Howdy.

I have an 01 Grand Caravan with a 3.8, 185k. It runs very well, but it started developing what I thought was a lifter tick recently. I generally use 15-40 diesel oil in all my cars. I could explain the logic, but I don't want to start a war over oil.


i was due for a change, so I switched to a 5-20 synthetic. I read that these lifters have small holes that restrict oil flow, which can lead to low pressure in the lifter. Changing oil made no difference though.


So I kept driving it, and it's getting much worse. Over the past couple weeks, and maybe 200 miles, I've gone from zero noise to a tapping noise that has me concerned about mechanical damage. I'm certain it's not a main bearing knock. I've had that issue, and this is a different sound.


The part I don't get is that it makes no noise when I first started it up. As it warms up, it starts tapping. From what I've read these lifters make noise when they're cold, due to the small oil passage that prevents them from immediately pressurizing.


So I'm guessing this probably isn't a lifter problem, but I have limited experience with this particular engine, so I'm not sure what I should be looking for or checking.


Any thoughts appreciated

 

Have you been able to isolate the noise to bank 1 or bank 2; or does it seem to be present on both?

Have you checked the oil pressure with a gauge (instead of assuming it’s good because the warning light isn’t on)? Dodge calls for at least 5 PSI at idle and anywhere from 30-80 PSI at 3,000 RPM (with engine at operating temp). My opinion is at least 10 PSI per 1,000 RPM.

This could be one or more lifters that are in the beginning stages of collapsing. I don’t know the specific details about the lifters in these engines but the principles of operation are the same for all hydraulic lifters - they need adequate pressure to work properly. Collapsing, clogging of oil passages, worn crank or cam bearings, and an oil pump that’s giving out will all cause low pressure.

The valve covers on these engines aren’t difficult to remove. A collapsing lifter is easy to check for removing the cover and rotating the engine by hand until you see a valve opening. Stop rotating when the valve is at its max opening (or close to it). If it’s collapsing, the spring pressure will cause it to bleed down and the valve will start closing.

 

From the drivers seat, it sounds like it's the left side of the engine, rear bank....so, cylinder 5 maybe.

I'll check oil pressure, an pull the valve covers. Thanks for the input.

 

You’ll have to listen to the engine directly - echoing, road noise, wind noise, etc can all affect your perception of where the noise is coming from.

While the noise is present, use a long screwdriver or length of wooden dowel as a stethoscope. Place one end against a valve cover and the other against your ear - if it’s isolated to one bank, it will be more noticeable this way. If you’re not sure, press the dowel against other areas of the block/heads/manifolds - wherever you can. The louder the noise, the closer you are to the source.

 

Try this first and see what happen. Add a qt of transmission fluid and drive for a few blocks. Change the oil and filter and see if there is any change. ATF has detergent and may help with any clean the holes in the lifters. This was a problem with the 3.0 liters back in the day.