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Discussion Starter · #1 ·
Hey everyone, my first post and annoyingly its bad.

I bought a very cheap 300c 5.7 that i knew had engine issues, but trying to diagnose it.

Basically the engine is sucking huge amounts of air from the crankcase, but not through the PCV. When you rev it, massive clouds of grey smoke come out and the oil filler and dipstick tube are sucking air in.

Never seen anything like it before. Is it possible that the intake could be pulling vacuum through the oil gallery gaskets that go to the oil filler and crank vents?

Or maybe something far more catastrophic? It has me stumped other than maybe taking the intake off and inspecting the gaskets and whatnot.

Any suggestions appreciated.
 

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Hey everyone, my first post and annoyingly its bad.

I bought a very cheap 300c 5.7 that i knew had engine issues, but trying to diagnose it.

Basically the engine is sucking huge amounts of air from the crankcase, but not through the PCV. When you rev it, massive clouds of grey smoke come out and the oil filler and dipstick tube are sucking air in.

Never seen anything like it before. Is it possible that the intake could be pulling vacuum through the oil gallery gaskets that go to the oil filler and crank vents?

Or maybe something far more catastrophic? It has me stumped other than maybe taking the intake off and inspecting the gaskets and whatnot.

Any suggestions appreciated.
It sounds like either the intake gaskets are shagged or the piston rings are shagged.
 

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Discussion Starter · #3 ·
It sounds like either the intake gaskets are shagged or the piston rings are shagged.
Well let's hope that it's the intake gaskets. I figured if the piston rings were worn you would get blowby, not negative pressure in the crankcase but I'm not familiar with the gen 3 hemi.
The local dealer doesn't have any of the gaskets in stock, are the aftermarket ones any good and where would you normally order them? (In Australia but happy to order from the US).
 

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Welcome to the forum. I'd be surprised if it is the intake manifold gaskets on a 5.7, unless the bolts are very loose. If it were a 6.1, I'd bet that was the problem. Intake gaskets on the 5.7 are really good and the 6.1's are totally different and often the port sealing rubber parts get ingested into the engine and cause massive leaks at the ports, even if the bolts are tight. You can check your 5.7 by using soap bubbles when the engine is running. You won't be able to check under the manifold, but you will be able to check between the intake and the valve covers. Also, check to see if the bolts are properly torqued. If you have access to a smoke tester, you can try that too.
 
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Discussion Starter · #5 · (Edited)
Welcome to the forum. I'd be surprised if it is the intake manifold gaskets on a 5.7, unless the bolts are very loose. If it were a 6.1, I'd bet that was the problem. ... Also, check to see if the bolts are properly torqued. If you have access to a smoke tester, you can try that too.
OK, the design is different between the 5.7 and 6.1? I think I will pull that manifold and look anyway, I am no sure this engine is original to the car so maybe the manifold has been bodged onto the wrong kind of motor or something.

edit: for a smoke test, is it enough to block off the PCV and air balance tube and see if the smoke is getting into the manifold? If the smoke is getting past the rings or valve guides or whatever what could I do to narrow it down other than maybe pulling a few spark plugs?
 

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OK, the design is different between the 5.7 and 6.1? I think I will pull that manifold and look anyway, I am no sure this engine is original to the car so maybe the manifold has been bodged onto the wrong kind of motor or something.

edit: for a smoke test, is it enough to block off the PCV and air balance tube and see if the smoke is getting into the manifold? If the smoke is getting past the rings or valve guides or whatever what could I do to narrow it down other than maybe pulling a few spark plugs?
What year is the vehicle? Can you see any evidence that the engine has been tampered with or possibly removed? What does the odometer say for mileage? Does it look like it has been properly cared for or does it appear to be neglected? Have you checked for Diagnostic Trouble Codes?

The design between the 5.7 and 6.1 are basically the same, but the intake manifolds and gaskets are considerably different....5.7 is plastic with o-ring type gaskets and the 6.1 is an aluminum manifold with real crappy aluminum gaskets that have lousy rubber seals surrounding the ports. See the pix below of when I took my 6.1 apart. Most of the rubber seals had been ingested through the engine, and the others were all distorted and half gone. The engine did have about 165K on it and probably never been touched.

Unless someone has grossly neglected the engine over a long period of time, I doubt you'll have a problem with the bottom end, the pistons/rings. If it has over about 100K you'll probably have some bad valve guides. If it's an 05-06 or early 07, dropped valve seats can be a problem, especially if the engine has been overheated.

The things you can do to determine the basic condition of the engine and find where the leak is coming from is to do a compression check first then, perhaps a cylinder leak down test if the compression is not real good and, finally, a smoke test if you're unable to find anything. You could also start with a smoke test if you wanted, but I wouldn't. Usually, a compression check and leak down test will tell you everything you need to know though.

FYI, 5.7's have an EGR Valve on the front passenger side head, as said, a black plastic intake with the PC Valve on top rear of the passenger side. 6.1's have the aluminum intake, no EGR Valve and the PC Valve is located on the front passenger side.

Smoke testing an engine is kind of redundant, a PITA and time consuming because you'll need to isolate each cylinder and check them one at a time with both valves "supposedly" closed....top dead center on the compression stroke. This is better done with the cylinder leak down test. IMO, the smoke test is best for checking for intake/exhaust leaks and such.

On a 5.7, the PC System and, especially the PC Valve, are one of the biggest weak spots on a 5.7. It's difficult to determine if the valve is good or bad, because the spring in it is so weak to begin with. After time it gets weaker and the old method of "shaking the valve" is not an accurate way of checking them. I've never seen one that didn't shake, no matter its condition. Just change it every 15-30K and be done with it. You'll be able to see how bad the PC System is by looking at the back side of the throttle body butterfly. It'll be all caked up with crud and, worst case, there will be oil puddling in the intake manifold plenum.

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Discussion Starter · #7 ·
What year is the vehicle? Can you see any evidence that the engine has been tampered with or possibly removed? What does the odometer say for mileage? Does it look like it has been properly cared for or does it appear to be neglected? Have you checked for Diagnostic Trouble Codes?


On a 5.7, the PC System and, especially the PC Valve, are one of the biggest weak spots on a 5.7. It's difficult to determine if the valve is good or bad, because the spring in it is so weak to begin with. After time it gets weaker and the old method of "shaking the valve" is not an accurate way of checking them. I've never seen one that didn't shake, no matter its condition. Just change it every 15-30K and be done with it. You'll be able to see how bad the PC System is by looking at the back side of the throttle body butterfly. It'll be all caked up with crud and, worst case, there will be oil puddling in the intake manifold plenum.
The car has been neglected. I have no idea if the engine has been changed but it looks pretty suspicious i.e. obvious home fixes on the wiring harness, EGR removed, wiring not clipped in at various places. Trouble codes on #6 cylinder and oxy sensors (according to a tech who refused to fix it ha ha). I guess the first real step is to remove the throttle body and look inside the intake manifold before pulling it off completely, but it doesn't seem like a huge job.

What would concern me is if they dumped a later motor into this 2005 and incorrectly re-used the intake manifold or something like that. It idles fine and sounds strong, no rattles or anything just volumes of smoke and hesitation when you hit the throttle.
 

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Discussion Starter · #8 ·
The car has been neglected. ...
I got to start pulling the intake system out today. There is oil pooled in the intake tube before the throttle body, the throttle body itself is pretty dirty. More troubling is the giant pool of oil in the intake manifold itself. I guess I have no choice but to pull that, drain it out and clean it up and then start trouble shooting again.

I noticed today that when you shut the car off, quite a visible amount of vapour comes out of the oil tubes i.e. out of the filler. While it's running it seems to be sucking quite hard at the filler tube which is something I have never seen before. The manifold bolts do seem not terribly tight so I will have a look at the gaskets carefully when I reassemble it.
 

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Discussion Starter · #9 ·
I got to start pulling the intake system out today. There is oil pooled in the intake tube before the throttle body, the throttle body itself is pretty dirty. More troubling is the giant pool of oil in the intake manifold itself. I guess I have no choice but to pull that, drain it out and clean it up and then start trouble shooting again.

I noticed today that when you shut the car off, quite a visible amount of vapour comes out of the oil tubes i.e. out of the filler. While it's running it seems to be sucking quite hard at the filler tube which is something I have never seen before. The manifold bolts do seem not terribly tight so I will have a look at the gaskets carefully when I reassemble it.
 

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I think I'd first take a look at the PC Valve and replace it. Have to go now but will be back later.
 
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Discussion Starter · #12 ·
I think I'd first take a look at the PC Valve and replace it. Have to go now but will be back later.
It just seems like waaaaay too much oil for a PC Valve. I'm thinking valve guides/valve stem steals.

How hard is it to pull the heads with the engine in there? My next move seems like it should be compression test all the cylinders, and if they come up good (which is likely given it runs strong even with the oil getting sucked through it) then pop the heads and do a valve job. Thanks for the pointers so far!
 

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magnuman said: "I think I'd first take a look at the PC Valve and replace it. "

+1
Results of a compression test are good to know, no matter what. However, before pulling heads or any more dismantling.... a PCV valve is cheap and easy... and should be replace as part of routine maintenance anyway.
 

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Discussion Starter · #14 ·
I'm going half way. New pcv ordered and will take a punt and just change the valve seals since its fairly simple and i have the tools handy.

I figure if the guides are bad the seals will still work ok for a few months until i get a chance to pull the heads.

Engine actually looks ok inside, no obvious signs of overheating or damage so far and it runs very quietly, no valve chatter or tick so I think the guides are probably ok.
 

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It just seems like waaaaay too much oil for a PC Valve. I'm thinking valve guides/valve stem steals.

How hard is it to pull the heads with the engine in there? My next move seems like it should be compression test all the cylinders, and if they come up good (which is likely given it runs strong even with the oil getting sucked through it) then pop the heads and do a valve job. Thanks for the pointers so far!
Don't get too hasty about pulling the heads. Troubleshoot the easy, inexpensive stuff first. Do the compression and, if necessary, the leak down test before you start tearing into things. IMO, this should be the next order of business.

As far as the PC System goes, the Hemi's have about the worst system possible and it's not uncommon to have puddling in the intake plenum. If the valve is stuck open, that amount of oil would not be out of the ordinary. Many of us with the Hemi's put catch cans on them to catch most of the oil that gets past the valve. This catch can goes in series between the PC Valve and the intake manifold. The catch cans seem to work pretty well and keeps most of the oil out of the intake....as long as it's serviced properly. Winter months generate more oil/condensation than summer months, unless you live in a very humid/damp area.

Valve guides may be some of the problem, but not to the extent that would cause that much oil contamination. I would also be surprised if the valve seals are bad too, again, unless it has been grossly neglected, been overheated or has a zillion miles on it. The valve seals on my 6.1 with 165K on it were still good. When I changed valve springs on both of my 5.7's (both under 100K), all of those seals were good too.

If the engine is a 2005, pulling the heads at some point may be a good idea, if for no other reason, to replace the valve seats. IMO, this should not be done until you've fixed most of the other problems you find and have found, and insured that the vehicle is fairly sound and worth throwing more $$$$ at it. Pulling the heads and doing seats, and a valve job could end up costing you around $2000, including the top end gasket kit. R and R'ing the heads is not overly difficult or time consuming, but you'll need to have a pretty good assortment of tools, including a good torque wrench.


magnuman said: "I think I'd first take a look at the PC Valve and replace it. "

+1
Results of a compression test are good to know, no matter what. However, before pulling heads or any more dismantling.... a PCV valve is cheap and easy... and should be replace as part of routine maintenance anyway.
All of this is true. I do compression checks on mine about once every other spark plug change....while I am changing them. That is about a 60K interval. As far as compression goes, know that altitude and weather conditions both have effects on your compression pressures and, if they're a little low, may need to be taken into consideration. I live at nearly 3000 ft. elevation (most of my driving is at 2500-4500 ft.) and my "normal" compression pressures are lower than that of someone's who lives at or near sea level. I am so use to driving at altitude that, when I drive one of the Hemi's down near sea level, it's like someone put a new high performance engine in it.
 
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I'm going half way. New pcv ordered and will take a punt and just change the valve seals since its fairly simple and i have the tools handy.

I figure if the guides are bad the seals will still work ok for a few months until i get a chance to pull the heads.

Engine actually looks ok inside, no obvious signs of overheating or damage so far and it runs very quietly, no valve chatter or tick so I think the guides are probably ok.
The valve train "valley" does look pretty clean, so it may not be in as bad shape as you think. Good to start with the PC valve.

You won't be able to EASILY change the valve seals UNLESS you have compressed air and a special "heads on Hemi valve spring compression tool".....about $150-200. Otherwise the heads have to come off to do the job.
 

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Discussion Starter · #17 · (Edited)
Don't get too hasty about pulling the heads. Troubleshoot the easy, inexpensive stuff first. Do the compression and, if necessary, the leak down test before you start tearing into things. IMO, this should be the next order of business.
...

Valve guides may be some of the problem, but not to the extent that would cause that much oil contamination. I would also be surprised if the valve seals are bad too, again, unless it has been grossly neglected, been overheated or has a zillion miles on it. The valve seals on my 6.1 with 165K on it were still good. When I changed valve springs on both of my 5.7's (both under 100K), all of those seals were good too.
...
I guess what I'm chasing here is the presence of negative pressure in the crankcase, even when the PCV system is blocked off. It's particularly pronounced at idle (I haven't driven the car more than 150 metres) and the oil sitting behind the valves just seems very high even with the intake cleaned out. Heads are staying on for the moment, should be able to inspect at least one of the intake valve seals today

edit: This tool is the correct one for valve spring compression with the cylinder heads in place?

I have a generic valve spring compressor and an air compressor (although I think I'll need a fitting that reaches down as far as the spark plug). Was just thinking of carefully locking the intake valve in place with a bit of rubber and a small set of vice grips since I am leaving the exhaust ones alone for now.
 

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Yep, that looks like a good one too. When I did mine about 10-11 years ago, the tools they had weren't that good. Be sure to have a some spare valve spring retainer "keepers" just in case you drop/lose one or two. Also, while doing the job, plug all the oil drain back holes and bolt holes that are big enough for one of them to fall into.
 
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Discussion Starter · #19 · (Edited)
Also, while doing the job, plug all the oil drain back holes and bolt holes that are big enough for one of them to fall into.
OK ordered and on it's way - a lot of this stuff is more expensive in dollarydoos unfortunately. Good tip on plugging the holes. For this exercise I'm going to skip the exhaust ones just to shorten the job and test my hypothesis.

Any preferences on valve stem seals? The Fel-Pro ones seem to be readily available here.
edit: very confused now about which ones to order. There seem to be two styles (a "hat" style and a more traditional looking one). Guessing I need to find the engine number to work out what to try and buy or will these work?
 

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No preference really. The ones in the picture look more "high end" than the ones on both of mine. Mine look the same but don't have the little spring tensioner on the top where it seals the valve stem. The factory ones are like the ones I have on mine. FWIW, when I pulled my 6.1 heads with 165K on it, the valve seals were all still good, pliable and no oil getting past them.
 
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