1975 350 Dozer leak

[C.miller]

Thank you for all the information. With everything said and research done im going to call it a 350-B but I will make sure to try to identify part numbers on any parts I replace with the existing part. Thank you all for help.

[Al Swearengen]

In my experience, every time I had one come in with a seal leaking they all led to having bad bearings that caused the seals to fail. The input shaft on the early reversers especially are very prone to do this.

Saying the bearings were good, has anyone ever used hydraulic sealant like the stuff Lucas Oil makes? They 'say' you can run it in anything, even engines to seal leaks. Curious because I see such good reviews for it.

[LeonardL]

There is no such thing as "Fix It" in a can. These things are marketing gimmicks. All they do is cause the material the seals are made of to soften and swell up. This result may stop a leak momentarily but inevitably you will have to go in and fix the problem.

[Al Swearengen]

There is no such thing as "Fix It" in a can. These things are marketing gimmicks. All they do is cause the material the seals are made of to soften and swell up. This result may stop a leak momentarily but inevitably you will have to go in and fix the problem.

I was just curious what folks thought. 4.9 out of 5 rating on Amazon with lot's of very positive comments.

https://www.amazon.com/Lucas-Oil-10018- ... 584&sr=8-2

For sure, everything wears out eventually.

[Jim B]

I have seen such additives temporarily slow or seal a small leak. Like Leonard said it may soften and swell the seal to hold for a bit but not a real fix. The seal may or may not swell. If the seal is worn it will not replace missing material on a worn seal. I do not see it working on something like a clutch pack seal.

[Stan Disbrow]

Hi,

If you want to try a seal sweller, put in a little brake fluid. That is an old trick. Works great. For a bit.

You will wind up with the leak again. Sooner rather than later. But it will allow you to finish a job. Most likely.

My guess: A bearing is going. Shaft is a little wobbly. And so a Quick Fix won't last long at all.

Stan

[Lavoy]

A band aid fix will likely yield a band aid result, more broken or damaged parts, and a larger repair bill.
Lavoy

[LeonardL]

You can buy this stuff and use it if you want to. I really don't care. In my fifty odd years of repairing equipment I have had dozens of these machines apart that have had these additives poured into them. And yes the additive stopped the leaks for a while. I agree that Lucas makes some good products and I'm not going to argue over whether it's a good idea or not. If you want to take Amazons advice based on their reviews go ahead. Ultimately you will fix it or junk it in the end.

There is always a reason for a seal to fail and yes sometimes bearings aren't the reason and the seal is the only issue. Sometimes they go bad from being installed wrong or they're a cheep seal and they just go bad. There can be hundreds of reasons for a given seal to leak. In this particular case it is a 350 with leaking seal issue. In my experience of working on dozens of 350's from the old straights through the 350Ds, when a seal starts leaking in a reverser or transmission it will nearly always be a bearing causing the failure. As Stanley pointed out a little bit of wobble is all it takes to ruin a seal.

I have replaced these seals at the owners behest only to have the machine return a while later with a bearing seized and a ruined shaft on one end or another. On most 350s it will be the front bearing on the intermediate shaft. Some will have an input shaft bearing going bad. On a transmission it will be the input shaft.

Another thing to consider is these older 350s are over fifty years old. Most have gone through some repair but there are a lot of them that have never been apart. The machine in question here is most likely a 350B which makes it closing in on fifty years old. Maybe it has been gone into or maybe not. Either way there is only one way to fix the thing and that is to go inside it and fix it. If this guy wants to take the chance with a can of fix it with Amazons help I'm not going to stop him. That's his choice. I really don't care what he does. I'm just telling him what he is going to find. What he or anyone else does with that information is up to them.

[Al Swearengen]

Settle down now, y'all! I was just CURIOUS!

[Lavoy]

I've tried it one time as far as hyd type stuff, very poor results. I like their oil additive; I use it for engine assembly lube, and in a pinch have used it in a noisier transmission such as one with some gear wear. But that is more of a cushion due to the increased viscosity, not a leak thing.
We also put some of the transmission conditioner/stop leak in my sons 86 Blazer when we developed a sudden seal leak, and had 1200 miles to drive home yet. The leak did stop, but I am skeptical that the additive did that, I think it was a heat issue at the time, and the seal in question was less than a year old.
Lavoy