The Stovebolt Site Forums The Parking Lot Big Bolts How do I properly fill my dump with fluid?

Trying to fill my dump with hydraulic fluid 1970 c50. I believe the dump is newer? any way it has no resivoir on the pump, it has a large lift piston. When it's raised the cylinder has a plug on it near the top. I am not shure if this is the fill, and don't want to find out the hard way ( that's how people get killed). having trouble finding who manufactuers the pump? I can't see a tag any where ( it is covered in grime) no mater what I will brace the dump body when it's up, I have been told two different storys by local guys. The first one said to never fool around with it when it's up, the other says that you have to fill it in the up position. Any help would be great. The reason I'm looking to fill it is that it goes up 3/4 of the way up then slows down and jerks, like it's low on fluid. Also what kind of fluid does it take?

my dump is a galion and the fill plug is at the same location as yours. first get something strong to prop yor box up with. i use 8"x8"x6' timbers and prop them under one of the channels on both sides! now you can do it two ways one, the quick and dirty method or the clean timely way. the quick and dirty is with box up remove plug from cyclinder housing, fill with hoist oil until it comes out of plug hole. slowly lower box completely (excess oil will be pushed out) raise box all the way up and put fill plug back in, drop box and clean up mess later because it will run off for days.

the clean and timely method is to do the same above and add a little oil at a time to fill it up without making a mess. either way once when it is filled make note of where the level is in the cyclinder so that the next time oil is needed you know when to stop filling with out making a mess.

You might check, you may be able to reach the plug with bed down and use a pump to fill it...that way with it down you dont overfill...or raise bed..remove plug, let it down then fill it.
you kind of have to be a monkey, or have three arms and ten inch fingers but can get it done usually... You can use just about any hydraulic fluid to fill it..

Fatweed is right if you can it is better to fill it with the bed in the down position if you can. It is easy to over fill these things and make a big mess a small hand pump like what they use to fill rear ends and transmissions will be your best bet as far as fluid I would use AW46 standard hydraulic oil. If you do a search here on the Bolt this subject has come up many times I think Dave (53moneypit) may have even written a tech article on the subject.

I did write a Tech article about hoists but I don't think I covered this part as it never occured to me. Even after you get it filled it will probably be herky jerky for 2-3 lifts as it works the air out of the system. That is what blows the oil out all over the place so lower it slowly and let the air out. I always like the idea of using a square pipe plug and drilling a hole thru the square part and into the cavity of the plug. Then I'd put a cotter key thru the hole which allowed air to escape but was small enough to keep out dirt. This only works on the old low pressure systems (1000 psi) and I would not recommend it on a newer truck which operate at 2500-3200 psi. The old underbody hoists were pretty forgiving but aeriated oil will kill a pump. Clean up that pump and make sure all your hose connections are tight and try to see where the oil got away. Might be a good idea to drain it thru a pump hose and refill with clean oil. Only fill it to the point where it will complete the stroke and not all the way as was mentioned by others as it will expand when hot, leak out and you get to do it all again.

CAUTION: this is not the proper way to fill a system that uses a reservoir and only applies to closed systems like an underbody design.

On one of mine I was able to get underneath it with the bed down. I used a suction gun to squirt the fluid into the cylinder.
If you do decide to do it in the raised position, be sure to do what the others have said, and leave the plug out the first time you let it back down. Otherwise, it's possible to blow the seals out of it. And that would not be good!!!

Would this work?
Raise the bed, block the bed and fill full.
Then put a pipe nipple in the fill hole with tygon tubing attached that goes back to a bucket.
Lower the bed slowly while monitoring the bucket.
Raise and lower the bed several times making sure the hose is out of the fluid and does not suck fluid back into the cylinder.
This should contain most of the mess and bleed the cylinder.
Then raise and block, remove nipple and reinstall the plug.

There are a lot of ways to do this and this is a way I would consider.
And I can't stress this enough,
MAKE SURE YOU OVER BLOCK THE BED FOR SAFETY!!
2-Ton

That should work fine but remember to leave a little extra room for heat expansion as Dave said above

I found that the reason my pump was a ball of grime was it was the source of the leak. You might consider cleaning it up, breaking it down, and resealing the pump. This accomplishes a couple things. First, you ge a good seal on the pump and a good eye on the guts to see if anything needs replacing. Second, you can get all the old nasty fluid (mine looked pretty gross, lots of contamination) out and all new fluid in.
Regardless, I found that you can get to the plug with the bed down just fine. If it's the square pipe plug, a big crescent is perfect. I pulled it off, and as mentioned above, used a pump & hose setup used for gear oil to fill it. Set your new fluid bottle on a 5-gal bucket or some such and pump away. I used almost two gallons to fill an empty system.
I ran it up & down a couple times and it went to full extension the 1st time and every time after, AND, I dont leave a puddle under the pump anymore.

Thanks I'll try to find a way to fill it in the down position first ( tight due to a crossmember there ). Thanks for all the info. I know the pump does seep a little. The truck has not been used in 5 years before I got it, so I'm shure some leaked out over time.