Take the trouble out of troubleshooting
As I type this, the sores on my hands are healing, but the memories of a recent bout of outboard motor troubleshooting are still raw. It all began innocently enough. The motor sprang to life after a winter of disuse. The usual winterization and spring revitalization chores had been taken care of: cooling system flush, oil change, cylinder misting, new plugs, fresh filters, etc. The throaty roar of the motor was accompanied by a deep groan of my own as I watched in vain for the spray of water from the proper orifice.
It was time for Step 1 in the troubleshooting sequence. Time to sit down, have a soothing beverage and think through the situation — not just do the last thing I did to the motor, or the first thing that pops into my mind.
Upon the discovery of an engine problem, I have the tendency to think the worst: The water pump has died; the engine is hopelessly corroded; I’ll need to replace the entire cooling system! In the end the solution is often some minor problem I overlooked.
Step 2 — now that I’m calm, cool and collected (right?), I start with the small, easy stuff. I find that this step solves the problem 90 percent of the time. For example, cooling problems are usually caused by no water or a plugged strainer, tube, or passage taking the water to the engine. With inboard engines, a lot of cooling and pump problems are caused by closed seacocks, plugged raw-water strainers or crud somewhere in the cooling system.
Gas engines not starting can usually be traced to the kill switch in the off position, lack of gas reaching the engine or dirty spark plugs. Get all three sorted out and the motor is very likely to start.
Diesel engines have similar requirements, except the spark plugs aren’t there. Instead spark plug problems are replaced by air leaking into the fuel system. Bleed the fuel system if in doubt.
Both types of engines can be crippled by a lack of electricity either causing no action on the part of the starter or a slow turnover. Frequently this can be cured simply by cleaning the contacts on the battery cables, at both the engine and battery ends.
These are just a few examples of simple problems that can look like big ones. If you eliminate the small stuff, which is really the important stuff, then it is safe to proceed to Step 3, but only after revisiting Step 1. In fact, Step 1 takes precedence over every other step. Don’t just do it &mdash think it over first.
Step 3 is where you might have to do an extended Step 1, depending on your experience and your knowledge of the engine. I pull out the shop manual, read outboard troubleshooting books, and mentally work my way from one end of the system to the other. It’s often a good idea to sleep on the problem so you can approach it with a fresh outlook. A good night’s sleep should always be in your toolkit.
Let’s take a common problem and work it through step by step. Outboard motor cooling starts with the water from the outside getting to the inside of the water pump. Ask yourself if the strainers are clear. Is the passage to the pump clear? If that all checks out, think about the water spinning around in the pump with the impeller, and then visualize it shooting up the long tube from the lower unit into the cylinder head. The water then circulates around the engine through the thermostat and the cooling passages, before some of it shoots out the little bypass orifice and some of it comes out with the exhaust.
This thought process often helps me visualize where the trouble spots might be and what the easy ones are to check &mdash remember, always do the easy stuff first.
In my overheating outboard problem, I pulled off the thermostat cover to see if water was indeed coming from the ocean through the pump, up the little tube and into the cylinder head &mdash it wasn’t.
Aha, I thought! It must be the water pump, which I had neglected for several years. Unfortunately, outboard motor water pumps are buried deep in the lower unit, requiring removal of the engine from the boat’s transom and possibly a difficult disassembly if the lower unit has not been taken apart for several years. The Aha! was a mistake on my part.
This brings up Step 2 again &mdash never assume it’s something difficult if you have not tried easier options. After I pulled the motor, struggled to get the lower unit off, replaced the water pump, and restarted the engine, there was still no water coming out of the proper holes! Back to a relaxing session of Step 1 before proceeding.
Step 4 is the classic back-to-square-one maneuver &mdash in other words, reassume it’s something simple, because that’s what it usually is. Revisit everything you’ve done up until now, and mentally work through each step to see where you probably screwed up. Yep, as painful as it is to admit, I frequently botch the repair in some insanely simple way. Common problems include not tightening something down, forgetting to reconnect something, reconnecting something in the wrong way, or leaving something out of adjustment. The more complicated the process, the more opportunities to get it wrong.
In my case I revisited Step 3 and decided to investigate where and when the water was stopping on its tortuous path to the engine and eventually to its escape through the little orifice.
This led me to the idea of using gravity to see if water poured into the top of the engine through the thermostat hole would come out the bottom through the water pump. It did, meaning that at least some of the engine passages were allowing water to circulate. So if water could get down the tube, it should have been coming up the tube from the pump, right?
Following the path envisioned in Step 3, I once again checked everything from the outside water grates right up to the pump, which had already been rebuilt. Taking apart the pump &mdash again! &mdash I discovered that an itsy bitsy part called a Woodruff key (I pity the poor guy it was named after) had somehow fallen out when the impeller was slid over the shaft, therefore allowing the shaft to turn but not the impeller. No impeller turning &mdash no water!
So everything went back together and I started her up &mdash a process that took hours longer than it took me to type this sentence. No water from that little orifice! Remember Step 1. Repeat. You’ve really got to believe in it.
On to Step 5, which is a repeat of Step 3, but using the knowledge gained so far. I had eliminated all water blockages from the thermostat to the outside world. I took off the top of the thermostat and observed water shooting out of the top of the engine when it was cranked over. However, that water was not traveling the few inches through the engine cooling passages to the water outlets. I also took off the cooling tubes running from cylinder head to the outlets and blew through them to make sure they weren’t plugged. Then I knew there had to be a blockage somewhere in the cylinder head.
Unfortunately, reaming out the various cooling passages can be a time-consuming chore due to the disassembly required. On my outboard I had to take off the valve cover and cylinder head, along with various other tubes and fittings, to find the places where salt and crud had physically blocked the small passages. If faced with this task, play relaxing music, and make sure there is no one around to displace your anger on.
Once I had completed sufficient disassembly, the clogged arteries became apparent and I surgically (with a small screwdriver) removed the obstructions. Reassembly generally requires new gaskets, though I have always had good luck salvaging old gaskets using gasket compound &mdash do as the manual says, not as I do.
If Step 5 indicates a Herculean task ahead, it may be a good idea to take an extended Step 1. It is always better to have twice the time available you think you’ll need. If you’re rushing you’re bound to need another Step 4 &mdash unscrewing the screw-ups. It’s also wise to do a long Step 3 to make sure you’ve thought through all the tools and problems you may encounter. Will you need replacement parts? Will you need special tools? Will you need help moving something heavy? Will you need extra lighting? Will you need shore power?
That’s it. Break down your outboard breakdowns into five logical steps that keep you focused on the simplest possible solution.
John J. Kettlewell is co-author of The Intracoastal Waterway Chartbook: Norfolk to Miami and The Intracoastal Waterway Chartbook: Miami to Mobile.