B7100 HST - new to me - oil pressure and running temp and lots more questions

[oz_chris]

Hi,

I have recently purchased a B7100 HST 4WD with mid mount mower.

When I inspected it, I noticed that it had new head bolts. The seller said the head had been off as there is an o-ring in the head that was leaking oil, which he said is a common problem. I asked if the head had any cracks as I had heard this can be a problem, which he said there wasn’t. I didn’t see any signs of bubbles in the coolant when running.

It had new oil, oil filter and coolant in it as he said it had just been serviced. Engine was clean.

It has a non genuine temperature and oil pressure gauges and an ammeter fitted.

When I first started it at home the oil pressure was reading about 200kPa (29psi) and after running around doing some mowing got down to 125kPa (18psi) and temp was reading about 140 C (280 F).

Today when starting oil pressure was reading about 150kPa (21psi), and after mowing for an hour at high speed/high load oil pressure was reading in the red zone on the gauge at about 65kPa (9psi) and temp was about 180 C (350 F). I didn’t see the oil pressure light on at all.

The oil pressure light works as it goes on then off when running.

Now for a couple of questions:
1. Do I have anything to worry about running into the red zone (<125kPa or 18psi)?
2. Is this normal operating temperature?
3. At what oil pressure should the light come on with my engine?

I have had a look at other posts and manual, but still not sure..
If I didn’t have the gauges, wouldn’t know any better, but as I have them, would like to know what they are trying to tell me…..

Thanks in advance.

Chris.

 

[gktilton]

I would question the accuracy of the temp gauge. Most antifreze will boil around 270 degrees. What do your fluids look like now that you have run for a while? Where is the temp sensor for the temp gauge installed?

 

[bruceatlam]

The idiot light comes on at 7 psi.

My tractor runs at about 40 psi oil pressure at operating temperature of about 170 deg F all the time. Cold I get about 50 psi oil pressure. This is all according to my gages. I read the temp in the upper radiator hose just before the radiator.

 

[oz_chris]

It's been a while now, as usual plenty of other jobs.....
Have probably done about 25 hours of mowing and the fluids haven't changed and the readings stay about the same....so not getting any worse.
Below is a picture of the gauges and what seems to be "normal" pressure/temp. for this machine,

and the position of the temperature probe in the top of the radiator.


This machine must of had a hard life...finding more dramas.
Replaced one of the non standard mid mower blades (has arms and small standard mower type blades on the ends rather than the one piece blade as std- so a bit cheaper) and belt so far.
Had the HST locking up and the Mid PTO popping out of gear.
Checked HST oil, smelt and looked OK, but bit the bullet and pulled covers off and dropped oil and filter (which had 05 marked on it - spin on filter - didn't realise that it also has the screen, thought it was one or the other so didn't clean it) hoping it would help....bit better but Mid PTO now pops out every couple of metres of mowing.
It looks like someone has done a dodgy before and cut the frame so that the top of the gearbox case can be opened without splitting the tractor (it has a canopy/cage mounted front and rear so would be hassle to split) and was considering doing same....but after speaking to a dealer, decided it was easier to drain oil and pull off the mid mount PTO housing.

When I pulled of PTO found the HST oil mesh screen kept dripping on me so pulled that out, not sure if you can see in picture, bits of metal on the screen and a picture of where it is located as have seen lots of questions on its location.

To be continued with more pics...might help someone...

 

[oz_chris]

Whilst checking my post and zoom of the pictures, just realised my initial reading of the temp gauge was wrong! Looks like temp is OK, just I was reading as degrees F not C......1 less problem on the list!....(I won't start and argument about having 2 bloody different measuring standards...)

 

[oz_chris]

So back to pulling off the mid PTO housing...pictures for anyone that hasn't done it, 4 bolts straight forward. This gear looks good. It's a pity this gear isn't the weak link as it would be easy to replace....

These next pictures are taken from under the gearbox looking through the PTO hole up. You can see the PTO selector fork against the side of the casing (black cast bit) which is on the RHS of the B7100. This picture shows the stick forward to engage the mid PTO gears so selector from below is to the rear of tractor. The closest shaft is the rear PTO output shaft and the two gears in the cluster around the fork slide in the spline on this shaft. In this position the shaft doesn't turn, but the gears engage the gears above and the mid PTO gear that I removed.

This picture is in Neutral, so gears not engaged and rear PTO shaft can turn but not engaged.

This picture is in rear PTO engagement position, so mid PTO gear not engaged but the shaft would turn.

As you can see, the gears at the end of the screwdriver (that engage the selector gears) and the spline on the rear PTO shaft, along with the selector gears are all worn.

What to do ????

 

[oz_chris]

Another thing I noticed is there is about 10mm of movement in the gears whilst still in the selector notch.
Is this allowing the gears to move enough so the worn edges of the gears to line up and then disengage the PTO?
Can this be tightened up? Can't see from below if there is a ball bearing that engages on the selector shaft that could fix this or if it is something in the fork???
It would be great if this could be done from here? doubt it....Is it possible to pull out shafts by only removing the differential?...still trying to avoid splitting the tractor!

What to do???
1. put it back together, and use a wire to hold the stick engaged then sell it and move on to next problem tractor?
2. try and remove differential and replace a couple of gears from there?
3. split the tractor and do it properly, but grass will be bit longer by then!
HELP !

 

[oz_chris]

Another day....another problem
According to local tractor dealer gearbox shafts come out the front of the gearbox, so option 2 of just pulling of diff is out.
After speaking to a customer that walked in that has rebuilt his HST (according to the guys a big job) he recons it is unlikely that my problem is caused by the worn gears. Thinks it might be due to the movement in the selector. So started looking there.
I thought that I may have been able to replace the ball bearing that holds the selector in position as the diagram the tractor guy was showing me had a split pin and spring that can be replaced from below (see first pic) but this was the later ones, so mine is the second picture so have to pull the shaft out to get at that...back to splitting the gearbox....if I want to fix it.

Got a price on the selector gear ~ $500 AU shaft about 100, so probably $1000 + in bits...plus the time....

I noticed on the PTO gear that one edge is bevelled, probably to make it easier to get into gear,so thinking of turning it around so hopefully it will also be harder for it to pop out and then put it back together so I can cut the grass while I think about splitting the tractor....

 

[oz_chris]

mmmm.... just looked at gear box picture again and had another thought..

What are my chances of being able to drill out the bottom of the selector to pull out the spring and bearing?
Then buy the later model spring and bearing and then find some other way of holding it in there???

 

[oz_chris]

Decided it would be too hard to drill out ball and be able to find a way to secure the new one in so swapped the gear around and put it back together - a bit harder to get into gear, no change in popping out. As soon as the PTO is loaded up, the lever moves back a bit, this is probably the movement in the selector ball bearing, then when mowing load increases, the gear then pops out. Must be due to the wear on the shaft and gears.

 

[oz_chris]

Another Year - another problem - whilst doing some spraying, noticed an unusual smell, and the ammeter sitting still, so lifted the hood and found the fan not turning. Turned her off before she got too hot and melted the belt, and wasn't able to spin the hand by hand. After reading the posts here figured out it must have been the bearings in the dynamo, so bit the bullet and pulled the front to bits to get it off. As per reading other posts, there is one painfull nut to get at, so that was a good excuse to buy a set of the ratcheting ring spanners! Rebuilding was straight forward, with the local bearing shop having the bearings on the shelf and cheaper than kubota dealer which didn't have them in stock. Whikst there replaced the bearing for the belt tensioner pulley as well, and new fan belt as don't want to have to pull radiator out again next month if I didn't.
Thought I would take pictures so others looking at doing this know what they are in for.
Engine with dynamo removed:

Dynamo back:

Dynamo front:

The difficult nut in centre behind the dynamo:

The tool for the job:

Whilst I had the front apart thought I would look for the oil bypass valve to hopefully address my oil pressure issue - but I will start a new post to cover it.

 

[oz_chris]

Now I need HELP - PLEASE...
I have found that the oil pressure relief valve bolt is covered by a plate on the side of the tractor. A massive job to pull front sub frame of tractor apart, so my plan is to drill a hole through the plate so I can get at it....but where to drill and what size??? I would really appreciated if someone can measure the distance from the four holes on the side of the block to the location of the centre of the relief valve cover bolt and tell me what size bolt head it is so I can drill the hole I need.
Picture of my issue:

Thanks....

 

[btackett]

Here is a cropped pic that I had. It is a bit fuzzy but you can see the oil pressure screw next to the block bolt. I don't have a measurement but it looks like it is close to 1" from where the block bolts up.

Hope this helps.

 

[oz_chris]

Thanks.
According to the parts diagram the holes closest to the block bolts (on the block #7 & #8) are just plugs???
The oil pressure relief valve and spring is #30 & #31 and located in the gear case.
Or is this not right and I'm on the wrong track??

 

[btackett]

You are correct. I misread your last post. I can see my bolt #30 by removing the front pto cover and with a long wrench get to it but it does not good and you don't have enough room to remove it. You should be able to see yours and get a measurement to cut a hole if you wanted. I found my service manual and it states that the bolt/ball/spring is non-adjustable and normal unrestricted oil pressure should be 28-64 psi. Relief valve opening is set 43-50 psi and non adjustable. I wonder if the spring is worn or could be replaced without doing an oil pump. If not, I would say oil pump replacement. It is accessable through the front cover after radiator is removed.

I would like to install an oil pressure gauge on mine just to see what it pushes.

 

[oz_chris]

Yeah I'm hoping that it is full of crud or a broken/worn spring that is the cause of my low oil pressure, but may be wishful thinking of an easy fix. I have the front off the tractor at the moment but can't see behind the plate to locate the bolt head to be able to make the hole. If I can't get a measurement from here I will have to find one locally to measure. Thanks.

 

[btackett]

Sent you a PM

 

[whitetiger]

The reason your PTO kicks out is most likly because the detent ball is sticking in the shiftfork and not seating in the slots in shift rail. Drill a small hole in the bottom of your shiftfork to flush it out. Drill the hole slightly larger than diameter of a straw that comes with a can of carburator cleaner. Use the cleaner to flush out the sludge / debris build up, spray then shift back and forth, spray and shift. You can also stick a piece of bronze rod in the hole to push the ball up once in a while.
Every PTO shift fork I have had out of this series of tractor has been sticky.

 

[oz_chris]

Thanks whitetiger I'll give that a go next time I get annoyed with it and feel like dropping the pto housing and oil out.

 

[oz_chris]

Got the dynamo back on today. Had no hope of getting the washer and nut onto that difficult stud, so ended up pulling the stud off and putting the nut on it when it was out so didn't have to try and get the nut on from in that small hole. Was straight forward after I stuffed around a bit until I thought of that.