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Dipstick raises
I've seen this addressed somewhere on the forum, but couldn't find it so wanted to ask the question.
My dipstick raises up on its own - typically only 1/4", but that is just enough for the cap to clear the tube. I know this has to do with pressure in the engine but not sure if I should be concerned or just leave it alone? My set-up: 427 side oiler PCV valve on one valve cover; breather on other Single Holley 750 carb |
It doesn't happen to have too much oil in it, does it?
Also, is the PCV valve, vacuum lines or breather clogged? Larry |
Hi Larry,
After installing the engine, I filled it with 8 quarts and calibrated the dipstick accordingly so the amount of oil is correct. I'll check the breather and PCV valve, but it has done this since it was new, so this isn't something that just started happening. I do have a second breather cap I can swap to see if there is any difference, but I wouldn't expect different behavior. I'm just not sure if this could be a symptom of something harmful or if this in itself is something to be concerned with. Kevin |
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I'd say you do have a crankcase pressure problem, higher than acceptable blowby under load.
Your breather filter can't flow well enough and the dipstick gets pushed out. |
Kevins,
Do you have any oil mist on your valve cover around the breather cap or PCV Valve? And is there any way that you can run a hose from the breather cap to your air cleaner to let it pull part of the pressure into it? I have had several big blocks and none of them have ever pushed the dipstick out of the tube. And if you made sure that the dipstick wasn't hitting the bottom of the pan, then it almost has to be a pressure situation unless your dipstick is so loose that the vibration of the engine can make it back out some. Ron |
Ron,
Initially, I had breather caps on both valve covers and the breather cap on the driver's side spit oil on the valve cover. Curiously, the other side did not. I then installed a PCV valve and the breather stopped spitting oil. There is no hose fitting on the breather cap, but I could look into a different setup if that might solve the problem. Again, this isn't a big deal unless it is harmful in some way, and that's what I'm not sure of. Thanks, Kevin |
The pcv system is a system on its own. The breather is the intake filter...pcv is the suction pump . The pcv must be large enough to allow sufficient airflow through the engine , without allowing the oil to bypass. If it persists you probably need rings....
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Kevin - you could run a leak down test on the motor and see if it is loosing cylinder pressure past the rings into the crankcase. It probably wouldn't be a fun experience getting the fitting into some of the plug locations.
I wonder if it would be useful to hook a fuel pressure gage up to the PVC hose and block off the other breather and see what type of pressure you have in the crankcase: confused: I guess an option is to install a vacuum pump system. |
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Kevin, if you are not experiencing either excessive oil consumption (blow by past tired piston rings or valve seals) or strong fuel odors in the crankcase oil, I doubt you have a rings issue and I'd just perform a simple fix and drive it. |
You mentioned that with two breather caps only one spat oil out, are you sure that both rocker covers have similar baffles built into them ( one might have none). I would try a spring or duct tape on the dip stick to prevent it raising up and check to see if the oil leak/stain increases around the breather cap or pcv . If the dip strick contacts a baffle or the oil pickup that might cause it to raise with vibration etc. At least the FE has the dipstick in a suitable place with reference to crank rotation.
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Inspecting the spark plugs might tell you if it's burning oil. A leak down test is a good idea if the simple tests don't lead to anything.
Larry |
To say the least ...some of these answers really make me wonder....
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From all the suggestions given, it is caused by either excess crankcase pressure or tension on the dipstick. You could get a second dipstick, cut it off shorter than the original, and see if it pushes out. If so, it is crankcase pressure. If not, it is dipstick tension.
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Thanks for the responses. I'm traveling but will start investigating further when I get home. I do need to get a better handle on oil consumption, as it does use some oil. I haven't tracked it closely since I've had oil on hand to add when needed. My best guess is about a quart in 3000 miles, maybe slightly more. I also have a small oil leak but not enough to add up to anything significant. I'll start documenting exactly how much is used and go from there.
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is it a loose dipstick that vibrates out, pressure not a problem?
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Maybe try running 7 quarts to see what happens? |
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I don't think you have an oil consumption problem. Ted |
Well, as I said, I haven't tracked the consumption - that's just a guess. I've had a couple cases of oil on a shelf and add a little when I see its lower on the dipstick. I need to track the mileage and how much I add to verify. Thanks again.
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