Hard to impossible to start glow plugs test good

[teddyanddebi]

First time user and tractor owner. I purchased a B7100 D750. Its hard to start even when turning the ignition switch to preheat the glow plugs. The person I purchased it from stated he's not sure the battery is the right size. When I jump it with my truck, it still has to crank 30 seconds or more to start. The glow plug indicator warms up but never glows. I tested the glow plugs by the ohm meter route and it test good. Could the problem be with the controller? or the indicator? Or can the glow plugs be worn enough to test good but be bad? Sorry for so many questions but i'm trying to learn this thing. I dont have a maintenance or owners manual. I would appreciate any and all advice you might have.

 

[hodge]

How many hours on the tractor? How long, time wise, are you allowing the plugs to heat up? Do you have the throttle set right? On my 7100, after shutdown, I put the throttle back into the approximate position for normal idle.
Are you sure that fuel delivery isn't the problem? Have you changed the fuel filter? Does it run good once started?
You also may have to check the compression, to make sure it is tight. If the compression is low, it will be harder to start.
And, welcome to OTT! This is a great site, BECAUSE there are great people here.

 

[teddyanddebi]

How many hours on the tractor? How long, time wise, are you allowing the plugs to heat up? Do you have the throttle set right? On my 7100, after shutdown, I put the throttle back into the approximate position for normal idle.
Are you sure that fuel delivery isn't the problem? Have you changed the fuel filter? Does it run good once started?
You also may have to check the compression, to make sure it is tight. If the compression is low, it will be harder to start.
And, welcome to OTT! This is a great site, BECAUSE there are great people here.

Unknown as to the amount of hours, the gage is I believe wrong or disconnected. I'm waiting at least 1 minute or longer sometimes and it doesnt help. It does run real good after it is started. When I stop it I cannot restart it. I try and the battery runs down. Because it runs well after it starts I believe the fuel is being delivered.As for checking the compression, I was under the impression to never attempt to check the compression of a diesel because it is around 4oo pounds and you cant use a auto compression tester. But when I hold the glow plug preheater isnt the indicator supposed to glow?

 

[Stumpy]

Welcome. Sounds like you've covered your bases on the plugs but if you want to test a bit further you can test in open air.

You want to leave all plugs in the circuit. You can test one at a time, leaving the others in the head or all at once. Use the stock wiring or run a hot lead to the head of each plug and another lead from the plug bases back to the frame or battery negative terminal. Make sure the plug isn't touching anything and see how hot it gets. It oughta glow a nice cherry red.

I agree with Hodge a compression test would be prudent if it's starting that hard with good glow plugs especially in Texas temperatures. You can find diesel compression testers from about $30 on up though I'd spend a little more for one with a good gauge. Your glow plug thread and thus adapter you need is 10x1.25mm, make sure the kit you get comes with it. Set the throttle to it's lowest setting, crack the injector nuts, remove all the glow plugs and crank for a couple of revolutions for each cylinder in turn with the tester. You oughta be up around 400-500psi.

I'd also make sure the compression release is fully releasing and your valve clearance is good, in fact that might be something to do first.

The indicator doesn't always glow from what I've heard or at least can't be seen especially in bright sun light.

 

[teddyanddebi]

Welcome. Sounds like you've covered your bases on the plugs but if you want to test a bit further you can test in open air.

You want to leave all plugs in the circuit. You can test one at a time, leaving the others in the head or all at once. Use the stock wiring or run a hot lead to the head of each plug and another lead from the plug bases back to the frame or battery negative terminal. Make sure the plug isn't touching anything and see how hot it gets. It oughta glow a nice cherry red.

I agree with Hodge a compression test would be prudent if it's starting that hard with good glow plugs especially in Texas temperatures. You can find diesel compression testers from about $30 on up though I'd spend a little more for one with a good gauge. Your glow plug thread and thus adapter you need is 10x1.25mm, make sure the kit you get comes with it. Set the throttle to it's lowest setting, crack the injector nuts, remove all the glow plugs and crank for a couple of revolutions for each cylinder in turn with the tester. You oughta be up around 400-500psi.

I'd also make sure the compression release is fully releasing and your valve clearance is good, in fact that might be something to do first.

The indicator doesn't always glow from what I've heard or at least can't be seen especially in bright sun light.

Okay now you've said something i'm lost on. The compression release valve is only to be used when the battery is discharged? that's what the sticker says. When exactly do you use it and for what reason? I have the pull lever for it but i'm greek to it's purpose.Thanks for the info on the compression test. I'll test the glow plugs tomorrow evening when I get home from work. I'll look around for a compression tester and again thanks for the specs on the adapter. Do you know what the battery shold be rated at? I appreciate your time

 

[Russell King]

Okay now you've said something i'm lost on. The compression release valve is only to be used when the battery is discharged? that's what the sticker says. When exactly do you use it and for what reason? I have the pull lever for it but i'm greek to it's purpose.

The compression release can be used at any time - it simply keeps the valves slightly open so the engine is spinning without any compression. This will allow the engine to spin up to a fairly high speed and then change to lever so it is in the position to have compression and the tractor should try to start. On my tractor that is a different model it is a pull knob (like a manual choke) and then pushed in is the running position.

Don't try to crank your engine for too long or you can burn the starter up especially if you are cranking against compression. After cranking for a few seconds then wait for a minute or two before trying again. Each time you will need to wait longer times after cranking to allow the starter to cool down. I can't recall the time limit on cranking but can look it up if no one else chimes in with it.

Sometimes the compression release system is stuck or out of adjustment so the engine does not create a good compression stroke to fire off. I would think that the engine would run rough if it was stuck in the released position but it would not hurt to check it.

My tractor will start easily (in Austin area) after sitting with glow plugs on for about 30 seconds and 5 to 15 seconds of cranking. After it has run I generally do not use the glow plugs again. Even in the "cold winters" we have to endure here in Texas!

As to the indicator for glow plugs you will probably not see it glowing unless you are trying at night in the dark with no lights around.

 

[hodge]

I use my decompression valve in the winter; I will pull it and let the engine spin over some, to build up some oil pressure before starting. I hit the glow plugs for the needed amount, pull the decompression valve and spin the engine over for 10 or 15 seconds, and while still turning over, I release the valve. With compression, it will hit right away.

 

[lreops]

I'll tell you of my experience I just had with my '83' L235. When I got it, I would have to use the GP for about a minute, at least, sometimes longer depending how cold it was. The indicator never, ever showed any signs of a glow, no matter how long I it warming. Decided to replace the GP's, as that they are not that expensive. Like you, I had checked them each to see if they were in fact working. I have gotten positive readings from all.

When ordering the plugs, I decided to also get a new indicator. After receiving and installing the new GP's, I gave it a test shot to see if there was any difference. To my amazement, My OLD indicator started to glow RED after about 12 seconds. As far as starting, when pretty cold, 30 seconds. Which I think is still a little longer than what it should be, but after all, 30 year old motor, with no idea of the total hours.

So, my suggestion would be to replace the plugs. Don't cost a whole lot and it won't make it any worst.


Ron

 

[tmessenger]

If the engine fails to start after it's warmed up, say you run it for 15 minutes then shut if off for 30 seconds and it fails to restart they I'd say you have a compression problem.

 

[motorhead]

Two things that are critical to diesel starting: Good compression and fuel delivery. I would check the valve clearance as tight valves will cause compression loss just enough at cranking speeds to not let the cylinder heat build up to proper temperature.
When you crank the engine for a while, do you see white fuel smoke coming from the exhaust? If you are NOT seeing white smoke then you might have a fuel delivery issue such as a air leak on one of the fuel lines. Diesels are very touchy if there is an air leak in the fuel system because it will not be able to compress the fuel to the pressures needed to crack the injector to spray.

 

[Orange Tractors]

First time user and tractor owner. I purchased a B7100 D750. Its hard to start even when turning the ignition switch to preheat the glow plugs. The person I purchased it from stated he's not sure the battery is the right size. When I jump it with my truck, it still has to crank 30 seconds or more to start. The glow plug indicator warms up but never glows. I tested the glow plugs by the ohm meter route and it test good. Could the problem be with the controller? or the indicator? Or can the glow plugs be worn enough to test good but be bad? Sorry for so many questions but i'm trying to learn this thing. I dont have a maintenance or owners manual. I would appreciate any and all advice you might have.

My suggestion is to physically check all wires in the circuit. I had the same thing happen on my L175, it had always been hard starting when cold.

Once I got to checking continuity, resistance and voltage; I found the indicator had opened and been bypassed by a previous owner, and the 12 ga wire that fed the glow plugs wasbroken and only had about two strands of copper intact.

Once I replaced that wire, the glow plugs worked. The tractor starts easier and faster than ever before.

Oh, go ahead and run the valves, it probably hasn't been done for years and you might pick up a few horsepower.

Robert

 

[Stumpy]

Russell's got it. Sorry I worded that poorly. The idea is you pull the compression release knob so the engine doesn't have compression, spin the engine up with the starter, and then while still turning the starter push the knob back in. That way the starter gets some help from the flywheel instead of fighting through compression from 0 rpm.

As far as batteries go more amps are always better. I believe Vic likes to recommend 750CCA or larger but anything over 500 oughta be fine especially since it doesn't get quite as cold down there.

Lreops might be onto something there. See what your plugs do, it might be worth it just to replace them and see what happens.

So check the plugs and replace if needed, check the valves and compression release, and if all that looks good do a compression test.

 

[teddyanddebi]

Two things that are critical to diesel starting: Good compression and fuel delivery. I would check the valve clearance as tight valves will cause compression loss just enough at cranking speeds to not let the cylinder heat build up to proper temperature.
When you crank the engine for a while, do you see white fuel smoke coming from the exhaust? If you are NOT seeing white smoke then you might have a fuel delivery issue such as a air leak on one of the fuel lines. Diesels are very touchy if there is an air leak in the fuel system because it will not be able to compress the fuel to the pressures needed to crack the injector to spray.

First I want to thank everyone for there inputs it is a real uplifting to understand there are people willing to help someone. AS for the replys, I will check the wiring, replace the plugs, check valves and do a compression test. As for the cattery its only 450ccw. I will definatly change it. I drove it around today and it runs great once started. Yesthere is white smoke after trying tocrank it for a little while. After driving it, I shut it down and tried to restart it and it didn't but then the battery went real low after about 15 seconds of cranking. Thanks for the class on the compression release knob. I went out late last night and saw the glow plug indicator glw very dimly after about 30 seconds of pulling the knob out.I removed the fuel hose from what appears to be the pump and cranked it a little and it pulsed fuel. Not very strong but it shows me the fuel is getting thru. Now for one more question, Orange tractors mentioned to go ahead and run the valves. I take it means to check compression or to adjust them? Also is there an additive that should be used in this tractor? and the final question (I hope) is has anyone out there filled the front tires with rubber? I have a lot of mesquite out here and we do this at the company I work for, along with 2 gals of slime in rear ones.
Thank you and God bless everyone of you.
again

 

[teddyanddebi]

First I want to thank everyone for there inputs it is a real uplifting to understand there are people willing to help someone. AS for the replys, I will check the wiring, replace the plugs, check valves and do a compression test. As for the cattery its only 450ccw. I will definatly change it. I drove it around today and it runs great once started. Yesthere is white smoke after trying tocrank it for a little while. After driving it, I shut it down and tried to restart it and it didn't but then the battery went real low after about 15 seconds of cranking. Thanks for the class on the compression release knob. I went out late last night and saw the glow plug indicator glw very dimly after about 30 seconds of pulling the knob out.I removed the fuel hose from what appears to be the pump and cranked it a little and it pulsed fuel. Not very strong but it shows me the fuel is getting thru. Now for one more question, Orange tractors mentioned to go ahead and run the valves. I take it means to check compression or to adjust them? Also is there an additive that should be used in this tractor? and the final question (I hope) is has anyone out there filled the front tires with rubber? I have a lot of mesquite out here and we do this at the company I work for, along with 2 gals of slime in rear ones. Sorry I forgot I did the compression release test and it didn't help.
Thank you and God bless everyone of you.
again

Thanks for all the help, I need every bit I can get

 

[Russell King]

Since it won't start after running for that period of time, I do not think it is the glow plugs.

I would first get a reliable battery with high CCA to trouble shoot with so you can eliminate that. While you are at that verify that the battery cables are good and that the terminals are well connected to the cable. Old cables will start to break down at the joints. Also verify that the ground cable is connected well to the frame (opposite the battery terminal). Rust or corrosion should be cleaned away.

Then get it started, after running about 15 to 20 minutes shut it down and see if it restarts.

If not then I would start to suspect the fuel supply/fuel injectors. I have been lucky in the short time I have owned mine never had to do much with the fuel system. There are additives for diesel that will help clean the system some but I have not used any of them and can not make any recommendation.

If you have no knowledge about the fuel age and the fuel system, I would start by draining the tank, changing the fuel filter(s) and then replacing the fuel with known fresh fuel. You can clean out the interior of the tank while it is empty with dowel sticks and rags if that is needed. (search for fuel problems on this forum and you will find help). You will need to bleed the system and that is "easy" also. Again - use the search function with some terms similar to "bleeding fuel lines" and your model number.

 

[tmessenger]

I have a low hours B7100, cold (30 degrees or warmer) I glow it for 20 seconds and it pops right off almost no cranking just enough to turn it over, when the engine is hot no glow plugs needed it starts immediately, this is the way a diesel should starts when it has good compression, clean injectors with correct spray patterns and good fuel

Good luck with your project.

Tim

 

[satchelh]

All good tips so far. I really think the valve clearance needs to be checked. The fact that it starts harder (or not at all) when hot makes me think the valve clearance is too tight. Valve clearance decreases as the engine heats up, causing the valve stems to expand. It might be just enough to effect the compression and cause starting issues.

 

[Orange Tractors]

First I want to thank everyone for there inputs it is a real uplifting to understand there are people willing to help someone. AS for the replys, I will check the wiring, replace the plugs, check valves and do a compression test. As for the cattery its only 450ccw. I will definatly change it. I drove it around today and it runs great once started. Yesthere is white smoke after trying tocrank it for a little while. After driving it, I shut it down and tried to restart it and it didn't but then the battery went real low after about 15 seconds of cranking. Thanks for the class on the compression release knob. I went out late last night and saw the glow plug indicator glw very dimly after about 30 seconds of pulling the knob out.I removed the fuel hose from what appears to be the pump and cranked it a little and it pulsed fuel. Not very strong but it shows me the fuel is getting thru. Now for one more question, Orange tractors mentioned to go ahead and run the valves. I take it means to check compression or to adjust them? Also is there an additive that should be used in this tractor? and the final question (I hope) is has anyone out there filled the front tires with rubber? I have a lot of mesquite out here and we do this at the company I work for, along with 2 gals of slime in rear ones.
Thank you and God bless everyone of you.
again

Sorry for not being clear.

When I said to run the valves, I meant to adjust them to factory specs. The ones on my L175 were very loose when I first got it, and adjusting them helped on both the starting and HP fronts.

Robert

 

[Battered Sav]

All good tips so far. I really think the valve clearance needs to be checked. The fact that it starts harder (or not at all) when hot makes me think the valve clearance is too tight. Valve clearance decreases as the engine heats up, causing the valve stems to expand. It might be just enough to effect the compression and cause starting issues.

+1

It should start easier after being warmed up, unless the valves are at their limit.

FWIW, when I start mine I: turn on ignition, turn knob to glow whilst opening fuel tap and setting throttle to ~2/3, pull out then return decomp knob and turn knob to start.

The decomp stays out for about a revolution than automatically closes, lets the motor spin up and build a bit of oil and fuel pressure before firing.

If I shut down then go to restart a warm motor the glow plugs are not required.

 

[teddyanddebi]

+1

It should start easier after being warmed up, unless the valves are at their limit.

FWIW, when I start mine I: turn on ignition, turn knob to glow whilst opening fuel tap and setting throttle to ~2/3, pull out then return decomp knob and turn knob to start.

The decomp stays out for about a revolution than automatically closes, lets the motor spin up and build a bit of oil and fuel pressure before firing.

If I shut down then go to restart a warm motor the glow plugs are not required.

Thank you all for your advice and experience. I will try just that. First the battery and cabeling. Then replace the fuel. Except I would imagine it would run poorly if the fuel was bad. The person I bought it from says it wasn't old because he just filled it after shredding 6 acres. The positive lead on the battery gives me concern because there are a few strands broken. Also when I jump it from my truck the ground on the jumper cable gets warm. I expect that is because of the cable on the jumpers. I will also check the valves. Another thing I noticed was the smoke and dripping oil that comes out of a vent tube, attached to what appears to be, some type of housing on the valve cover. This makes me suspect something is not right. The old owner says it uses a little oil. I told him it isn't using it it is leaking it, out the vent hose. But anyway, thanks for the heads up and a place to start troubleshooting. Is there any way to find out the valve specs without buying a service manual? I'm not real computor literate. Thanks again
Ted