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482 fe intake issue
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Hello.
I own an all aluminium 482 FE (pond) built by Brent Lykins in 2012 with 13500 miles. Since weeks I noticed excessive oil consumption and smokes at start-up. I've checked all cylinders compression and find 246 psi except on N°2 at 188 psi. I removed all spark plugs and found oil on N°2 spark plug. After disassembling engine I didn't find piston rings broken / no damages on cylinder walls. ==> I'm going to measure all cylinder bores and pistons diameter. When I removed the intake manifold and cylinder heads I found all intake valves plenty of burned oil and in intake tunnels. Some valve seals are worn and I discovered one worn valve guide. I don't have a PCV valve / just 2 breathers on valve covers. Questions are: - if ring gaps of first piston ring (top) and second piston ring are very close (5° to 10° and not 180° as they should be can it be the source of the low compression in N°2 cylinder ? - how can I get oil in intake tunnels and intake valves in that excess ? not sure it could only be due to a worn valve guide and 3 or 4 worn valve seals.... Here are pictures to illustrate my problem. Thanks for your help. OliveR |
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I’ll let other comment on the oil issue. On the rings, the rings rotate constantly and randomly in operation due to the cylinder honing and maybe some other factors. So they will likely be in a different orientation every time you shut the motor down unless your cylinder walls are worn glass smooth and even then they may move around some.
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You have a lower compression reading on one cylinder. Did you perform a wet test on that cylinder? How about a leakdown test?
I see insufficient diagnosis before you pulled the engine down, possibly unnecessarily. I would say you have some valve seal issues, and/or worn guides. Valve guide lubrication is a "catch 22", no lubrication gives worn guides, some lubrication gives good life, too much contributes to high oil consumption. |
I second showing Brent the pictures. He will know what to do.
John |
I saw most of the pictures a few weeks ago. I asked him to check the intake gasket to see if it had been compromised at all.
However, you normally don't get oil way up into the intake plenum like that unless it's a bad PCV or something similar. The only other way oil ends up going backwards like that is if a loss of ring seal has occurred. Then you get oil on the cylinders combined with reversion from the cam and it pushes the oil up into the intake tract. Valve seal wear or valve guide wear could have contributed to it, but I would look to see how much crosshatch is left on the cylinders. If a lot of the cylinder looks shiny without crosshatch, I would look toward an overly rich carburetor condition, which would wash the oil off the cylinders and then you'd lose ring seal. Also, you can't bet on it 100% of the time, but if you pull all the pistons out and a lot of the top rings are very near each other or the gaps lined up, it's often a sign of detonation. Could be a multiple of issues in a perfect storm....oil consumption due to bad valve seals, leading to some stuck rings, then pushing oil back up into the intake tract, etc. |
Well, it's not the end of the world, just time for a rebuild.:cool:
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Thank you for your replies.
To reply to Brent, my engine is exactly like you sold it to me. I let the 2 breathers you installed on the valve covers. I have no PCV. Intake gaskets are in perfect condition, no cracks or anything else. Moreover I have no breather on intake manifold. Could it be a problem ? too much pressure in engine ? Crosshatch on each cylinder is OK, absolutly no shiny cylinder walls. As I wrote before I've noticed worn valve seals and worn valve guides. WHY with an engine with only 13000 miles ? Thanks, OliveR |
I didn't say you had a PCV, I was speaking about the issues that PCV valves cause.
I don't know if you have worn valve seals or guides, so I'm basically just trying to throw things out there to see if they stick, since you're about 5000 miles from me. Hard to diagnose something without really putting eyeballs on it. Lots of things can happen in almost 10 years, so I'm not sure what the reason is. |
I have worn valve seals and worn guides.
Would it be an improvement to add a breather on the back of the intake manifold ? Thanks. |
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Did you plumb one or both of the valve cover breathers to the bottom of the carb? It looks pretty well oilly there-------do you have the baffels in the valve covers?? The drain back shields??
Many times I have found severe oil leakage like yours resulting from intake manifolds that have been ported-on the FE engines this often results with leakage around the pushrod hole----- |
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Ed |
Your compression test pressures are wierd?/ what kind of numbers are those???Not PSI----
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180-200 would be good for a healthy street engine, with a tiny cam. Gary |
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No my 2 valve covers have just standard breathers not connected to bottom of the carb. I haven't got baffles in the valve covers. |
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Brent didn't install a tiny camshaft. |
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