new jeep owner and have questions

[cnabowboy]

Well as i posted this is my first jeep. So far i love the bodystyle and the ride is comfortable. It is a 1999 Grand cherokee larado with a 4.0 straight 6. I dont no what transmission i have other then its a 4 speed automatic with overdrive.
Anyway it seems that my transmission pan is leaking as is my valve pan gasket. Ive been told this is a common issue and is a easy fix.
1 i have been watching my oil pressure gauge and if i am sitting at idel the needle seems to be in the norm. as i drive off the needle jumps higher but as time goes on it drops back to normal, and when the needle jumps it is still in the normal range. what is making it do that???
2 sometimes when i start out in the mornings the jeep is fine but a mile or to down the road it acts like it is starving for gas. I pump it a few times and it runs fine for a couple hrs and does it again.
3 i was sitting at a red light with my foot on the brake and it wanted to lerch farward like someone is giving is gas
and the last is my left front caliber is sticking when the weather is hot and i am on the highway. now if im in town it seems fine. think i should just replace the cailber or is there a easy fix for this

 

[clydethepirate]

I had to replace both calipers on my 04 grand cherokee but they were leaking instead of sticking.

 

[69jeepcj]

Your engine drives your oil pump. idleing it will be lower then when you are driving. Mine go,s up higher than normal when I am taking off as well and then settles back down. Your oil sounds normal. You can replace the one caliper. I had a ford ranger that learched as you discribe, cant remember what it was, but it was quite scary the first time it did it.

 

[Jeeps4life]

This may sound silly, but ur foot isn't half on the break an gas is it? When I'm wearing my work boots or snow boots I'll some times do that while breaking, and it's a weird feeling fer sure.

 

[69jeepcj]

^ No, I was sitting at a red light behind traffic and all of a sudden the truck just learched forward as though I had hit the gas. I can't remember what it turned out to be though, it was back in the late 90,s.

 

[Small Block TJ]

I had a 99 GT Mustang lunge forward when the A/C was running while stopped. People would look at me like I was a D-bag tryin to race them. Lol.. I just shut off the A/C when coming to a stop. I never fixed it so I guess I'm not any help.

 

[Utah_jeepster]

Lets see if I can shed some light on this for ya,
1 your 4.0 has a simple oil passage system and the mechanical oil pump can slightly over drive your your oil pressure. This is normal on all 4.0L inline six motors. Most see a 40-60 PSI run first thing after starting and as the motor warms up and you drive through town you get a 40-50 PSI reading.
2 this could be something you don't want to hear...but the Grand Cherokee has a known issue with a fuel delivery problem. Because the ECM monitors the pressure and cycles the fuel pump for you, a few GC's have reported that they have experience starving for fuel conditions when running and or no fuel pressure when restarting( most find some residual fuel pressure in the fuel rail but the ECM will not fire the injectors because it thinks its in a low or no fuel pressure). The only fix is replacing the ECM with an after-market ECM. It seems the part of the ECM that works the fuel controls gets a bit hot and starts to mis-behave as it were. Most after-market ECM's run a heat sink over this area and it cures the problem. Run yours as long as you can but be prepared for it...one day.
3 Your lurching while stopped is most likely a small vacuum leak. Your brakes are a vacuum assist system. just like all of ours. The term most use is 4 low brake creep. Jeep in her infinite wisdom put a barley adequate brake system on her jeeps and at low idle there isn't enough vacuum to help hold your jeep at a stop. Have your vehicle smoke checked for leaks to find if you have a small vacuum leak, R&R your brake fluid ( most never replace there "working" brake fluid) brake fluid is hydrosopic: I.E. it means it can take in water from the air, and even if it doesnt look bad there could be a higher percentage of water in your fluid than MFG norms. Water molicules in your brake fluin can affect your brake fluid hydrolic action.

 

[cnabowboy]

Lets see if I can shed some light on this for ya,
1 your 4.0 has a simple oil passage system and the mechanical oil pump can slightly over drive your your oil pressure. This is normal on all 4.0L inline six motors. Most see a 40-60 PSI run first thing after starting and as the motor warms up and you drive through town you get a 40-50 PSI reading.
2 this could be something you don't want to hear...but the Grand Cherokee has a known issue with a fuel delivery problem. Because the ECM monitors the pressure and cycles the fuel pump for you, a few GC's have reported that they have experience starving for fuel conditions when running and or no fuel pressure when restarting( most find some residual fuel pressure in the fuel rail but the ECM will not fire the injectors because it thinks its in a low or no fuel pressure). The only fix is replacing the ECM with an after-market ECM. It seems the part of the ECM that works the fuel controls gets a bit hot and starts to mis-behave as it were. Most after-market ECM's run a heat sink over this area and it cures the problem. Run yours as long as you can but be prepared for it...one day.
3 Your lurching while stopped is most likely a small vacuum leak. Your brakes are a vacuum assist system. just like all of ours. The term most use is 4 low brake creep. Jeep in her infinite wisdom put a barley adequate brake system on her jeeps and at low idle there isn't enough vacuum to help hold your jeep at a stop. Have your vehicle smoke checked for leaks to find if you have a small vacuum leak, R&R your brake fluid ( most never replace there "working" brake fluid) brake fluid is hydrosopic: I.E. it means it can take in water from the air, and even if it doesnt look bad there could be a higher percentage of water in your fluid than MFG norms. Water molicules in your brake fluin can affect your brake fluid hydrolic action.

i took off the caliper cleaned it up and greased the risers it only got stuck 1 other time and has been fine sense. and thank ypu all by they way i found out my o2 sensor is out and im going to replace it when i can. the lerchinging problem quit and i havent had any problems sence.

 

[cnabowboy]

now the only other thing i need to figure out is when i run my defrost it sounds like its grinding.

 

[69jeepcj]

now the only other thing i need to figure out is when i run my defrost it sounds like its grinding.

probably leaves and twigs in you heater fan.

 

[cnabowboy]

i will check that out today and let you know also im looking for a used hitch anyone have one for sale??

 

[superj]

They are only 100 bucks at pep boys. I always hod to put them on my xj and zjs.