7745 lift dropping

[rujib]

Hi,

My 7745's lift seems to drop a few inches and than shoot back up again on a constant basis.
I cannot identify and external leaks on the assistor ram or anywhere else for that matter.
Is it likely that this problem is caused by in internal leak somewhere. In the assistor ram for instance?
If yes, is there a repair kit available to fix it?
Would it be a difficult job?
Would I need any special tools of equipment?

I have just sorted out a long standing problem with the steering on my 7745 and installed new brake cylinders all round aand given it a thorough overall service, so the tractor is really in great shape except for this one last annoying fault with the lift.

Would appreciate any guidance from the experts.

Thanks in advance.

Rujib.

 

[dave_peters]

You can check the assistor ram by removing the small pipe that returns leaked oil and seeing if there is leakage past the piston seal. Otherwise the only option is to take off the hydraulic top and replace main ram seals. before you do this, check that the small lever on top of the hyd cover that is operated by the flow control on the "wall" in front of the hyd control levers, hasnt worn a bit and dropped nearer the cover. this can cause a small leak like you describe. if it has, you will have to take the cab floor out, drive out the tension pin that holds the lever on and put a shim washer under it. Or if you never use it, as most people dont, wedge a piece of thin tin bent double under neath to hold it up and stop it moving.
Dave

 

[irish7211]

Did you sort out the problem with the lift dropping on your 7745. I have a 7211 with the same problem. How did you sort it out

 

[bcrosehill]

I had a 3321 that was doing the same thing. I noticed a piece of rubber o-ring when I changed the hydraulic filter. My dealer replaced the spool valve and it completely fixed the problem.

 

[rujib]

Did you sort out the problem with the lift dropping on your 7745. I have a 7211 with the same problem. How did you sort it out

Hi,

Well I just changed the assistor ram seals as they were actually leaking a bit. However, no improvement to my problem.
I guess I just have to bite the bullet and take off the cover and replace the internal ram seals.
Dose anybody know if I can get better quality seals for the internal rams as opposed to those provided by Zetor . If the answer is yes I would be tempted to go that route, so as to get a longer life between replacements.

Any ideas?

Thanks
Rujib

Rujib

 

[ixer0]

Hi

You can't get better quality than genuine Zetor seals.

Mike

 

[markku]

Take the original seal off and go to specified hydraulic shop with it. They can sell better quality seals to you. It is standard size (mm) seal. You need too 2pcs O-rings for preussure oil pipe that comes to hitch cover from pump. (If you have 7745 or older model)

 

[Renze]

Mostly it is caused by the big o rings around the main hydraulic piston. replacement is easy, just hard to get at as you have to swing the seat and cab floor forward and then lift the dead-heavy lift cover off the rear axle.

 

[markku]

There is no O-rings, there is "good quality" Guffero seals And one steel ring. I changed those seals to mine 7745 this year. I havent ever seen any as worned seals!!!! There was only some rubber pieces left. Only thing that kept oil in the cylinder was that steel piston ring. 69)

 

[david_lindsay]

I just bought a 1988 Zetor 7745 with 1128hrs. When stopped for an hour or so the rear 3 point hitch drops to the bottom. On start up it has to be lifted back up.The front 3 point stays up fine. The tranny is hard to shift from high to low range and vice versa. The muffler is cracked at the bottom. Is this a weak spot on Zetors? Comments and suggestions welcome. Fox

 

[Renze]

You sure it isnt 11.120 hrs ? 1120 is a bit low for 20 years of operation...

 

[ixer0]

Hi

The hydraulics could be dropping because either the assister ram seals or the main lift cylinder seals are leaking.
Hi-low shifting problem is probably because you have the 4WD engaged and are using it on a hard surface causing the gears to "wind up". Try reversing up to see if it frees off.

Regards

Mike

 

[Renze]

This is usually the main lift piston. Older tractors with no assister ram did the same thing.

 

[david_lindsay]

Still trying to learn postings etc. The clock reads 1128.66 I purchased it from the wife of an old couple. He is 86 and used the tractor for pushing snow. They bought it new and say the hrs are genuine. It was stored inside a garage for most of it's life and I wonder what damage or things to watch out for from excessive storage. The tires are original, not sun checked and with little wear. I'm hoping they are not rooten or something. Foxman

 

[david_lindsay]

Guys; Thx for the responses and I will try to free up the low range by reversing. The muffler looks new but is cracked at the bottom just above the manifold. I could weld it but is an after market muffler a better way to go or is Zetor original a special muffler?. I live in northern Ont and have emailed two dealers but so far no reply. Any one know of good Ontario Canada dealers? Thx Foxman

 

[Renze]

excessive storage:

If the engine never reached its operating temperature, expect leaking piston rings and clogged up head and manifold.

These engines are notorious for their leaking piston rings, when you buy them from old people that never put them to work
We bought a 1986 5245 a few years ago, it was lazy as a dog and was performing far worse than its predecessor, a 1974 4712 which was basically the same tractor, just no 4wd and cab.

Mean time the engine cleared its throat and ive opened the fuel pump a bit. I expect to get 57 flywheel hp now.

Just change the oil first, then put it to heavy work. when the sparks from the exhaust are gone in about 20 hrs, change the oil again.

The additives like Bar's nural, or slick 50, they do work to clean these clogged up engines.

 

[david_lindsay]

This is a 7745 FWD We've changed fluids and put her to work. Lots of power, no smoke and good temps. Only problem is right brake has little stopping power but left seems OK. I need to buy a repair/shop manual . Anyone know where to get one? Foxman

 

[Renze]

http://www.zetorusa.com/

these guys sell parts for reasonable prices, and are not affiliated to Zetor itself nor the USA importer.

 

[david_lindsay]

Thx for info. I changed oil and oil filter/spinner canister. It had a good 1/16" of black crud/dirt that I scraped off. Would this be normal accumulation after 200 hrs or so. seems excessive to me. I've never cut open a paper filter but was wondering how much dirt and crud gets in them. Foxman

 

[dave_peters]

Thats about normal, I have had nearly 1/2 " on the filter of a tractor that was only doing light work in 150 hrs.
Dave