instron 1331 shematics and manual

A teaspoon of finely ground black pepper in that cylinder might plug that leak, after a little while. Works for car radiator leaks. Unlike a car water system, the hydraulic fluid is not circulating, so getting good particle distribution near the leak may be a problem.

Black pepper is good because it's easily available, doesn't rot or swell, and it won't score metal surfaces. It also passes through water pumps without a problem, but that doesn't apply in your case.

snipped-for-privacy@gmail.com wrote: I can keep operating the machine with the leak, but would like to know the possible sources and repair options before getting an Instron technician. A teaspoon of finely ground black pepper in that cylinder might plug that leak, after a little while. Works for car radiator leaks. Unlike a car water system, the hydraulic fluid is not circulating, so getting good particle distribution near the leak may be a problem.

Black pepper is good because it's easily available, doesn't rot or swell, and it won't score metal surfaces. It also passes through water pumps without a problem, but that doesn't apply in your case.

Fonzlopez, I think Mark Thorson forgot to include a smiley face at the end of his post. Introducing pepper, or any other type of solid into a hydraulic system is an exceptionally bad idea. Don't do it!

I suggest that you continue your search for a service manual. If your search is unsuccessful, then go ahead and try to fix the leak on your own. Hydraulic systems are usually relatively simple and easy to service. Just take your time when disassembling your system. Take careful notes and digital photographs of the process. Try to keep everything clean and avoid introducing contamination into the system. The most likely cause of the leak is a torn gasket or a worn out o-ring. O-rings can be purchased at most industrial supply retailer. You can also purchase gasket materials and make your own replacement gaskets.

Good luck!