Hi all,

I recently pulled the gauges out of my 1954? 300U because the oil gauge was cracked, the temp gauge didn't work, and the tachometer cable was leaking. I bought new gauges and tach cable. A couple of questions on this.

First, I bought a new tachometer (the old one was working, the cable was just leaking) because when I took the cable off and tach out, the tach face filled up with oil when I tipped it up. Why would there be oil in the tach like that? Is that normal and I just caused by turning the gauge upside down? Could the leaking cable have caused this somehow? Could I have some other issue?

Second, on the back of the new tach I bought there is the normal connection hole which matches my old cable. However, there is also another hole that has a little brass screw in it. My old gauge didn't have that. What is that screw for? The part numbers didn't exactly match, even though I'm told this is the right tach for the tractor. Is this screw just something for different models the tach may fit or some kind of adjustment I'll need to deal with?

Last, is there anything I should know before installing the new tach, tach cable, temp guage, or oil pressure guage? Any tricks or anything to watch out for? As of know I'm planning on pulling the old ones off, hooking the new ones up, and firing up the tractor. Any info at all will be helpful. Don't assume I know anything b/c I don't!

As always, thanks for the help guys.
Ben

I don't think there's supposed to be any oil in the tachometer cable or tachometer.

What I suspect is happening is, the rear seal on your hydraulic pump has failed. It's pumping oil into the distributor, which is working its way up the cable into the tachometer.

Your tach or cable should not fill with oil. A seal is leaking where cable is driven. You old tach should be just fine, the oil shouldn"t hurt anything and should drain back when uprighted. Make sure the tachs are the same height and width, the 300U and 300 rowcrop use different tachs. One thing to watch when re-assembling the instrument cluster is to not kink the oil line for the pressure guage and to make sure no wires are pinched. Other than that it is straight forward.

Thanks for the info guys. Dang, I was hoping I didn't have a bigger issue. Given what you say, looks like I probably bought some parts I didn't need since the old tach was working. How big of a job is it to change the seal on the hydraulic pump?

In addition to the other advice, be sure to check the back of the oil pressure gauge for leaks after a few minutes of engine operation (just dab it with a paper towel or something, you don't have to be able to see it).

I was going to tell you the brass screw on the tachometer is a drain to let out the oil after it leaks in, but maybe we don't share the same sense of humor. ;-)

Mark W. in MI

That's a good thought on checking the back of the gauge. The way my jobs go though I might not want to know!

If you would have had me if you would have told me that screw was for draining the oil if you were the first one to reply. For all I knew the oil was supposed to be in there!

I realized I replied above to the general post and not to your follow up. So given that, what does it take to replace the rear seal on the hydraulic pump? Is that something a novice can handle or is it a big job?

A follow up to this. I got home tonight and pulled out the tachometer drive gear and a bunch of hydraulic oil came out of the housing. Does that indicate that I have a leak in the hydraulic pump seal? Is there supposed to be oil in there? There was maybe 1/2 qt or so.

Thanks.
bp

Your pump is leaking. There should be some grease in there. Be prepared for a seal not to fix the leak, as the pump shaft and bearing might be worn.

So how big of an issue is this if it's leaking like that? Will it do any damage or just waste some oil? I only use the tractor maybe once a month for a few hours so if it leaks a little I can live with that. But obviously I don't want to leave it like that if it's going to cause damage to something else. Just thinking over my options...

Thanks for your help.