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Old 11-22-2021, 01:10 PM
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mwood65 mwood65 is offline
258 I6
 
Join Date: Jul 17, 2017
Location: Payson Arizona
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Oil pressure gauge problem?

I have always had good oil pressure in my 74 Cherokee and the stock gauge worked fine.
4 days ago the gauge quite working and I am sure I have oil pressure still.
After the Jeep sits a few day and I start it the top end clatters for a few seconds after I start it then after about 5 seconds it quits making noise once oil gets up there. It still does and when driving it makes zero noise and runs perfect.
I replaced the sending unit and still no gauge action except it starts pegged at the bottom and when I start it it goes up to just above zero (1-5 psi?)
and it jiggles around a tine bit.
I pulled the dash out and the plug on the back is tight and seems fine.
Is there a way to test the gauge itself?
On the wiring schematic it shows the circuit goes to the dash then to the radio noise suppressor or am I reading it wrong, and why the radio noise suppressor? Is than just where it grounds to?
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Old 11-22-2021, 06:31 PM
wiley-moeracing wiley-moeracing is offline
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Are you using a oil filter with a check valve in it?
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  #3  
Old 11-22-2021, 08:05 PM
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Tripwire Tripwire is offline
hey,does anyone here know how to.......
 
Join Date: Jul 30, 2000
Location: WA State
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buy a cheap ass mechanical one for a test...then run from there? clattering is a bad sign, could be as simple as lifter bleeddown?
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Last edited by Tripwire : 11-23-2021 at 08:00 AM.
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Old 11-23-2021, 06:17 PM
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mwood65 mwood65 is offline
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Quote:
Originally Posted by wiley-moeracing
Are you using a oil filter with a check valve in it?






??? Using a Wix filter
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Old 11-23-2021, 06:18 PM
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mwood65 mwood65 is offline
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Location: Payson Arizona
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Quote:
Originally Posted by Tripwire
buy a cheap ass mechanical one for a test...then run from there? clattering is a bad sign, could be as simple as lifter bleeddown?


I guess I will just get a set of guages and mount them under dash. And yeah, I think one or more lifters are bleeding down when it sits for a few days or weeks
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  #6  
Old 11-24-2021, 12:46 PM
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babywag babywag is offline
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easy test to check wiring is good/gauge functional...
@sending unit wire should have ~6v key on engine off.
if yes wiring to sender from gauge probably good
if no have an issue with cluster/gauge/wiring

if voltage is present @sender wire momentarily grounding it should peg gauge.
do not keep it grounded only momentarily!!
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Old 11-24-2021, 12:56 PM
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mwood65 mwood65 is offline
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Quote:
Originally Posted by babywag
easy test to check wiring is good/gauge functional...
@sending unit wire should have ~6v key on engine off.
if yes wiring to sender from gauge probably good
if no have an issue with cluster/gauge/wiring

if voltage is present @sender wire momentarily grounding it should peg gauge.
do not keep it grounded only momentarily!!




Alrighty! I will check it out but still am going with new gauges I believe, mechanical ones not electric.
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Old 11-24-2021, 07:17 PM
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letank letank is offline
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Location: San Francisco
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check the TSM, section 3 (the second part)


https://oljeep.com/edge_74_tsm.html




The 78 manual has much better schematics for debugging, page 353 for the oil pressure



https://oljeep.com/gw/78_tsm/1978_Je...alComplete.pdf
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74 wag, 349Kmiles on original ticker/trany, except for the rust. Will it make it to the next get together without a rebuilt? Status: needs a new body.
85 Gwag, 226 Kmiles. $250 FSJ test lab since 02, that refuses to give up but still leaks.

See Ouray 2013, Engine bits and Fuel and brake lines, and Body work
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Old 11-29-2021, 02:49 PM
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letank letank is offline
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Otherwise the quick and dirty is to connect your DVM on ohm scale directly to the sender unit on the engine, one probe to ground the other to the top of the sender signal pin output (yes disconnect the oil sender wire). Secure your leads away from moving parts such as fan and belt... crank and start the engine... depending on oil temperature, at 50ish you should read around 28 ohms which is the mid range of 40 psi, 15 to 18 for the higher pressure of 60 psi
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Michel
74 wag, 349Kmiles on original ticker/trany, except for the rust. Will it make it to the next get together without a rebuilt? Status: needs a new body.
85 Gwag, 226 Kmiles. $250 FSJ test lab since 02, that refuses to give up but still leaks.

See Ouray 2013, Engine bits and Fuel and brake lines, and Body work
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