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Fresh 401, Quest for Oil pressure |
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rang-a-stang 
AMC Nut 
Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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 Topic: Fresh 401, Quest for Oil pressurePosted: Oct/11/2020 at 8:14pm |
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OK, Here I go. I am going to post my efforts as I go. I am not an expert engine builder and am happy to take any advice as I go.
Symptoms: I have low oil pressure on my freshly rebuilt 401, as read from my factory Jeep electric gauge and a crappy mechanical gauge. I currently have 20W50 Castrol GTX with Motor Honey in it and that gets me to 55psi at cold idle and ~10 at hot idle. Cruising hot I have about 30 psi. I have been fighting with oil pressure since my engine first fired off. I have about 8k miles since rebuild, engine is running pretty good otherwise. Configuration: Stock oiling system, no oil line, supply channel not enlarged. Crank was polished and balanced but was not ground. Clevite 77's on the mains (with the oil channel on half only), rods, and cam. Stock blueprinted rods. Cam is a new comp cam 268H. Lifters are new comp cam 822-16 hydraulic flat tappets. Comp Cams pushrods, Harland Sharp rockers, Comp Cams valve springs. Comp cams non-roller timing chain. Oil pump was blueprinted during the rebuild. Engine builder set my main bearing clearances to .0023 plus or minus 3 and the rods are are .0026. Inspection plan: I pulled my engine but left the oil in it. The oil has 3k miles and is ready for a change but I wanted to leave it black so it would be easier to see if it is leaking anywhere. 1) Pull the intake and valve covers, spin the pump and look for any obvious problems up top. 2) Start measuring and inspecting the top end first. Such as lifter bore clearance, lifter operation, etc. 3) Pull the cam and inspect it and it's bearings. 4) Rotate and measure/inspect the bottom end. 5) Remove, clean, inspect oil pump. 6) Correct any "issue(s)" I find. I do not think I have one smoking gun problem, I think I will find multiple little items. ****************************************** Yesterday I pulled the engine, today I removed the intake and valve covers. Initial thoughts: a) I didn't find any grit or bearing material (whew). b) apparently I had a vacuum leak at the bottom of my intake. All my intake valves and ports are oily but the inside of my intake runners were not.  c) all my stainless exhaust valves looked chalky white and consistent, like this:  and their plugs look good. Like this:  ....EXCEPT #3. I don't think this has anything to do with my oil pressure but my valve is not as white and chalky (seems like it does not get as warm):  And #3's plug was slightly wet and smelled like un burnt gas:  d) This looks like I was leaking exhaust gas into the valley from the cross over. True?  How do I get my intake to sit correctly? I did use the rubber end seals, should I just use a bead or RTV next time? e) Then I spun up my oil pump with my drill and observed. I had oil at all rockers except for 3 that were open:   f) I notice oil leaking out of my 2 galley plugs. Not enough to kill a pound of pressure but these will be corrected:   g) I noticed that oil came our from this lifter bore, pretty heavy. I was looking at a few things at the same time so I didn't look super close at it but will tomorrow when I get back in to this.  Edited by rang-a-stang - Oct/11/2020 at 8:21pm |
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79 Cherokee, 401
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rang-a-stang
AMC Nut
Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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Posted: Oct/12/2020 at 4:58pm |
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I started today by drying out the lifter valley so there were no oil puddles. Set my phone on the engine lift and spun the oil pump. I videoed the oil movement in slow motion so I could see where it was coming out. For some reason oil pours out of the lifters for #4 quickly. They are already spilling out into the valley and puddling up before any of the other lifters start showing any oil at all. I looked at the video closely and it is coming out of the top of the lifter, not the bores. Could that mean I have too much pre load in there? I have a video to post but I am not sure how to post on here.
I took all my lifters out, disassembled them, cleaned them, measured them, reinstalled them. I paid particular attention to #4s lifters but found nothing of concern on any of them. All 16 lifters had wear on their bodies about like this one (I consider this normal for 8K miles):  Bottoms all looked normal, push rod ends looked normal:  Measured all their bodies. They were all between .9044 and .9048. This is the biggest one:  I inspected each rocker. None of them had any abnormal wear in the pushrod seat. None had any abnormal wear in the fulcrum and all of them rocked smoothly.  Next, I inspected the rocker studs and valve tips. None of them showed ANY wear.  The last thing I did in here was check all the oil drain back holes I drilled. I wondered if I had punctured the oil galley when I drilled them. None of them appeared to have punctured the oil galley. Moved on to the oil pump. Pulled the filter to verify my bypass plug was in and seated. It was:  Then the horror show. Here is my first "issue"; look at my impellors:   Oh CRAP!!!  I REALLLLLY hope my oil filter did it's job and filtered out whatever did this to my impellors. I must have let some sort of contaminant into my engine when I was working on it. Here is the pump cover. Notice, not only are there scratches but there are little pock marks on it. This pump has less than 8K miles on it. I decided to plasti-gauge the cover. I see .001 clearance (no gasket).   Last part of today was to inspect the pressure relief plunger and spring. They look good, no scratches or anything.  Tomorrow I will pull my cam out and inspect it, it's bearings and the main/rod bearings. I am scared I am going to find more horror show in there but we will see. For now my shopping list is a new oil pump gear set.
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79 Cherokee, 401
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Rebel Machine
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Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5122 |
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Posted: Oct/12/2020 at 5:11pm |
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Check the cam bearings and make sure they don't look like this:  This was my engine years ago. Had low oil pressure, there was too much main bearing clearance. -Steve- |
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DMack
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Joined: Mar/27/2019 Location: California Status: Offline Points: 227 |
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Posted: Oct/12/2020 at 5:32pm |
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Hi Marc,
It looks like you checked this, but I just had a very similar issue with my fresh 360. I started the car up for the first time and it had run about three hours total. Had 35 PSI at startup when I first fired it up. Taking it out for my second or third 5-15 mile trip, just to road test. 69 miles on the odometer. Engine started "clacking" like it was starving for oil. Shut it down and towed it home...Turned out that the oil pressure relief valve was sticking in the bore. After I disassembled it, it turned out that a small piece of silicone gasket sealant had lodged down in the bore and not allowing the plunger to move freely. Pulled it apart, cleared the piece, blew compressed air through the pickup (back into the pan) reassembled and it works perfectly. One other area that the Forum guys mentioned to me was the pickup being too close to the bottom of the pan. They indicated that they had seen where the pickup actually sucked itself to the bottom the pan and restricted oil flow. Just a couple of basic things to look for...hope it helps.
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Boris Badanov
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Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Posted: Oct/12/2020 at 7:03pm |
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The normally bad AMC problems are not manifest here
because thick oil tends to make them worse. My bet is on a accumulation of slightly excessive clearances or excessive oil temperature. There is one thing I learned early is that AMC cooling systems tend to be marginal at best. Also the intake heat exhaust crossover needs to be blocked in any engine that see's no winter driving. Block both sides... This also disables the choke, so be warned. Headers make this situation worse. Far higher Under hood temperatures' and a close fit to the oil pan can send oil temps over the top. Also the use of headers can make the exhaust crossover become hyper active and bake the oil in the lifter gallery. My bet is your motor has minor little issues, nothing a new gasket can't solve. Focus on oil temps and use straight grade 30 or 40 grade and enjoy driving it. |
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Gremlin Dreams
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Steve_P
AMC Addicted
Charter Member Joined: Jun/28/2007 Status: Offline Points: 3806 |
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Posted: Oct/13/2020 at 7:30am |
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Not a cause of your problems, but what type of oil galley plugs did you use behind the timing cover? The ones in the lifter gallery look long and you don't want them at the front as they can block the passages.
I wouldn't use a straight grade oil- it's not 1960; oil has advanced greatly. Your bearing clearances are fine. You do not need to block the intake heat crossover. You can, but somehow, 99% of all engines had this open over their lifespan and didn't have any issues because of it. Headers are not the issue. Again, how many of us run headers with no oil coolers on the street? Sand the oil filter adapter, ideally on a granite block, to remove the wear marks. |
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White70JavelinSST
Supporter of TheAMCForum 
Joined: Aug/08/2012 Location: Minnesota Status: Offline Points: 4866 |
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Posted: Oct/13/2020 at 11:39am |
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I suggest you purchase a new oil pump gear set from Bulltear. I'm not sure that the damage to the gears that were in your engine is the reason you have low oil pressure. The damage to the gear side of the oil filter adapter might be contributing somewhat. Bulltear makes a midplate that may help as well. Hope you find good bearings, but if the engine oil was contaminated, that might have messed with bearing clearances. Punch a hole in the oil filter that was on the engine, cut it open with a metal snip, check for contaminates. Check the bottom of the oil pan as well. There are labs that can analyze the oil and it's contaminates for you if you send them a sample.
Edited by White70JavelinSST - Oct/13/2020 at 11:41am |
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70 Javelin SST, second owner, purchased 1972
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BassBoat
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Joined: Aug/29/2008 Status: Offline Points: 1719 |
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Posted: Oct/13/2020 at 1:46pm |
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Please correct me if I am wrong, but you had 0.001 based on plastigauge clearance with out a gasket and I'm "pretty sure" its supposed to be such that the gears stick out of the housing. Typically 006 proud with a 012 gasket gives 006 clearance and typically I run a 007 or 008 gasket and shoot for 001-002 clearance. This alone will cause your oil pressure problem
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rang-a-stang
AMC Nut
Joined: Sep/25/2018 Location: Camarillo, CA Status: Offline Points: 272 |
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Posted: Oct/13/2020 at 3:23pm |
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For sure! Today I hope to inspect the mains, rods, and cam.
Copy that. I checked the pressure relief and it seemed to be working correctly. When I did my first build on this engine, I added a small nut/bolt to the pickup to keep it from sticking to the pan floor. Not saying it is not sticking, but we'll see when I pull the pan later today.
I agree in that I think I have an accumulation of clearance issues. Pump is already known. Mains and rods will be verified today, and We'll see how my cam bearings are faring. I run an edelbrock Performer with EGR so I can't totally block the cross over. Well... I guess I can now (just passed smog for the last time). I run a TBI so I am not too worried about choke or cold weather starting. I have one of those plates that go between the oil filter and it's mount that has 2 nipple and could mount an oil cooler. HMmmm....
I used some stainless NPT plugs that came in a kit with my freeze plugs. I'll post pictures after my inspection later today.
I agree (I do not think it is the ONLY reason for my low oil pressure). Copy, I may get some of those gears. We'll see what else I find down below. I shied away from the midplate because it makes for another location for a leak. I had thought of sending off my oil for testing but not sure I want to pay for it. I also hope to get my truck back on the road in the next week or two. I open all my oil filters and have never found anything of concern as far as metal shavings. My break in oil filter was a fram and I DESTROYED it. CHeck it out:   Again, that was the break in filter NOT the current filter. I will open my current filter later day.
Copy. As I start re-assembly I'll make sure I pay alot more attention to this.
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79 Cherokee, 401
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jcisworthy
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Joined: Jul/23/2009 Location: North Carolina Status: Offline Points: 2805 |
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Posted: Oct/13/2020 at 4:30pm |
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If you have .001" clearance without a gasket that is loose. I set them around .001" with a .010" gasket.
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Specializing in dyno services, engine building, and cylinder head porting
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