1999 jeep cherokee 4 liter straight 6 auto 4x4.
I have owned this Jeep for 2 winters and summers. It runs great. The issue is, everytime it gets cold outside, the oil pressure gage reads lower then normal and drops to zero (or very low) at an idle. Even when it records no pressure, there is oil circulating to the top of the engine and once the warm weather returns, it returns to normal. There are no knocks or ticks associated with this as well. Anyone with ideas?

 

Hi and welcome to CF from Tj in NJ.What type of filter are you running and what weight oil?...Tj

 

just bypass ur factory dash gauge pick up a real oil pressure gage(vacume) ....wats happening is that the oil pressure sending unit is goin bad and the factory gage is not a mechanical gauge....the SU is on the passanger side of the block right below where your oilfilter threads on ....its a thread in sensor ....unplug it(2 prong plug i blv) ,remove the SU ..and any mechancal gauge you buy gives you the adapter you will need.....installed my S to F in 10 min max in the autozone parking lot and now you will acually get a "true pressure" reading its going to fluxuate more than ur stock obv bc its mechanical no engine holds the same pressure at warm idle vrs driving its just because the factory unit is electronic sensor opporated.....just be carefull where u mount exp in interior applications remember that there is 200+ degree oil running in the line to the mechanical gauge.....its not rocket science as im sure ur aware no need to panic...otherwise a wiper screen mount is also very easy........ either way dont fix junk only to break again when you can upgrade to the proper equip for the job and save money over buying the sensor...good luck

 

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Is it just the sending unit? I really have no desire to go beyong stock. In other words will a new sending unit solve the problem? Any ideas why this only happens when its cold out even when the engine is at temp?

 

My guess would be what ever the manufacturer calls for as I have it changed at lube stop.

 

Ok I would check the connections near the Oil pressure sender (near distributor) to see if there is a bad connection or just dirty contacts...Tj

 

either way.... i threw it out there bc i had to replace one more than once....its not a big change(15-30$max) i just imagined one would want to have the most accurate fix.....then there is no guessing any more....basicly the stock desine is poor to begin with and in my eyes electrics can short or melt, and let me down, this allows you to take awake the weak links n eliminate the issue for good....i cant tell you to fix it with more junk just to have it happen again thats why these forums exist to help each other out to fix the little bugs that arise and share our ideas and fixes.....best luck try your local parts store first next time first if thats the route you want to go...

 

and no its not a new sending unit....it eliminates it, and you go true vacume line from the block to gauge....there are no parts or sensors to leave you stranded thats wat wrenching is about...imrproving or fixing a from the factory problem and make it better???

 

First off, thank you for trying to help. But jeesh dude, you don't have to get so defensive. I fully know what these forums are for. I am not a moron. All I asked was would the SU fix the problem. I was looking for the cause of the problem, hoping someone else already had it and knew the actual fix. I am going to sell it to upgrade to a Grand and most people don't care for mods.

 

Thanks Tj.

 

no defense but please reasearch b4 u ask thats all .....u asked......i gave my advice n u want to be at the dealership....y talk online about a stock part when u can go see a tech at ur jeep dealer(even call on phone) an have him get hands on n look?....would make more sence ...take it easy and good luck with that.....