Hard Starting/ Possible glow plug problem?? M35 Engines & Fuel Pump Wiring

[Mike and Joanne Stimmler]

Is there an easy way to tell if my glow plugs are working? My engine has been hard to start for some time now but it does always start.When the engine is cold I usually hit the glow plugs for 45 seconds, crank for 10 seconds,no start, Then I hit the glow plugs for another 45 seconds, crank for 10 seconds, no start. Then I wait for about 5 minutes then do the same thing a third time and it ALWAYS starts on the 3rd attempt. The cranking is always strong so I don't think it's a battery problem and when the engine is warm it always starts no problem, I do not have the solenoid on my glow plug circut but with the amount of time I'm heating the plugs, that shouldn't be the issue either although I'm sure it would help. Would I have this issue if one of my plugs is not working? I do see a definite voltage drop when I'm hitting the glow plugs so I know that something is drawing.
Any ideas?
Thanks in advance     

Mike

[Craig Illman]

1. Do the glow plug project!!  2. Take an ohmmeter to each glow plug and measure the resistance to ground (after disconnecting the wire). I think you'll find in one of the Kubota manuals (toward the end of #2), elsewhere in this site, that the resistance should be about 1 - 1.2 ohms. Zero resistance means it's shorted, infinite resistance means an internal wire is broken. If you find a defective one, get the Kubota part number from manual 3 and order it from your local Kubota dealer or tractorsmart.com for about $8 vs. about $50 from Marine Diesel Direct.

Craig

[Stu Jackson]

Mike, as in all things electrical, try checking your connections, and those for the grounds.  You may have to drop your alternator to do it, but check all the wiring on the starter, including the connector from the fuse to the slip on inboard of the solenoid.  Check the fuse and holder.  Check the glow plug button in the cockpit panel.  Carefully check to see if all of the glow plugs are hot after your first button push.  Check the connections at the glow plugs -- just loosen 'em, squirt with a suitable lubricant and re-tighten.  Keep track of what you do, step-by-step, try the easy ones first.  I don't remember hearing anyone talk of having to replace the glow plugs themselves.

If it turns out you do have to go to a Kubota dealer for anything, and if tractorsmart.com doesn't work for you, try the sources mentioned for Kubota parts in : http://c34.org/bbs/index.php?topic=3133.0  they'll take your order and ship anywhere.

Also, remember Dave's post a few weeks ago about the engine kill switch being left on?  Before you do all the electrical stuff, check that.  It could well be that a little shaking when cranking could free up whatever seems to be stopping your engine from starting.  I.E., maybe it's NOT electrical, too.

[Stu Jackson]

Also, thinking some more about this:  Is your electric fuel pump working and do you have more than a half a tank of fuel?  I know, sounds crazy, but before you rip your boat apart, you may want to consider all the off-the-wall ideas.  My thought was that you're not starting, but your batteries are fine, or else you wouldn't be able to keep cranking.  So, what is it that stops an engine from running?  Air, fuel or electrical.  Just trying to play detective and what I'd do if it were our boat.  Keep us posted.

Also, in checking the connections, make sure the lugs are really connected.  They may look good, but pull on 'em.  We found that out the hard way in our fridge-not-working post recently.  And, as John Nixon reminded us in his comments on that post, check behind the electrical panel, unless you're absolutely sure that everything back there is getting juice to everything out there.

[Ron Hill]

Mike : Before you blame the glow plugs answer this question " is your electric fuel pump working??" and is fuel flowing?

To check the glow plugs is a simple task.   You can use a meter as other have suggested, but here's another trouble shooting measure. 
When you turn on the glow plugs you should see about a 2 volt drop on the engine voltmeter.   After you have engaged the glow plugs for 45 seconds GINGERLY feel the top of the glow plus - they should be very warm.   A glow plug is a item that can, but seldom goes bad.  The usual problem is the connections or the wiring.

If you haven't made the glow plug improvement upgrade by installing a solenoid and rewiring that circuit you should do it now!!
You can cut the glow plug ON time to 10/15 seconds!!  I wrote an article in the Mainsteet and it's in projects. 
A few thoughts.   

[Mike and Joanne Stimmler]

Thank you all for your ideas! I know the fuel punp is working, I can hear it running and I can start and stop it with the bleed screw. The most fuel I have ever had to use on a fill up is 5 gal and I just filled up last week so I think we can rule that out, filters have been changed recently. The starter and batterys seem to be OK because cranking is good, I am seeing the voltage drop when activating the plugs. The kill switch is physically pushed down while starting but I will check if there could be an issue with play in the cable. The cable was replaced about 6 mos ago, could a small movement make the difference between on and off? I will also check all the connectons and feel the top of the plugs to see if they are hot to the touch. I will be going back to the boat the day after Christmas to do some cruising around San Diego and Oceanside and will check things out then if I can dodge the kelp beds.

Thanks again,     
Mike

[Ron Hill]

Mike : You and any of the other readers that have not upgraded your glow plug wiring, should seriously conside doing that easy upgrade for the M25 and 25XP engines!!

What's happening now is that when you engage the glow plugs the current is coming from the starter solenoid connection at the engine.  It then travels up to the key switch and back to the glowplugs thur a #10 wire.  That's about 18 feet!! and the glow plugs by their nature are high resistance and draw many amps.  The 18 feet of wire (NONmarine grade) reduces the amperage drasticly by the time it gets to the glow plugs.

The modification calls for running a #6 wire from that same starter solenoid around the back of the engine to a Ford truck solenoid + on one side (the case is negative) and then from the other side + to the #3 aft glow plug.  You connect the glow plug wire from the key switch to the "I" terminal on the truck solenoid.  That truck solenoid is acting as a switch that opens and closes the heavy #6 (marine grade) wire from the battery connection at the starter solenoid (less than 3 ft of wire) to the aft glow plug using nearly twice the size wire!!  The key switch "opens and closes" the truck solenoid.  This allows the glow plugs to REALLY heat up in a fraction of the time!!!!

Try it -- your engine will love it!!   

[Stu Jackson]

Mike, another piece of the puzzle just got to me:  you said -- "...when the engine is warm it always starts no problem,.."

We never (or rarely) use the glow plug button after sailing around.  The engine is still warm enough, and starts right up.

That started me thinking, along with Ron's post, that your original startup issue is with the power to the glow plugs.

So, try this:  Change your startup procedure for one time --- instead of your 45, try, 45 try, wait, try it works, just hold the button in twice as long the first time, then try it. 

If it works, you just KNOW that the power you DO have isn't getting to the glow plugs.  Could be the wire, could be a simple loose (but not failed) connection somewhere.

But it'll lead you to the conclusion to do the solenoid project, which is really all of a ten minute job, well documented, as you already know, in Projects: http://www.c34.org/projects/projects-glowplugs.html

[Bob K]

This might sound rather silly, but I had some trouble with cold engine starts, and I found that the engine starts easier when cold if I give it more throttle. 

[Footloose]

Mike,

I have to believe that you have a bad ground in your system.  What leads me to this is that you have no problem starting when the engine is warm and the amount of time you need to "glow" before you can start.  With a small amount of resistance there is a large power loss.  After pre-heating the cylinders with the plugs you probally have several minutes before needing to crank the engine to get it to start.  The fact that it is not starting is from the cylinders being cold.  After you heat them for several minutes with a weak voltage they are eventually getting warm enough.  Check all of the connectors in the wiring harness and upgrade it if you need to.  Solder, crimp, and shrink tubing as has been said.

The glow plug solenoid upgrade is easy.  My engine will start after 7 seconds of glow even when the air temp is in the 40's and water in the 50's.

This stuff usually goes back to Ohm's Law.

[Mike and Joanne Stimmler]

OK, here's what happened on my last visit to the boat. In testing the glow plugs I found that only one of the plugs(the forward most one or the last one in the loop) was getting hot to the touch and all connections looked OK.The engine started as usual (after 3 attempts)then the next day it wouldn't start at all and I also noticed that the volt meter was now pegging to the low side, indicating a dead short in the glow plug line. At this point I'm seeing that the conditions have changed somewhat. So, I disconnected the plug that was getting hot and that cleared the short however the other two still connected are not getting hot after checking the voltages to be good to them. What I'm thinking is that the glow plugs have gradually been going bad one at a time and that I've been working on one plug for a while, which finally shorted out, the others going open. Does this sound logical? I was able to start the engine using starting fluid (ether) and I thought I had a new best friend (glow plug in a can)because it started like right now!!!Then a friendly mechanic told me to NEVER use starting fluid because the combustion is so strong that it can actually break pistin rings and other components! Anyway, I have ordered 3 new plugs from Tractorsmart.com for $11.81 each for my next trip. I was told that you can also test glow plugs when you have them out by simply connecting 12 volts to the top threaded part and grounding the base threads that screws into the block and the element at the bottom should actually glow if it's good.
Here are some part numbers and prices for glow plugs for the M-25XP

Universal #299685 for $63.69
Kubota #15951-65512 for $11.81 at Tractorsmart.com
                                 or $19.26 at TDC

I'll let you know how everything works out on my next trip.

Mike

[Craig Illman]

Mike -

Ron may correct me, but when I changed my glow plugs a few weeks ago pro-actively, I was only able to change two of the three in my M25-XP. There wasn't clearance to remove the center one without removing the intake manifold. Since I wasn't yet having starting issues to the degree you're experiencing, I left the intake manifold in place. I went with the $11~ versions from tractorsmart.com.

Craig

[Ron Hill]

Guys : NEVER use ether or starting fluid as it had a very very low flash point.  What happens is it ignites as one of the pistons is still coming up and that explosion forces the piston DOWN.   You can really screw up a diesel using that stuff!

Crag : You're correct, you'll have to remove the intake manifold to get all of the glow plugs out.  Removing that manifold is easy as the gasket on my M25XP stayed in place and it slid off and on nicely.   

[Mike and Joanne Stimmler]

Ron,
So does that mean that I should not have to replace the gasket on the manifold? Will I need to use a gasket sealer after taking it off?

Mike

[Ron Hill]

Mike : The gasket that is already there should not have to be replaced.  Mine stayed completely attached to the engine rather than the removable manifold.  That manifold doesn't need an absolute seal so if there's a small leak it'll be OK.  So when I replaced the manifold, it slid back on and I snugged (don't crank) down the bolts.