Weak Valve Spring ('97 G. Cherokee)

[myunghong]

1048993

My '97 Grand Cherokee has 'Check Engine' light on, and I took it back to the dealer ship and naturally got ripped-off. Ever since then I do everything by myself.

Anyway, the 'Check Engine' light came back on again, and someone told me it could be my valve not closing completely due to weak value springs. Over a period of the time, it has been that way, and carbon might have built up.

It is so bad, I can't even accelerate on a 5% slope with my 4.0L engine.

I am thinking about replacing the springs and possibly the valves as well.

I have no experience with this kind of major work, and I would like to do it in my garage.

Any advise?

Yes, I am planning to get a manual and all necessary tools.

Please help

Thanks.

Myung[addsig]

 

[MudderChuck]

1048999

I´m not going to say impossible, but I will say unlikely. Broken valve spring maybe, if it was a manufacturing flaw or something. Weak springs come into play usually at very high RPM.

With the trouble light coming on, I´d be looking at a faulty sensor or fuel supply (mid ninty XJ´s have a rep for bad fuel pumps).

Jedi.com has a list of diagnostic codes and how to retrieve them. I believe it will work on the 97.

If the trouble codes turn out negative, I´ll talk you through a compression test and a valve leak down test, before you start tearing the motor down.

http://www.jedi.com/obiwan/jeep/dtc.html[addsig]

 

[dingus]

1049007

i beleive you can check for bad valve seals by pulling off the oil fill cap and putting your hand over the hole while the engine is running (oil won't come flying out don't worry). if air is pushing up through your fingers, then your valves aren't sealing fully.[addsig]

 

[myunghong]

1049379

O.K. Nate,

I have tried your advise, and don't fell any air coming out of the oil fill cap.



Chuck,

I was ready to perfom your suggestion, but the warning light went away. I didn't say this, but the warning light comes and goes. I don't know if I still can read the codes out by the Jedi.com's way (which I haven't try). In the mean time, is there anything I should check or test?



Thanks guys!!!

Myung[addsig]

 

[dingus]

1049391

hopefully it just cleared the code/check engine light on its own... but good luck!

stick around here... you'll love it![addsig]

 

[MudderChuck]

1049543

Most times, when I was getting an intermittant warning light, it was the 02 sensor acting up. Most times, the codes stay in the computer until the battery cable is removed. They can be retrieved even when the light is out.

Many of the sensors are interrelated, and not always what is apparent is the problem. But a faulty 02 sensor is a possibility, my warning light used to come on, most times, with a faulty 02 sensor at highway speeds.

I´ve used most times alot, the test equipement at the Jeep dealer is wrong many times. So it can have alot to do with luck, if the sensor fails completely things get easier.[addsig]

 

[dingus]

1049548

hey chuck, do you have to bring it to a dealer? or can you count blinks on a light somewhere?[addsig]

 

[MudderChuck]

1049703

On the Xj´s mid 90´s you can turn the key on, off, on ,off, on and then leave on and count the blinks at the check engine light and match to the codes in the book. My last test said 1-2 (12) battery disconnected in last fifity starts, 5-5 (55) end of test. Not a diffinative test, but will usually indcate when a sensor has failed completely and is supposed to be pretty good at troubleshooting the fuel pump. Supposed to not work after the end of the 97 model year but I don´t really know for sure.



Pretty much the same as the GM test, never has helped me much, but heck it´s easy and worth a shot.[addsig]