peterkvs
Active Member
Just wanted up update the story here. After talking with some people that rebuild these transmissions I learned that the filter caps should be tight enough to not be able to turn them when installed. Mine nearly flop around in the hole and could easily be turned. I also learned that the filter cap is on the suction side of the pump and that if you leak too much air by the cap you could cause foaming of the fluid which could reduce pump pressure which can cause you clutches to slip, overheat and kill your transmission. Fortunately I did not learn this the hard way. One of the transmission rebuilders I talked to said that he always puts some transmission fluid around the filter cap after installation and while the transmission is running to make sure it is not sucked into the transmission past the seal. I believe that my filter caps were leaking transmission fluid out while operating at low speeds. I say this because I took of the filter cap right after I had run the engine for a couple of minutes and the filter chamber was so full of fluid that it shot all over the bilge. The fluid would only drain back into the transmission after I removed the dipstick, so there must be a slight positive pressure inside the transmission, perhaps due to the fluid returning from the cooler to the transmission? I don't really know. I was also able to get some measurements of the orings on a filter cap that the rebuilder I talked to had and he measure it at 6mm. When I measured the orings I had, they both measured 5.6mm. This is very disturbing because both the orings came with the new ZF brand replacement filters I purchased last year! I went to the oring store and bought some 6mm and #407 (approx. 7mm) imperial orings to try. The 6mm orings were much tighter and were closer to being right, but the #407 orings were the cats meow. When using the #407 orings you could see that the oring would actually pull the cap slightly into the case as it was tightened and there was no way you were going to turn the cap once the bolt was tightened.
So, I don't think that I am going to see any further leaks from the transmission, and hopefully I got the problem fixed before I did any damage to the clutch plates. I am going to take a sample of the oil and send it out for analysis and compare it to last years analysis and between the two transmissions. Word of caution, watch out for undersized orings from the mfg and make sure those caps are tight after installation.
Pete
So, I don't think that I am going to see any further leaks from the transmission, and hopefully I got the problem fixed before I did any damage to the clutch plates. I am going to take a sample of the oil and send it out for analysis and compare it to last years analysis and between the two transmissions. Word of caution, watch out for undersized orings from the mfg and make sure those caps are tight after installation.
Pete
