HST Fluid coming out of transmission filler plug - TYM 273

BruceV43 · May 27, 2014

I have a TYM 273 with mid mounted mower (TYM). Tractor has done 700 hrs and bought 3 mths ago s/h.

The more I use it the more it leaks HST oil from the filler/breather at the top of the transmission. I am planning to service the transmission shortly but reluctant until I understand why it is 'leaking' so much oil - any ideas anybody?

I have confirmed that the oil is emerging directly from the filler plug which has a small hole, presumably to prevent any build of pressure although there is a separate vent pipe for this, which appears to leak very slightly.

The leakage amounts to about 1 litre for every 2-3 working hrs, which is a massive amount by any standards. In other respects the tractor runs well and all hydraulic systems are apparently normal - surely somebody must have some ideas??

One further point: I have run the tractor with the filler plug removed to see what happens. It's all ok when idling, ie low revs, but on increasing the revs, there is a fast flow across the filler opening (from rear to front), this ceases as soon as the auxiliary spool control (sticking out from below the driver's seat) is moved left or right to raise or lower the mower; normally it would be in the central position to neither raise or lower, ie a sort of neutral position. Is the leakage simply as a result of this 'churning' of fluid directly onto the base of the plug - if so, how can it be stopped?

Very puzzled TYM owner

NB This post was originally under Oils & Fuels - was wondering why no replies, so have 'moved' it. Apologies if this is wrong but still learning.

J_J · May 27, 2014

You may be churning up the fluid and generating air bubbles, and the expansion forces the excess volume out of the filler cap.

You do have the fluid at the correct level? Check when warm.

You might also have a suction leak generating air bubbles.

CalG · May 27, 2014

What do you get when you pull the level plug? Or does your tractor have a dip stick?

Is the unit over filled is the question?

Johnny g · May 27, 2014

I would check for plugged vent pipe or over filled.

BruceV43 · May 28, 2014

Thanks for your suggestions guys - indeed my first thought was overfill, but then I realised that when I first saw the tractor the transmission oil level was correct! It has a little peep hole in the rear axle case and is easily seen from the rear and recently I have have allowed the oil level to drop, so that I could measure it, to the point where it was only visible in the peep hole if the front was raised.

It has taken 5 litres to refill, out of a total capacity of 22 litres. Having cleaned all round the filler cap and run the tractor without the proper seat, oil slowly emerges from the cap (it does have a small vent hole) in a gentle stream without any bubbles or throthing after a few minutes of running at normal revs. Running the engine with cap removed and there doesn't appear to be any throthing although there is a very strong flow of fluid across the base of the filler hole from rear to front - is this flow simply being pushed out of the cap through the inherent force of flow? If so why?

BruceV43 · May 30, 2014

Still hoping JJ or other users may have some thoughts on this as I'm getting a bit desperate as, apart from the cost of oil which is almost on a par with the diesel consumed, it's leaving oil trails all over the grass especially anywhere where I have had to go very slowly or simpled parked for a while!! This is enough in some spots to kill the grass.

Incidentally I have logged a query to TYM (UK) via their website about this over a month ago and tried a direct email to an admin account very recently and not so much as peep from them - it doesn't seem to be a very good way of fostering customer loyalty, does it?

Here's hoping!

J_J · May 30, 2014

You generally do not dump return fluid into an air space. Fluid just does not float up.

Take a look at your parts manual and see if a down tube/deflection tube or something to direct the fluid.

About the only way for fluid to exit the filler cap is the fluid is forced out by pressure or air bubbles raising the level of the fluid or heat expanding the fluid.

Other than the above, I can't think of a logical reason for fluid to pour out of the filler cap.

You might try a metal strip attached to the filler cap to deflect the fluid.

Perhaps one of those small inspections cameras can look inside the reservoir and provide some answers.

I have one of those cameras on the end of a flex tube that can plug into my laptop and let me see things that I never could see before.

Check with your dealer and see if other tractors have had this problem.

vabiker23518 · May 30, 2014

I have the T233, which is very similiar; thankfully haven't had the issue but look forward to hearing what the ultimate solution is. Do you have a dealer close by? Here in the states TYM has a 5 year warranty on drive train and it sounds like you should be covered.

BruceV43 · May 31, 2014

Unfortunately the tractor is out of warranty (7 yrs old with 780 hrs) and I am using it in France, having exported it from UK 2 months ago. It seems that in FRance TYM is an unknown make - there are no dealers as far as I can establish, so difficult to get professional help.

I have spoken to a UK dealer who believes that it is most likely that faulty connections to the input side of the pump, mounted on the engine, is the most likely source as he says that he has seen this on Mitsubishi tractors but not on TYM, although T273 does have Mitsubishi engine and a brilliant one at that.

I will report back when the problem is licked - many thanks JJ (still working out how to make a reliable deflector plate)and others