam area, around the lifters and springs, and a bit into the valve stem seals to start them off.

The fun operation of torquing the head bolts now begins! It seems like some times you’re recommend to torque them to specification and then check it again after a few hundred miles or several cycles, and other times you’re recommended to give it some extra goose to ensure you don’t have to do that. But either way, that sounded like “old school car guy” advice…. for people who can just pop off the valve cover in their very clean and accessible open engine bays without having to remove half of the vehicle (because 50% of the length is hood) and just crank on the bolts a little harder.

You know what, I think I’ll stick with the “Extra Goosing” strategy. Beforehand, I thoroughly washed the head bolts themselves as well as made sure the clamping surfaces under the washers were clean – this was one area where I could see “Torque it a little more” being the cure-all for dirty or oily head bolt threads and lands.

With the head bolts secure, the worst of the storm is now history. Everything else from here on is making sure I don’t forget how to plug something in.

The task of reattaching all the random hoses and lines now begins. I moved all of the aft heater hose connections and clamps to more accessible positions that I could get at from the top only…… if, for instance, I had to run back in here shortly.

Some of the more snowflakey connectors had to be routed through the intake manifold curve, like the oil pressure sensor harness. They don’t reach otherwise – I contemplated extending them so they could be routed around if needed, but the idea is I shouldn’t have to keep doing this, right?

Now it’s time to try and remember what my gratuitous labelling meant. I not only drew on the connector themselves, but the connector mounts and seats, and even on the cables. And even in regions where the cables had to go. I wasn’t leaving anything up to chance.


….except, apparently, where I put two of the small M6 flanged mounting screws. What? I thought I sequestered all of the hardware in little baggies with their associated parts!

Who knows – maybe I will find these screws randomly one day in the back somewhere. In the mean time, I had to sub in two of my M6 socket cap screws.

Okay, my mechanic friends were right – things really only do go back together one way.

Making the connections on the intake side now, including several vacuum lines and water temperature sensors.


After all that was complete, I discovered what is so far the only incongruity between the original Mitsubishi head and this chinesium special: The power steering pump bracket is displaced an additional roughly 2mm in offset distance from the side of the head.

Hmm. Well, it could have been worse, I suppose. This meant the PS bracket and alternator mount don’t line up with the hole they need to. This was resolved by turning the PS bracket hole into a C-shaped slot with two quick Dremel cuts.

All of the accessories and cable and hose connections were now reconnected. By this time, night had fallen again, and I elected to not repeat my mistakes and try to put the timing gear back on now. That battle was for another day.

In the mean time, before I put the thing back together, I decided to tackle an additional demon:

The exhaust manifold has been cracked since time immemorial, and it’s only gotten worse over time and heat cycles. I figured while I had everything dismounted, I would try to repair the crack as much as I could. It was cracked not only through the collector region on both sides, but also in the valley, which was going to be rather hard to reach.  And honestly, it looks like several people have been here before me – as usual – so I probably can’t make it all that worse!? I picked up some nickel filler rod for the purpose after doing some research on welding and brazing cast iron.

Oh, and my new valves came in finally.


So for now, the old head also sits at the ready if it has to be recalled into service…