jillsogw

I'm a new Jeep owner to a '94 Grand Cherokee 4.0L. I need some help as I'm trying to get it to pass Calif smog.

I failed the smog test with high (2x-3x normal) NOx reading. I took it to an Autotech Service and Repair for a diagnostic. They show a high HC of 135ppm and are telling me they found hydrocarbon in the coolant and I need a valve job

Before I got the Jeep is had sat for at least a year. The previous owner had driven from Sacramento to Seattle in 4WDH. I have had to rebuild the transmission, put in new plugs, air filter.

It is driveable, the engine is pretty smooth. I did notice a slight missing this morning that is new.

Any suggestions as to what might be wrong? If I can help it I really don't want to be fixing a bunch of stuff trying to "solve or find" why I it won't pass smog test.

Thanks in advance for your help.

Gary J.

Bustedback

Get a second opinion. Hydrocarbons in the coolant would indicate a bad head gasket, needing a valve job would not cause that symptom.

jillsogw

Its been a while since I've done this type of engine work.... Would it be a good idea to do any work on the head while its off or might it cause more issues? There's about 176,000 miles on this engine. Would this year have the 0331 head?

Bustedback

It couldn't hurt to do the valves while the head is off, but it may be more cost effective and faster to buy a reman head. Do some research and compare.