Mahindra 7520 - Possible KSB issue - (bluish-white smoke / running rough)

[wbb]

Folks, I need some help.

I have a 2006 Mahindra 7520 FWA and loader. Currently it has 4xx hours on it. I really like the tractor as it is heavy and has a phenomenal FEL and 3-point lift capacity. Also, it fits me very well. The controls are well placed. I call it my mule. I even pulled a Deere 4630 out of a pond recently. I have had the tractor going on three years now. It is used primarily as a hay mover and bale feeding tractor. Sometimes used to grind feed, pull a wheel rake, occasionally a disk mower, and all around general farm work.

For the last few months I have been having an issue with the tractor. The engine runs rough, belches bluish-white smoke, and loses power.

It started doing this only when it was cold and worst during the winter. Once the tractor warmed up, it ran fine. But now it is happening more often ( warm / cold / summer / winter ).

We have
Changed the fuel filters.
Bled the fuel system.
Checked the air filters

I read with great interest this thread

Cuz-Pat: My Mahindra 7520...I am sick of it!!!

http://www.tractorbynet.com/forums/mahindra-owning-operating/99138-cuz-pat-my-mahindra-7520-a.html

I have heard tales of an issue with a KSB sensor that is supposed to adjust injection timing or fuel delivery. Is this the first thing I should check (replace) before I start tearing into anything else? Does anyone know what the correct part number(s) are for the newer model KSB sensor(s)? And I am a little confused, are there two pieces to it or just one? I read somewhere (not here) that there was a component of the KSB sensor that was attached to the injection pump and a module that was installed up in the engine compartment.

If I did this correctly, the links below should point to some shared videos on my Skydrive shared cloud storage. (A picture is worth a thousand words). Also, if this is the KSB issue the videos might help others diagnose similar problems.


20121022_175956.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Startup slow idle (800 RPMS) bump up to 1200 then 1500 then varying engine speed. It may not be obvious in the video, but the shed was chokingly full of bluish smoke by the end of the video.



20121031_172733.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Idle to 1500 RPMs then back to idle.



20121102_123239.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Tractor sitting still running at PTO speed.



20121102_124204.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Driving through the woods to go get hay. Every little bump or hill, it would act up. Almost like even the slightest demand for power caused it to act up.



20121102_131750.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Sitting in the cow pasture. Engine speed at 1500 RPMs. Notice how it runs smooth, then acts up, then runs smooth again. A repeating cycle.



20121102_174645.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Several of the videos of the tractor running badly are from today. I shut it down, went to town to do some shopping, and came back later on in the evening to (try) to grind feed. The tractor ran perfect.



20120922_081505.mp4
https://skydrive.live.com/redir.asp...!Aro-TFuFAkS8dlk&Bpub=SDX.SkyDrive&Bsrc=Share

Also have a weird electrical issue. When the tachometer works, all is good. When the tachometer quits working, the low oil pressure light starts blinking. Sometimes the tach will work for several days and sometimes it will be non-functional for several days. Just recently the fuel gauge has stopped working also.

 

[wbb]

Well, i guess I hadn't searched as well as I thought. Just ran across this...
-------------------------------------------------------------------------------------------
Originally Posted by RedRiver
I'll respond since I didn't see a response to this.

It sounds like you are having a problem with the KSB sensor/timer. It's a very quick fix, takes 1 minute to replace. The KSB timer adjusts the amount of fuel the engine gets when the engine is below a certain temperature, therefore the tractor will smoke and sputter because it is getting too much fuel while the engine is still cold. You should received a jumper plug and a new KSB Timer relay, this will more than likely fix your problem.

These are the part #'s you need..

KSB Timer #007700570D91
KSB Jumper #007700572B91
---------------------------------------------------------
Are these the newest part numbers for this fix ?
---------------------------------------------------------

 

[MtnViewRanch]

As far as the problems with the dash, a few of us have similar problems and a smack on the face of the dash always takes care of it for me. I believe that it is some sort of grounding problem. But it is to easy to just smack it and all is good again vs actually tracking down the problem and fixing it.

 

[JerryK]

Your dash problem MIGHT just be a cracked solder joint. Printed circuit boards are notorious for getting cracks around where pins or other large components are inserted thru the board, then held in place by solder. If you don't mind tearing into your tractor, and feel like a little adventure in your life, carefully take the dash panel out and take a look see. A bright light, GOOD EYES, and a magnifing glass.... and maybe you will find your problem. Should look like a VERY small crack around the joint in the solder. If you find one, resolder the joint. Make sure you use good non-acid core solder and an appropriatly sized pencil soldering iron... or find someone who knows how to work on stuff like that. Worth a try........ [ add disclaimers here ]

PS: Those part numbers check out as current, but just with a quick looksee on the net. You should contact/email whoever you are going to get the parts from to make sure... or maybe someone will chime in to help you......

 

[wbb]

This post is almost one year old - but - I always like to hear the follow-up on issues...
I apologize for not updating sooner - but the events of today reminded me...

I think the video links are still good.

We fought this tractor all winter last year.
-Changed fuel filters - twice
-Drained the fuel and lines
-Replaced the KSB sensor - twice

Nothing seemed to help.

When the tractor was plugged in all night, but in an unheated shed, it still usually acted up.
If it was in a warm shed, plugged in or not plugged in, it started and ran fine - until you had been outside 10 or 15 minutes - then smoke-smoke-sputter-sputter.

We just lived with it - or used a non-MFWD tractor all winter.
'Sometime' this early spring, like magic, it started running fine again.

The tractor ran fine all spring / summer / fall - UNTIL TODAY.

This morning it was in the 40's here. Went to put out hay and smoke-smoke-sputter-sputter
d@mn!

Any other suggestions as to what to look at?
(I know, bad grammar - but I am tired)

Thinking back - I don't recall doing anything at the injector pump (jumper-?) I don't think we received a jumper when we ordered new KSB sensors. Something about the new style KSB relay didn't require a jumper at the pump...?
So maybe I will start by re-investigating that.

Thanks,
Brad

 

[Coyote machine]

FWIW, I have a few suggestions for your issues with your tractor. 1st, so you know, I know virtually nothing about Mahindras specifically, BUT some things are common to most tractors.
What I'm hearing you experience so far is this: warm start in heated shed, no problem. Cold start in unheated shed, problem occurs. Bumpy or hills, problem occurs. Run it- sometimes OK, sometimes acts up. Go away, come back problem not there. Ran FINE most of spring, summer.fall until cooler temps around 40 degrees- problem is back.
You've been tracking fuel issues, changing filters, draining and changing fuel lines/tank to no different result.
You have an intermittent dash cluster and it acts up at will.
You've replaced the suspect KSB valve twice with no resolution.
You're tearing your hair out in frustration over this tractor's reliability, and rightly so.

Now, here's what I sense is happening. You have an electrical/ temp sensing issue(s) that is/are intermittent. I'm not familiar with what a KSB valve is, but let's put that aside for a second and get you on track to diagnosing the issues. Have you talked to a dealer about these issues you're having and if so what do they tell you? Are there any service bulletins for these issues?
Will the tractor run without the KSB valve connected? How is it connected? Screwed into head? Attached to firewall? Is it electrical and mechanical- meaning does it have a probe inserted into the head, for instance, or is it just a stand alone part?
Are there any sensors that connect to it or through it to the head or block?
Is it in any way connected through the dash cluster and have you ever seen the tach and the run issue at the same time?
Have you ever changed your coolant? Does your temp run normal- any overheating or too cool on guage readings?
I'm trying to determine if something like a stuck thermostat, opened or closed might be effecting the KSB or other temp reading sensors, that would 'lie' to the injection pump, telling it to send the wrong, in your case excessive fuel, to an engine it thinks is colder than it actually is.
Do you see where I'm going with this logic?
I suspect you have been chasing fuel when you might want to be chasing what tells the IP to deliver a certain amount of fuel at different times. They're not the same. It's like changing a tire when the problem is the wheel bearing- close but not on target.
I suggest keeping a log of exactly what is happening every time you attempt to start and run the tractor.
Start tomorrow. Look at it like a plane: it's not ready to fly until ALL systems are go. Check any and all sensors plugged into the head or block. Check all wiring to and from the engine, ESPECIALLY the ground connection at the frame and at BOTH battery terminals. Make sure all basic systems are in go condition, fan belt tight, no corrosion at ANY ground connections, no rodent chewed wires, clean fuse connections and none blown or marginal condition. Any loose connections of wiring- FIX. Any damaged wires of any kind fix. make sure battery is in good condition and that it has plenty of water in each cell to the split ring- wear glasses.
Log what ambient temp is each day when you go to start it. Log whether dash cluster is acting up and when how long, etc. You said it's better when warmed up- how long does it take in minutes at what temp?. Any sensor that might be screwed into the block or especially the head that is readily accessible remove it and clean the sensor probe and re-install with copper antisieze applied to the threads.
Please answer the questions I posed to help narrow the problem down.
Are there any others experiencing the exact same problem with their same model Mahindra?
Hope this helps.

 

[EMB5530]

This is just a guess but it sounds similar to the problem many of us have had w/ our 30 series mahindra's, but I would (after checking everything just to be sure as coyote machine said) advance my injector pump timing just a little and see if that helps.
Be sure to mark the original position and only go a little at a time but if it starts to improve you can keep moving until it is running well.

 

[Coyote machine]

EMB5530 could be correct in your pump timing is not set correctly, BUT before you go into messing with something that is a critical adjustment like pump timing I'd tend to first run the gauntlet with the KSB issue. I'd also be hesitant to adjust pump timing since Mahindra has a special tool to use to set it correctly, and without the tool you could cause more issues at this point.
Since I wrote above I've had time to read the threads you linked to and it would seem that there are various versions of the KSB unit and a relay that interconnects with it to produce what should be the correct amount of fuel on cold start conditions. Obviously, in your case the components are not working in sync, or at all. It seems that it is possible to have the wiring plug to the KSB installed incorrectly, so just to eliminate that possible glitch, check to see that it is in fact properly connected.
It also seems that because there are various versions of the KSB 'kit' that it is important to make sure you have the latest version. And in my mind, I'm hearing that Mahindra is struggling to fix this issue on certain tractors- one of which is yours.
So it may be one of those in field fixes that works for some and not for others. What to do? Check all other possible areas of potential problems, especially temp sensors, and verify that your cooling system is functioning correctly, as already suggested. If, for instance, your thermostat is taking too long to open it could throw off another sensors ability to find the temperature it is looking for and thus cause the smoking, rough run, until proper temperature is realized. I'm not saying that is the problem, BUT something like it could be contributing to a combo of factors that render your machine inoperable.

 

[SPYDERLK]

You are cold stacking. The tractor has an automatic injection timing advance during warmup. As I understand the advance is initiated by starting and times out rather than senses temperature. It is when the timing retards that you are getting cold stacking. When it happens, turn it off and restart. Does it go away? ... then recur later?
,,,A small advance in the pump timing cured mine.
larry

 

[wbb]

Put out cow and calf hay this evening.
I let the "wait to start" light go out.
Mid 40's.
Started tractor.
Smoke-smoke-sputter-sputter.
I let it run for 30 seconds or so, then burped the foot throttle maybe half/thee-quarters open, then back to idle.
Tractor settled down and ran fine after that.

Coyote machine - you sound like one heck of a diagnostician.

I may have tunnel vision, but I am going to exhaust all possibilities with the KSB circuit first.
Seems like I only have issues when it is cold. Then I have what seems to me to be a timing or fuel delivery problem.
Which sounds like what the KSB circuit messes with.
And sometimes revving up the motor half throttle or so eliminates the issue.
I have the Mahindra Owners/Service manual on CD. Was in my purchased folder.

I'm going to try to attach a couple of pictures.

From the Service manual on the CD
-ksb1 describes the function of the KSB system
-ksb2 is the troubleshooting guide
-ksb3 is a wiring diagram

I have replaced the KSB relay twice.
Looks like I need to check/replace the "KSB unit" and check/replace the "Temp switch"
The KSB unit is at/attached to the injector pump - I'll have to find the Temp switch.

If this doesn't solve the issue, I'll move on to the next tier of possibilities.

I have previously checked the thermostat. The tractor seems to run very warm (almost hot) when
operating at pto speeds for a length of time. For instance, mowing cornstalks or running the grinder mixer.
If I am mowing stalks/weeds/grass, I have to come in every couple of hours and blow out the radiator.
My coolant overflow bottle cracked and I bought the new design replacement. (new mounting bracket and all).
This is one of my two complaints with the tractor. The other being numerous electrical issues.
Lights work - sometimes. Gauges work - sometimes. Warning lights work - sometimes.
I've spent hours tracing wires, looking for bad connections, checking grounds.
Seems to be a weak point to what is otherwise a beast of a machine.

Thanks everyone - little things can sometimes be the most infuriating.

 

[Coyote machine]

Thanks for the complement! I appreciate that.
Brad, it seems you're on the right track with the KSB, especially since you've already done a lot of what I was suggesting- checking wires, grounds, etc.
So, I think you definitely want to locate the sensor that is connected into the KSB circuit so it can be eliminated as a possible cause of your troubles.
The service manual page said it is located in the intake manifold. The sensor is in effect until the intake manifold has 40degrees C= 104degrees F. So it is NOT a coolant temp the KSB responds to; it IS an AIR temp it is reading, SO if your thermostat is delaying the engine coming up to temperature it could affect the intake temperature too. Find that intake sensor and remove it for inspection. It should have a range of temp it works at and you could test it to see if it is within specs. OR your dealer could give you another one and a thermostat to exchange and note what changes. If you do both, do one at a time to see which has what effect. As far as running near hot when having worked the tractor I would suggest changing out the t-stat and see if anything changes. Have you ever changed the coolant in the radiator? If not, it may be time to do so. Coolant naturally breaks down over time and should be changed every couple of years. It can turn to almost sludge like consistency and does not provide adequate cooling and corrosion protection after a lot of hours of use. This could also dull/delay the sensor readings the KSB unit is looking for to tell it how much fuel to deliver when coming up to temp in colder weather.It is hard to read the wiring diagram, and when I blow it up to readable size it is too blurred to see clearly. But I think I get the jist of it. There is a 15amp fuse in the circuit, so verify it is good, and clean. Keep taking notes, especially of ambient temp and such like you did today- it will help you keep focused and narrow down exactly when the machine does what.
And it sounds like you have a good tractor that has some nasty bugs that need to be worked out so you can get it to being what it should be- reliable for your use.
I would keep on your dealer about a list of ALL the issues you just mentioned to get them to remedy them under warranty. This is their job.
The temperature thing I believe is tied into the situation. You say it tends to run hot when working it hard. This is not what I would call normal. And your persistent slew of wiring issues is not good, nor normal either. For the wiring I would take a serious look at your battery negative cable and where it attaches to the frame and clean it by removing the bolt at the frame, removing any and all corrosion, grease, dirt etc. Then shine up the ground lug at the frame, coat it's bolt with copper anti-seize and then spray the frame/lug/bolt with battery protection spray after tightening the bolt real tight. Do the same to both the pos and neg at the battery, in addition to using the felt washers available in any auto/tractor store. Then have someone grab the negative cable and move it around while you crank the engine to see if there is any effect on gauges/lights/ etc. If there is any fluctuation, replace the entire cable with new lug and battery post end. Cables do corrode internally, especially with intermittent issues like you have in your system.

 

[rustyjeep]

If you get this figured out let us know. I've been dealing with this same issue for 6 years now.

 

[sd455dan]

Has any one tried disconnecting the 12 volt wire to the ksb from the relay that is switched on by the thermosenser switch

after reading the description and the schematic it would seem the easiest thing to try would be to disable power to the ksb

since the description says

(No sooner the temperature reaches above 40*C and engine achieves stable condition the sensor STOPS electric supply to relay AND KSB solenoid. thus normal timing is restored.)

it would seem that disconnecting the relay wire to the KSb should disable the solenoid , thereby stopping the pressure increase and timing advance and the tractor should act like every other mechanically injected diesel without any cold start timing or pressure changes and it would act as if the outside temp had not ever dropped below 40*C

thinking it might be worth a try... and that If the Ksb is staying on and powered up when it shouldn't be -that the overly advanced injection timing- may be hard on a fully warmed up engine...

 

[SPYDERLK]

If you get this figured out let us know. I've been dealing with this same issue for 6 years now.

Have you tried advancing the injector timing by rotating the injector pump about 1/16 inch? Cured mine completely. I now have 1300Hrs.
larry

 

[rustyjeep]

No I haven't tried that. I'll have to research that.

Not trying to hijack the thread, but how is everyone elses tractor on fuel? Mine drinks it like crazy

 

[SPYDERLK]

1 to 3 GPH depending on load. ... seems worse because its a small tank. ?What yr is your tractor? The rubber filler hose leading to my tank cracked and started leaking at about 6yrs.
larry

 

[rustyjeep]

I bought mine in sept. 2007. My tank is under the floor board,no filler hose on this one.

 

[SPYDERLK]

So is mine. Where do you put the fuel in?

 

[rustyjeep]

My tank is molded so the cap sticks out just past the floor board. I'll try to get a pic for ya

 

[SPYDERLK]

Oh. Mine, 2006, comes up behind the seat. I didnt know they had changed it.