WHY? PCV hose not connected.
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From: Arkansas
WHY? PCV hose not connected.
I been attacking the usual leaks on my 2000 C-5. Have done everything but tear it down to try to stop leaks. Oil pan bolts did help some. Im out of ideas. I have read where PCV valve being bad will cause leaks. I have ordered the complete PCV and hose kit from GM. I had not checked mine but figured it needed a new one. I took off the oil cap and checked to see if there was any suction or blow by. There was no suction or blow by that I could tell I decided to look at it this morning just to see what shape it was in. It seems someone had took the PCV hose out of the driver valve cover. I plugged it back in and took off the oil cap again and could not tell any change. Is there and advantage in taking the hose off the valve cover. Would this cause oil leaks?? No telling how long it had been off. Im open for any ideas on this guys.
Burning Brakes
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That hose being disconnected won't, in itself, cause oil leaks. But it'll create one heck of a nasty vacuum leak. I'm surprised you're not posting about idle issues and air/fuel ratio related problems. I would certainly disconnect your battery for 10-15 minutes to allow the computer to reset the short/long term fuel trim and idle back to base values. I'd bet yours are all out of whack from the ECM trying to compensate for all the unmetered air entering the intake.
If the PCV system/valve was clogged it would cause higher then normal crank case pressures which would indeed cause leaks eventually. It sounds to me like you have the opposite problem and something else is causing your leaks. When the PCV system gets clogged, often times the dipstick will be pushed out of the tube a little bit from said increased pressure. That's a good warning sign that something isn't quite right.
Can you define "the usual oil leaks"? The LS1/6 platforms don't have many oil leak problems that I'm aware of. Some notoriously burn oil....but don't often leak. Maybe I am wrong. So you have oil leaking from multiple seals throughout the motor? Did you use non-synthetic engine oil for your last oil change by chance?
If the PCV system/valve was clogged it would cause higher then normal crank case pressures which would indeed cause leaks eventually. It sounds to me like you have the opposite problem and something else is causing your leaks. When the PCV system gets clogged, often times the dipstick will be pushed out of the tube a little bit from said increased pressure. That's a good warning sign that something isn't quite right.
Can you define "the usual oil leaks"? The LS1/6 platforms don't have many oil leak problems that I'm aware of. Some notoriously burn oil....but don't often leak. Maybe I am wrong. So you have oil leaking from multiple seals throughout the motor? Did you use non-synthetic engine oil for your last oil change by chance?
Last edited by wscott62893; Mar 22, 2019 at 03:29 PM.
Burning Brakes
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Sounds odd to me, unless they were trying to keep oil out of the intake manifold, which is a common issue on the LS1. I'm not familar with it being detrimental to the performance (oil in the intake). Maybe someone else has a thought.
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At first it seemed oil was leaking from both ends of oil pan. I cant see any fresh oil on top side. After many cans of brake cleaner I got it clean and put dye in oil. THe leaks were from the back of the pan. Passenger side where pan meets block and some on driver side. I tightened the bolts a little and this seemed to help. There does not seem to be oil on the front of pan. I took of the rubber inspection cover and could see a little trail coming from what seemed light above the main seal. I changed oil today with pennsoil high milage10w30 full synthetic. Im hoping it may help some. I was hoping the PCV hose not plugged in was some of the problem. It appears maybe the leak is up higher but Im not positive. The car has always had a good idle. No lights or codes. When I plugged in the hose to the valve cover it changed nothing I could tell.
Last edited by GS963; Mar 22, 2019 at 03:43 PM. Reason: more
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Im still curious though why when I plugged the PCV hose back in there was no difference in idle or anything else. There must be another hole or something in the system
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After making sure oil pan bolts were tight and plugging pcv hose back into valve cove that was not attached. I changed oil with high mileage Penn’s oil synthetic and added a bottle of lucus stop leak additive. Today I went on a 150 mile drive. Before I left the driveway there was a softball size puddle of oil on the ground. I decided to go with the leak and hope it got better. After about 80 miles I checked car. Could see oil on pan under car and also the back of car had oil spots on it from leaking. I decided to clean it off and see what 80 more miles did. Amazingly there was no oil on car when I got home. I jacked car up and cleaned pan again. Drove car another 30 miles. The leaks have almost stopped. Nothing on ground and very little oil on pan. I’m not sure if the high mileage oil the lucus stop leak or the pcv being plugged in. Or all three.
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Burning Brakes
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Glad you were able to see positive results! I’d still plan to diagnose the root cause of the leak and prep to get it fixed “properly”, but sounds like you’ll be able to get by for a while if the leak completely stops from the additive. Good news! 
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Im not one to use stop leaks to solve a leak issue but I have read good things about lucus products. As I said Im not sure if it was plugging the PCV back in or the lucus But I will keep this updated to see what happens. Appreciate your input.
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Wow, well drove car today and it is leaking again. Crazy how it stopped now started again . I’m out of ideas. Could oil sensor possibly stop leaking then resume. I would think not if it is even leaking. I’m out of easy fixes. Lol
Burning Brakes
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Maybe with the fluctuations in oil pressure as the engine revs, the temporary seal worked but eventually deteriorated? Not sure. I have little to no faith in those oil additive “seal makers”. Unfortunately, I think the next step is disassemble/diagnose/repair.
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Could be the sealer done it. Im not sure. But its seems the next step is to remove the intake and look at the back of the motor. Focus being on as you say the OPS. for now its just gonna leak unless it decides not to again. lol wow.
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Was a mess under intake. This little guy was living there once. Actually looked like someone had put rat poison pellets in intake. Crazy dirty
. Yes I know. I took it out and looked at it. O ring looked ok but who knows.
Last edited by GS963; Apr 4, 2019 at 08:46 AM.