Disassembly of oil pump on 990 with AD4/47 engine

Posted by tsandrews01 on 2017-11-11 00:42:00 

I'm trying to disassemble my oil pump to clean it before reassembling the engine. I've got the pump out of the block and I am to the point in the manual where it says to use the drift to remove driving shafts from driving gear. The instructions get a little vague at this point. I was wondering if anyone has ever messed with this and had any advice on how to do this part. It looks like I should be able to use the drift and knock the drive shaft back through the gear and pull it out of the pump body from the pinion side. However, I did notice a key in the drive gear. I was not sure how big the hole was in the pump body since the gear covers the hole. I was not sure if the hole was big enough for the key and I did not want to damage the body trying to force it through. I couldn't find a parts break out to see what the details of the parts look like.

Thanks
Troy
Posted by: ollek on 2017-11-11 08:27:00 
If the pump is working, why would you want to dismantle it? There is no reason to dismantle a working oil pump, just clean the inlet screen and flush the complete pump in a basket with kerosene.
Posted by: db2d on 2017-11-11 09:00:00 
I also recommend leaving well alone. The spiral drive gear can easily be damaged causing failure when reintroduced to the engine. If this gear fails the camshaft will be irretrievably damaged.
The gear has to be partially removed and then extracted with a puller so that the key can be removed to enable the shaft to be removed.
Posted by: tsandrews01 on 2017-11-11 15:12:00 
Thanks for the replies. The pump feels like it is sticking in one spot as you rotate the shaft. The tractor has done a lot of sitting in the past so I'm trying to determine if it has trash that has gotten down around the shaft in an area that I can't see or if it is damaged. The reason the engine is apart is it spun a connector bearing. So I am also trying to make sure the oil circuit is good and clean and everything is operating like it is supposed to before I close the engine block back up.

It sounds like some special tooling might be needed to get that apart then. If that is the case, would I be better off just to replace the pump? I'm just hesitant about putting a questionable pump back in. I'm still not 100% sure of what caused the bearing to spin so I was trying to ensure the oil circuit is working correctly and within spec. My plan was to measure the spacing in the gears and all the other checks it recommend in the manual but if it requires the purchase of a lot of tooling I may consider just getting a new pump. Talking to some diesel mechanics who work on frieght trucks, they most of time go ahead and replace the oil pump when a bearing spins to make sure a weak pump was not the root cause. But some of the machines they are working with are not near as forgiving when things are not at optimal spec.

Thanks for the replies.
Posted by: db2d on 2017-11-11 17:03:00 
If the pump had seized the keys would have sheared or the spiral gear would have disintegrated. I think new pumps are probably unobtainable but they can be refurbished in this country. Be certain that the pressure relief valve is seating properly,it only takes a minute particle of dirt to lose the oil pressure.
What grade of engine oil was in the engine when it failed?
Posted by: tsandrews01 on 2017-11-20 00:41:00 
Ok, thanks. I will check the pressure relief valve. Hopefully, I can get back working on it this next weekend. To answer your question, I have been using the Rotella 15w40.

Thanks
Posted by: db2d on 2017-11-20 08:37:00 
15/40 grade engine oil is suitable
Posted by: Wheelie on 2017-11-22 21:27:00 
Just on the oil pump topic how can the pump be checked for proper operation when it's removed anyone know , have one out myself off 1490
Posted by: ollek on 2017-11-23 14:55:00 
Wheelie, look in your Private Message inbox.