1983 V45 crankcase pressure?

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mdegood · #1 Unread post by **mdegood** » Tue Jun 27, 2006 11:35 am

Hey guys, need a little help. I have a 1983 Honda V45. My question is that when you check the oil (using dipstick) while running I get a lot of pressure (blow by?) out of dipstick hole, also out of crankcase drain tube. Is this normal?

flynrider · Tue Jun 27, 2006 12:16 pm

If you've got excessive oil coming out of the dipstick and the breather, it could be the result of blow-by. That's combustion gasses getting past the rings and pressurizing the crankcase. Get out the shop manual and a compression tester to see if you've got leakage past the rings.

Some bikes are equipped with a PCV valve. If that gets crudded up, it can also cause your crankcase pressure to rise.

#3 Unread post by **9000white** » Tue Jun 27, 2006 1:19 pm

you cant check the dam oil with the engine running.
that is the reason there is a cap on it where you put the oil so it dont sling all of ot out.

mdegood · #4 Unread post by **mdegood** » Tue Jun 27, 2006 1:25 pm

Will do a compression check tomarrow. As far as checking oil while running. The owners manual tells you to check while running!

fordthunderz · Tue Jun 27, 2006 1:43 pm

The book says start the bike and run it 2 to 3 minutes. Shut it OFF and place on center stand and check the oil with a dipstick.

#6 Unread post by **9000white** » Tue Jun 27, 2006 2:20 pm

ok. check it while it is running.

TechTMW · #7 Unread post by **TechTMW** » Tue Jun 27, 2006 8:06 pm

Please don't attempt to do anything else to your motorcycle.

Air will naturally pressurize a crankcase because when the pistons move down, they push air down as well. There is usually a vent on the crankcase to prevent this from affecting your case seals (Like the vent/hose from the case to the airbox.)

Stratus311 · Wed Jun 28, 2006 1:03 am

You really shouldn't check the oil while running. If you check it while running, the level will change when you shut off the bike to add oil. Alot of your oil is in the top half of the engine when it's running. And yes it is common even on an engine in perfect shape to have some pressure in the crankcase. Hence the need for a PCV system.

mdegood · #9 Unread post by **mdegood** » Wed Jun 28, 2006 3:23 am

I apologize for the oil dipstick thing. The book is really vague on checking it. Says run 2-3 minutes then check oil. Dah, for oil warm up (sorry 9000white). I know it is common sense to check oil with out it running. But back to the point at hand, I know there will be some crankcase pressure, all engines have that. As far as a pvc valve, well I am still looking into that. I was trying to find out at what point do you say to much pressure. I will do compression check today. And go from there. The bike only has 14k on it and has been sitting for @ a year. I change the oil yesterday and think there might have been a little to much gas mix with the oil. Am thinking the main cause would be probably a sticking float needle. Bike runs ok, little sluggish on the ramp up and down. Have noticed that card 1&2 (from left to right) when covered by hand increase rpm (as choke would) and 3&4 tend to try to make engine die. What direction do I need to hunt in?
Thanks everyone for the input.

Wed Jun 28, 2006 12:51 pm

you need to ride it some before you check compression.you could have a stuck ring that might free up after running a little while.do not check compression with the engine cold.readings on cold engine mean nothing unless a cylinder is completely dead.more about the gas problem later.have to go.check compression with throttle wide open.