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leascotia · 05-06-2016, 15:42

This is my first post but I've been a reader for a while, so thanks in advance - I've gotten lots of good tips/advice from these forums before.

I've got a Yanmar 4JH-TE that won't crank. It has never given us any problems, always starts first try. Has about 2800 hours on it. We were marina bound all this past winter (in Alaska) and I'd been running the engine about a half hour every two weeks. Well, last month I got lazy and didn't so it hasn't been run in approx 6-7 weeks. It's last good workout was probably September when it was putting in 6-8 hour days between 2600-2800 rpms.

The engine / starter just makes a really loud "clunk" noise. The crank pulley on the front of the engine turns 1/4-1/2". Engine's always in neutral when trying to start and the prop shaft doesn't move at all. Here's what I've tried thus far:

1- First thought was lack of battery / electrical. My clamp amp meter maxes out at 400a and it reads "over" - e.g. 0.L (for anyone with the Mastech). Just to be sure, I also used an emergency start battery rated for 500a for 3 seconds, and lastly also jumpered in my 800 ah house bank. Same reading on the amp meter for all. The voltage does drop but given the loudness of the clunk and that the whole engine seems to shudder I'm thinking this is just abusive to the starter motor/gearing more than anything. Not to mention we've had a low start battery before and the engine turned over slowly in that case. Fairly certain it's getting plenty of juice.

2- Tried opening the injector caps (don't think there's decompression levers on this model engine) and also turning the engine by hand. I wasn't able to find a turning bar / breaker bar to fit, so I used a 5/16" hardened bolt with a 2' cheat pipe. The bolt goes in about 1/2" and I've bent it a few degrees trying to turn the engine by hand both clockwise and counter clockwise. I can't budge it at all (not even the 1/4" the starter motor does).

The only thing I can think of next is to pull the head off, however I'm a bit nervous doing that - we're in a remote Alaska fishing town and I don't think the local diesel mechanic has much experience with Yanmars (going to talk to them on Monday anyway and see). I'm fairly mechanically inclined but haven't done any major engine work before so am worried I could easily do more harm than good. I don't have a torque wrench but could get one - not sure what else I'd need.

One last bit of info - last year I started noticing a little bit more white/grey smoke than normal. It seemed to persist even after a full day of motoring (though was less than at startup). The general thinking at the time was everything from head gasket to coolant / water getting in to something with the turbo to don't worry about it older diesels smoke.

Oil looks good from the dipstick, no discoloration and has about 80 hours on it. Was going to change it anyway so that's what's in progress this afternoon.

Can I put something like PB-Blaster or ATF in the injectors to help loosen things up or would that risk more problems? (or do nothing- I gather it takes a bit of pressure to get anything through them?) Also I assume I've put enough pressure on the crank pulley with the bolt/pipe but to be honest I have no idea how much force it'd take to turn by hand since I've never done it before.

Any other suggestions greatly appreciated.

model 10 · 05-06-2016, 16:07

You removed the injectors and it would not turn? Not sure what you mean by "caps". You cannot squirt anything through an injector. You need to remove the whole thing, then the combustion chamber is open. If you have 6 week old water in there, is should blow out.

leascotia · 05-06-2016, 16:20

Guy - thanks, yeah I didn't remove the injectors themselves - just the bolt that attaches the fuel line at the top (the operators manual suggests this for bleeding air from the engine so I figured it might help). I'm guessing without removing the actual injector it won't relieve any pressure or get water out. I'm guessing that's the best next step then which I'll start now.

That said I'm at a loss as to how water would've gotten in there since we've (sadly) been sitting dockside the whole time. I forgot to mention the engine also sat almost 2 months for Oct/Nov last year while we were out of town, and though it was a little slow to start it ran without issue (other than the aforementioned smoke).

**GordMay** · 06-06-2016, 04:21

Greetings and welcome aboard the CF, leascotia.

Badsanta · 06-06-2016, 04:37

If you over crank the motor you fill up the exhaust with water and it backs up into the motor. This causes the motor to lock up from the water in the cylinder. You would be unable to turn it over with starter or pry bar. The easiest test would be to remove the injectors and see if you can crank it. If you can turn it over and water pumps out the injector hole, thats it. If no water its another problem. Not an uncommon problem. The sooner you fix this the better. Look up hydrolocked diesel.

sailorboy1 · 06-06-2016, 04:48

Have you taken the starter off and tested it?

Captain Bill · 06-06-2016, 05:38

When you try to turn the motor by hand/with your bolt when you come up against compression in a good engine the air in the cylinder on the compression stroke will slowly drain past the rings and the engine will continue to move though quite slowly if you keep pressure on the pipe. If it doesn't continue to move slowly you have a something seriously wrong like hydrolock. If you are hydrolocked some water/collant would have leaked past the rings as well, but since the engine hasn't been turned over it will not have been mixed with the oil and the oil might look perfectly fine at this point. The water would be at the bottom of the sump, not near the dip stick. If you are changing the oil and can reach the drain bolt at the bottom of the sump you would find any water in the oil when it's drained. Getting to that oil drain bolt in my engine is just about impossible. There is an oil change vacuum line attached to the dip stick assembly on mine and it does not drain the entire sump. It appears to me to leave about a pint of oil in the sump when I drain it that way and that might not pick up a small amount of water at the bottom of the sump if you have to change your oil that way too. Since your engine has not been run the only symptom of Hydrolock I would expect to see in your oil without draining the sump is an increase in your oil level and that may not be much.

Taking out the injectors is not very hard and is probably the correct thing to try at this point. Even a novice marine mechanic should be able to handle that without a problem. I don't have a turbo but on mine the injector are only held in by a hold down clamp which is held to the head by a single bolt. Once the clamp is removed I put a wrench on the flats of the injector where the hold down clamp was and wiggled the injector back and forth just a couple of degrees to break it loose and lifted it by the fuel return tee. It's an easy DIY job if you are so inclined. I guess I assumed that since you had disconnected the fuel lines you had also disconnected the return lines but if not you'll have to remove them too.

k. michael marquardt · 06-06-2016, 08:32

As soon as possible remove all injectors, turn the engine by hand at least 10 revs.
If water shows from the injector 'hole' turn the engine by starter to get higher revs and blow the water out.
Then fill up the cylinder with clean lube oil via injector 'hole' and turn it over 20 times.
Then have an oil and oil filter change.
Refit the injectors and start the engine.
This is the cure we did regulary in submarines when we had water in the engine by leaking exhaust valves.
Then run the engine with 1/3 load for 10 minutes and have another oil and oil filter change.

But your next job will be to find the cause for the water entering the combustion space in the first place.
Did you notice a drop in the circulating cooling water level? Did the engine vaccum sea water back through the exhaust system?

**Symphony** · 06-06-2016, 09:42

that Yanmar is also famous for having a weak, thin wire from panel ignition switch to the starter, ask me how i know.

sometimes problems drive you crazy because there is more than one problem

leascotia · 06-06-2016, 10:41

First, thanks everyone for the responses. Here's an update.

Spent a good bit of the afternoon trying to get the injectors out - they're stuck pretty good. Will be putting some penetrating oil on today and trying the wrench trick.

However after having the fuel lines off the injectors for most of the day, I was able to get the engine to crank at least a full revolution with the starter (still can't budge it with my makeshift prybar.. looks like I'll need to see what else I can find). It then went back to moving an inch or so - I stopped after a few more tries not wanting to burn out the starter.

Captain Bill - your description of my injectors was better than in the service manual- I only found the hold down plate like you describe, not the additional bolt like the manual does. Additionally my drain plug is impossible to access and I pump it out via the dipstick too. Good to know - I was about to change the oil but will wait till I get the injectors out and it cranking since it sounds like a few oil changes will be in order.

Symphony - I know about the weak starter wire - mine was replaced with a relay and beefed up wire a long time ago

k. michael - no noticeable drop in coolant. Don't see how it could've syphoned seawater back in - it has a very tall vented loop in the exhaust. Also didn't notice any increase in oil level (it was right at the full mark where it usually is).

The engine does burn a bit of oil - not sure exactly how much - maybe 8oz in 10 hours or so? Is that high?

I haven't changed the coolant since I owned the boat (probably not good) - so it's been almost 3 years. No idea when the previous owner did. The color looked ok but would it be possible it's lost it's anti-corrosion properties and things are just a little rusted / corroded in there? (seems like that shouldn't affect the cylinders since the coolant's supposed to stay away from them and in the jacket right?).

From the rest of the responses, it sounds like I shouldn't be too worried about bending / breaking things by trying to turn the engine over- I'm gathering that most of the damage from a locked engine comes from if it was running (e.g. oil level too low, etc).

For possible root causes, right now I have exhaust backflow (seems unlikely given vented loop and only run in the marina) and leaking head gasket (which, given the description of white smoke in my original post, may be more likely?) Any other suggestions?

I'm working on getting the injectors out and also a local mechanic out today - it's fishing season so they're hard to come by (that and I haven't been very happy with local help up here so we'll see...).

leascotia · 06-06-2016, 12:53

Got all the injectors out. They look pretty crusty, especially #3 & 4 (I numbered them 1-4 starting with 1 at the front of the engine as I read somewhere they should go back in the same cylinder they came from).

#3 was full of water, I couldn't really see anything in the others, #4 may have had a little as well.

Good news is engine cranks no problem with the starter now (and spews water /diesel / whatevers in there all over the engine room)- if anyone's got tips to avoid that to clear the rest of the cylinders that'd be appreciated!

Bad news is I'm still not sure how it got there. Thinking exhaust back flow is unlikely (see previous comments). That leaves head gasket or am I missing something? I can't really tell if it contains anti-freeze - the anti-freeze / coolant is quite green, this doesn't look very green but again hard to tell. It also doesn't appear to be 100% diesel.

My understanding is the engine is fresh water cooled via the loop with diluted anti-freeze, which is then cooled via a heat exchanger to salt water. So theoretically the only way salt water would get in is via the exhaust.

Attached is a photo of the injectors, I'm planning on having these cleaned while they're out. I saw this done on youtube (famous last words right?) and it doesn't look too hard - anyone done this themselves before on a yanmar 4JH series engine and have suggestions? Only problem is I have no way to test them before re-installing. Going to talk to the local mechanic and see what they have to say and how much $ they want.

So questions:

1- Thoughts as to root cause?

2- Cleaning the injectors - do it myself or take it in?

3- If I'm replacing head gaskets, is this something I could tackle myself with basic mechanical skills or is there a high risk of me doing more damage? Do I need anything more than a torque wrench and basic tools?

4- Anything else I should be doing? We were supposed to leave to start our summer cruise end of next week, not sure that's realistic at this point... but we'll be in remote places in Alaska and a reliable engine is a prerequisite. I'd rather do it right and delay the trip than run the risk of it freezing up again.

Thanks!

jkishel · 06-06-2016, 13:15

First, I'd say that 8 oz of oil consumption in 10 hours is quite high, but probably not related to water in the cylinders. Since the fresh water coolant level is up, there are probably no leaks in the coolant tank/intake manifold, but you might want to verify that with a pressure test. Water can also get into the cylinders if the exhaust system is malfunctioning. Check the exhaust manifold and gasket for cracks and leaks, anti-siphon valve for proper function and hoses and muffler for constrictions. Take the injectors to the shop to see if they can be saved. You can replace the head gasket yourself if the head isn't warped, but this doesn't sound like a blown head gasket. If you're concerned about reliability, I would address the oil consumption issue ASAP.

**Lepke** · 06-06-2016, 13:28

What you describe is a hydraulic lock from water in one or more cylinders that will not compress like air.
The way water gets into the cylinder is salt water leaving the engine goes into the exhaust manifold and then into an elbow where it joins the exhaust gasses and into the muffler. The salt water continues to flow thru the engine while you're cranking. The exhaust pressure forces water out thru the stern. With a non-running engine there is no exhaust pressure to push the water thru the muffler so as you continue to crank, the water backs up to the mixing elbow and into the engine thru the exhaust valves. If your muffler has a drain, open it, let the water out so when you do start, there is little back pressure.
It's simple. Take out the injectors, crank the engine. Trying to lever over a hydraulic locked engine can bend rods in small engines.
I have auto valves on my mufflers that drain the mufflers when the engines stop and there is no exhaust pressure. It makes it easier to start in cold weather and keeps stuff from growing in the muffler. Not to mention you're problem.

Ndavies · 06-06-2016, 14:13

Are you sure the starter motor is good? You say it makes a "clunk" - it could be that the bendix gear is not retracting. Try hitting it with a pretty heavy mallet and re-try, or remove the starter (2 bolts) and check that its spinning freely. I have an occasional problem with mine that the solenoid clunks and the starter does not spin. I think its a common problem on the 4JH-2TE and I am suspecting either a bad ignition switch or a wiring problem. I've been told the wiring was undersized.