304 Oil pressure advice

Noticing a drop in my oil pressure mainly @ idle when its warm. I have pretty good perssure when I'm running down the road but it drops to around 7 to 10 when I pull up to a stop. Question is would a new oil pump help or am I going to need to change out the bottom end. Any suggestions?

 

AMC V8s are notorious for low oil pressure at warm idle. The oil pump is housed in the aluminum timing cover and wears out faster than the rest of the engine.

10psi/1000rpm is ok... so you're marginal at warm idle (assuming the stock oil pressure gauge is accurate). If it were mine, I'd fix it up now though. Here's a site http://www.jedi.com/obiwan/jeep/wagoneer/401/timingcover.html The Crown timing covers had QC problems, but Brent at BJ's Off Road http://www.bjsoffroad.com/cartgenie/prodInfo.asp?pid=420&cid=3 assures us that they've been fixed.

 

Thanks Tim I'll have to look into it. Any idea on time to change this out?

 

Oh, it's not so bad on a CJ. First I'd measure the gear clearance and see if leveling the oil pump cover and a new gear set will be enough. If I needed to change the timing cover, I could do it in an afternoon pretty easily if I had the puller and kept at it (with no surprises and no broken bolts). If you're not trying to beat flat rate, it's probably easiest to pull the radiator first so you have plenty of room to work. If you pull the cover, you'll probably want to install a timing set too.

 

Thanks again for the Info. I read the article I'm curious how he measures 5 ten thousanths I don't have a feeler guage that thin or did he add an extra 0 to his notation which is what I think he did I can get the gaskets and all except the actual cover from NAPA i'm sure and since I work there I get a heathy discount which keeps the costs in the budget. I didn't know about the timing cover issue and always wondered why there was so much talk about the covers on some of the part sites I've surfed. Your info just might save me from having to tear down the bottom end.

 

I did this last summer: changed timing cover, oil pump, damper, and main bearings. I was dealing with American Performance in Florida and had some troubles with their parts. The damper was mushroomed so it didn't fit properly, almost damaged my threads. Oil pump filter housing had a casting crack (Crown? I later bought Chrysler) so I had to tear that out and while that was off I pulled the oil pump gears and the wear inside the timing from 5 minutes or so of oil pump gear turning showed to be offset slightly. The timing cover is Crown. There was a problem several years ago with the alignment of the distrubuter with the oil pump drive gear. That is now fixed, I hope. The problem I had with the Crown cover was at the bottom where it meets the oil pan (sides), they are not parallel. There is too much room to use a gasket, so I had to use an ocean of rtv.
When the real rebuild comes along, I will pony up with Chrysler
parts.
I can't tell you if this is isolated or not, just don't take for granted that the Crown parts will fit, double check.

Before:
Idle warm: 12psi
3000 rpm warm: 32psi

After:
Idle warm: 18psi
3000 rpm warm: 48psi

 

No, 0.0005 is right. It's the same in my 1977 TSM. Check the clearance for each tooth, along the plane that goes through the center of both shafts and the tooth you are measuring. I think the 0.0005 spec is moot (since you can't easily measure that), and just tells you that the gears shouldn't rub against the body. If your 0.003 gauge will slide in, it's too loose.

 

Ok Thanks Tim & Fred for the info and advice

 

I think the recent drop on the gauge is partially due to the fact I have had a few issues with the points and I reset the dwell and dropped the idle to about 650 per a info sheet the was with the dwell meter I borrowed from a friend. It was aroung 1000-1100 when I started. I'm planning on some engine work over the winter and I'm going to just monitor for right now. I'm also going to bump the idle back up as I'm having a stalling problem when I first start it until it gets up to temp. I'll post an update after the reset of the idle.