Question:

I have a 98 Jeep Grand Cherokee w/ approx. 219K mi. When I start it up it takes 15 to 30 seconds before the oil pressure gauge comes up to about 40#. After it runs for a while (5 to 10 min) the oil pressure drops to zero, and in another 5 to 10 min (idling) I start to hear light valve knock. Is it the oil pump or main bearing wear? Is there a way to determine which?

Answer:

Probably a little of both. No way but to remove the oil pan and measure the bearings by removing a bearing cap and using plastigauge to measure bearing clearances. Its almost as much work to get to the oil pump, so its worth investigating the bearings while you are there. I would suggest that if the bearings are within spec, replace the oil pump and consider yourself lucky to get another 50,000 – 75,000 miles from the engine. If the bearings are out of spec, I would look into a rebuilt or used engine from a reputable source like www.gotengines.com.

Question: My 2001 Dodge Ram 1500 5.9 gas engine stumbles and backfires when cold. After short warm up seems ok. Any suggestions? 180,000 KM.

Answer: Two possibilities come to mind…

1. Faulty coolant temperature sensor could be causing the ECU to
think the engine is warmer than it is, thus not enriching the air/fuel
mixture. This usually trips a check engine light though.

2. Dirty throttle body could cause issues like this as well. You can
clean with throttle body cleaner, making sure to get the IAC (Idle Air
Contoller)

Since its easier to tackle, go to your local auto parts store and get
a can of throttle body cleaner. Take off the air intake hose, and
spray everything inside. You may also want to check out
http://dodgeforum.com/forum/dodge-ram-van/68174-diy-how-to-clean-the-iac.html
for free instructions.

If cleaning the throttle body does not help, I would then check out
the temperature sensor by hooking the ECU up to a scan tool and see
what the temperature reading is at start up, to see if its accurate.
Most auto parts stores will allow you to borrow a scan tool, but if
you cant find one, you may have to go to a mechanic to have this step
done.

Thursday morning the dreaded flying spark plug hit me. Yes, you heard me right, a flying spark plug. It seems that the Ford Triton engines from 1997 to 2003 had a problem where spark plugs would randomly fly out the cylinder head. This appears to be due to a few issues… First there are insufficient threads in the head to properly hold the spark plug. Second the threads in the head are not inserted, in other words the threads are in the aluminum and are not very strong. Many ford owners have had problems and the shop who repaired my head claimed to have done over 100 repair jobs on Ford Triton engines in the past 5 years. If you are faced with this problem here are your options…

1. Go to your dealer, bend over and pay up to 12 hours of labor to repair the hole (time quoted to me by my local dealer) or get two new heads with properly designed spark plug holes for $3500.

2. Buy the kit and do it yourself… from my research Timesert is your best option. This will cost you between $200 and $400 depending on which kit you buy. Lisle and Helicoil also make kits and are available online and from your favorite tool supplier.

3. Find a friend who already has the tool to do the job. I doubt a repair shop will lone you the tool, but you can check out this forum for some members who have bought the kit and will rent it out to other forum members.