My Yanmar 2GMF has been starting and running fine all summer but over the past couple of weeks it seems to take much more cranking before it starts when cold. Once it starts it runs fine both under load and at idle and when I shut it down and start it again it starts right up. There are no exhaust problems, no knocks or clicking. I have not checked for water in the filter but if that was the problem then it would not run well under load. I am wide open for any ideas on what the problem may be. Reg
Cold start problems
- Thread starter Reg M
- Start date
You didn't mention how many hours you have on the Yanmar. On one of our previous boats we had a similar hard starting issue that was eventually traced to compression issues. The valves and seats had a corrosion issue caused by water coming back in the exhaust (which we didn't know about). It got progressively harder to start, especially when cold because it had lost just enough compression so as not to fire right up when cold. A local diesel shop fixed us up over the winter. Not 100% sure that is your problem of course, just adding two cents. We have a mechanic in the yard next to our club that really knows his stuff.
Yanmars, without glow plugs, seem to be cold-hearted beasts. When the weather turns cold, I put a hair dryer up next to the air intake on my 30 yr old 2GM20F. The engine thinks it's mid-summer and starts right up. Give that a try.
Diesel fuel starts as the air/fuel mixture is ignited by the heat produced by compression. Upon start up compression is built up by successive revolutions. Every time the exhaust valves open in a revolution you are loosing previously built up compression so a certain cranking speed needs to be maintained for positive compression build up. Cold weather thickens oil and reduces battery power which can cause the engine to turn slower requiring more time to build up compression. It helps to open the throttle while cranking as it creates a more volatile fuel mixture. (fuel burns but air does no, a higher concentration .......). Your problem could be engine wear (piston rings, valve seats, valve springs, starter, wiring .....) that over the years have reduced the ability of the engine to build up starting compression. Check the starter and the wiring for any voltage drop which could be causing the starter to turn slower. Use a multigrade thinner oil like perhaps a 10-W30 during the winter months. Check for any air intake obstructions like a dirty air filter and open up the throttle to 3/4 before cranking. This should help.
The boat is a 1984 and it is the original engine. There is no hour meter. This is my first season with the boat and the engine has always started right away, at least until the weather cooled off so I suspect that is the problem. The previous owner apparently had the engine maintained by a mechanic and if appearances mean anything it is in great shape - looks like new, was always in fresh water and is fresh water cooled. I don't think compression is a problem as it will push the boat along at 6 knots at 3000 RPM and there is no smoke from the exhaust. This is the first diesel I have owned in northern climate, all my previous diesels were in Bermuda and the Caribbean so I never ran into this problem before Since posting my original thread I have been searching the internet and learned a bit more about it. I will try the hair dryer trick as well as a bit more throttle. I have been using some throttle but maybe I need more. From what I am reading there is a bit of technique to be learned here. I'll post the results of my next startup which will be Saturday which is haulout day.
if yours is the 2GM20F where the start key switch is on a B panel in your cockpit , 1st thing i'd check is corrosion on the back of that panel. the start switch of that outside panel often gets really corroded . figure that the volts from the engine start battery down in the hull travel up to that B panel , the key switch allows a connection to start and then voltage then has to travel from the switch back down to the starter solenoid. often the B panel connections corrode so that you're losing enough voltage to make starting very difficult. and it gets worse with time, and in cold weather. PS - you can also install a momentary start switch right next to your engine, with a short loop from battery to switch to starter solenoid, so you can start your engine when you are next to it . you eliminate the voltage drop going p to the B panel then back to the solenoid. it's also handy and beats running into the cockpit in the rain then back down the stairs to the engine to see what's going on. . .
Not the 2GM20F, I have the old 13 HP engine but the start button is on the engine control panel in the cockpit. I don't think corrosion is the problem though because the engine is turning over pretty good, it just takes a long time to start and from what I am hearing it all points to the cold weather. This boat has spent its whole life in fresh water and corrosion is not a problem. As previously stated, the engine looks almost like new and all the wiring looks good. Also, that voltage that goes from the battery to the starter does not go to the control panel first, a smaller wire goes to the switch then to the solenoid and that is not a high current wire, that connection in turn activates the solenoid which makes the connection between the battery and the starter via the heavier starter cable which does carry the heavy current. As long as there is enough current to activate the solenoid and the battery and starter connections as well as the solenoid connections are not corroded there should be no problem and I have inspected all of those connections. I'm going to try the hair dryer tomorrow rather than waiting till Saturday - my curiosity is killing me. Thanks to all for the suggestions. stay tuned.
I don't know who the mechanic was and I really don't want to bother the PO with any more questions, he has already been more than reasonable in answering a lot of questions for me but I don't think its right to continue hounding him. I'll see what the hair dryer does for now and over time I will do things like setting the valves and getting the injectors cleaned and set. I also plan to install an hour meter so that I can set up a structured maintenance schedule. Also need a battery monitor.
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The starter motor is a part that wears out over time. The bearings and brushes wear out from friction and reduce the unit capacity to push a load. If you want to check and see if your engine has lost compression on account of ring wear start it up and remove the oil fill cap, place the palm of your hand about an inch from the opening and feel for back pressure. In a new engine it will be like a steady gentle feel but in a worn engine it will feel like a thump in sync with each cylinder revolution. Most of us fall somewhere in between.
Amazing, I went down to the boat early this morning while it was still quite cold and put the hair dryer up to the air intake and hit the starter. I don't think she even turned over a full revolution before roaring to life. What a neat trick. Thanks a bunch guys, I just love this forum and all the great people who are so willing to share their experience and knowledge.
That is good news, Reg.. Don't forget the valve set.. that is the only thing besides oil, impeller, and filters that should be a regular maintenance item on your diesel.. Lots of folks ignore it and that can lead to some very costly repairs.. Yanmar maintenance schedule for your engine is to have the valves set after the first 50 hours of run time then every 500 hours after that..
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My 2GM20F with ~ 800 hrs does the same thing--starts almost immediately in warm weather months, but more difficult to start in colder weather, which I assumed was normal for these engines. My mechanic suggested in the winter months starting the engine initially with the seacock closed and then of course opening it up immediately once the engine starts. This completely took care of the problem.
Matt
Matt
I have a 25 year old 2GM20F too. The colder it gets, the more cranking needed to get it started. Never thought of the hair dryer method. I was thinking about a magnetic type block heater maybe on the oil pan.
Hair dryer works for my GM30F. I have a friend who installed a glow plug in the air cleaner - and that also worked.
yanmar does make a 12v block heater to warm the air coming in , i have one but never got around 2 installing it because it requires some diss assembly of various parts. and a hair drier is ALWAYS on board ...except when you're anchored out. (so don't anchor out without shore power in cold weather, haha...)
On my engine I turn the key counter clockwise for about 15 seconds in cold weather (heat or glow position) then it cranks fine
You actually can use a 110v hair dryer when anchored. All you need is 12v inverter. Since it only takes less than a minute to blow hot air into the intake, is doesn't use up any significant battery power. Works for me.