dongfeng tractor with y385t wont start help

[Bob Rooks]

My F-350 has a turbo boost gauge, two temperature gauges, and a fuel gauge, plus tach & speedometer. Guess they think I don't need to know anything else. When I upgraded the instruments on my dozer I installed Murphy Switchgages and connected them to a strobe light. I now have high temp. and low oil pressure alarms. A good thing.

20P7-100: Lockout Pressure Swichgage®

20T-250-4-1/2: Temperature Swichgage®

On your fluctuating meter; is that an ammeter or a voltmeter? It sounds like it's just your voltage regulator cutting in and out, but I would check all your battery cable connections to be sure.

 

[reelnative]

I like those gauges bob thats a great idea, me im kind of like a pilot, i scan my gauges about every 20 to 30 sec hahaha old hab from operating boats out at sea with nothing better to do, im a lic USCG captain and on the smaller boats I ran i didnt get to have a eng like yourself looking at all that stuff, I had to do it myself, hahahhah, hey bob is there a pressure switch in the oil system of these tractors and that is why my pressure drops from say 65 to 50 when the rpms are up or could I have an oil pump cavatating, I thought a pressure switch cause it allways did it at the same rpm and pressure ? and on that meter yea i thought it was the reg comming on and going off it just looks strange, my new gauge ill just hook up to the batt or keyed power

 

[quicksandfarmer]

is there a pressure switch in the oil system of these tractors and that is why my pressure drops from say 65 to 50 when the rpms are up or could I have an oil pump cavatating, I thought a pressure switch cause it allways did it at the same rpm and pressure ?

There is a bypass on the filter that opens when pressure gets too high. I don't know if that's what you're seeing.

 

[reelnative]

cold start up it is dead on 60psi and when at 80c and 1000rpm its at 42psi, so to me that sounds about as normal as can be, there was one weard thing tho and maby you guys can tell me what is going on I think i have an idea but when i add throttle the pressure goes up until it hits about 65psi at 1800rpm then when i hit 2000rpm the pressure drops to about 50psi, im thinking that there is some sort of bypass

 

[Bob Rooks]

cold start up it is dead on 60psi and when at 80c and 1000rpm its at 42psi, so to me that sounds about as normal as can be, there was one weard thing tho and maby you guys can tell me what is going on I think i have an idea but when i add throttle the pressure goes up until it hits about 65psi at 1800rpm then when i hit 2000rpm the pressure drops to about 50psi, im thinking that there is some sort of bypass

I'm thinking you have the terms "bypass" and "relief" confused, and no, I'm not playing semantics.
The symptom you describe where the pressure drops 15 psig at 2,000 r/m sounds like the oil pump relief valve dumping excess volume - a lot of it. Enough to hold it open until it re-seats itself. Is this repeatable?
Quicksand also makes a viable point about the oil filter bypass. However, that takes place around 15 psid, and that most likely happens at around 30 psig, so you may not even notice it happening.
So the question arises; Why is the relief valve popping?

 

[reelnative]

I'm thinking you have the terms "bypass" and "relief" confused, and no, I'm not playing semantics.
The symptom you describe where the pressure drops 15 psig at 2,000 r/m sounds like the oil pump relief valve dumping excess volume - a lot of it. Enough to hold it open until it re-seats itself. Is this repeatable?
Quicksand also makes a viable point about the oil filter bypass. However, that takes place around 15 psid, and that most likely happens at around 30 psig, so you may not even notice it happening.
So the question arises; Why is the relief valve popping?

yes bob it is repeatable, when i hit 2000 to 2100 it does it and the pressure is at 65psi when it drops back down to 50 it doesnt do it like a dump it goes down as you increase rpm just as it climbs when you add rpm, at 1800 its at 65 then as you add rpm it dropps till it hits 50, so say if i was at 1900 it would be somthing like 55 or so, could my oil pump be cavatating, and why would it be popping if it is at 65psi thats not a real hi psi, is there an adjustment that can be made

 

[Bob Rooks]

yes bob it is repeatable, when i hit 2000 to 2100 it does it and the pressure is at 65psi when it drops back down to 50 it doesnt do it like a dump it goes down as you increase rpm just as it climbs when you add rpm, at 1800 its at 65 then as you add rpm it dropps till it hits 50, so say if i was at 1900 it would be somthing like 55 or so, could my oil pump be cavatating, and why would it be popping if it is at 65psi thats not a real hi psi, is there an adjustment that can be made

Okay, my bad. Bad choice of words. By "dump" I meant to open. The relief valve is spring loaded so the regression of pressure would be linear with the increase in engine speed. You haven't checked those bearing inserts yet, have you. No problem - for me anyway.

 

[reelnative]

no I didnt Bob , well not yet any way hahahha, i wanted to ck out the oil pressure with a real gauge before i dug in, does my pressure look high for this eng even tho the bearings and rings are new ? and if that pump is opening at 65psi isnt that kind of low I saw a post were quicksandfarmer was running up to 100 psi on his 385 ?

 

[greg_g]

I wouldn't be so quick to conclude there's an engine oil bypass on that machine. I seem to recall discussions that recommended making sure that any replacement filter purchased has its own internal bypass, since the OE filter housing does not. Or perhaps just some OE filter housings did not, I don't recall the specifics anymore. That said, the drop to 50 psi @ 2000 rpm does suggest a relief valve somewhere.

That said, your pressure figures seem a bit high compared to the 4 Chinese tractors I've owned. Cold pressure among them averaged perhaps 50 psi, hot idle between 7 and 10, working temp at PTO speed around 35-40. When working them hard on a hot summer day it was not out of the ordinary to see 25-30.

Does your filter housing have a pressure adjust feature? It might look like a screwdriver adjust locked down by a hex nut. If so, you could lower the pressure so that it hits 50 max.

//greg//

 

[Diamondpilot]

I wouldn't be so quick to conclude there's an engine oil bypass on that machine. I seem to recall discussions that recommended making sure that any replacement filter purchased has its own internal bypass, since the OE filter housing does not. Or perhaps just some OE filter housings did not, I don't recall the specifics anymore. That said, the drop to 50 psi @ 2000 rpm does suggest a relief valve somewhere.

That said, your pressure figures seem a bit high compared to the 4 Chinese tractors I've owned. Cold pressure among them averaged perhaps 50 psi, hot idle between 7 and 10, working temp at PTO speed around 35-40. When working them hard on a hot summer day it was not out of the ordinary to see 25-30.

Does your filter housing have a pressure adjust feature? It might look like a screwdriver adjust locked down by a hex nut. If so, you could lower the pressure so that it hits 50 max.

//greg//

On my tractor my pressure is right in line with Gregs.

Its a 2004 Jinma 284 with a 385 engine.

Chris