Yanmar 2GM Won't Fire - Troubleshooting

[Compass790]

Check that your pushrods aren't bent.I did that in mine putting too much oil in trying to get it to start, water will do the same thing. Just hammered pushrod straight in vee-blocks. But agree with other suggestions if they aren't bent. Full throttle, dash of oil in bore, hot air dryer in intake & maybe crc.

[seabreez]

Originally Posted by Guy

I would keep trying before tearing it apart. You have allready scraped off the loose rust so not much harm from getting it started now. If it has compression you should be good to go. Give it a shot of starting fluid. It it fires you know you have fuel problems.

Last week I started a Lister Diesel 2 cylinder that was parked in the rain for 7 or 8 years and has the same setup as a Yanmar for injectors and I had to bleed the lines and filter and it started and ran rough at the beginning and settled down after 10 minutes of run. Yes I used starting fluid at the beginning and now starts on it's own. If you have white smoke... this is normal, it is warming up the moisture that it is steaming... it will start... use the proper staring fluid for the start. Open the throttle a little, do not worry about over reving it... if it starts throttle back until it idles on it's own. Once it starts you will probably notice it will spew out oil out of the exhaust for a bit. The rings are not seating right... there is a cure for this without taking anything apart. DO NOT take anything apart except bleeding the lines. Compression wise if the compression was able to pop out an injector... I would guesstimate that compression is good. As far as getting a hydrolock of water and thinking that you bent rods... discount this for now... Good luck in trying and keep the posts up so that I can help a little more...

[seabreez]

When you spay starting fluid, assure yourself that you do so when the engine is turning over... to prevent pre-ignition...

[seabreez]

Originally Posted by Evan Burkosky

Looking for help troubleshooting my old raw-water cooled Yanmar 2GM. Here are the symptoms and circumstances so far:


Hypothesis:
- Hand cranking with raw water intake open allowed water to enter cylinders.
- After sitting for 8 months water seeped down past rings and gathered in crankcase.
- Resulting corrosion resulted in at least one seized piston.
- Top end corrosion resulting in improper injector and/or valve operation leading to lack of combustion.

Based on the above circumstances and symptoms does this hypothesis sound accurate? What are the next steps to diagnose? I plan to remove head and thoroughly inspect and clean, then re-install with new head gasket. What should I watch out for? Boat is on a mooring, very far from the nearest mechanic, and I'm operating on a tight budget.

Appreciate any help!

Last week I started a Lister Diesel 2 cylinder that was parked in the rain for 7 or 8 years and has the same setup as a Yanmar for injectors and I had to bleed the lines and filter and it started and ran rough at the beginning and settled down after 10 minutes of run. Yes I used starting fluid at the beginning and now starts on it's own. If you have white smoke... this is normal, it is warming up the moisture that it is steaming... it will start... use the proper staring fluid for the start. Spray starting fuid only when the engine is turning over... to prevent pre-ignition... Open the throttle a little, do not worry about over reving it... if it starts throttle back until it idles on it's own. Once it starts you will probably notice it will spew out oil out of the exhaust for a bit. The rings are not seating right... there is a cure for this without taking anything apart. DO NOT take anything apart except bleeding the lines. Compression wise if the compression was able to pop out an injector... I would guesstimate that compression is good. As far as getting a hydrolock of water and thinking that you bent rods... discount this for now... Good luck in trying and keep the posts up so that I can help a little more...

[mowerandy]

As others have said, suggest you do not pull down just yet. Give it a good blast of Ether (Aerostart, or if in Oz, "Start-ya-bastard", or similar) while cranking at low throttle. Full throttle if it starts to pop. In my single cyl Yanmar it doesn't even sound like its firing - more like someone tapping on the block lightly with a hammer, but you can hear the revs picking up.
If it doesn't pop, of commence running after two or three attempts I guess I would compression check next. If it does start expect it to be rough at first while (hopefully) your rings reseat and valve seats clean themselves up a bit. If it stays rough, a compression check is probably next. Likewise if it still needs ether to start again after running for 10 minutes.
Good luck!

[boatbod]

GM series engines usually need around 400 psi compression before they will light off on their own. Several things can cause lots of compression;
- hydrolock (cranking against a cylinder full of liquid) causing a subtly bent rod.
- corroded rings
- sticky valves

Based on your description you could have suffered any one or more of these conditions.

Measure compression.
Perform a crush test (measures gap between piston crown and head)

Check if the numbers are within spec and proceed accordingly.

[seabreez]

Originally Posted by boatbod

GM series engines usually need around 400 psi compression before they will light off on their own. Several things can cause lots of compression;
- hydrolock (cranking against a cylinder full of liquid) causing a subtly bent rod.
- corroded rings
- sticky valves

Based on your description you could have suffered any one or more of these conditions.

Measure compression.
Perform a crush test (measures gap between piston crown and head)

Check if the numbers are within spec and proceed accordingly.

I think you mean "loss" of compression... Anyway GM diesel are two stroke and start much easier than four stroke. There is injection every time the piston reaches top dead center. They have less compression than four stroke engines.

[Wotname]

Originally Posted by seabreez

I think you mean "loss" of compression... Anyway GM diesel are two stroke and start much easier than four stroke. There is injection every time the piston reaches top dead center. They have less compression than four stroke engines.

Err... we are discussing the Yanmar GM series which are 4 stoke engines, not 2 strokes.

[seabreez]

Originally Posted by Wotname

Err... we are discussing the Yanmar GM series which are 4 stoke engines, not 2 strokes.

Oups... my mistake... I deal in a lot of different types of diesels... I misread it... Thanks for keeping me inline. Roger

[Evan Burkosky]

Great advice everyone, thank you very much!

Away from the boat for a few days but here are the next steps planned when I can get back out to her:

- ensure battery fully charged and starter cranking at proper speed.
- will purchase ether based starting fluid and spray into air intake while cranking over at medium throttle after first cranking over a few times at low throttle.
- if she still won't fire will undergo crush test by removing injectors, inserting soldering wire into injector inlet (attempt to bend at 90 degree angle) to get a rough measurement of piston head to combustion chamber clearance.
- if visible gap or any difference between cylinders will assume rods are bent. Will open seacocks, take dinghy to shore, and stand solemnly with hat over heart as she goes down. (Kidding) will save up till I can afford to get a tow to nearest marina with a lift and pull engine for bottom end rebuild.
- if no visible gap but still won't fire will pull pushrods to check for any bend
- if pushrods straight will pull head, clean, and re-diagnose

I'll report back after I've tried the above steps.

[jimbunyard]

Originally Posted by Evan Burkosky

Great advice everyone, thank you very much!

Away from the boat for a few days but here are the next steps planned when I can get back out to her:

- ensure battery fully charged and starter cranking at proper speed.
- will purchase ether based starting fluid and spray into air intake while cranking over at medium throttle after first cranking over a few times at low throttle.

Good plan of attack, but I would make the following small (but crucial) changes.

Do not continuously 'spray starting fluid into air intake while cranking', you can cause serious damage by doing so.

Do not use glow plugs (if you have them) while using ether.

A short puff of ether into the intake manifold, before turning the engine over, will not cause any problems and will prevent getting too much into the combustion chamber; the natural induction will pull (roughly) the right mixture for combustion into the cylinder.

Do not use any throttle until the engine fires, doing so defeats the purpose of spinning the motor over in a no-fuel mode, which is to dry the cylinders out. The engine will actually run on short bursts of ether and no fuel, but as soon as it starts to 'catch' gradually open the throttle...

Best of luck with it.

[svsputnik]

I had a very similar problem last year, where I got water flowing in back in the head and sitting there for the whole winter. Compression on one of the two cylinder tested below 200psi and the problem turnout to be sized piston ring. The "good" news is; it ain't so complex to fix by yourself. I did it even though i didn't know what does a spark plug does (and that there's none in a Diesel engine). So that gives you an idea of how little I know before starting that. The bad news is; gaskets can get expansive quickly. Do not hesitate to ping me if you need info / have questions; it still fresh in memory. (I have a 2gm20f-yeu)

[Evan Burkosky]

Right, so just a puff of ether based starting fluid into air intake, then try cranking with no throttle at first, see if she fires.

svsputnik - Very keen to hear your experience with replacing that ring in your engine! Could you describe the process here for posterity in case anyone else has the same problem and finds this thread?

Was it necessary to pull the engine out of the boat in order to replace the ring, or where you able to do it in place?

[JohnAsk]

Before using the ether I would make sure the battery is charged to full capacity. Throw both decompression levers to the no compression position, throttle lever full open. Crank the engine, then as its cranking move one lever to compression and then the other. She should fire. These are pretty old school engines - if you have fuel and compression she should run. To check the injection timing you need to remove the starter to see the timing mark on the flywheel. Number 1 cylinder is the one closest to the flywheel. Remove the injector and fuel line, put the throttle halfway, rotate the engine by hand and fuel should start bubbling out of the top of the injection pump for no 1 cylinder just before you get to the timing mark on the flywheel 1T. From your previous posts it would appear that you do have compression and the nozzles are spraying and not dribbling. Fine cone shaped mist is required.
Good luck
John

[svsputnik]

Originally Posted by Evan Burkosky

Right, so just a puff of ether based starting fluid into air intake, then try cranking with no throttle at first, see if she fires.

svsputnik - Very keen to hear your experience with replacing that ring in your engine! Could you describe the process here for posterity in case anyone else has the same problem and finds this thread?

Was it necessary to pull the engine out of the boat in order to replace the ring, or where you able to do it in place?

Yes, removing the engine from the boat is almost mandatory, unless you have tons of room in yours. Once I got a compression tester on hand and got the bad reading, I suspected either a bent connecting rod or a problem with the piston itself (either the rings or the piston head that could have cracked). To remove the pistons, you need to remove both the engine head and the oil pan. In order (let me know if you want more info):

- Take 200 pictures of everything (thrust me, you'll be glad to be able to see how it was when in doubts. And you'll doubt!)
- Remove the mixing elbow
- Disconnect the electrical harness
- Disconnect stop, throttle and transmission cables
- Disconnect prop shaft
- Disconnect the diesel lines (intake & return)
- Disconnect the water line
- Disconnect the engine of the mounting blocks (at least, that's what I did. I figure out it would be easier for props re-alignment after)
- Get the engine out of the boat
- Get a beer or two
- Get a shop manual and go through all the steps a few times in your head
- Remove the raw water pump
- Remove the engine head (I had to remove the heat exchanger and a few hoses, but I'm guessing you won't need)
- Remove the oil
- Remove the oil pan (that took quite a while for me. The whole thing was stuck forever there. I finally found a small lip on the front of the engine where I've been able to pry it open with a screwdriver
- Remove the connecting rod bearings
- Use a soft mallet handle to push the piston up and out of the engine block. Be very careful on this step. Mine jammed before getting out and I had to "more than gently" tap it out of there, which resulted in denting the bearing. So I had to change them (80$ CAD...)

At that stage, I then brought :
- the head to get it check for flatness & cracks. I chose to get it re-machined (i had a bit of corrosion due to the hydro-lock) (300$ CAD)
- the pistons to get them check for cracks and connecting rod to make sure they weren't bent (they weren't, which was a real surprise) (100$ CAD)
- The injectors to get them check (50$CAD). One tested positive, so they cleaned and rebuilt it (200$ CAD).
- The mixing elbow to make sure it wasn't corroded (It wasn't. They both inspected with a camera and tested it under pressure. 20$ CAD)
- The push rod (all good. they didn't charge me a dim. Probably per pity)

Since everything was in pieces in my basement, I decided to rebuilt it with new gaskets. Now, I understand that some people will say that it's not always necessary. I was on the "let's save money" side of the thing when I started the project. However, after getting that thing down the basement with a friend, I change side to more of a "I'm never bringing that thing back in those stairs, so let's make sure it will start once I put it back in the boat" type of mentality! So, I bought, new :
- head gasket
- oil pan gasket
- heat exchanger gasket
- hoses for the heat exchanger that were very supple
- mixing elbow gasket
- connecting rod bearings
- pistons rings

All in all, I spent 800$ CAD for the rebuilt. That includes the machining time, the parts, the manual and a torque wrench. The mechanic shop had the whole procedure estimated to 10 hours (125$CAD/hour) + parts. So more than half the costs in savings.

If you want to know more about something / want to know the steps for rebuilding it after, let me know: that will be my pleasure.

Disclaimer: I am no mechanic guru or anything. So if somebody want to correct me or chip in, be my guess!

sam