candymancan

My mom has a 98 jeep grand cherokee inline 6 4.0 with 160k miles on it. I have been learning alot about this car recently because for my first car i am going to get a Jeep grand cherokee myself not sure what year but between 96-98 would be preferable to me.

Ive been doing alot of work on the car, ive never changed anything in a car until recently. Basicly i have changed the spark plugs with a .035 gap, the wires the distributor cap and rotar, the ignition coil, I also found where the transmission leak was comming from it was simply a bolt so lose on the transmission pan i could turn it with my finger. I also changed the transmission output sensor and the check engine light my mom has ignored for over 10 years i finally off.... Yes she ignored the high RPM shifting and check engine light for 10 years. Also changed the air filter.

As for the transmission leak she had the transmission fluid changed twice in the cars 160k miles the one most recently less than a year ago i suspect the dude never changed the transmission filter because if one of the bolts was so lose i could turn it with my finger and it was leaking then the pan has never been taken off. Im thinking of draining the transmission fluid myself and changing the filter. I dont know if i should tho.

Only thing wrong with the Jeep now is the ABS light comes on and off and I suspect its because she ran the front and back breaks until the rotars started to get grooves in them lol. The break i have in hand and the rotars will be flipped and grinded by a mechanic. So i think the ABS should turn off then.

The other problem i noticed is when under the car i saw oil splatterd all over the bottom of the car on the differential units and stuff. I followed it up to the engine block, and its leaking out of the Gasket Valve cover in the back by the number 6 plark plug. Its leaking where the bolt is and the gasket seal. Aparently its a really slow leak because i dont see it dripping however it is leaking because oil i put my fingers around the cover and seal i get fresh oil on my hands. The oil level according to the dipstick is on full so its not low from this leak.

Here is a picture click on it once, then click again to zoom in


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The last issue is the oil pressure, i could have sworn the Jeep in the past was always around 40 PSI, and now when its cold started it hangs around 32-37 going up and down as the engine warms up. Then as you drive it around the oil pressure is always at the 30psi mark. If the RPM's go to around 2k then the oil pressure will go up to around the 37PSI mark. On idle the pressure is 30psi.


Now to my main question (sorry for making this so long) my mom doesnt know when the oil was changed last or what oi was used either synthetic or conventional .. because the Jiffylube sticker she usually has on the window fell or something. I suspect its been at least 3k miles probably more and was conventional oil because it was only $20 for the oil change. I checked the dipstick and the oil is a dark brown color, and when i put it on my fingers its pretty much black. Its not thick or tar like and its not gritty either. I opened the oil filler cap and looked inside as best i could and it looks clean no thick tar or anything lol. Should i change the oil and filter ? If so what oil should i honestly get ? The manual says 10w30 however there are so many brands so many kinds of oil im getting confused. People say to get synthetic however is synthetic oil for a 160k mile engine really good ? Especially one that obviously has a small leak on the gasket. I read synthetic will just make the leak worse and it might actually leak from other places. What kind of oil filter should i get ?

Also when i change the oil, can i park the car on a slight incline with the engine at the incline so when the oil drains it will all drain out. Or is that a bad idea ? Its only like a 10 degree incline

OverlandZJ

Use regular oil, non synthetic till you get all the oil leaks taken care of. Synthetic is thinner and will leak more. I like Castrol GTX 10w30, or Mobil1 full synthetic... i alternate between them. Castrol i run 3K miles, synthetic 6K miles.

Grab yourself a valve cover gasket and replace that.

candymancan

I added a picture not sure if you saw it yet.. Does it look like its leaking from the gasket based on the picture ? If so how do i go about replacing it ? Obviously i take the cover off. However do i have to drain the oil ? Or cover the engine with something so i dont get stuff in it ? Or what

OverlandZJ

Thats a common place for the gasket to leak. Not difficult to replace and you dont need to drain oil to do it.. just make sure any debris from old gasket is cleaned off.

Disconnect the cables to throttle body and hoses from the valve cover and clean all the mating surfaces very well. Get some Hi-Tack gasket adhesive and install new gasket to clean surface.

Where are you located? Maybe someone is local and would be willing to show you the procedure.

candymancan

woodbridge virginia.

also ppl say to get conventional oil for the jeep. what brand should i get ? im looking at the catrol gtx high mileage.. however other ppl say dont get high mileage just normal oil .. A dude who works at Advanced auto parts works on his own Jeep and friends and he suggested i get the 10w30 blend synthetic and conventional oil. The Valvoline oil, he also said he replaced a Gasket on a friends jeep recently and it was leaking in the same spot as mine. He mentioned the leak can cause missfires and engine vibration when the oil gets into the sparkplug socket. Which in the picture you can see the oil is getting into the socket.

He also mentioned the light knocking noise im hearing on the Jeep is the lifter is dirty or something needing to be cleaned. He mentioned he has some kind of cleaner that i can use when i drain the oil to clean it up ? What do you think ? Cause the knocking noise i thought was a bearing going bad, however he said if it was a bearing then it would be really loud, mine is barely audible.

Bustedback

Any name brand 10w30 or 10w40 will work fine for you. Don't worry about the little bit of noise, they all make it. Do not flush the oil system, you're just asking for trouble when you do that. Over maintenance is almost as bad as no maintenance from what I've found throughout the years. Just follow the owners manual and you'll be fine.

candymancan

Here are a couple pictures of the inside of the valve cover with the refill cap off. I dunno if you can see it good enough, but to me it looks filthy i dunno.. The engine hasnt been on all day.


Click the picture once, then click again to enlarge it



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candymancan

Well i drained the oil when it was hot, replaced the filter and refilled it with Valvoline Max life Synthetic Blend 6 quarts. Seems to be running fine and i checked the oil level after i ran the engine for a few minutes and it was perfect.

Bustedback

The 5.2 in your Jeep is a very good engine and should last a long time. It really is nearly bullet proof, ranks right up there with the 4.0 I6.

candymancan

my jeep is the 4.0 i6 hehe

Bustedback

Oh, very good then. So many threads, I tend to get them confused.