Looking for any help diagnosing my car's oil pressure problems. I have oil pressure light and tappet noise. When I remove the filler cap and look into the valvetrain, there is no oil visible. I have replaced the oil pan O-rings as per the instructions pinned at the beginning of this forum (thanks!). The job went well, and the O-rings for the pick-up tube, the dipstick tube, the float sensor and the two on the underside of the engine were all replaced. I used the pink volvo sealant and the job went as detailed and planned. But, still no oil pressure!
I've read here and other forums that the oil pumps on these engines rarely if ever go bad. (this car has ~150k miles), and I assume it's the original engine. I have read about a faulty plastic releif valve in the oil pump. Has anyone had experience with this? Could this be a culprit?
One note regarding the pan O-ring job. The larger of the two O-rings on the underside of the engine did fall down while I was putting the pan in place, but I was able to reach through the wheelwell and place it back into its spot before final installation of the pan. I suppose it's possible that it could have fallen while I was returning underneath to install the pan (but it seemed securely installed). What do these two O-rings do, and should I be losing sleep over whether this one may have dropped back down, or moving on to bigger issues?
Any help is gratefully welcomed.
Greg

There must be a leak somewhere... I am sorry I cant be of much help here. Hold on awhile. OK?

My next guess would be the oil pump. Either that or one of the o-rings slipped while installing the oil pan.

Thanks. I mentioned the O-ring falling in my first question because I am wondering if one of these is slightly out of place (fell again) would that cause no oil pressure on its own?
Another question: I've been told to have the oil pressure checked at a shop, using a guage, but I'm wondering if this will check the pressure before the sender unit and before the valvetrain, as both of those are already telling me there is no pressure. A couple of threads I found mentioned that the pressure guage goes on in place of the sender, but because I know there is no oil in the valvetrain, I am sure the sender is working, and the pressure guage will get the same info that the sender is getting now. make sense?
Come to think of it, does the sender read off the pump? Would it be an indication of a broken pump, along with lack of oil to the top end? What's the "pecking order" of these components?
Thanks for any help as always!
Greg

Here's some new info. I drained the oil today to start preparing for removal of the pan again so I can check the O-rings and make sure they are all in place; especially the two that fit on the underside of the engine and are hanging there as the pan is reinstalled. When I pulled the filter off, it was bone dry, as if never out of the box (except for the oil I put on the seal). After reinstalling the pan, I probably ran the engine a good 10-15 seconds, maybe a few more, but surely long enough for oil to reach the filter. Right?
So, I'm hoping this is a sure sign that one or both of those O-rings fell or moved during reinstallation of the pan. They seem to be located right above where the filter goes on the pan if I recall correctly. Is the filter the last thing the oil goes through before returning to the pan? The first thing out of the pan? It has to come after the pump at least, right? Maybe my pickup tube isn't picking up (perhaps because my pump isn't pumping)?
Ideas?
Sorry to bore you all with this, but it's now a challenge, and maybe my trial and error will help another down the line. It's a 100 plus-mile tow to the nearest shop that I'm comfortable with, so I am trying to eliminate all the factors that I can before taking that step. And I want to know as much as possible about this issue. Thanks to this forum for the help!
Greg

After the oil goes up the pick up tube it goes through where the o-rings are supposed to be. If they fell out then the pump will be sucking air.

I would start by pulling the pan again. When I install then I put a little of the sealant on the o-rings and have someone help install the pan so I can watch the seals.

Thanks Tech. That's what I was hoping to hear. Well, I hope one of the O-rings fell and it's that simple a fix. I don't mind pulling the pan now that I've done it, and will get it done tomorrow with help as you suggested. I did put a small amount of the pink sealant on the one that fell when I put it back up, but I wasn't sure if it was okay to do that so I didn't put very much on there.
For curiosity's sake, do you know what color the original O-rings were for 94 cars? My old ones were black with a green stripe. The new ones were solid black, and they seemed a little smaller. Not the diameter of the ring, but the thickness of the rubber seemed skinnier. My old pickup tube O-ring was red, and the new one is green. Same with the dipstick tube. I'm just wondering if this has been done on this car before or if I am the first. The old ones were in tact, but a bit hardened.
Thanks for your help.
Greg

The original should be black or similar.
The orange are stock. They went to the green ones because they are better. If you noticed the orange ones are stretched and swollen.

Tech, that's right. The old O-rings were hardened and came off a bit easier than the new ones went on. The old pickup tube O-ring allowed the tube to pretty much fall out once I removed the bracket bolts. The new green one had to be pressed in as I inserted the pickup tube. It wouldn't just slide in the hole at all. I felt good about that tight fit sealing well.
I did receive via email today, a diagram showing oil flow in the engine. As you stated, the oil flows through the pickup tube to the pump, then into the filter and out to the crank journals, then up to the valvetrain, inlet bank first, then exhaust cam bank before draining back to the sump.
I'm still hoping to find a bad O-ring, but am also beginning to research how to replace my pump. I haven't done the timing belt since buying the car in late summer, so I'm trying to buck up to go all out on the front end of this engine if the pump is bad.
Thanks for the advice and help. I'll keep y'all posted and any tips are always welcomed!
Greg

I will be waiting to hear what you found.

Okay, here's the latest. Got the pan off (so much easier this time, knowing the procedure and having a clean pan to work with - 20 minutes once the wheels were off the ground). The O-rings in doubt were right where they were supposed to be. slightly squashed, no shreds or tears to indicate misalignment or anything.
So...I guess that leaves me with a bad oil pump. No other possibilities, right? Now, I think I'm going to dive in, do the oil pump, T belt, and water pump. From what I've researched, it seems to be pretty straightforward (famous last words).
Questions - you knew this was coming: Any special tools I need? I've done T-belts on our 240 Turbo, a Lancia (uuuggghh), and VW dohc. So I feel okay about being careful with timing marks, checking two, three times to make sure things are lined up. Any gremlins in this job? Any tips? Looks like I need a puller, right? What should I get? And finally, how do I know if the idler and tensioner are okay to re-use? I'm not loaded with parts money, but I don't want to do this twice either.
Thanks for all the advice!
Greg

You will need a Vise to compress the tensioner(A big vise or a press).
You will need a puller to remove the lower timing belt pulley. The outer one will come off after a few taps with a hammer.
To check the idler and tensioner pulley to see if they need replacing look at them good. If it looks at all like the grease is starting to come out of the bearing replace them. Also if they feel s little gritty replace them.

Once you get the timing gear off the oil pump is held in with 4 torxes screws. Then it should come out.

If you have anymore quiestions feel free to ask.

Thanks again Tech. What's the best way to hold the crank pulley while I break the nut loose? I'm assuming it's going to be a real bear, and I am assuming the engine is going to just turn as I try to loosen it. I don't have an impact wrench, is there a "manual" way to do this?
Also, I've never needed a puller, so don't have one of those either. Do you have a recommendation, and is it something I can get at the local AutoZone? That's about as good as it gets here. Nearest Sears is an hour away, but I'm willing if it's a better source and tool.
And if I just buy a new tensioner, is it going to come already compressed and pinned, ready to install? I keep seeing warnings about damage from compressing old ones, and it's not worth the $70 gamble to me. I'd rather have new and be done.
Thanks as always,
Greg

You should be able to borrow one from Auto Zone (Puller) They might also loan out 12V impact guns also that should remove the nut. You will need a 1 1/4 socket. Thats what I use it is actually Metric but the 1 1/4 works fine.

I have compressed many of the tensioners and never had a problem. The new ones come compressed already and pinned for installation.

Not sure about a manual way to get the nut off never had to do it before. I have always used impacts.

When you compress the piston just be sure to go slow. Line up the hole in the shaft with the hole in the body first, then put it in the vice. Turn the vice until you get some pressure, wait a minute, turn more, wait a minute, etc until the shaft and body holes line up.
I got the gear puller from the local tool shop, about $20.
Be sure you KNOW what the timing marks look like on the crank and cam shaft gears. They were very small and hard to see, at least with my old eyes.
Once you get practice at this part you'll be able to change the belt (and tensioner) in about 1/2 hr.

Thanks Papa John. I keep reading that those marks are hard to see, so I appreciate the word of caution. Someone suggested to (with a light hand) fine sandpaper on the pulleys to bring up the marks. How do you feel about that? Shouldn't harm the marks, right? They are grooves in the metal pulley, correct? I hope to get into this job this weekend. I am going to get the belt off, and the oil pump out, then see what all I need to replace. But most advice is to go ahead and replace the tensioner along with the water pump. I'm not sure if my vice opens wide enough to fit the extended tensioner, so even if it's good, my vice may determine whether I replace it or not. It's less expensive than a new vice, plus it'd be good insurance to just do it.
Seems like a pretty straightforward job, cautions about timing marks heeded, so I feel pretty good about doing it.
I will be throwing flares out if I get into trouble on it, though, and I appreciate all the help.
Thanks, Greg

I mark the top marks with White out to help make the clearer.
You won't need to use sandpaper unless the pulleys are very dirty.
I will be around if you need help.