Underneath the engine, in between the flywheel (the dustpan cover I have removed) and the oilpan looks like the rear main bearing cap. Looking at the shop manual, it looks like this cap holds a rope (wick) seal, to keep the oil from leaking from the rear main bearing cap. Am I correct so far? Do I have to remove the oil pan to pull the rear main cap off? Is it easy to put in the new rope (wick) seal, after the rear main bearing cap has been removed? 100-110#'s of torque (from shop manual) to resecure the rear main bearing cap seems alot. KentC
110 pounds isn't that much for a main cap. Those are the caps that hold the crank in place. The crank comes out there, so the rear main needs a seal otherwise it would just dump oil out back. The pan also seals in the back right there too. You could get lucky and it's the rear pan seal and not the main. Changing the main would suck, but either way you have to drop the pan.
Unless it's really pouring the oil out , leave well enough alone . You didn't mention what engine it is and a 216 will have shims between the bearing cap and engine block that _must_ be kept in the correct order . If it's a high milage 235 and the oil pressure gauge dips to zero at idle , you may want to replace the main bearing shells as they wear allowing the crankshaft to settle a tiny bit and drip more oil . Use a cotter pin with a smooshed head to roll out the upper main bearing shells... All this is covered in your trusty Motor's Manual ~ what ? you don't have one yet ? cost is about $35.0 for a brand new one , under $20.00 for the originals , make sure it's the correct year for your _engine_ by looking in the tech pages under specifications . I hope this helps... -Nate
I am not sure I understand the answer. The oil pressure, when the pan is full, drops to about 5-10 at idle, 25-30 at 40-60mph cold, 15-20 warmed up. At a quart low, near 0-5 at idle, 15 warmed up 40-60mph. It smokes, out the oil inlet cap, exhaust and the vent. I do not see the process covered what you describe - in my manual. I tried to attach a picture of what I think is the rear main bearing (no luck there). It is the C-clamp between the oil pan and the flywheel. The engine is a 1960 235cu. Is there are rope-like seal (what you call shells?) that I can replace on the inside of this bearing cap? I must remove the oil pan to remove the bearing cap? I can only replace the bottom 1/2 of the rope seal, assuming I do not to deal with removing the crank, right? Yes, it is leaking quite a bit, not in extreme, but too much for my liking. All under the rear of the oil pan and where the dust pan cover bolts covering the flywheel has fresh oil droplets, lots of them. Thank you for the response. KentC
Good morning Kent ; Here's the deal : your oil pressure is fine , keep on changing it every 3,000 miles / 6 months when hot and the engine should last quite a while yet . The ' shells ' are the replaceable bearing inserts , as they wear , the crankshaft sits sever so slightly lower and the oil mostly weeps out the top 1/2 of the rear main seal ~ yes you can replace the bottom rope seal but it may not make any differance in leakage . The wispy blue smoke out the oil filler cap can be either worn piston rings -or- loose valve guides , as long as it runs well I'd leave it alone as a proper rebuild can co$t well over $1,500.00 in parts , even and in frame overhaul can cost $1,000.00 . -Nate
Ouch ! . De-grease the engine and ensure it's coming out the rear main _before_ you tear into it as oil can travel a l o n g ways along the edges of this 'n that before dripping off elsewhere making you think it's leaking at that point . You might want to try tying a soup can onto the road draft tube to see if it's simply blowing the oil out... -Nate
What is the road draft tube? Engine is degreased. Yes it is from the main bearing, I fixed the valve cover gasket and it leaks not from the rear of the head. I see nothing from the pan. What else could it be? Where to look? KentC
Really a good step by step procedure on replacing the old rope seal on stovebolt.com under tech tips. Exactly the way we used to do it only I guess he doesn't have a "sneaky pete" which was a thin flexible cable with a pull handle at on end and a chinese finger grabber at the other end to latch onto one end of the rope to drag it up over the crankshaft. Don't know if they still sell this tool, haven't seen mine for years.
RE: Road Draft Tube ...Commonly known these days as a ' crankcase breather ' it's on the right side of the engine near the fuel pump and has a long (ish) tube that hangs down to catch the venturi effect of the air rushing past to help suck out the fumes back when the engine was new and tight . What ? you look and all you see near you fuel pump is a freeze plug at an odd angle ? guess what , you just found your oil leak , the breather has gone missing and the freeze plug is causing the crankcase to get pressureized and force oil out past the rear main.... Guy here had this happen to his freshly rebuilt truck's 235 , sadly he knew everything and so I was unable to help him solve the oil leaks , he was pissed ! . Anyway , the open end of the road draft tube , put your hand underneath it , engine running and warmed up ~ it should give healthy puffs of air , if not , remove the set screw and gently bump it up & out , wait for SWMBO & kids to go out then fire up a charcoal bar-b-que and toss it on there , cook the living hell out of it , lots of stinky smoke will come boiling out of the BBQ but leave 'er cooking untill no more smoke then remove and wire brush clean , re-paint glossy black and re-install as they often clog up and cause oil leaks . there should always be wet oil up inside this tube from the normal oil mist . Sneaky Pete rope seal tools are still made by Lisle and KD Tools , sold in FLAPS or NAPA auto parts stores . -Nate
RE: Road Draft Tube Thank you. It is smoking from the vent pretty good, as from the oil cap and exhaust too. But I will burn out the inside of vent anyway. After all has been tuned I think I will watch the oil usuage and see if there is any improvement, it could not have hurt (all the tuning and timing) on using oil. But it looks like I will replace the rope in the rear main seal - don't like greasy/oily looking machines, even if on the underside. KentC
RE: Road Draft Tube See photo(s). http://iserver.chevyduty.com/dcforum/User_files/4356d59a0904b32a.jpg http://iserver.chevyduty.com/dcforum/User_files/4356d6020978be49.jpg Attachments: https://talk.classicparts.com/images/attachments/4356d59a0904b32a.jpghttps://talk.classicparts.com/images/attachments/4356d6020978be49.jpg
RE: Oil Leak & Pictures Are those before & after pix ? if so you have much to be proud of . My point about the road draft tube et. al. is : if it smokes out the exhaust , the rings are prolly worn and the crankcase pressurized so be aware it may still lear a fair amount after you change the rope seal . I hear you about oily , greasy machinery but that is the design of these things... Adding a PCV device will really help , AC and NAPA both sell an oil filler cap with a nifty hole punched in the middle of it with a rubber grommet for the PCV valve then you just plumb a hose from that to the big fitting on the intake manifold , this will reduce much of the dripping . You _DO_ make regular _HOT_ oil changes , correct ? and have a thermostat , preferably a 180* one ? . 64/40 coolant , not just water in the radiator ? . -Nate
