FI and what happened after

The time spent since the excellent moment when I got a cough out of the engine showing that it was not dead entirely has been quite full. I've managed to find new challenges and discover why mail-order is not always desirable.

First was the Fuel Injectors. I can have the four vintage ones cleaned for $80 shipped. That is assuming I'm willing to wait six weeks for the round trip AND that all four of them are salvageable. This is instead of paying $175 EACH for Bosch replacements.

I cheaped out: I mail-ordered GP Sorensen from Autozone and got away for $103. Or thought I had.

It turns out that these clowns do not ship the $0.01 cost o-ring seals with the injector, the way everyone else does. (Who sells new injectors and puts old seals on them? What fat head at Autozone thought this up?) So after getting the injectors, I discovered that the seals were missing. I ordered the seals for $3 and then enjoyed the indignity of paying $6 shipping while waiting another week for them to show up.

Type4 engine on an assembly stand with the engine mantling removed.
Here you  can see the considerable angle that each of the plugs sits at.
The hole in the mantling to access them is directly OVER them, rather than
on axis with the plugs. NOT a friendly design.

I returned to the bus feeling pretty burned, but decided to complete the installation of Autolite copper core plugs. This is when I learned about the tendency of the Type4 engine to 'eat' spark plugs. The engine mantling which holds the pressurized air over the heads and cylinders stands off quite a ways from the top of the engine. As in, 4+ inches at the rear distance between the top of the mantling and the top of the heads. That's a long way to reach into a blind cave with a spark plug dangling from a 13/16 socket. Then you must get the socket over the existing plug blind (because the plug hole is only big enough to admit the socket.) The final coupe de grace is that the plugs do not fit in straight down, but at an angle, in two axis of rotation.

With this is stack of difficulties arguing against the owner, it is no surprise that these engines often go for 100 thousand miles without a plug change. It's just too much of a headache. But I needed the plugs out for other reasons: with the plugs out, this is how I'm going to test the compression of each of the cylinders to see if I have an engine or a slag heap. Having removed the injectors preparatory to replacing them (when the seals got in) I decided to tackle the #3 (forward, left) first, since it is farthest from the cooling and and the state of its plug can tell you the most information in the least time. With a lot of digging and grunting and maneuvering, I got the socket on to the plug and it clicked loose from its bore and came out. I pulled it up out of the bowels triumphantly and got the shock of day: never mind how the plug looked (carbon fouled, no surprise) what the hell is that sleeve around the plug!?!

Oh, dammit. When some ape with an impact wrench (or just no sense) stuffs a new plug into the bore and cranks down on it to a dying strain, bad things are going to happen. In the case of the VW engine, the heads and case are an aluminum-magnesium alloy; light, strong, dissipates heat well...and soft. Well, soft compared to carbon steel threads on spark plugs. So you had better not cross-thread a plug when installing it: the softer alloy of the threads in the bores won't stand a chance.

Remember what I just said about what a nightmare these engines are to change plugs in? Your chance of cross threading them is very high, and your visibility poor. When the threads in the head bore are ruined, your combustion chamber won't seal, and burning gasses escape under pressure. As the engine heats up and expands, the fit around the plug becomes looser until...FOOM! You shoot the plug right out of the head. When I was twenty, I had a 1971 Super Beetle which had this fault; someone in its past had been too zealous with the wrench and ruined the threads. That engine spat up a spark plug about twice a week, because at the time, I didn't know that there was anything that could be done about it.

Above is the classic Helicoil, a stainless steel wire wound into a coil.
Below is the time-sert, a solid insert with threads on the outside
(to bite into the head) and threads on the inside to hold the plug.
Helicoils are classic 'field repair' tech, but time-serts are Mil-Spec
inserts and designed to last the rest of the life of the engine.

Enter the Helicoil. This is a dingus that looks a little like a wound spring made of very thin, hard metal. You twist this down into the bore and then thread the spark plug in after it. This makes the helicoil cut into the sides of the bore, locking the plug in place. A helicoil is fine...for a temporary field repair. But it can never properly guide a plug into place.

The super-duper improved version is called a Time-sert, which does the same thing only more expensively and more permanently. The Time-sert is a precision cast insert that looks like a sleeve with threads on the inside and outside of the sleeve. Using special (and expensive, for a single use) tools, you drill out the bore removing the original threads, then use a second tool to cut new threads, and then use a third tool to drive this self-locking sleeve into place. When complete, an engine with Time-sert inserts in the head probably is more durable and resistant to cross threading than when it came from the factory.

In this case, however, the portion of the time-sert which had locked into the head had failed when I tried to remove the plug. Instead of getting the plug, I got the whole assembly, plug AND time-sert. I couldn't put the plug back in; the business end looked like it had been painted with coal-tar. The goo had clearly made its way up the threads and glued the plug to the time-sert, which is why the time-sert gave up its hold on the head first.

So either quit now, buy a new head (no!) or find some way to put a time-sert BACK into that hole, and make sure it STAYS there. I opted for the third option, and did so with the intention of being a cheap skin-flint about it. I was NOT going to buy the whole tool kit to prep the bore for a time-sert. The bore was fine. Also, there was no practical way to perform the work when the engine had its mantling on it, which means pulling the engine and stripping it. Too much time / headache / hassle. So I traded out the mild steel time-sert which had come out of the head for a new copper time-sert (the better to match the aluminum-magnesium alloy of the head with) and some Loctite 266.

If you're thinking that Loctite isn't going to last long at 400*F (the operating temperature for this head) you'd be right...normally. However 266 is the industrial strength extreme application Loctite. Once it cures, it won't let go or weaken until it passes 600*F. I'm not too concerned about that: the head would be a pile of slag if it  hit that temperature, and the Loctite 266 is only to hold the time-sert in place and not let it rotate out of the bore.

So more days waiting for time-serts and Loctite. None of these parts are available locally, so I was forced to mail order. (Really? 10 miles from Philadelphia, 70 miles from New York City and I can't buy this stuff at an automotive outlet? Nope.) When I received them, I lubricated a 'short' Autolite plug (only 13mm of threads) and screwed the copper time-sert onto it as far as it would go. Then I carefully added light beads of Loctite 266 to the outer threads, and carefully screwed the plug into the bore with my socket. Snug-and-add-a -tug. Then I backed out the shorty spark plug I had used to seat it, leaving the timesert in place.

With the time-sert in place, I waited 24 hours for the Loctite to set. Finally, I installed the correct Autolite 455 copper core plug with a 19mm reach on the threads.

That's one lousy plug replaced. Next time, I'll tell you what I learned about the other three, and how this engine develops an appetite for plugs and tools.