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Forums > Active Threads > Other Tractor Brands > Jinma Farmpro Agracat Nortrac

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Jinma Y485 injector pressure

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MontyJones
Join Date: Mar 2014
Posts: 9 Jefferson, Maine
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2014-03-20          189664


I have a jinma 35 HP 4 cylinder tractor with a yangdong Y485 engine. I have two bad injectors and two that function properly. The bad ones are sticky and can be cleaned but the good ones are adjusted to two different cracking pressures, neither of which meet "book" standards. One cracks at 2200 PSI, the other at 2400 PSI, book says 1914.5 PSI. The injector that requires 2400 PSI was tested as it was received new, the other is original with about 500 operating hours, both have uniform spray patterns. Which setting is correct? I have called every major dealer in the U.S. and not one of them has a good answer because none of them test injector pressure. I really don't want to re-assemble the engine without setting the injectors properly and uniformly. My manual also states that setting injection pressure too high may cause engine knocking.

Sincerely,

Monty Jones

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Jinma Y485 injector pressure

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greg_g
Join Date: Jan 2004
Posts: 1816 Western Kentucky
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2014-03-21          189696


More important than the "cracking" pressure is the need for all four to "crack" at the SAME pressure. Otherwise the difference between 2200 psi and 2400 will indeed cause engine knocking. The 2400 will induce additional back pressure via the steel lines and disrupt the pump timing. And with this older diesel engine architecture, smooth running (and fuel economy) is all about pump timing.

Unlike electronic injectors on a common rail system where it's possible to replace only a single bad injector, this mechanical pump design should have all 4 replaced at the same time. You haven't mentioned the source of the new injectors. Did you actually get them from a Jinma dealer? Or are they aftermarket?

//greg// ....

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____________________________________________________________________________________
Jinma Y485 injector pressure

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MontyJones
Join Date: Mar 2014
Posts: 9 Jefferson, Maine
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2014-03-21          189700


Greg: Thanks for the reply. I agree with all that you are saying but the crux of my problem is not knowing what the optimum cracking pressure is for this particular engine. Again, the book calls for 13.2 +/- 0.5 Mpa (1914.5 PSI) but all the original injectors were set above 2050 PSI. I have cleaned the injectors and adjusted them to 2100 PSI and am ready to reinstall but still would like to know for certain that my "best guess" is rational.
Monty ....

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Jinma Y485 injector pressure

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greg_g
Join Date: Jan 2004
Posts: 1816 Western Kentucky
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2014-03-22          189711


My opinion is that the fact they're now all opening at the same pressure more important than the numbers printed in what is likely a 10+ year old document. The Chinese update their tractors regularly, but are notoriously poor at keeping their manuals current.

It may relieve your anxiety a bit to note that the same engine - when configured for pump use - specs injector release pressure at between 19.6 and 20.6 MPa. That strongly suggests to me that the Y485 engine can definitely handle your current 14.5 MPa.

//greg// ....

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Jinma Y485 injector pressure

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MontyJones
Join Date: Mar 2014
Posts: 9 Jefferson, Maine
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2014-03-22          189713


Greg: Thank you for the information, its worth a lot to get a reliable second opinion before I reassemble the engine. I agree with you about the JINMA documentation, it was inadequate when I bought the tractor five years ago and I can't find any updates. Part of my problem is that I have the obsolete Yangdong Y485 engine.

Thanks again,

Monty ....

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Jinma Y485 injector pressure

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stevek924
Join Date: Aug 2014
Posts: 17 West Virginia
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2015-09-14          193660


Quote:
Originally Posted by MontyJones | view 189700
Greg: Thanks for the reply. I agree with all that you are saying but the crux of my problem is not knowing what the optimum cracking pressure is for this particular engine. Again, the book calls for 13.2 +/- 0.5 Mpa (1914.5 PSI) but all the original injectors were set above 2050 PSI. I have cleaned the injectors and adjusted them to 2100 PSI and am ready to reinstall but still would like to know for certain that my "best guess" is rational. Monty


Monty,
How did you set your injector cracking pressure?

....

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____________________________________________________________________________________
Jinma Y485 injector pressure

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MontyJones
Join Date: Mar 2014
Posts: 9 Jefferson, Maine
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2015-09-14          193661


Steve: I have a 75 year old JD injector test set. Take your injectors to a service center for testing and setting or buy a new set.It might cost as much to service the old injectors as to buy a new set. Caution, there are several suppliers of this part and in my experience, they are inconsistent in pressure settings. I have received new ones that crack in a range of 1900 to 2600 PSI. Try to find a supplier that can set them properly.

Good luck, Monty ....

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Jinma Y485 injector pressure

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stevek924
Join Date: Aug 2014
Posts: 17 West Virginia
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2015-09-14          193669


Thanks Monty. I took them to the local farm equipment dealer and they actually had the adapters set them for me. Well, three out of four anyhow. One was bad so had to order a new one. I'll take it up to them to make sure the pressure is set the same as the other three before I install it.
Had to tear into the timing again but I'll post on my other thread. I think I have it this time. We'll see. ....

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Jinma Y485 injector pressure

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jadezhang
Join Date: May 2015
Posts: 8 Jiangsu, China
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2015-11-29          194121


Y485 engines and engine parts for sale
All the Jinma tractor spare parts for sale
jade(at)shunyumachinery.com ....

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Jinma Y485 injector pressure

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MontyJones
Join Date: Mar 2014
Posts: 9 Jefferson, Maine
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2017-03-09          196369


Quote:
Originally Posted by jadezhang | view 194121
Y485 engines and engine parts for saleAll the Jinma tractor spare parts for salejade(at)shunyumachinery.com
I notice that this is an old thread but do you actually have a source for Jinma Y485 engines in stock? If so, I would like to get a quote on a replacement engine for my 2007 Jinma 354


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