 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / October 2005BB 366 - rockers clatter; oil pressure but no oil at rockers
Hi - I'm working on my farm's chevy 87 c-70 w/ 366 v8 (which came out of an early 1970's era truck). The motor runs and has good oil pressure (according to the gauge) but there is no oil coming out of the pushrod tubes and the valves are very noisy as a result. What would cause this to be? There is only a little trickle of oil coming out the pushrods for the number 1 piston (the front one on the drivers side), none at the rest. I'm noticing it now because I just had the head off the drivers side to fix a broken exhaust valve and once it was all put back together the noise was terrible; before taking the head off there was no noise but still hardly any oil coming out the tubes. I pulled the oil pan off and the pump looks fine - no plugged screen or damage. I also pulled off the bearing cap on a couple of the pistons and that looked ok - no visible problem. A local motor shop told me that if the cam or cam bearings were bad we might have oil at the back (closest to firewall) tubes but none torwards the front. SO - I'm at a loss. All and any help is greatly appreciated. Distributor 180 deg out? > Hi - I'm working on my farm's chevy 87 c-70 w/ 366 v8 (which came out > of an early 1970's era truck). The motor runs and has good oil [quoted text clipped - 17 lines] > > All and any help is greatly appreciated. I don't know - how could I tell? > Distributor 180 deg out? Right.....the motor runs, but the dist may be 180 out? Where do you guys come up with these guesses? Even with the dist 180 out, what does that have to do with the oil pressure? Ian > > Distributor 180 deg out? > [quoted text clipped - 4 lines] > > Ian It's not a guess but a foggy remembrance of some engine that has a distributor body that impedes the flow of oil to the lifters if fitted correctly. If fitted incorrectly it blocks the flow of oil completely. Now do you have some advice for the OP? >> Right.....the motor runs, but the dist may be 180 out? >> Where do you guys come up with these guesses? [quoted text clipped - 7 lines] > correctly. If fitted incorrectly it blocks the flow of oil completely. > Now do you have some advice for the OP? Yes, I just gave him advice...hopefully he'll take it and not fool around with his distributor hoping for more oil pressure. Ian I'm back with an update. Thanks for all the help so far. I tried losening a couple of the rockers with the motor running as suggested but it didn't work; still no oil even after 30-60 seconds of running like that. I also hooked up a trusted mechanical oil pressure gauge and found that I do have 50psi at cold idle, so I'm ruling out oil pump and any serious bearing trouble. Here's a little background that may help the experts. This all started when I took the truck on a trip much longer than we normally use it. Typically, on the farm, it doesn't run for really more than 30minutes at a time, but I was helping my brother move and had to drive it on a 3 hour trip, including some highway. On the way, after about 2 hours, I started hearing a ticking in the motor. It's hard to describe the noise; it was louder than the tick that comes from a loose rocker, but not as loud and deep as a connecting rod problem. It's frequency was dependant on RPM, but the noise did not get louder if the motor was revved up; it just ticked faster. I had no idea what the cause was, and since I was far from home anyway I figured the motor was toast and I tried to make it as far as I could. It made it the rest of the way to his house and back, running the same way. I started working on the motor and found the spark plug on the #5 cylinder was smashed flat on the end, and that with a new spark plug the piston was not working right; it skipped and removing the spark plug wire from that spark plug made no difference in how the motor ran. I pulled the valve cover and found only a tiny amount of oil flowing down the rockers when it was running, went farther and pulled the drivers side head and found the exhaust valve on #5 was broken - 1/2 of the outer ring of the valve was gone and the piston dome was pretty lumpy. No pieces inside. I had the head checked and fixed, put it all back together. Now the motor runs very smooth, but the loud ticking is still there. With the motor running, I loosend the rocker on the #5 exhaust valve, and the noise got less and less; with no tension on the pushrod tube (it just going up and down but not compressing the valve, it was almost gone - the loud ticking noise (normal valve ticking was going on though cause it was loose). As soon as I slightly tightened the rocker the ticking started again. I pulled the intake off but everything looks ok, but what do I know? So - what does this mean? Can hydraulic lifters go bad and cause this? Could a bad lifter keep oil from going to the top of the head? Oh, and by the way - when I took the distributor out I think I know where the idea about the distributor came from. The channel in the rotor housing that passes oil from the pressure port behind it to the lifter ports on the side is not a consistent shape; one side narrows down and is much smaller than the other side. I think if it was in 180 degrees backward it could impede the oil flow, but it didn't look like it would block it completely on my engine. It was in 'wrong' from what I could see - the narrower restricted side was towards the oil pressure port in the block. Tomorrow I will replace the lifters and spin the oil pump with a drill to make sure oil is getting up there. If that doesn't work I do not know what to do next. Thanks again. > I'm back with an update. Thanks for all the help so far. I tried > losening a couple of the rockers with the motor running as suggested [quoted text clipped - 53 lines] > to make sure oil is getting up there. If that doesn't work I do not > know what to do next. While doing all that, ensure ALL holes are open all the way thru the pushrods--no crud, no battered ends, as oil MUST flow thru these. Note that those short 30-minute running sprees cause undue wear on lubricated parts; and these cold sprees can also cause oil holes in push rods to stop up ( as well as oil return holes in the heads and internals of lifters ) due to constant cold running & oil never heating enough to let the detergent do its cleaning. Ever tried to wash grimy hands with bar soap and cold water? Then try it using warmed, detergent engine oil: you may be surprised how well it cleans! Re: your questions: yes, hydraulic lifters can go bad and cause this. ...and: Yes, a bad lifter can keep oil from going to the top of the head--they are what actually what pump oil thru the push rod holes to the rocker arms. HTH, s Ok, I am going to go along with the distributor clocked wrong from what you are saying. I think it may have been clocked wrong before you started as well. It really sounds like your distributor has to fit one way only and if it is off a tooth it will impede or totally block oil flow. The vehicle can 'run' easily with the distributor 'body' physically pointing in any direction as long as the wires are clocked to the rotor. Before I went totally nuts on it, I would find a book or photo that shows the proper positioning of the distributor body and set it that way. You might have to rotate the oil pump pickup and reclock the plug wires to do this. I also think you have at least one collapsed lifter on that #5 valve or the oil pressure is just too low to pump it up or pump the crud out of it. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > I'm back with an update. Thanks for all the help so far. I tried > losening a couple of the rockers with the motor running as suggested [quoted text clipped - 55 lines] > > Thanks again. > Ok, I am going to go along with the distributor clocked wrong from > what you are saying. (laugh) you guys kill me! Ian This is why oiling the top end through the pushrods is a bone-headed way to do it. The engineers that insisted on oiling through the rocker shafts (Chrysler, Olds, Cadillac, etc.) were a few notches brighter than the pushrod guys. Short burst operation over a lot of years is a good way to crud up the insides of an engine, and those small passages through the pushrods are prime candidates. I once pulled apart a Ford 302 that had done years and years of short-operation work on our farm, and the darn thing had *ONE* open pushrod on the driver's side, all the others were filled with sludge. My guess is that the long trip freed up a lot of goop in the engine and added a collapsed lifter to the problem. New lifters and cleaning out the pushrods will probably get things back in shape, though the bearings may have taken a beating from crud passing through them as well. Be sure to break in the new lifters as though you were breaking in a new cam (first 20 minutes should be sutained at no less than 1500-2000 RPM, and use a good break-in lube on the bottom of each lifter) or else you may wipe a cam lobe in the process. > I'm back with an update. Thanks for all the help so far. I tried > losening a couple of the rockers with the motor running as suggested [quoted text clipped - 55 lines] > > Thanks again. I'm going home now to install the new lifters, clean the passages, and make sure the tubes are open. My brother, who is helping me, was going to get out of work early and pull the head again (intake already off so we're half way there) and make SURE that the piston is not hitting the valve due to the lumpiness on the surface. I've ordered a new piston and rings just in case it is. I will also make sure to install the rotor 180 degrees oposite to the way it was. Will let you all know how it comes out. Thanks for all the advice. > I'm going home now to install the new lifters, clean the passages, and > make sure the tubes are open. My brother, who is helping me, was going [quoted text clipped - 6 lines] > way it was. Will let you all know how it comes out. Thanks for all > the advice. If the vehicle runs fine but your not getting oil LEAVE THE DAMN DISTRIBUTOR ALONE. IT CANNOT NO WAY NO HOW BLOCK THE OIL FLOW UNLESS YOU STUFF THE OIL PASSAGES FULL OF CRUD. The oil channel goes all the way around the dizzy, notice that? Guess where the oil also goes? That's right it will go around the distributor, regardless of the position of the housing. Doesn't make a bit of difference. NEVER. I would bet that when you started running the engine some old crud broke free and plugged the oil passage feeding the lifter gallery. Pull it apart and clean it out or you WILL trash the cam, lifters, rockers, push rods. Oil pressure at the port means that oil is getting there BUT it is probably bypassing back into the pan because the passage is blocked. DON'T install the new lifters on that used cam that has been running without oil. It will eat them REAL fast. Ok - back again. First - I don't want to start anything here about the distributor position, but I DID find in the Chilton's manual (big thick hard cover one) last night a paragraph highlighted in bold and set apart by lines that said: ------------------------------------------------------------------------------------------- "CAUTION - the distributor on some Chevey V8 engines is part of the lubrication system and must be installed in the correct orientation or oil will not flow the to the right cylinder bank valve train" -------------------------------------------------------------------------------------------- I will also say that this did not apply to my 366 - the oil port for the right bank goes through the channel in the rotor housing, and although the channel is smaller in one section I don't think it would impede the flow. So - I think both camps are right on this. As for last nights progress - intake pulled, pushrods removed for both banks, lifters removed. Ran the oil pump with a drill and had good oil flow to the fist lifter hole, where it drained down into the pan as the lifter wasn't in there. Checked all passages between the lifter holes; they were clear. Made decision to leave head alone and not check to see if contact was being made to the exhaust valve because we could believe it was - the noise wasn't that severe. New lifters put in after soaking in oil, reset pushrod tubes, blowing each one out first. reset valves (tighten until no up and down movement possible, then 1 turn tighter, intake back on, distributor reinstalled in same position. Started it up; after a few minutes we had oil running down every rocker. BUT - THE NOISE IS STILL THERE. Let me tell you - it is not rocker noise that we here; it is somewhere in between rod knock (loud) and rocker noise (soft and clicky). With the motor running, if I back off the #5 exhaust rocker until the valve is not being depressed at all, the noise almost completely goes away. My plan now; pull the head and see if contact is being made between the #5 piston and the valve. Pull piston and inspect wrist pin, clips, and such. If no indication of a problem is found, I think we're going to pull the motor and rebuild it; I'm not putting it back together in the truck again to have it continue to make the same noise. What do you all think? My bet is you've got a cracked piston . You might pull the plug wire on that hole to see if the noise goes away but you're going to have to pull it down any way to "really" see . Sounds like your pretty familiar with this thing by now . I'll say - I've gotten quite good at pulling that intake off... "Let me tell you - it is not rocker noise that we here; it is somewhere in between rod knock (loud) and rocker noise (soft and clicky). With the motor running, if I back off the #5 exhaust rocker until the valve is not being depressed at all, the noise almost completely goes away." Rod knock starts off "soft and clicky" but it's hard to hear. When it gets loud there goes the oil pressure/flow. If the crank is "ok", bearings and a high volume oil pump should work. wws I pulled the head last night. Found that the top of the #5 piston has been making contact with the head - the top of the piston was pretty beat up from the piece of exhaust valve that came off, but I thought it would be ok. Now I see that some of the raised bumps are making contact at the flat area of the head - not the dome where the valves are but the squish area at the back. I'm going to replace the piston, rings and bearings and check to make sure the rod is ok. I don't understand why baking the exhaust rocker would make the problem less - maybe the pressure in the cylnder from not letting the gasses out is keeping it from touching as hard? The bumps are small - maybe the size of #2 pencil lead, but there are several and they are shiny from hitting. Will post a followup when it's all back together. Thanks again for all the help - lot of smart people here. > Let me tell you - it is not rocker noise that we here; it is somewhere > in between rod knock (loud) and rocker noise (soft and clicky). With > the motor running, if I back off the #5 exhaust rocker until the valve > is not being depressed at all, the noise almost completely goes away. I wonder if in the process of pounding that piece of valve around, the #5 piston hurt itself. Cracked maybe? Or egged out the wrist-pin hole. Bent the #5 connecting rod slightly? When you back off the valve on #5, you're basically shutting down that piston so its not getting combustion loading. See if the sound goes away when you just pull the #5 spark plug wire. I'll bet it does.... My problem is fixed. Once I got the piston out and examined it on the bench in good light, I saw that the bumps on the piston were actually pieces of the exhaust valve that were embedded in the top. The biggest one was probably sticking up 1/16 of an inch, overall there were 2 or 3 pieces. Just enough to make noise when running. Thanks for the advice on the piston; I replaced it with a new one and new wrist pin, with new bearings and rings. The bore was actually in good shape, a few passes with a hone cleaned it up. Put it back together - runs like it should, no noise, oil everyplace it belongs. Thank you to everyone who helped me get through this - the truck was done today and is needed for corn harvest, which we started today as well. > The oil channel goes all the way around the dizzy, notice that? Guess > where the oil also goes? That's right it will go around the distributor, > regardless of the position of the housing. Doesn't make a bit of > difference. NEVER. What I want to know is what genius (not) thought it was a good idea to stick the distributor right in the middle of an oil passage anyway. Another reason I rarely touch anything Chevrolet. Shims on starters, distributors in oil passages, connecting rods that are too short for a model airplane engine, oiling through pushrods, skinny lifters that limit the cam profiles that work... GAH!!! >> Distributor 180 deg out? > [quoted text clipped - 4 lines] > > Ian That guess is so far off it can't even be described as "wild assed" Bob Had this happen more than once .Try backing them off while it's running one at a time and see if the oil will come through . Sometimes they get partially collapsed and won't pump up after they've "sat" for a bit . Ok - I can try that. Will post back later. > Hi - I'm working on my farm's chevy 87 c-70 w/ 366 v8 (which came out > of an early 1970's era truck). The motor runs and has good oil [quoted text clipped - 17 lines] > > All and any help is greatly appreciated. You might go to a local autozone and "loan a tool" the oil pump primer tool. You put it in place of your distributor and use a drill to spin the oil pump shaft to give you oil pressure without running the top of your engine without any lubrication. -Bruce |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.