880 selectamatic hydraulic by pass filter

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philedge
Posts: 296
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

880 selectamatic hydraulic by pass filter

Post by philedge » Wed May 13, 2020 10:31 am

My early 880 doesnt have a by pass filter fitted and has a well made blanking plate where the filter should go but its not the factory supplied oil return plate with threaded tappings. Ive looked at original parts manuals which suggest that the bypass filter was fitted to all tractors up until the full flow paper filter was introduced. I cant understand why anyone would remove the bypass filter and blank it off so the question is, were all early selectamatics fitted with a bypass filter?
Second question is what part of the oil system did the bypass filter clean and what did it 'bypass'? I assume the filter is filtering return oil as its fitted where a return oil tapping can go? Are there any system drawings that show the bypass filter. Ive seen the parts manual drawings but they dont really show what the filter is connected to
'66 880 Selectamatic rat.

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ollek
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Re: 880 selectamatic hydraulic by pass filter

Post by ollek » Wed May 13, 2020 12:49 pm

All early Selectamatic tractors had the by-pass hydraulic filter on top of the rear axle on the left hand side. Tractors with a by pass filter had a suction screen only for the pump inlet, and no filter at the suction pipe. Later production tractors had the paper suction filter and screen at the front end of the pump inlet pipe. The later filter type is much better as it is a full flow filter, and there is no need for a second less effective filter. A by-pass filer cleans some of the oil that gets into the transmission lubrication system from an open by-pass valve in the valve chest. The by-pass valve is open when the hydraulic system is in hold or lowering mode.The pump sucks oil through the screen only if the tractor has a by-pass filter. It is important that the paper filter (by-pass or full flow) is changed with stipulated interveals. The position where the by-pass filter was fitted, became a return point for oil returning to the transmission, return from front loader spool valves for instance.

philedge
Posts: 296
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 880 selectamatic hydraulic by pass filter

Post by philedge » Wed May 13, 2020 1:14 pm

Thats great, thanks. So the bypass filter is a low pressure return oil filter?
Beyond me why someone would remove it and blank it off. Were there ever any issues with the bypass filter that might drive someone to remove it??
'66 880 Selectamatic rat.

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ollek
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Re: 880 selectamatic hydraulic by pass filter

Post by ollek » Wed May 13, 2020 4:32 pm

Tractors without the paper by-pass filter had a paper suction filter from the factory. The filtration capasity must be wery bad if someone has removed the by-paas filter bowl, without fitting the suction filter. The only reason I can see where removing the by-pass filter bowl, is a situation where sonmeting heavy has dropped on the bowl, damaging the bowl. The first tractors with the paper suction filter had the by-pass filter connections blanked off and a 7/8 UNF return plug added from the factory, please see the following link https://partstore.caseih.com/us/parts-s ... 85ar285661 Please look at ref 46 to 51 and read the text conserning these parts.

DRM
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Location: Warwickshire

Re: 880 selectamatic hydraulic by pass filter

Post by DRM » Wed May 13, 2020 10:21 pm

My 880 Selectamatic (s/n 544543) also has the blanking plate which I assume was factory fitted. However, it does have the full flow filter and vacuum switch as expected for the serial number.

Looking at various editions of the operator manual, the evolution of this oil return appears to be as follows:

1. Tractors before 543157 had the bypass filter. Oil returned from external equipment should be via the camels hump.
2. Tractors from 543157 had the full flow filter and the bypass filter connection blanked off with the rectangular plate. Edition 3 (July 68) states that if the camels hump is unavailable due to a double acting take-off valve being fitted a "special oil return plate (U1056)" should be used. Was this an option?
3. Edition 4 of the manual (July 69) shows that the blanking plate has been replaced with a 7/8 UNF plug. Not clear from what serial number this started to be fitted.

This doesn't help the original problem which is indeed strange. Would it be possible to get the parts to fit the full flow paper filter as fitted to tractors with s/n 543157 onwards?

David
Attachments
bypass filter cover.png
bypass filter cover.png (234.31 KiB) Viewed 122 times

philedge
Posts: 296
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 880 selectamatic hydraulic by pass filter

Post by philedge » Wed May 13, 2020 11:32 pm

The blanking plate in the picture looks the same as the one fitted to my tractor so maybe it is a DB plate I have and not homemade. Why the bypass filter has been removed is still a mystery but may have been damaged as suggested. The other thing that crossed my mind was maybe it got removed by someone thinking there was a paper suction filter not realising there wasnt on early tractors??
Just for clarity of item 1 above, early tractors dont seem to have had an oil return point to the LP pipework as the early camels humps had bleed nipples and no threaded tappings.
I think you can retro fit the full flow suction filter to earlier tractors but theres quite a bit of work involved to get the later suction pipe and internal vacuum switch fitted. Although probably not as good a set up as the full flow filter, refitting a bypass filter is likely the way I'll go......just need to find one!!
'66 880 Selectamatic rat.

DRM
Posts: 25
Joined: Thu Oct 17, 2019 11:56 am
Location: Warwickshire

Re: 880 selectamatic hydraulic by pass filter

Post by DRM » Thu May 14, 2020 12:30 am

There is one on eBay at the moment!

https://www.ebay.co.uk/itm/164191809754

David

philedge
Posts: 296
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 880 selectamatic hydraulic by pass filter

Post by philedge » Thu May 14, 2020 12:52 pm

Thanks for taking the time to look for that
'66 880 Selectamatic rat.

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