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My 351c is spraying oil out the dipstick tube. It only happens at higher rpm's, starting at around 4k or so. If I have more oil in, it sprays sooner, with less oil, it doesnt really spray at all. The problem is with less oil, I get pressure drops on corners, so I don't let it get too low. Problem started recently, but until recently I havent gone much over 4k, so I didnt noticea problem. It kinda drips out the dipstick tube at 4k, at 5k it will move the dipstick out, and spray a bit. What would be causing this? There isn't a lot of blowby coming out the valve covers, compression is good, and it happens wether i have the pcv hooked up or not. I don't know what could be causing this, anyone have some suggestions on what to do/check or do I need to replace something?
 

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Assuming your "dipstick & tube" are all normal it just sounds to me like crank case pressure finding a way to escape ...

Dipstick tube is a straight unfettered passage.

At higher RPM the pressure will be higher than at low RPM ...

Depending on how tight your rings are able to seal the cylinder ... the cylinder pressure that slips past the rings and into the crank case is going to be more or less than "normal" whatever "normal" is


Then keep in mind, when the engine is running, there is a Typhoon going on inside "oil is flying everywhere" ... as pressure escapes ... Oil will be carried with it.

By all means make sure all "breathers" on the engine are working as in tended ... excess pressure can cause main seal leaks, etc. Other than that ... doesn't sound like a huge problem.

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Larry Madsen
Las Vegas Nevada



<font size=-1>[ This Message was edited by: monstermach on 1/24/02 6:20am ]</font>

<font size=-1>[ This Message was edited by: monstermach on 1/24/02 6:24am ]</font>
 

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What are you running for breathers on the valve covers? You might need to put some K&N breathers on there to help evacuate the crankcase at higher rpm. I know blower cars have that prob with poor ring seal, but don't know if that can happen normally aspirated.
 

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Discussion Starter #4
I have a breather on the passenger side, hooked to the air cleaner, and a pcv valve hooked up on the driver side, to the base of the carb. I am pretty sure I have a decent ring seal, its a fairly new engine, only 30 or 40k on it, and compression is even and good. If its just normal, what can I do about it? Twice now I have had to pull over, because of the oil and smoke from it blowing onto the exhaust.
 

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Maybe try a new PCV just to make sure it's functioning correctly ... If the other breather has some sort of "screen element" check to be sure it's not been around so long it's plugged up with old "oil and crud" from use.

If you are "Blowing" the dipstick up out of the tube ... you clearly have some crank case pressure going on
 

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i know some guys that yank the breather tube and pcv and go with two breathers. Don't know if this would correct a problem with a clogged breather you have, or just mask some other problem. That stock stuff may not have been designed to flow a lot of pressure from 5,000 rpm runs. I guess an easy check would be to just run down the road with nothing plugged into either side just to see what happens.
 

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I run 2 breathers. It seems to be working ok. I think the biggest thing though is your valve covers. Do they have baffles? When I put the new tall Moroso Valve covers on, I needed to go to 2 breathers. The Stock covers, I just had one, and the pcv. I never had any problems then. Now I get a little bit. Try the 2 breathers. They are pretty inexpensive. That can be your quick fix. If nothing else, and you are running valve covers without baffles, maybe that is your problem? I am not too sure on the issue, just saying somethings that I have heard, and been told to do.

Jeff Given
 

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As you probably know, Clevelands are notorious for having thin cylinder walls. Because of this they tend to have more cylinder wall flex under heavy combustion pressures and piston side loading, which in turn leads to more blowby. Your problem might simply be too much ignition timing at high rpm. Most single plane Clevelands need a timing curve that all in at 3000 RPM but the total doesn't usually need to be more than about 35 - 37 degrees because the combustion chamber is quite compact and has a good shape. Another solution might simply be to run an air breather in each valve cover. At wide open throttle the PCV valve has no vacuum and isn't much more than a plug for the hole in the valve cover. It's only effective under high vacuum conditions. K&N makes neat looking high flow breathers that work great and flow lots. There are also some Chrysler style push in breathers available that fit into big one inch diameter grommets. Just make sure that both valve covers are baffled which helps seperate the oil from the expelled crankcase gasses and will help keep the top of the valve covers oil free.
 

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Hey cool, I've been having the same problem on my 302 cougar. I'm running really cheap filters in the valve covers so I suspect k&n's would help. Sucks buying new or cleaning air filters all the time too hu?
 

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Most of the high rpm cleveland racers will tell you that you had a good run if your dipstick is lifted up. Even after a fresh rebuild with a good leak down test it still happens when over 5000rpm.
 
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