Thread: Oil Pressure Question

I have an 06 Grand Prix with a 3800 Series III engine with just over 300k miles on it. A while back, the engine developed a "tick" coming the rear valve train. My neighbor (who is a boat mechanic and shade tree car mechanic) and I removed the valve cover, and all the valve cover and inspected the valves. Everything seemed to be tight, and the ticking did not subside when we manually lubricated the valves. This lead us to the conclusion that is must be something lower (lifter, etc.). I decided to not pursue it any further due to the complication of getting to the lifters. At the time, the noise only appeared when the engine was cold, but once warmed, it went away. Over the past few months, the tick has become constant, but I still wasn't terribly concerned.

This week, my low oil pressure light has started coming on when I stop or turn sharp, but it goes off almost as quick as it appears. I immediately checked the oil level, and it was about a half a quart low. Considering where I was in my oil change cycle, this made sense. I've had this car since 07, and it's always used a half quart around halfway through the cycle. I added some oil to the proper level, but the low pressure light still comes on when I stop, but goes off once I am stopped. A few weeks back, my parent's Ford Explorer was doing something similar and it was the oil pressure switch. My car has both the original pump and pressure switch.

My current thought process is that it may be the switch has gone bad. The good thing about this is its a cheap and easy fix, but now I'm wondering if I have something more going on. Maybe the tick was actually a symptom of either a bad oil pump or a sludge build up in the system. Another thing I have considered is doing an engine flush with Liqui Moly Engine Flush (seems to be highest rated everywhere), but my concern with that is that with my mileage, the engine may begin burning oil as long gunked over oil leaks are free to leak again.

Does any have any thoughts on what is the most likely problem or have a suggested course of action?

Thanks.

I don't have an oil pressure gauge, so I made an appointment on Monday to have someone check the pressure for me. I'll let you know what the results show. From what I understand, the pressure switch has to be removed to check the pressure. Is that correct? If so, wouldn't it make sense to go ahead and have a new switch handy to replace it with while the old one is out? They're like $20, so even if the pressure test shows the worst, I'm not out much.

Thanks for the help.

Yes, the sending unit has to come out to install the pressure gauge. Also, the stock pressure senders are known to break internally and leak oil. Another reason why I have a true pressure gauge in my car and eliminated the factory "change engine soon" bs. I had 2 stock units fail before I switched to the gauge and both times I was loosing oil in a hurry. Luckily I didn't drain the system and screw up the lower end.

I took the car to the shop today to have the oil pressure checked, and I got good news. The oil pressure was a little low, but considering the mileage, it was to be expected. It seems to have only been the pressure switch going bad, and since I already purchased a replacement, he went ahead and replaced it while he had the old sensor out.

He also came to the same conclusion that I had regarding the ticking noise. He believes its in the lower half of the engine. Thanks to everyone for the feedback.

What was the actual oil pressure reading on the manual gauge? I'm just curious since I have more miles than that on my 00 GP.

If the noise is a "tick" and not a "knock" (there is a difference) that goes away when warm or subsides a bit then it's likely just a lifter. I have that noise on my 95 Bonneville and it still runs just fine and has good pressure. These engines are known to have a tick to them even with lower mileage. Injectors can tick enough to make you think it's something else. Also can have a cracked rear exhaust manifold that can make a similar sound. A mechanics stethoscope could probably help pinpoint it if it really bothers you.

I didn't think to get the actual reading from him. Later on, I realized that I didn't get the actual reading. When I asked about it, he just told me that it was about 5 psi low.

This is an actual tick, not a knock. Using my stethoscope, it seems to be coming from the valve train towards the rear of the engine, but when I had the cover off, it doesn't look to be coming from the valves themselves. When it first started, it only did it when the engine was cool, but now it does it all the time.

I do have bad news. My low pressure light returned. My drive home from work is an hour long, and by the time I got home, it was coming on every time the engine went to low RPMs. The more I think about it, the more I think it may be the oil pump. I've noticed that it seems to be worse in the afternoons than the mornings. I live in south Alabama, so we're in those days with a heat index in triple digits. I suspect that as everything gets hot on my drive home, the oil thins, and the pump has trouble handing it at low RPMs due to wear. Does this theory make sense to anyone else, or does anyone else have other ideas?