If the dipstick pops out under full throttle its not oil pressure, its crankcase pressure
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what if someone didn't have their pcv hooked up or the line from the vc to tb and there was no real "vent" or circulation for the crankcase? He should idle the car and take the dipstick out and maybe check if anything is blowing out?
Im curious if theres any other causes for this as well. I have just a click over 100k on the motor and theres no visual smoke being burnt coming out the tailpipes, but every once in awhile i check the dipstick and its not in all the way. I wondered if it was the pcv... but then again, my vc gasket on the left bank is leaking.... power seems good, ill do a compression test i suppose
90 lx coupe - too big of heads and too big a cam, 4.10s
10.69 @ 127.8 NA stock bottom end
if he has the pcv hooked up (assuming its not plugged up) and also the line going from the vc to tb then there is no way the bottom end will become pressurized. If it became pressurized then I don't know if the dipstick is necessary the first place for things to shoot out....we're talking about more than just a few psi to cause this. Don't know about you guys but it'd take a good amount of pressure to blow my stock dipstick out. Yes, I've heard of boosted cars shooting them out but come on......NA?? How about his rear main? How about his vc gaskets? Combustion happens and forces air past his "loose" rings and then just builds up and up and???? You don't think it would bleed back past the rings on the next intake stroke?
Excessive crankcase pressure is what pushes out dipsticks. It finds the weakest link - the weakest link ain't the same thing on every engine.
Exactly. It would help to know your oil pressure and more about your motor. Strokers can easily push the dipstick up and out of the tube a good 1-8 inches or more. We need more info to help you.
398, Hydraulic roller 248/252 @ 50 total being 597/608, Victor Jr intake, AFR 225 heads, Pro Systems Carb, T56, 4.10's, Detriot Locker, 31 spline strange axles, 9'' housing ends, 98 GT front brakes, 96 cobra rear disc, Pa Racing K member, Strange 10 way struts, Coilovers, back Koni's
There is a reason your crank case pressure is so high that it is blowing the dipstick out of the tube. The problem is most likely with your pcv valve. If the pcv valve does not open properly pressure will build in the crank case, thus pushing your dipstick out. If your engine is not heavily modified you should be able to get by with a pcv valve or just using a breather.
69 Mach 1 - 357w: ported Canfield heads, FTI billet solid roller cam, Vic Jr., 850 Mighty Demon
Full manual AODE transmission w/ 9.5" Art Carr converter; 4.11 detroit locker
so if I somehow put a pressure sensor on the filler cap and datalogged it during high load and wot there would actually be pressure? Constant pressure or would it be pulsing or???? I know there are a lot of variables but I wonder how much pressure..
Tell us how much blowby there is and how effective or ineffective your crankcase ventilation system is and we'll tell you have much crankcase pressure there is. SOME cylinder pressure bleeds by/blows by the rings each time each piston goes up and fires. As rpm increases the blow-by which technically is 'pulsed' into the crankcase cylinder by cylinder appears, as a practical matter, as 'pressure' in the crankcase. The crankcase ventilation system is designed to deal with the crankcase pressure that blow-by creates. As the engine ages, or as mods are done to increase cylinder pressure (peak cylinder pressure occurs at peak torque) blow-by increases. As blow-by increases crankcase pressure has the potential to increase IF the crankcase ventilation system isn't capable of dealing with the excess pressure. Clogged or partially clogged PCV valves, oil traps/screens are a contributing factor. Engine age contributes. Modifications that increase peak torque contribute. Boost and/or significant displacement increases both can contribute significantly to increased crankcase pressure --- because more cylinder pressure (boost) and more displacement can contribute to increased blow-by.
If the crankcase pressure being generated overwhelms the ventilation system then the pressure finds the weakpoint. Sometimes it's an already leaking valve cover gasket. Sometimes it's a front main or rear main seal. Sometimes is pushes the PCV valve up out of the grommet. Sometimes it's the dipstick. Sometimes it does a little of each. Or, like a Chinese menu, pick 2. Or pick 3.