Author Topic: oil fouled plugs (Read 8165 times)

femtnmax · « **Reply #15 on:** February 26, 2011 - 01:38:55 PM »

Quote from: willard on February 26, 2011 - 08:47:10 AM

Is it possible oil rings fail while compression rings seal ok?

The top ring handles the compression, the second ring helps the oil rings handle the oil consumption. The second ring is cast iron reguardless of what top ring you have (moly or cast iron). So if the cylinder bores are not exactly perfectly round it will TAKE TIME and running the engine to seat and seal the second ring.

Quote from: willard on February 26, 2011 - 08:47:10 AM

I also repost my question: if pistons' tops are washed with oil why are they shiny aluminium and in the same time the oil leaves a burnt black film on the cyl walls above rings and on the plugs and combustion chamber?

From my experience, excess oil washes the piston top clean, the more oil the further toward the center of the piston that gets washed clean...
Why the deposit at the top of the cylinder wall....Well, the cylinder wall is going to run cooler than the piston top, so maybe this promotes oil deposit build up.

And YES, run the engine hard for several HUNDRED miles, then do a LEAK DOWN test.

willard · « **Reply #16 on:** March 03, 2011 - 02:33:32 PM »

Checked the PCV hose and it's clear - no oil there.
Also the heads look ok - they didnt leak oil before the rebuild.
So rings are the culprit here - maybe they were installed wrong, maybe they are too loose, maybe the manufacturer put wrong part into wrong box...

What type of rings and cylinder bore finish do you recommend? I'm leaning towards swapping the rings asap but dont want to make another error. I heard iron rings are more "forgiving" but take time to seal. If I should stick to moly rings what is the proper finish? 400 grit and 60 deg honed?

72cudamaan · « **Reply #17 on:** March 03, 2011 - 05:07:58 PM »

Moly rings require a 45 degree crosshatch, preferably with a plateau finish.
Cast iron rings will seat with a regular dingleberry hone if you want to do it yourself. But cast rings won't last nearly as long.
I agree with Phil that the top ring handles compression. But that is on the upstroke. The second ring is usually a reverse torsion ring that seals the cylinder on the down stroke (preventing blowby) The only time I ever saw the oil control rings fail is when they get sludged up or with carbon, keeping them collapsed ( popular problem on the older Honda's)

My opinion after looking at the pic's is ,you should have the cylinders checked for roundness and rehoned, reassemble and run. And do not use synthetic oil for at least 1000 miles.

the_engineers · « **Reply #18 on:** March 03, 2011 - 10:08:20 PM »

Cast iron may not last as long as Moly, but they'll still go 50,000 miles or more. Odds are he'll be back into the motor by then for a stroker kit or more upgrades.

mopar12372 · « **Reply #19 on:** March 04, 2011 - 12:55:40 AM »

if the valley pan is or was sealed good then i would look into the heads . the stock umbrella style valve seals are a pain in the ass sometimes when it comes to sealing oil . when you get a chance i would check valve guide and install the good seals . a good leak down test would have told you a great story . hope you find the problem with out takeing the engine apart . good luck.

willard · « **Reply #20 on:** March 12, 2011 - 05:23:23 AM »

I thik we piponted the problem. Wet sompression thest on the other head madealmost no difference: 160 vs 170 psi on #2 and 150 - 155 psi on #4. I took the head to the shop and the guides are loose plus the stock umbella type seals on exhaust valves were lifted so the oil flew down the exhaust valves and then poured into the cylinders.
I'm gonna get the guides reworked or maybe installed the bronze inserts.

What is the stock OD of the guide? I guess it's 0.50" like for the standard MP seals? - will the comp vition seals fit without machining then (summit says 0.50 OD, no machining needed:

Brand      COMP Cams
Manufacturer's Part Number      514-16
Summit Racing Part Number      CCA-514-16
Valve Stem Diameter      0.372 in.
Valve Stem Seal Type      Positive stop
Valve Stem Seal Material      Viton�
Machine Work Required      No
Valve Guide Diameter (in)      0.500 in.

mopar12372 · « **Reply #21 on:** March 12, 2011 - 12:16:25 PM »

ya valves are not sealing , while your at it i would do a valve job . 20 psi between cylinders is alot , believe its supposed to be 5 psi at the most .
is the engine out of the car? if it is check rod side clearance loose is good for raceing(burn pil too), tight is good for street . what you want is the side clearances to be simular . crank end play is important make sure its within spec. very important /good luck

willard · « **Reply #22 on:** March 12, 2011 - 03:37:30 PM »

Engine's in the car and I dont want to put it out as it is freshly restored/painted/detailed.
I'll take the heads to a reputable machine shop to get the guides done and all valves checked. It seems Normcar workshop failed this task - they should have noticed that during rebuild.

Will I have to machine the guides to get these comp positive seals? Summit says 'no' but I doubt... ?

Moparal · « **Reply #23 on:** March 12, 2011 - 04:09:48 PM »

Willard, When you go and get valve guides, the machine shop will fit the vinton seals for you. All auto shops do that. They have to cut the guides down anyways for the lift and coil bind procedure. When you run a srong valve spring, with more than one spring, it will need sizing and shortening. So your seal install should not be extra, it never is as far as I know.

Aussie Challenger · « **Reply #24 on:** March 12, 2011 - 09:15:08 PM »

When they fit the new guides they will have to re-cut the valve seats and any reputable machine shop will re-face the valves as well so you will have a fully overhauled head.

beekppr · « **Reply #25 on:** March 12, 2011 - 09:37:51 PM »

I had this problem with my new engine. The guy who did my heads used lousy seals and they would move up and allow oil to get under them. The guy who redid my heads went with a different type of seal (sorry can't remember which) and he assured me the seals would not move out of position. He was right and my oil on the plug problem disappeared.

Also, this same guy told me his old timer secret about getting rings to seat well. I ran my engine 1000 miles and the rings never seated. He claimed the cylinder walls should be dry of oil to allow good sealing. I used a good degreaser to wipe the cylinders nice and clean. When I put the heads back on and tried it out, my problem disappeared and I got the rings to seat fairly quickly. 200 miles later, my cylinder pressure is higher and even all around.

This guy is an old racer who is also an experienced engine builder. I learn great stuff from him all the time and he always seems to know the right solutions to my problems.

Good luck with your engine.

willard · « **Reply #26 on:** March 14, 2011 - 10:51:11 AM »

Bad news...

Took the head to 2 machine shops. Both examined the guides and confirmed ther's slight play in exhaust, intake's ok but... they say it is impossible to have such amount of oil in cylinders passing by exhaust valves. A drop or two but not that much.
Also my d/s head cant be machined for positive seals as one guide was cracked and a sleeve already installed. So I'm gonna put mopar umbrella (not hat) type seals on the exhausts and try to seat the rings...
If I was sure the heads cause the problem I'll swap em for 440source but spending a grand when I'm not sure that's too much.

Thank you all for ideas and help. Will let you know after next 200-300 miles.

72cudamaan · « **Reply #27 on:** March 14, 2011 - 12:32:51 PM »

The shop can cut out that cracked guide and install a new one. Then you can still use the positive seals.

beekppr · « **Reply #28 on:** March 14, 2011 - 12:51:46 PM »

I'm not so sure about your shop claiming very little oil comes through the guides. I'd find a way to use a seal that stays put even if you have to cut the guides out and replace them. Since your rings are not sealing though, it's hard to know how big the valve seal problem is.

72cudamaan · « **Reply #29 on:** March 14, 2011 - 05:57:13 PM »

Quote from: beekppr on March 14, 2011 - 12:51:46 PM

I'm not so sure about your shop claiming very little oil comes through the guides. I'd find a way to use a seal that stays put even if you have to cut the guides out and replace them. Since your rings are not sealing though, it's hard to know how big the valve seal problem is.

I do agree with this. When the exhaust valve is opening and the piston is going down, there is suction there which will draw oil down a loose guide.
So what's the verdict. Are you gonna have these heads machined?

Author Topic: oil fouled plugs (Read 8165 times)

femtnmax

Re: oil fouled plugs

willard

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72cudamaan

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the_engineers

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mopar12372

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willard

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mopar12372

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willard

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Moparal

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Aussie Challenger

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beekppr

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willard

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72cudamaan

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beekppr

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72cudamaan

Re: oil fouled plugs