Oil pressure blues

[Desert465]

Hi guys, I have a 72 Duster with a 1968 318. The motor was bought from a friend that swears it worked fine before he pulled it from his car but it did sit for 5 years in his garage before I got it.
It was rebuilt and has about 2000 miles( his miles not mine) on it with not a lot of big upgrades, 30 over new pistons and rings, crank was re-ground and all the bearings and necessary parts for a rebuild. Cam is nothing special from what he tells me (RV cam.)
Now for my dilemma. After I got it in and started it up everything looked and sounded ok except for a leak around the oil filter and some ticking noise coming from the lifters. Thanks to this message board I found out that there was a gasket behind the oil filter plate and changed that. The ticking noise eventually went away, oil pressure was always a little low to me it is about 40 on start up and goes down to about 5 after the oil is warmed up. I have checked with two real (Mechanical) gages.
I finally had it ready to take for a ride and once I got on the highway and about 2500 RPM (oil pressure about 25) the ticking noise came back with a vengeance, got off highway and started slowing down and the noise goes away…….
Cant have this now can we?????
After doing all the usual stuff, changing oil and filter 4 times, tried Marvell mystery oil I decided to pull the pan and see what’s up. (What a Pain).
First thing I noticed that seemed strange was that the pickup had Teflon tape on it….Is this wrong or right.
Pulled the Oil pump (High volume by the way) and the gasket was defiantly shot so I am hoping that this is the problem.
Question Time

I was thinking that since I have all this apart that it would be a good idea to change the oil pump, from looking at the screws it seems that it was opened at some point. Yes or no.
If I do change the oil pump should I go with another high volume or stock?. It has a stock oil pan and the motor is not heavily modified.
Where the intermediate shaft goes into the pump, is there any gasket, does it need to be a airtight seal like the pickup???.
I think I no the answer to this but should there be any Teflon tape on the pickup to oil pump threads?.

I really don’t want to have to pull this all apart again so any advice would be greatly appreciated.

PS: The guy I bought the motor off of got laid off about a year ago and have not heard from him so it would be hard to ask any quest

[Ausydad]

I have a '74 Duster w/ a '68 318. I would go fresh on everything and eliminate any chance of the prior owners mistakes coming back to bite you in the a#&!!! What I've also discovered is that you can have better cooling if you go to a L.A. timing cover. Same gasket, bolts right up, but gives you a much better water pump!

[dewme5]

if your pan is off. pull some of your caps, and check clearances. I had a problem close to what you describe. seems i had fried my crank really quick.

[lgjhn]

I've rebuilt several small blocks and agree with everything that has been posted so far. I would also add the following "opinion" and comments:
I've never used teflon tape or any other sealant on the oil pickup. I just screw it in until tight and that it is even with the bottom of the pan. No, there is no gasket or seal between the intermediate shaft and the pump. Yes, I would put a new HV pump in just to MAKE sure that you got a good one I have recently been using Mellings (some will argue against that) but so far, no problems. They did have a batch of pumps awhile back that were brand new and were bad. You may have gotten saddled with one of those. The new ones now are working great for me.
Also check the oil pickup screen itself and MAKE SURE there is no trash way up in there anywhere. Spotless is the word.
Also, there is a bushing in the oil galley from the rear main to the pressure sending unit. IF this bushing has been left out, you will have very, very low oil pressure regardless of what you use for a pump or anything else. You can check this by sticking a piece of wire down the oil pressure sending unit hole. It should hit "bottom" only a few inches down, and not bottom out at the crank. From everything you describe, I would guess you either got a bad pump or that bushing is missing, BUT it would not hurt to check clearances etc. while you got the pan off.
Hope this helps.
LJ

[Jims451]

Don't use teflon tape anywhere on a car. It's not that it is a bad thing if properly used, but if it comes loose it can plug up passages and such. For the oil pickup, I use a bit of Indial head gasket shalic on the threds, on external pipe thred fittings I use the paste type teflon sealer, and on flare fittings like the gas, transmission, and brake lines do not use any sealer as you want the flare seat to seal, not the threds!

I also have had good results with the Melling High Volume oil pumps, and they are reasonably priced through mail order. I think about $40?

Use some plastigauge and check the main and rod bearing clearances too while the oil pan is off.
Also check the pickup screen and pan to pickup clearance. Make sure the oil pump sits flush on the rear main cap too.

If you still don't have oil pressure, you will have to start digging into the engine, checking the tappets, and oil passage plugs, etc.

[6pakman]

i'd just change the oil and subsistute it for vegtable oil. ( see post from 2 weeks ago) just kidding, do every thing that is posted and DO check those clearences on the bearings. if you see any copper color on them . change em. but crosious cloth the journels first, just to smooth out. good luck.

[Karl43]

On my first smallblock, I had an oiling problem. Had similiar symptoms to yours. Cold start would have only 20-25 psi and down to 10 warm. After five engine pulls and some good advice from Ken Neve I made a oil pump priming shaft and found the two oil galley plugs were missing from behind the camshaft thrust plate in the front of the block. Make a priming shaft and then turn the pump over and look where the oil is gushing out - that is where you are losing pressure. Learn where all of the oil galley plugs are supposed to be and make sure that they are there before you put it together. I have never made that mistake again. I double check all cup plugs when assembling blocks now.

Oil pumps Melling is a good brand. I stay away from TRW as I installed one on a 340 and it made 500 miles and then the oil pressure relief valve stuck. They skated out of the warranty claim by trying to claim "the pump failed due to tiny minute particles small enough to pass through a stock pick-up screen" had stuck the pressure relief valve. If their pump can't take what the pick-up screen can't filter out it is worthless!! They rebuilt the pump and sent it back to me - I sold it to someone else after explaining the history. Told them if they have any problems call TRW. I still do not use TRW to this day. I now use the Mopar Performance pumps with the high pressure relief valve spring. You have to bang the stock oil pan a little for clearance with a ball peen hammer at the radius, but after that it goes in well. It does come with a paper gasket to go between the pump and the rear main bearing cap.

Teflon tape around the pick-up tube will not hurt if not used excessively, but beware of any that may get caught up in the engine.

It sounds like after the engine warms up and the oil thins, you are losing oil pressure and then the lifters bleed down. Definately do not drive the car until you find the problem. Check all of your oil galley plugs to make sure that they are there. Once I installed my cup plugs, the oil pressure went to 40-55 psi. Trust your mechanical gage.

[Desert465]

Thanks everyone for all the tips. I will check it all out and let you know.

[Desert465]

Ok, so I took the pick-up off and found some teflon tape in the screen?????. I hate when that happens.
Off the the store to have a look at some new pumps and something was differant about mine.
Got home and started having a closer look at my pump and what I think is the pressure release valve (round hole on the side) there is a cotter pin missing.
The one in the store had a pin in it. Cant find the pin in the oil pan and I am not sure if it was ther to begin with.
What does this pin do an would it cause my oil pressure problem????

[Desert465]

This is going from bad to worse.
I decided to start off checking one of the suggestions lgjhn had, checking for the bushing down the oil sending unit oil, put a peice of wire down the hole and it bottoms out at 7 1/2 inches???
Is this wrong? lgjhn said it should be down a few inches.
Does anyone have a part number for this bushing thing and how do I go about changing it?.

[Desert465]

g

[lgjhn]

7.5" sounds like its missing and the symptoms seem to indicate it. Unfortunately, I'm out of town travelling this week or I would just walk out to the shop and measure for you on one of the small blocks I got sitting out there just to verify. Won't be back home till this weekend., but it sure sounds like the little cup plug is missing out of the rear center oil galley. This is a very common occurrance when someone doesn't realize what they are doing or what the fucntion of plug is. Lots of times, the machine shop work removes it or it gets "boiled out" during the cleaning. I normally remove it myself prior to any machine work and it is one of the first things I install once I have my newly machined block nice and clean.
The plug is not very large and it is normally included in the MP small engine package. I do not know the exact size of it, but I would suggest swinging by a Moparts dealer (if you can find a friendly one), get them to look up the part# and see if they have one. It is not hard to install, but it does go in far enough to butt up against a shoulder that is machined in the oil galley. You can see the shoulder in there using a small fashlight. Unfortunately, it goes in from the bottom (rear main bearing) which means it goes in from the crank end, which means crank has to come out, which means mains/rods have to be disconnected (be sure main caps go back on in the exact same position etc that they came off and retorqued to spec), which means front cover has to come off, which means new gaskets for cover, water pp, fuel pp, etc.
This is a lot of work under the car. I would double check to verify that it is, in fact, missing, then pull the motor, put on engine stand, cuss a lot, and do it right.
LJ

[Desert465]

Thanks lgjhn, I am going to check the bearing clearances this weekend so if you could let me know what you find out on the distance on the plug that would be great.

[lgjhn]

No problem. I won't get back down to Louisiana until real late tonight, but tomorrow morning, I'll be in my shop and I'll measure a couple of them and post what I find on here for you. I've got 3 small blocks out there on engine stands (the one I just replaced in my Ramcharger, one that I built over the fall for whatever, and then one that I just got back from the machine shop last week and in need of a good thorough cleaning including that oil galley cap plug installation itself. Hopefully, I can get that done too.
I'll let you know.
IF, in fact, yours is missing, it will need to be installed in order to get any pressure regardless of anything else you do. But you stilll should check clearances while it is apart, plan on a new oil pump just to make sure etc. It is very unfortunate that such a small part that costs less than a buck will make you have to tear a motor apart like that, but do not feel bad, most of us have made the same or similar mistakes, especially us old guys. When I started messing with these things back in 1968, there was no MoparChat forum or anything else even close to gather information from. It was all either learn by doing it the hard way or hanging around with other guys that had been doing motors too. I made the mistake of not cleaning all the machining debris out of one of my first motors and after about 3000 miles, I was out a complete set of bearings and needed regrind the crank. So hang in there. I would suggest though that you get a service manual for you vehicle AND the Mopar Performance Engine Book....Lots of good necessary info in both of em.

[lgjhn]

Measured one of my blocks as promised. 7.5" looks about right. IF you have the tranny and flex plate off, and you look at the back of the engine, you can see the outline of two horizontal oil passages kinda on the pass. side of the crank. The plug actually ends up between these two passages.
May just be your pump. Hope this helps.
LJ

[Desert465]

Thanks lgjhn, Thats great news. I did not get around to checking the bearing clearance yet but if they are bad can the bearings be changed with the motor in???
I hope it's just the oilp pump too.

PS: Thanks again lgjhn for taking the time to check that oil plug measurment.

[lgjhn]

I have changed bearings with the motor in before and it is very tough. First off, the rods have to be pushed as high as possible, put rubber hose on bolts to avoid scratches to the crank journals. The crank is one heavy mother to be removing/installing from the bottom. I've tried with varying degrees of failure of trying to just do one bearing at a time etc with the crank in. In all honesty, I wouldn't do it that way ever again. I would just pull the motor, put it on an engine stand and save myself a lot of headache, sore muscles and cussing....but then, I'm an old geezer....lol

[Desert465]

Ok, the scoop.
Put the new oil pump in and still had the same problem. I decided to have a good look at the valve train again, I had replaced the rockers and shafts before thinking this could be part of the problem. I removed the rockers and when I removed the bolts holding down the shafts I had a real strange sound ( sort of like pulling your foot outa mud) so I decided to clean them out, they where full of old oil sludge ( this could have affected the torque). Next I noticed that the rocker shaft retainers where really worn, worn to the point that the holes for the bolts where not round anymore. Ordered new shaft retainers and bolts from MP.
All parts back in and startup time, Oil pressure seamed a little higher on startup (45). The car had been running for about 1min and I went to check for any leaks under the hood, for some reason I decided to remove my oil filler cap on the valve cover (don’t know why I just did) and when I did I had the suction from hell. I did not know if this was normal but I didn’t t think so, I left the cap off and let the car heat up and all was good.
Hot and at idle it reads about 12 (always had 0 before),Went out and got a breather to replace the oil filler cap, took it for a run and at 2500 rpm it reads about 35 (22 before). Yippyyyyyyyyy.
Now I don’t really know if it was the bad rockers shaft retainers, sludge in the bolt holes or something to do with the passenger side bank not breathing correctly but I am not going to try and find out.
Thanks to all that helped with ideas and advice.

Note: Driver side I had the PCV valve and passenger side I just had the oil filler cap, so I guess it would make sense that both sides need to breath??????? Yes or no.

[Desert465]

Ok, two years later and a move from California to Florida and it finally runs. I thought I had it licked after my last post but it started ticking again and the oil pressure was still low so after I moved I pulled the engine and it sat on a stand in the corner while I fixed the car up. New interior, paint and such.
I was trying to decide what engine to get as I cant afford to just go out and get one built and I decided to call a local MOPAR engine builder to see if he had or new of anyone selling a good used engine. I discussed at length with him the problem I had with the engine and he said usually what happens is folks get there Mopar engine rebuilt at places that have never done one and they always forget something.
This is what he told me to check.
Oil gally plug down the oil pressure hole. This one was there because I checked it before.
Oil gally plugs behind the thrust plate. MISSING
Oil gally plug at the back of the oil gally on the driver side just beside the oil pump drive MISSING

I was pissed and very happy. The guy that sold me the engine said it ran and he was a friend from work and I even have the receipt of him spending 2 grand to get the motor done.
What to do next. The right thing would be to get it redone again but no funds to do that so I bought a complete gasket set, torn it down to check everything and put it back together and hope for the best.
After it was done and before it went into the car I put the primer on it and spun it up and it had almost 70 on my oil pressure gauge, wow…the most I got before with straight 30 was about 30 to 40.
Put the motor in and it runs great and the oil pressure is great.

Morel of the story.

Don’t trust any place to work on your Mopar that hasn’t done it before.
Even if it’s a friend don’t believe the 3000 miles on a good engine thing. Hell I would have still bought it from him if he had just told me it ticked and then I could have gone down a different road with my trouble shooting, I kept thinking to myself ( it ran fine before) so I did not consider a lot of things