Machine is a Caterpilar D3G 2005 Dozer. Serial # BYR01003 I am having problems finding the right seal. Does anyone know what these plugs are called and what type of seal goes on them? Photo: These are the dual hydraulic pumps; the one on the north end of the photo is the front pump. The plugs that are leaking are the twin plugs just in front of the main hydraulic line that comes up out of the pump and does a 90 degree and goes back to the right final drive motor. The plugs are much like a bolt, with a 3 mm hex tap, and the head of the bolt has a trough into which fits the seal (whether it is a o-ring seal or not I don't know, when I took them off they were flat). The hole the bolt goes in has a distinct edge which mates to the head of the plug. Because the tank is higher than the pump, there is head pressure and you cannot leave the plug out or you lose hydraulic fluid.
These small 152-9144 plugs come with the seals on them. They are M8 STOR boss so you should be able to just match up an Oring if you dont want to buy the plugs. There is head pressure but make sure you loosen the hyd cap to relieve any pressure.
Lee-online, Thanks. I placed my order. What is the purpose of these plugs? Or maybe, what is the purpose of the holes?
I'm not the Cat expert that Lee-online is, but would agree if the plugs come with o-rings fitted, I would go that route as opposed to attempting to find an o-ring that works. I'm more familiar with SAE o-ring port fittings, not much experience with metric port fittings, purchasing plugs with o-rings fitted would be the best shot at getting it right. As for reason for the plugs, can't say for certain, but "plug holes" are typically for either test ports or to block holes from internal cross drilling of components. As for the oil loss when plug is removed, for sure vent pressure at fill cap. I have used a vacuum on hyd fill neck to minimize oil loss, but in this case, if you're installing new plugs with seals, remove the old one and stick a new one in, minimal oil loss.
Hi Willie, abit of topic here, but was wondering what kind of vacuum pump you use for this task? we had one when i work at the Volvo dealer and always liked it! i haven't been able to find one like it since! Be interested to here what pump you use! Thanks Aiden
I wish I had a vacuum pump that applied a small and steady amount of vacuum on a hyd reservoir Aiden, unfortunately, I don't have one, have simply applied some vacuum on a tank by fitting hose from shop vac in reservoir fill neck, leave enough opening so full force of vac isn't applied to tank yet enough vacuum is applied to break components apart. I have thought about modifying my "suck bucket" by fitting a valve on lid of bucket, fix suck bucket hose to top of reservoir, open valve on bucket to allow air in, then apply vacuum from shop vac, start closing "air valve" to maintain steady but low vacuum on hyd reservoir.
I have a simple device that pulls a very strong vacuum. It is a cap for the tank, some tube in the shape of an upside down y and a small ball valve. It uses shop air and the venturi effect to make the vacuum. On smaller tanks the air need slowed down else it will pull out the oil.