943 B It loses performance when warm.

[cat951b]

Look in the 9J-0365 & the 9J-8554, Replenishing Valve (LH & RH). The seals are listed in both.
You need #10 & 11 - 4J-8996 Seal O-Ring, and 9J-8086 Ring - Backup

View attachment 307016

Hi Nige,
thank you very much for your quick professional help!
Unfortunately, I missed this drawing in the parts book. (Unfortunately, I don't speak English and I use Google translator and it often doesn't work exactly, so it makes it difficult to interpret accurately.)

Yes, we agree that this is a worn O-ring and it is probably leaking. I thought it wasn't cracked or torn.

 

[cat951b]

Actually there is damage on at least one O-Ring when the photo is zoomed. See below.

View attachment 307048

I also think that I know why the Teflon backup rings have worn, and it all revolves around the fact that the O-Rings were originally a circular cross-section when they were new but now they appear to be almost square.

The material of the 4J-8996 Seal material when new is 3.53mm in diameter - shown by the black circle.
If the seal is flattened over time until the cross section transforms from that circle to effectively a square with rounded corners then the "height" of the seal in the groove reduces to approximately 2.9mm - shown by the red square.
This is what I think has caused the load to move from the seal to the Teflon backup ring and caused the wear to said ring.

View attachment 307049

thanks for the detailed analysis and part numbers.

 

[cat951b]

Dear Nige,

I would like to ask for one more help.
Regarding the sealing of metal pipes inside and outside the Hydrostat. I couldn't find the part number of the sealing kit shown in the attached pictures either. Could you find this for me too?

Thank you in advance.
Have a nice day.

 

[cat951b]

Under the valve cover there are metal lines that go to the servos the fittings sometime leak they are like a compression fittings and need replaced I have repaired a few by doing this. It would act up when warm

Hi Dave,

Are those metal pipes and seals?

 

[Nige]

Dear Nige,

I would like to ask for one more help.
Regarding the sealing of metal pipes inside and outside the Hydrostat. I couldn't find the part number of the sealing kit shown in the attached pictures either. Could you find this for me too?

Thank you in advance.
Have a nice day.

See the illustration below.
If you want the big black seal seal on the right the Part Number to buy it separately is 8T-9502.

None of the other three parts in your photo are available separately. If they are damaged then order 5P-8752 Nut Assembly.
You will find 5P-8752 listed in the parts for the 3G-7395 Hydrostatic Case Lines Group.
5P-8752 Nut Assembly also contains the 8T-9502 Seal.

 

[cat951b]

See the illustration below.
If you want the big black seal seal on the right the Part Number to buy it separately is 8T-9502.

None of the other three parts in your photo are available separately. If they are damaged then order 5P-8752 Nut Assembly.
You will find 5P-8752 listed in the parts for the 3G-7395 Hydrostatic Case Lines Group.
5P-8752 Nut Assembly also contains the 8T-9502 Seal.

View attachment 307098

Hi Nige,

Thank you very much for the detailed information and your work.
I'm already ordering the parts.
I wish you a nice day.

 

[cat951b]

Hey guys!
I found the following problem in the diesel fuel tank. (However, the inside of the tank was nice and clean!)
Look at the photos...
The suction pipe elbow was almost completely blocked with some old pieces of rubber or plastic!
The engine could not get enough fuel under load, which could also result in poor performance!
It is not enough to just check the filter system!
Even small things can be very annoying

 

[thepumpguysc]

Oh WOW.. good find..!!
If it has a black plastic tank, I’ll bet money it came from there..

 

[Nige]

IIRC the wire mesh screen in the filler neck of the fuel tank has a plastic structure to which the mesh is bonded. What's the betting that plastic started to fall apart and someone threw the screen away - but not before some fragments of it got lodged in the fuel line elbow.?

 

[cat951b]

The filter and tank interior are in good condition for their age!
I'm guessing some foreign material, because I found a metal ball suction head in the tank earlier, which may have fallen in at some point when they wanted to suck the diesel out of it.

 

[Welder Dave]

If I recall the plastic around the fill strainer is a white/yellowy colour from the diesel on my 931B.

 

[cat951b]

Greetings to everyone.
I am sending here some pictures of the inside of the tank, of the filter.
All parts are intact and original, only minimal rust is visible in the tank.
Because of the suction head found in it, I concluded it was a foreign substance.

 

[cat951b]

x

 

[cat951b]

In the meantime, the aforementioned seals and connecting rod bushings from Caterpillar arrived. I have already installed the rubber seals and O-Rings in the hydrostat.
The inside of the hydrostat was "pharmacy" clean There was no sediment in the oil pan, I found few, very fine metal particles on the filter magnet. (I think they come from the gears)
Unfortunately, I didn't take many photos in the rush of work