So I was sitting at a light today, heard a ding and my check gauges light came on. Oil pressure was pegged at zero. It's always been dead center at all times. Light turns green and as I accelerate, pressure junps back to center.


Got home, checked oil level and it was good. I always stay on top of that. I proceeded to run a motor medic flush through it + changed oil and filter. Upon starting, the oil pressure climbed steadily to center.


I've been using synthetic since I got the truck and the oil had about 5500 miles on it. Previous owners records says that the oil pressure switch was replaced in 2013, at 229K. It was quickie oil change that replaced it, so must be aftermarket . Truck now has 260.5K


Am I looking at a new oil pump? How much work is it to replace on in this 4.7?


Thanks in advance.

 

It very well could be the sender. Before you do anything else put a mechanical gauge on it to verify the electric one.

Mine did the same exact thing and it was the sender.

Did you hear the engine rattling when the ding occurred? The lash adjusters would have made a lot of noise.

The oil pump is on the crankshaft. You'd need to drop the oil pan and then remove the timing chains/tensioners, etc. It's a lot of work. If you're going to do it then replace the timing set while you're in there.

 

I agree with Dan, it's probably the sending unit. I am on my third one now. I replaced my OE sending unit back in 2012. It was reading wonky, but never dropped to absolute zero, the needle was jumping all over the gauge. I bought the "good one" from Napa, an Echlin part that was supposed to be the same quality as OEM. It lasted until earlier this year, then started reading erratic too. When I went to disconnect the electrical connector to remove it, the top half of the sensor came off with it. Napa did a warranty exchange, that one lasted until about 3 months ago, then started doing the same thing, wonky reading both at idle and speed. It also came apart when I went to remove the connector. I bought a BWD sensor from O'Reilly and so far it has been fine. If this BWD fails I will probably bite the bullet and pay the dealer price for OEM or maybe look online for a better price on the OEM.

Jimmy

 

Man, I really hope you guys are right about it being the sender. I have zero desire, time or funds to dig into the engine right now. I'm not used to sending units going bad that fast. These things are usually vey long lived, at least in the other cars I've owned.


Dan, I noticed zero change in the way the engine sounded or felt. It kept running smooth the whole time and I didn't hear any chatter. Since the motor flush, it hasn't dropped to zero but when I start it, the needle goes to the quarter mark, then climbs to center in about five seconds. I don't remember it doing that in the past, it would just jump to the halfway point immediately.




I'll definitely check the pressure and change the sending unit. Saw this set at HF. Do you guys know what PSI I should be looking for on this 4.7L?


http://www.harborfreight.com/engine-...kit-98949.html

 

From Dodge, the minimum is 4 psi at idle.

25-80 at 3000 rpm.

The general rule of thumb is 5 psi per 1000 rpm.

Without any change in noise level it is likely that you DID NOT lose oil pressure. Another reason to suspect a bad sender.

 

The HF test kit should do fine, but you might ask at the parts store if they have one to rent. You have to "buy" the tool but when you bring it back after using it you get a refund. I use a credit card when I rent tools, that way I don't even have to worry about money coming out of my bank account and then waiting for it to be credited back after the refund. On a credit card it's just a wash.

You may also need to check the parts stores for an oil pressure sending unit socket. It takes a special size socket to R&R the sending unit. A parts store may rent that one out too, but I bought mine at Napa when I bought the first Echlin sending unit. It has come in handy since I have had to R&R mine a few times.

Jimmy

 

Thanks guys. Found the Mopar sender on Amazon for about 25 bucks.




Jimmy, it looks like I could easily use a pair of channel locks to pull/install it. If not feasible, I will get the socket.

 

4.7 must be very different from my 3.9. On mine the OPSU is on the back end of the manifold to the right of the distributor. There is no way to get at it but with a socket, universal joint and 10" extension.

Jimmy

 

Looks to be right next to the oil filter, according to what I've read. Haven't actually looked yet.


I'm elated in thinking it's the sensor. This morning, as I drove to work on the highway, it went back to zero again for a good ten minutes (not a comfortable feeling while doing 70 mph, let me tell you). Later, when I was sitting at a light, it was back at the halfway point. It fluctuates all over the place. Engine sounded smooth the whole time.

 

It's a common problem, the sensor failing.