TJGC

Hello everyone

This is my first online forum so please bare with me.

I have a 2000 JEEP Grand Cherokee 4.0L. I bought the car from a nurse who obviously had a very busy lifestyle and couldn’t properly care for the car anymore.

When I bought the car it would turn over just fine but had a very very faint engine tick to it. It had low oil pressure light (0-10 psi) whenever stopped at a light after the car was on the road for over 15-20 mins.

I didn’t notice any difference in performance while this was happening and made a poor choice to ignore it for approximately 2 years with 10-W30 royal purple oil changes every 3,000 miles.

One day when I was leaving work the car just couldn’t go on any longer. I got about a 1 mile from my job, noticing that the low oil pressure light was activated upon start up now and sounded pretty rough. I drove up this steep hill and the truck just lacked power. I was pushing the gas was close to the floor and it just clunked out so I pulled over. I was working over time at the job and was late for an oil change that week. I went to the store filled it with 2 quarts of oil from the station. I had it towed and parked it at my parents house for 3 and a half years.

I developed an interest in cars recently and started using this truck as a project car. With the little knowledge I acquired from reading and watching YouTube, I immediately blamed the head gasket for the issues so I ripped apart the engine bay finding a massive amount of sludge in the valve train and taking off the cylinder head (out of sequence smh... ) to replace the head gasket with a new one from 1Aauto. The sludge made me question the oil pump and the oil pan so I removed both (a massive pool of sludge at the bottom of the pan) and replaced the oil pump with a new one from 1Aauto.

I put everything back together with all new gaskets (oil pan, head, valve cover gasket, intake manifold gasket, exhaust manifold gasket) and in proper torque spec and sequence. I did not do any machining to the head or block because the car never overheated and this was just a project anyways. I also cleaned the head using 4 or 5 cans of brake cleaner and cleaned all the sludge from the lifters and the valley (cam seemed nice and smooth).

With everything put back together and fluids topped off. I charged the battery and attempted to start the car. It wasn’t pretty. The engine seemed as if it was redlining a start up and it was loud as hell!! (the missing exhaust flange bolt probably didn’t help the cause)

Scared half to death, I turned it off but noticed it had a check engine light on. I can’t remember the code (Sorry about that) but I know it was some sort of transmission sensor.


I would love to use this truck as a budget beater for my lawn care service until I can replace the engine someday. If you guys give me a clue I would really appreciate it.

Heaving Earth

I have a '99 Cherokee with the 4.0. Back in April of 2018 while I was replacing the exhaust manifold I had the redline at startup issue. Turns out while lining up the intake manifold I had it very close but off just enough that it didn't seal properly, although it looked ok from a visual inspection. This essential created a massive vacuum leak between the intake and the cylinder head. With t​​​​he leak being so big when the engine tries to idle, not restricted to the size of the throttle body, it sucks in way too much air causing the engine to rev to redline. Anyway I losened everything up and securely placed the intake manifold in the correct spot and reassemble the vehicle. Problem solved.

Hope this helps resolve your issue.

Heaving Earth

I have a '99 Cherokee with the 4.0. Back in April of 2018 while I was replacing the exhaust manifold I had the redline at startup issue. Turns out while lining up the intake manifold I had it very close but off just enough that it didn't seal properly, although it looked ok from a visual inspection. This essential created a massive vacuum leak between the intake and the cylinder head. With t​​​​he leak being so big when the engine tries to idle, not restricted to the size of the throttle body, it sucks in way too much air causing the engine to rev to redline. Anyway I losened everything up and securely placed the intake manifold in the correct spot and reassemble the vehicle. Problem solved.

Hope this helps resolve your issue.

dave1123

There are 2 dowels in the head that the intake manifold locates on and if the manifold isn't resting over them but sitting on top of one of them, it won't bolt up tight against the gasket thus creating a huge vacuum leak resulting in the engine racing out of control. I sort of knew right away when you said you pulled the head that this was the probable cause. It's a common mistake and one that even experienced people sometimes do when in a hurry or working in low light. I've done it myself working outside in a cold rain under a tarp.