October/November 2011 - A Surprisingly Long Stay in La Paz
Yes, I know, I'm three months behind. Here's catching up with October/November 2011.
I only intended to stay in La Paz for a couple of weeks to deal with immigration,
get some new house batteries, and then jam over to the mainland. However,
about 10 miles north of La Paz my engine overheated. I'd been watching it
run about 5 degrees hot for a while, and had been doing little troubleshooting
exercises just to eliminate possible causes, but hadn't figured it out.
Finally, it jumped to 240F, so I shut it off, drifted for a while, and then
if I ran at 1500 RPM it stayed cool. So I limped into Marina Palmira,
pulled everything out of the back of the boat so I'd have total engine access, and pulled out the tools.
I have to mention a couple of things before talking about the engine.
You know when you're a cruiser when your glasses are broken beyond repair, and you fix them with adhesive lined heat shrink electrical tubing. Thank goodness for spare parts.
Of course, the only things that break on a boat are the things for which you don't carry spare parts. Sometimes you have to do what you have to do to get the job done.
That's pretty much what this web page is about.
My first chore in La Paz was to put in new house batteries. My Trojans were shot after only three years. Cruising is hard on batteries. Three years sounds like a short time, but I don't spend much time in marinas. A good set of deep cycle batteries can be cycled to 50 percent depletion about 500 times, and over the course of 2.5 years I've spent about 9 months of each year exclusively on the hook, using computers and a 12V TV and radar and lots of power hungry stuff. That's about 680 days on without shore power, and I have easily cycled them deep 500 times.
The old Trojans only could hold about 50 percent of rated capacity, and the cases were swollen near the bottom from material that had eroded off of the plates.
I put LTH golf cart batteries in, because that's what you can get here in Mexico. I'll watch them for a while before I form an opinion. Some people say LTH stands for "Less Than Happy" and other people say they're great. I'll form my own opinion after a couple of years.
So, anyway, I started taking the raw water and coolant systems apart, piece by piece, to see what the overheating problem was.
The raw water pump, which pumps sea water through the heat exchanger and into the exhaust system, was the first thing to check.
I replace the impeller annually, which is slight overkill but is important because this raw water pump is a royal pain in the but to work on. I have a V-Drive, so my engine is mounted backwards in the boat. That makes the transmission really easy to work on, but all the little stuff on the front of the engine is an exercise to access.
It's a Sherwood G908 pump, which doesn't have a plate on the front for impeller replacement, but requires one to pull the whole front of the pump off. Maybe it's cheaper to manufacture, but it sure is a pain to maintain, and I honestly know that I couldn't do it in a seaway with the boat bouncing around, a hot engine, and the contents of the lazarette strewn about.
The impeller was fine, but I did notice that the ceramic seal was cracked. That won't make the engine overheat, but it will make the pump leak sea water into the boat. It hadn't been leaking, yet, so I caught it in time. Fortunately I had a spare seal kit.
In the pic above you can see that the seal is pressure fitted onto the pump. Back in the good old days when I had my shop in the garage, I could have dealt with this in about ten minutes. Now, though, I spent a day looking at it, coming up with a plan. Then I spent two days riding around on my bike trying to find cheap pipe fittings that worked.
After finding plastic pipe fittings that fit inside the pump and around the seal, I tapped it into place with a bit of scrap plywood and a hammer.
This is a big part of the cruising life:
Trying to get the job done with the resources at hand.
With the raw water pump rebuilt like new and the engine still running hot, I tried the next thing. The thermostat.
Fortunately I had a spare. Using the slowly boling water test, I checked the old one, and it seemed slow to open and close, but not *too* slow. The new one was a little bit faster on the draw, starting to open at 160F and being fully open at 180F, while the old one (on the right) was clearly acting tired.
So I put the new one in, announced for the third time that I had solved the problem. But I hadn't really stress tested it.
Now, bear in mind that I'm tied up to a dock with other boats around, and the problem really only manifests itself when the engine is in gear at the higher RPMs. So testing involved making a spiderweb of dock lines, because some of the cleats here are a little weak and a boat at full throttle generates some serious force.
Anyway, when it was cool to tie her up in full bondage mode and crank the throttle while in gear, she still overheated.
Okay, so there are a few dozen things I did worthy of mention here.
Another cause of marine diesel overheating is exessive back pressure in the exhaust system. I removed and inspected the exhaust system that I built five years ago, and it was clean. I scrubbed it with a toothbrush down to metal, just to verify that there was no buildup.
And after that, I disconnected the entire exhaust system and let the water run into the bilge. That was a stinky, smokey the bear day, but it verified that there was no blockage or excessive back pressure in the muffler, or the exhaust hose between it and the outside of the boat.
So, now, it's the heat exchanger.
I didn't have a spare heat exchanger on board, so decided to clean out the old one.
For non-boat folks, a heat exchanger is the boat exquivalent of a radiator. Salt water is pumped through it, and antifreeze/coolant is pumped around the salt water. The salt water absorbs the heat, and is then dumped into a mixer elbow behind the exhaust manifold, to cool the exhaust down so it doesn't damage the muffler and exhaust hose.
After a day's search, I found an 1/8" rod at a nearby hardware store, and used it to ream out all of the little tubes. Not all of them are accessible, since there are these annoying dividers that direct sea water back and forth through the unit.
Well, that didn't solve the problem, so I 'boiled' it out using a mild solution of muriatic acid. That's a pretty weak acid, available in any grocery store with the household cleaners. It boiled nicely, so there were some mineral deposits in the raw water side of the thing.
Well, that didn't solve the problem. I started getting really fussy, and removed every hose and fitting on both the raw water and coolant systems, cleaning them and even pulling a rag through the hoses to polish the insides.
Well, that didn't solve the problem. I decided that it *had* to be a problem in the heat exchanger, so I boiled it out again with a stronger muriatic acid solution, and let it sit for a few hours.
Well, that didn't solve the problem. But, it *did* eat a hole through the inside of the heat exchanger, allowing the engine to pump all the coolant out through the exhaust.
That's when I knew I'd be in La Paz for a while.
Getting parts down here can be a challenge. Shipping is easy, but it can be a real challenge getting parts through customs, unless you bring them through yourself or have an agent who works with customs.
Lopez Page is a freight forwarder with offices in San Diego and Tijuana. They have thier own trucks making regular runs through Baja. Since I was going through this much hassle, I made up a shopping list and shipped it all to thier San Diego offices.
There were a few other things I should have bought, but didn't want to slow
down the process. It took about 10 days to figure out all the part numbers
and get the parts delivered, and another 10 days to get them from San Diego
to La Paz. The second part seems long, but I learned that the truck leaves
San Diego at the end of the week, so even though I had everything there by
Monday we still waited until Friday for the truck to leave. Hey, that was
my learning curve, not a problem with Lopez Page.
I probably would have packed a few other things into the shipment if I'd known that I had until the end of the week.
Anyway, I have a brand spanking new spare raw water pump, which I painted all nice and pretty.
Note the impeller in the pic to the left. For boat folks, this might be important. I've heard that you should remove the impeller and store it separately, unless the pump is to be installed immediately. The impeller blades are slightly deformed from being stored in the pump. Removing the impeller means that it will still be flexible when I need it.
And here's the new heat exchanger. After some internet research, I found the original manufacturer, who makes a higher quality part (Copper Nickel instead of just Copper) for a lower cost than the Westerbeke/Universal part.
I bought two, so now I have a spare. Heck, not having this spare $400 part cost me $600 in marina fees. It's just another 20 pounds of metal on the boat, lowering the waterline.
One major good thing came from sitting in La Paz for two months.
It rained twice. I hadn't seen rain in three years. Sprinkles don't count. This was good rain, that dumped a couple of inches on the boat and gave the rig a really good rinse. The boat needed it.
Sitting in the marina for two months was starting to really bug me.
Finally, the boat is ready to go.
It was time to say goodbye to my mascota. I put the elephante on the dock box with a note saying "Free to a good home" but there were no takers.
It's amazing, but this little toy had been outside 24x7 through the entire Sea of Cortez summer, and was just starting to show UV damage.
Anyway, see you next time, La Paz.
I'd stocked up for at least two weeks underway, just in case I had to hang in Muertos for a good weather window.
A good norther started to blow, so I waited it out, then the following calm, and when the next good north breeze started up, so did I.
Ah, it's good to have the sails up. I raised with a reef initially, just because it's been a couple of months and I need to get back in the groove. Once I knew the running rig was all clear, and things weren't flying around down below, I shook the reef out and settled in.
But that's another story.