Thermostat-glow plug-intake manifold heater question

dapper · Mar 15, 2009

Evening all. Looking for some information on a thermostat/glow plug. This is on a 96 NH 3430. Book calls it a thermostat I believe. Parts listing says it is an "Intake Manifold Heater". It is more of a glow plug in the manifold which should get hot, ignite the fuel, (has its own fuel line) and heat the incoming air. Should then fire right up. Book says so!!!! Couldn't be wrong

Mine has not worked since I purchased the tractor, so I thought now that warm weather was here, and I don't need it, I would repair, or replace the unit.

First checked fuse. 25a. Checks good. Checked that there was voltage when key was turned. Good 12v. Ok me thinks, must be bad thermostat plug unit. So off to the blue dealer I gets, and 25$ later I am home, shiny new thermostat in hand. Shouldn't be to bad, just 2 wrenches?. yea right,

and it turns out that taking the battery bracket off is not all that hard after all?.

Any way, out with the old, in with the new. Done! Checked fuse, and voltage, and still all good. Turned the key and waited the recommended 15 seconds, and then felt the manifold, and thermostat, and no heat. Cool as before. Fired tractor, thinking maybe it did not have fuel getting to plug.Tractor started and ran fine. Shut off, and tried the 15 sec thing again, and still no heat. I am convinced it still isn't working.

Could be a out of the box failure, but since I have the same symptoms as the original, I am inclined to believe that it is more likely that there something I'm missing.

Hoping that some of the experience on here may have a thought to try. Other than parking it inside to keep it toasty, I don't know what else I might try. Any suggestions?

Thanks for listening.

RickB · Mar 16, 2009

Did you have fuel at the fuel line when you replaced the thermostaRt unit? Did you run the tractor after the replacement so the fuel you lost could be replenished? Did you remove the intake air tube from the manifold and observe the thermostart unit from the front to see if it turned red when activated? Did you time the full 15 seconds, or give up on it too soon? 15 seconds is none too much to expect to feel warmth at the outside of the unit or around the manifold; try 30 seconds. In severe cold, 45 seconds can be required.

dapper · Mar 16, 2009

Rick,
Tanks for the reply. Yes. Fuel at line when disassembled. Yes. Ran the tractor after replacement. No. Did not remove intake tube. Didn't think of that one. Yes. I gave it a full 15 seconds. Before and after I started tractor. Probably as long as 20 second, but not as long as 30sec. After the first try at 15 seconds, I couldn't see any starting improvement. Seem to crank as long as usual. After I had started the tractor to make sure there was fuel at the thermostat, I couldn't see any improvement as the tractor always starts right up after that initial start.
I will try 30 seconds tomorrow on a cold tractor and see how she starts. I was thinking anything longer than 30 seconds may cause damage to new thermostat? No problem you think?
I looked at the old unit, and it does not look damaged, or coil burnt out. Can't I read the resistance of the coil and tell if the unit is good, or bad? Not sure what this resistance would be, but if it has continuity then the coil is not open. That would be a good thing.
Can I attach 12v and a ground to the old unit, and see if it glows? This would tell me if the unit was bad, or if I need to look further.
Pretty simple unit really and if I have 12v and a ground there, doesn't seem like much else to go wrong. What am I missing?
Thanks for your help.

RickB · Mar 17, 2009

I can't tell what you are missing from here. Yes, you can power the old or new unit externally with 12V and a ground. You can ohm each unit and compare them as a check of the old one. I would guess 5-9 ohms for a good unit, but that's only a guess.

dapper · Mar 17, 2009

Rick,
it may well be the darn thing is working. I held as you suggested, and after 45 seconds intake started to feel warm. could it have been I just wasn't holding key long enough?
Cranked tractor after the 45 seconds, an she fired right up, but it would as it is about 64deg now.
How long can you hold the key on these things without doing any damage?
I will still do resistance check on the 2 units and post the results. Thanks for your help and time. Always appreciate your posts.

RickB · Mar 18, 2009

dapper said:
Rick,
could it have been I just wasn't holding key long enough?

Probably.

dapper said:
How long can you hold the key on these things without doing any damage?

Can't help with that, I haven't enough patience to find out.

dapper · Mar 18, 2009

Thanks for your help Mr.Rick.
Do I read your profile correct, your BACK at NH? How long have you been with them? From your post, I can tell you have a little experience.

My Dad worked for them in Lebanon Oh. not too many years ago. Taught me a lot about the old ones, but I sure miss his help with them now.

Wish I had ask more questions.

Look forward to your posts.

RickB · Mar 18, 2009

I've been back at the dealership about 18 months. About 11.5 years total.

dapper · Mar 20, 2009

R, Small dealership, or large? What is it like from dealership point of view? You are obviously computer savvy, and right on with practical advice. Is your dealership "net" worthy, or do you just enjoying the tractor forum? Don't think I have seen you put out dealer info, and was wondering if you just doing this on your own? Not all dealers are on line savvy , and just wondering if yours is? you are a tremendous asset to your dealer if they know the help your so often offer. I have a good dealer (small-old) close to me, and he is just trying to hang on. Seems to stay busy as he likes to be, but don't see much in the way of web sense. Would love to see all dealerships networked. Guess it will come, but may be too late for some. Interested in your thoughts.

RickB · Mar 21, 2009

In today's world, my workplace would be considered a small dealership, a one store location with about 20 total employees. I don't insert my dealership into my posts as I feel doing so can be an intrusion into the purpose of forums such as TBN. Some dealer principals and personnel (e.g. Neil Messick) do a very good job of balancing self promotion with providing opinions and guidance. Others use this place as a source of free advertising and an outlet for badmouthing competitive brands. I am here for my own entertainment, on my own time, and my postings are a reflection of that, if for instance, I have a less than flattering opinion about a product or manufacturer, I can choose to post it. Since you asked, I work here:

Pine Plains Tractor & Equipment, Inc.