An M.G. Locost Build

November 28, 2013

We're still waiting for our official SPCNS certificate to arrive in the mail from Sacramento. But we're not in a hurry. We have permission from the state of California to drive the car whenever we want, at least through February, and we even have insurance coverage. So now we're just looking for excuses to drive.

  Closest we can get to trunk cover with a camera
click to enlarge

We installed all the snaps on our vinyl trunk cover last weekend, and glued on genuine Velcro(R) hook-and-loop fasteners to keep everything from flapping around too much on the freeway. So far so good, although something still needs to be done about the sewing job on the holes around the roll bar supports, which look truly unfortunate if you get too close, or even if you don't. Despite that, we think the vinyl cover looks better than the open wiring in the trunk, and the uneven row of exposed rivets around the perimeter. Although not a lot better.

We also laid up our fiberglass hood scoop mold last week, and that looks even worse, but it's just a mold and not the actual scoop so there's hope. We'll patch it up as best we can and see how it turns out. In any case we can't worry about any of that now, because we have a more important project to take care of, and that's getting the cooling system to work better. We've found on our longer drives that we have to take it easy to keep the car from overheating, and we've also found that we don't like taking it easy.

Hood scoop mold actually looks worse in person  
click to enlarge

The donor ran hot too, but we didn't worry about it back then because we figured it would magically fix itself when we installed everything in the Locost. We're not exactly sure why that didn't happen. Possibly the radiator is bad, so we're looking into new radiators, and we have a couple of options on some aluminum models with big cores and extra cooling capacity. In the meantime we've taken a couple of measures so that when we do overheat, we won't embarrass ourselves (again) by dumping our expensive antifreeze all over the street.

We've long known that our radiator sits too low in the car. In every other automotive cooling system in existence, the radiator header tank is the highest point in the system, so if you lose coolant the header tank takes on a little air and steam, and the water jacket stays full. The Locost cooling system isn't like that. If we lose coolant, air and steam fills the cylinder head, where it just sits there and watches the valves fry. It's not quite that bad because the water pump still gamely forces coolant into the head. But it's bad.

  New tank takes over header duties from radiator
click to enlarge

So we bought a new aluminum tank from Summit Racing, and we mounted it as high up in the car as we could, which is not very high but still slightly higher than the cylinder head. We routed this tank to the heater outlet on the head, which involved a lot of cutting, grinding, and welding, which we managed to do without breaking anything, although as usual it's not pretty. We then routed the radiator overflow to the new header tank, because the tank has an extra inlet fitting, and the radiator overflow had to go somewhere.

So it's a little complicated, and also a little weird, but we should be okay so long as the coolant continues to circulate as usual. The important thing is, coolant can't get out, except possibly from the header tank pressure cap, which we'll eventually hook up to a plastic overflow tank, which will catch anything the header tank loses, and possibly put it back when everything cools down. We actually had a car like that once, seperate radiator, header tank, and overflow tank, all shiny stainless steel. That car overheated too.

Bad filler  
click to enlarge

By far the best thing about rearranging our cooling system is that we got to get rid of our stupid remote coolant filler pipe. We originally installed the remote filler because you can't check the coolant level at the radiator, because it's too low and all of the water would spill out. For pretty much the same reason you can't add coolant to the radiator, so the radiator is basically useless for anything other than keeping the coolant from getting too hot, which by the way we now know it doesn't do all that well either.

But the remote filler had it's own problems, not the least of which was sticking up out of the hood like just about everything else in the engine bay. It also required a heavy-duty 21-25 lb. pressure cap that was impossible to remove and replace, it added weight, it stretched the upper radiator hose well beyond anything you'd consider normal, and it wasn't well supported so it was eventually going to fail of its own accord. So getting rid of it was almost worth the $90 cost of a new header tank all by itself. Although not quite. Maybe half of that.


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