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Finished rear main seal/oil pump...now its knockin

P

pikey77

NAXJA Forum User
Location
dfw
Changed rear main/Oil pump out

Removed Starter and Bell housing inspection plate.

Oil pressure came up after about 2 seconds and now its knocking. I put a screwdriver to the bottom of the oil pan and its definatly louder in there than in the trans. What did I do? How do I fix it?
 
Did you by chance go with the mopar high volume pump? If you did, then did you check to make sure it cleared the crank? I have heard on some models there might be a clearance problems with the "mopar" high volume pump. Either way it sounds like you need to pull the pan and take a look. If you do pull the pan rotate the crank by hand and see if its hitting the pump.

Tim D.
 
no i used the melling HV pump.

It seems to go away as the throttle is applied and comes back when you let off the throttle So I'm guessing its the rear main bearing that I didn't tighten down enough.

The rear main bearing looked real good with no noticable wear on it. My oil pressure before was around 10 at idle and around 28 at highway speeds. I think the clogged pickup on the original is why. Heres a pic of the old against the new. It didn'thave any opening in the screen.

oilpump.jpg
 
sounds like you just ruined your crank

if you didnt torque that cap, and the bearing spun, time to pull the motor
 
sounds like you got your self a BLOWN motor. same thing happened to me a while ago. i changed my rear main seal went around the block for a test drive. half way around the block i felt a clunk looked at the oil pressure and then pulled to the side of the road. good luck
 
5150xj said:
Did you by chance go with the mopar high volume pump? If you did, then did you check to make sure it cleared the crank? I have heard on some models there might be a clearance problems with the "mopar" high volume pump. Either way it sounds like you need to pull the pan and take a look. If you do pull the pan rotate the crank by hand and see if its hitting the pump.

Tim D.
Click to expand...

Neither the Mopar HV pump (it's a Melling) nor the Melling HV pump have any clearance problems from the crankshaft (4.0 and stroker). Any clearance problem is with the oil pan, and that can be fixed by "massaging" the pan:

http://www.angelfire.com/my/fan/HVOP.html

I suspect the knocking is being caused by the no.7 main bearing cap not being torqued down properly (it should be 80lbft). You'll need to pull off the pan and investigate.
Best case scenario? You've only worn the no.7 main bearings and replacing them should cure the problem.
Worst case? The no.7 main bearing journal's scored so you'll need to pull out the whole engine, have the crank journals reground, and fit undersize main bearings.
Good luck.
 
Dropped the pan and the bearing does not appear to be "spun" as I would assume there would be some damage to the bearings and the crank. When I removed the #7 cap the pax side bolt seemed to be allot easier to losen thanthe right. I'm thinkin that after 9 hours under there I forgot to go from 40-70-80lbft and left it at 70. The crank shows no visible wear and the bearing looks good.

The only difference I see is a slight crazing or hazing of the bearing near the top pax side. Other than that its stil shiny with nothing i would note as unusual.

Just so there is no confusion oil pressure was up the entire time - at least 60

bearing3.jpg



bearing1.jpg
 
Last edited:
looks good, torque her to 80 see what happens

are you sure the pump isnt hitting anything, usually if u can hear a knock, the bearing is shot, maybe its something else
 
how would I double check to make sure the pump isn't hitting anything.

There was no problem with clearence with the pan when I put it back on, this would be the first i've heard of the HV pump hitting the crank.

I gotta head to work but im gonna stop by the dodge house and let a mechanic there take a look at the bearing to see for sure. I DONT WANNA DROP THIS FRIGGIN PAN AGAIN! although it only took me an hour to get it down the second time and nearly 4 the first!

Thanks for the help so far...keep any advice comin..I believe I've reached my limit on desire to work on the junk. Hopefully i can finish up tonight.
 
Pulling the pan is the hardest part of a rear main change withouut a doubt. Pulling off the steering dampener and the bolt helps as does disconnecting your shocks to get as much droop from the front axle as you can. A bottle jack in to help force the axle down gives you that extra centimeter you need for it to come out easy. I've found a twist/rotation with the back going to the passeneger side and the front toward the driver side gets you around things. ALSO the bottom passgenger side bell housing/inspection cover bolt is usually in the way. Pull that as well.

REMEMBER too much RTV can keep the bearing cap from seating properly. This picture shows RTV as per the FSM EXACTLY. No more is needed. really!! (orange RTV, upside-down L's)

bc1.jpg


Also a PRE LUBE/Assembly lube should be used on the bearing itself and on the lip of the seal so it doesn't scortch on startup.

bc2.jpg
 
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If you sill have the oil pan off, you might want to check all the bearings for wear. Just remember to re-torque them. After checking all the bearings (crank and rod) pull the oil pump and inspect it. Use a drill to spin it up and see if it knocks. If, everything looks good inspect the distributor gear and shaft. Use a flashlight and check the camshaft and cylinder walls.
 
SON OF A !!!!!!!!!!!

alright just got the pan back on and the engine fired right up....sure enough..tink tink tink tink tink tink tink tink.

I crawl underneath to put an ear to it again and it sounds like its coming a little farther forward the the rear main. Move the screwdriver up and the sound gets less hollow the closer I get to the front of the sump...I'm not 100% sure but IM 95% sure that damn oil pump is hitting the side of the pan. No clearence problems going in but just enough with the vibration of the engine at low rpm to hit the side of the sump....rpm goes up smooths out and the sump quits tapping the side of the pan...that is my new theory.
 
pikey77 said:
SON OF A !!!!!!!!!!!

..I'm not 100% sure but IM 95% sure that damn oil pump is hitting the side of the pan. No clearence problems going in but just enough with the vibration of the engine at low rpm to hit the side of the sump....rpm goes up smooths out and the sump quits tapping the side of the pan...that is my new theory.
Click to expand...

That's a good possibility. As you've seen from my pics, I used a ballpeen hammer to gain some clearance between the pan and the HV pump. Yeah I know it's a PITA to remove the pan again but you'll sleep better if you get the job done properly.
 
Well, finally got it finished up today.

The problem was that the sump on the new pump was to far to the drivers side and rubbing the inside of the pan!



Results were
Idle oil pressure still around 13 but highway Im up from 28 or so to 40-45. So the higher flow plus less clog brought it back up to spec.
 
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