glow plug testing

[Bobg]

HI All, after reading previous posts on glow plugs for about a hour, I learned a lot of information, but am still confused.  I tried to start my boat 1988 C34 Hull 613, this weekend, Temp about 40f, I engaged the glow plugs, got the voltage drop as usual on the gauge,  knowing it was cold, kept the glow plugs engaged about 40 seconds, the motor felt like it would start but wouldn't, I then engaged the glow plugs a little longer, noticed the voltage drop was less than the first time, the motor started for like one revolution and stopped, I waited for awhile, then engaged the glow plugs again and found no voltage drop at all. At this time, I shut the intake water and turned the engine over several times, hopeing it would start but no luck.

I put the voltage meter on the glow plug and with the ignition in the first position, voltage was zero, had a helper turn the key to activate the glow plugs, and got a little over 14 volts to each plug, held it on for about a minute, at no time did any of the plugs get even remotely warm. I then jumped a wire from my start battery 2 feet away and held it on the glow plug, it still read over 14 volts, no heat, tried starting motor anyway, but did not start.  At this time in as much as I had to move, I did the no-no, I barely fogged starting fluid about a foot away from the intake and the engine started instantly, I motored about 5 miles to my new slip with no problems.

Question:  I am obviously getting 14+ volts to the glow plugs testing each one of them individually, I did not do a Ohm test, I guess I didn't know how, or what the resistance should be, I now know it should be 1 -1.2 Ohms.  I have not done the solenoid upgrade yet.  it always started  after about 20 seconds. Do you think all my plugs went out that morning?  Perhaps they have been going out and the last one went.  When I do the Ohm test, can I do it while the plug is in the engine, and do I disconnect the positive wire

If my plugs were good, isn't  jumping a wire from a good battery to the plug the same as turning the key to activate voltage to the plug? I can get the wire from the pos side of the battery to "spark" on the intake manafold, but can not get it to spark on the glow plug, if that means anything.

I am 160 miles away right now in lake superior, and will do the Ohm test when I get there, Any help I can get would be highly appreciated, Thank you   Bob   

[Craig Illman]

Bob - I don't know what your time is worth, but you can get replacements for about $10 each. Kubota p/n 15951-65512 or NGK-Y103V. The only tricky part is that you'll likely have to loosen the intake manifold to replace the center one. I managed to burn out my glow plugs last winter by engaging them for too long with the shore power charger engaged. If you have a way to measure amps, they draw about 7 amps each. I never noticed much warming externally. If you remove them, they indeed glow when you give them 12V.

Craig

[Terry Forshier]

I have a 1988 C 34 and the same engine as you. I am # 570 I replaced my glow plugs and managed to get them out and in without removing the manifold. Now it is not easy and takes patience, small fingers to start threads and slowly tighten with a small wrench a little at a time. I paid about $15 a plug here in Naples at the Kabota dealer. Took about 2 hours. Terry

[Bobg]

thank you, my time isn't worth much (retired) but are we in agreement here that all 3 of my plugs are bad? is there in fact a way to test them on the engine.  I am thinking they are bad after seeing 14+ volts at the plug but no drop in the voltage meter on the instrument cluster like it used to, Just seems odd that they would work one minute and not the next.
I will pick up 3 anyway at the kubota dealer close by.

[Ken Juul]

It sure sounds like they are all bad.  My guess is they have been dieing one at a time.  Last one finally quit so the engine won't start.  I'd pick up gaskets for the intake manifold  also just in case you have to remove it.

[joe]

craig, your post indicated that you burned out your glow plugs because of use while shore power is engaged. when i first start my motor at the slip the shore power is almost always plugged in. is this an error on my part. i have had no problems. is this just dumb luck. joe

[Craig Illman]

Joe - It's a little longer explanation. I have a Lead-Calcium starting battery. It was pretty well drained from multiple starting attempts (more on that later). My shore charger will send over 15.5V to a highly discharged Lead-Calcium battery. I also activated them for a long time, probably over a minute. I have the solenoid upgrade, they should have been plenty warm enough after only twenty seconds. That's my theory on why they burned out.

Turns out my starting problem wasn't related to the glow plugs. I'd managed to foul the injectors when I had removed the original lines from the pump to get the compression tester in the glow plug holes.

To top this all off, while I was shuffling from the aft cabin to the front of the engine last December, my right foot slipped on the cabin sole and rolled all my weight on my left ankle, the inside tendon popping off a piece of bone. All by myself, nobody around, 700 feet out the dock from the car. Seven weeks on crutches and a boot. Still went down to the boat in the intervening time, with accompaniment.

One other comment. You don't have to remove the intake manifold, just loosen it about 1/8 - 1/4", or you may be lucky and not have to.

Craig

[Ken Juul]

I was under the impression that starting the engine with the shore power on was almost guaranteed to blow the diodes in the alternator.  Or am I confusing this with turning the Battery Switch to off with the engine running, also a good way to blow the diodes.

[Stu Jackson]

I was under the impression that starting the engine with the shore power on was almost guaranteed to blow the diodes in the alternator.  Or am I confusing this with turning the Battery Switch to off with the engine running, also a good way to blow the diodes.

1.  Starting the engine with the shorepower connected usually means that the batteries are topped off and full, so when the engine starts with the sp plugged in, the alternator sense doesn't tell the alternator to work.  No harm, no foul.

2.  Yes, 1-2-B switch to off when engine is running MAY, (only MAY) damage your alternator.  Two cures:  wire your alternator properly away from the 1-2-B switch and driectly to your house bank and not thru the switch; second, I need some time to find the link about this in an earlier thread and will post later: essentially it depends on how hard the alternator is working.  More later.

[Stu Jackson]

Here's the link:  http://c34.org/bbs/index.php?topic=2977.0, particularly Reply #11

[Stu Jackson]

...when i first start my motor at the slip the shore power is almost always plugged in. is this an error on my part. i have had no problems. is this just dumb luck. joe

No, it's not an error, just that it's unnecessary, but will casue no issues, just the alternator won't output.  You actually may find that your tach doesn't work, since if the alternator's not putting out, the tach says zilch.

Why do you start your engine with the power connected anyway?  It takes a while to unplug, and idling your engine isn't doing it any good.

[Stu Jackson]

Bob, from your first post it appears you've done your research, just wanted to confirm you've seen this one: http://c34.org/bbs/index.php?topic=3347.0

[Ron Hill]

Guys : It's not a good idea to start the engine with the shore power engaged.  As Stu mentioned the engine voltage regulator SHOULD sense that the batteries are full (and not engage the alternator). 
But why take the chance that the engine and the shore power charger BOTH might try to charge the batteries at the same time!?!

After you have engaged the glow plugs for 20/30 seconds (during that time you should see the voltage drop by at least 2 volts) go to the engine and touch the glow plugs.  If they aren't HOT then they need to be replaced!!