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Oil Pressure on a Super 77 Diesel

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Brian

07-02-2003 19:36:09




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Can someone tell me what the oil pressure should be at idle and at wide open when hot? Mine is only 10 psi at full throttle. Thanks.




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Duane

07-03-2003 20:20:06




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 Re: Oil Pressure on a Super 77 Diesel in reply to Brian , 07-02-2003 19:36:09  
The specifcation for hot wide open oil pressure is 14-18 psi. It sounds low but this is all that is required. Make sure your restricter pipe is in place on the oil filter base before doing anything major. I have seen fleetline Olivers with lower pressure than yours run a long and happy life.



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Brian

07-04-2003 14:33:09




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 Re: Re: Oil Pressure on a Super 77 Diesel in reply to Duane, 07-03-2003 20:20:06  
Duane & J. Schwiebert That restrictor that you talk about, is it that little pipe sticking up out of the filter base? Mine is in place. I have just the one upright filter. Is there a relief valve built into the pump with that regulator spring you mentioned?



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J. Schwiebert

07-04-2003 19:20:17




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 Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to Brian, 07-04-2003 14:33:09  
The answer to your questions. The restrictor disk goes in under the tube. It has about a .060 diameter hole in it. This restricts the flow of oil. Remember pressure is caused by resistance to flow. Is your filter base aluminum or cast iron? They used both,In time heat worked on the aluminum bases and the tube would work loose. How long is your tube? The late ones (and now memory is comming into play) have a shorter tube. I don't recall having problems with them but it is possiable. The tube works loose in time and when you change filters it gets stuck in the filter and the disk "falls out" There used to be a repair kit which included a new stem with the disk wired to it. Those engines use a vane type pump, never seen one fail. No regulator valve is built into the pump. However there is a pressure regulator for the whole system located underneath the generator in line with the oil gallery. It is a 13/16 hex plug with a copper sealing washer. Behind this plug is a spring and a plunger.If the plunger is not free to move or the spring is not up to tension then you will have low oil pressure. I have seen those plunger stick. I am not where my shop book is located, but given a day or two (if no one else does first) I can find you free length and test data for spring. We used to streach them a little and see what happens. If you are close to an Agco dealer part number of the spring is K-303 or when the 770 tractor came out the part number changed to 7K-303. After that we mostly stocked the later spring. It can be used. The 770 runs a little higher oil pressure. Questions, ask away or post them on the hart/parr form and we can e-mail direct .

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Brian

07-04-2003 19:49:31




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 Re: Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to J. Schwiebert, 07-04-2003 19:20:17  

I have the cast iron housing. I'll check to see how loose that tube is. I'll also check that spring and plunger. Thanks J. Schwiebert



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WFE

07-03-2003 04:44:38




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 Re: Oil Pressure on a Super 77 Diesel in reply to Brian , 07-02-2003 19:36:09  
I don't know what the service manual quotes, but 10 is almost surely not up to par. I'd say 25 psi when warm at full throttle is a good minimum. Try adjusting oil pressure regulating spool in oil gallery.



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J. Schwiebert

07-03-2003 06:41:51




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 Re: Re: Oil Pressure on a Super 77 Diesel in reply to WFE, 07-03-2003 04:44:38  
Does it have the two original oil filters or has it been converted to one filter. It is a bypass filter system. Your regular spring could be weak or someone may have lost the restrictor disk from the filter base. As far as a screw to turn to adjust the oil pressure there is none.How good is your gauge and what weight oil are you using? How much pressure do you have at an idle?



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WFE

07-08-2003 22:19:55




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 Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to J. Schwiebert, 07-03-2003 06:41:51  
There is the oil gallery adjustable relief valve on the front, right side of block. One can add shims to spring to increase pressure, provided the problem of low oil pressure isn't due to severe wear. The spring of the relief valve can weaken over time and may require shimming. Have also seen these springs strangely disappear... go figure.



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Brian

07-03-2003 19:32:23




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 Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to J. Schwiebert, 07-03-2003 06:41:51  
I believe it has straight 30 weight in it. I screwed a new 0 - 30 psi gauge in at the filter base. At idle it goes to almost 0 when warmed up. Can I get the pan off without without pulling the engine? Thanks.



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J. Schwiebert

07-04-2003 06:25:16




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 Re: Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to Brian, 07-03-2003 19:32:23  
I would check the filter base and the regulator spring first. Yes the pan comes off. However remember this engine has a little different means of oiling the bearings. The mains are pressure fed, The rods are squirt fed front a seperate gallery.Loose rod bearings do not affect engine oil pressure! Also if you do take it apart, the engine has offset connecting rods so three go in one way three the other. Check the external stuff first, Questions send me an e-mail.
It is easier and usually the problem in 90 plus percent of the problems.If you do need to take it apart take a leak detection test first!

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Ollie

07-04-2003 02:32:22




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 Re: Re: Re: Re: Oil Pressure on a Super 77 Diesel in reply to Brian, 07-03-2003 19:32:23  
You've never really stated what's important. That is, what is COLD idle pressure and what is the WARM idle pressure. The proper specs are shown in the operator's manual. If it has some cold pressure and shows zero warm, most likely the engine's bearings are toast.



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