For all those who noticed,
and as usual all those who didn't, we've been away for the past several weeks, to various points
around the globe, all of them within the continental U.S. however. Most of our travel was
work-related, but some of it wasn't, and in either case none of it allowed us to enjoy tinkering
with and/or driving our Locost, and reporting on it here. But all of that changed last Saturday morning when we woke up in our own bed, went out to
the garage, climbed in the car, and fired it up after just half a dozen tries.
Hiding in the parking lot at work
Since then, the car has started easily on the first try, and we've gotten back to our regular
commute, the weather cooperating beautifully, and recent distributor and valve repairs apparently
holding forth after five weeks sitting around unused in a cold garage. The car needs a tune-up, as
it usually does, and it's still pretty loud, and it goes through a quart of oil as fast as it ever
did, but none of that detracts from the driving experience, or the joy of seeing the Locost nestled
among the giant SUVs and pick-up trucks in the company parking lot.
Shift knob missing functional Lotus badge
As a further treat, we've also gotten back to tinkering with the car. We replaced a broken pedal
spring, installed a new fuel filter, and fixed our fancy wooden Lotus shift knob. A few months ago
we somehow lost the miniature Lotus badge that came with it. The missing badge had little effect on
shifting, but the knob looked kind of sad with a hole in the middle. Searching online, we found the
source of these badges, a company on eBay that sells automotive-themed tie tacks. After clipping
the pin off the back, the tie tack pressed in easily with a handy bench vise.
Lotus tie-tack a perfect press-fit
The other bit of tinkering involved our Locost cooling system. For awhile now we've been thinking
that two burnt exhaust valves in two years might be trying to tell us something, and not something good.
We've long believed that our makeshift cooling system has not been providing a lot of relief for our cylinder
head, due in large part to the radiator sitting lower than the engine. We've explained the problem
in the past, and mostly ignored it, or ignored it altogether, but now, two crispy valves later, we
had to start thinking about what we might do to fix it.
The highest point in virtually all automotive cooling systems is the radiator header tank. Air in
the system, which can be hundreds of degrees hotter than the coolant itself, or maybe not hundreds
but certainly hot enough to allow valves to burn, will rise up through the cooling system and find
its way to the header tank. This air (a.k.a. steam) can't do any harm there, because the radiator
is designed to take it. If the header tank pressure gets too high as a result of the heat, the
radiator cap, conveniently located nearby, has a built-in relief valve.
Moroso tank in its old useles configuration
In our Locost, the radiator is lower than the engine, because the car doesn't have any places
higher than the engine, at least for a radiator. When we first built the car, we mounted a Moroso
catch tank on the firewall, slightly above the engine, and tried to make it work as a header tank,
but coolant kept spewing out of it, and so we had to demote it back to a catch tank. Of course the
spewing wasn't due to using the catch tank as a header tank, but rather to our limited knowledge of
MGB cooling systems, which we've hopefully improved upon since then. Hopefully.
After considerable thought, we eventually realized the mistake we made with our early header tank
attempt, and decided what we really needed was a simulated heater. The heater in an MGB sits high
up on a shelf at the back of the engine bay. Coolant is routed to the heater from the side of the
cylinder head, and exits from the heater to a branch in the lower radiator hose. This seems to work
just fine in an MGB, with minimal effects on engine cooling, and unfortunately also minimal effects
on cockpit temperatures, although that's not a concern for us.
Giant heater installation in an actual MGB
The heater from our donor car is far too big to fit in the Locost, but our Moroso catch tank,
dented last year by an exploding intake manifold plug but still serviceable, is much smaller. It
also has hose fittings similar to those on an MGB heater. So all we needed to implement our plan
was a couple of parts, an MGB radiator hose with a heater hose branch, and a fitting for the hole
in the side of our cylinder head. We actually had a fitting like that two years ago for our header
tank attempt, but then we took it off and stashed it somewhere. And then we moved.
MGB heater valve normally goes here
Fortunately we never throw anything away, and after a lengthy search we eventually found the
fitting in a box labeled 'M.G. parts', of all places. As soon as our new radiator hose arrived, we
installed everything in less than eight hours, most of that spent cleaning spilled coolant off the
garage floor. We routed a new hose from the cylinder head to the smaller NPT fitting on the Moroso
tank, a second hose from the larger NPT fitting to our new radiator hose, and as far as the cooling
system is concerned, the Moroso tank is now just another ineffective British heater.
Pipe mounting clips slightly longer than stock
We wanted to use the original MGB heater pipe between the header tank and radiator hose, because a
fixed metal pipe in this location seems like one of the rare things M.G. got right. But the pipe
bolts to the valve cover, and trying to fit the hood (bonnet) over the installed pipe was an
unpleasant reminder of the many similar clearance issues that plagued us during the build. In this
case, fortunately, it turned out to be only a minor impediment, way down on Locost clearance issue scale, and all we had to do
was extend the mounting clips a bit, or slightly more than a bit, and we were good to go.
Our new cooling system allows us to add coolant through the cap on our simulated heater, a.k.a. Moroso coolant tank. This
is a vast improvement over our previous system, and it let us eliminate our old and unloved
filler pipe that extended from the thermostat housing and threatened to break loose every time we removed the
cap. Of course you don't fill the cooling system in a real MGB through the heater, but so far it's
working, and whenever we check the coolant level, the header tank is always close to the top, and
more importantly, higher than the top of the cylinder head.
Heater hose plumbed to new radiator hose branch
Of course the Moroso tank is now under quite a bit of pressure whenever the coolant is hot, something it hasn't
really experienced before, but it seems to be handling it okay, and may have even been designed for it. The filler relief valve dumps into
a plastic overflow tank, which doesn't appear to be in immediate danger of overflowing, and actually is
empty right now. With all of these changes we're not sure our cooling system cools any better than it did before, but the
temperature gauge reads about the same, and we no longer worry about the valves, although we
probably should.
Right now we're just happy that everything on the Locost appears to be working, even if it only
means the car is momentarily between repairs, and could fall apart at any moment. We'll see how it
does this summer, and how cool it runs in the Sacramento heat. We have many exciting events planned
for the coming months, including several drives with the local British car club, a trip or two to
Monterey, and the Bay Area Maker Faire again in May. We'd like the car to be running for most of
these.