normal pressure from oil fill tube/crankcase

[Bostonian1976]

hey all, working on my truck trying to determine oil leak or possibly blowby - wondering what normal pressure / fumes should be seen and felt when taking off the oil fill cap ? I have a fair amount and am wondering if that indicates blowby. Thanks

[1961 109 WAGON]

i have oil that comes out that tube if i run it down the interstate around 65-70 mph for long periods of time. i run 10w40. now if i go around town,it never spits out of the top:rolleyes:

[Bostonian1976]

well I think I'm SOL.

after running the truck for 15 minutes or so (and getting smoke in the cabin), I opened the hood to find both breather caps steaming like an exhaust pipe.

Let the engine teardown begin...

[daveb]

yo dude.

before you tear it down, do a compression check to see where the damage/wear is. it may be something isolated to one cylinder. that will also give you an idea of the overall condition of the valves and rings.

people seem to have different ideas of how to do a compression check.

my method is to get the engine up to operating temps and then shut it off. block the throttle wide open and disable the ignition. that way you get full VE. and a truer reading. the difference between throttle closed and WOT can be as much as 50psi.

crank the engine 7 times or so until you reach the highest reading. record that. do all 4 clyinders dry and then do them all again after adding a squirt of atf or motor oil to seal the rings. if the reading doesn't go up then you have a problem with the valves in that cylinder.

good luck






well I think I'm SOL.

after running the truck for 15 minutes or so (and getting smoke in the cabin), I opened the hood to find both breather caps steaming like an exhaust pipe.

Let the engine teardown begin...

[Bostonian1976]

yo dude.

before you tear it down, do a compression check to see where the damage/wear is. it may be something isolated to one cylinder. that will also give you an idea of the overall condition of the valves and rings.

people seem to have different ideas of how to do a compression check.

my method is to get the engine up to operating temps and then shut it off. block the throttle wide open and disable the ignition. that way you get full VE. and a truer reading. the difference between throttle closed and WOT can be as much as 50psi.

crank the engine 7 times or so until you reach the highest reading. record that. do all 4 clyinders dry and then do them all again after adding a squirt of atf or motor oil to seal the rings. if the reading doesn't go up then you have a problem with the valves in that cylinder.

good luck

thanks Dave. I'm new to any serious engine work (won't be for long!), but if I think it through, wouldn't the problem lie in the rings and not the valves if the oil fill pipe is steaming with pressure like an exhaust pipe? just thinking out loud here. I'll do a compression test this weekend.....

(and thanks very much for responding to this!)

[daveb]

yeah it is probably the rings. but it could be a really bad case of valve wear/damage. and it could be both.

you could just yank it and redo everything. I like to know what exactly is goin gon. I do a compression test of any motor before I pull it for any reason. then I know what is up and where to look when I open it up.

you may just have one cracked ring. or the whole motor may be toast.

good luck
dave


thanks Dave. I'm new to any serious engine work (won't be for long!), but if I think it through, wouldn't the problem lie in the rings and not the valves if the oil fill pipe is steaming with pressure like an exhaust pipe? just thinking out loud here. I'll do a compression test this weekend.....

(and thanks very much for responding to this!)

[Bostonian1976]

yeah it is probably the rings. but it could be a really bad case of valve wear/damage. and it could be both.

you could just yank it and redo everything. I like to know what exactly is goin gon. I do a compression test of any motor before I pull it for any reason. then I know what is up and where to look when I open it up.

you may just have one cracked ring. or the whole motor may be toast.

good luck
dave

ack! don't say that!! haha. I've barely gotten use out of this truck in the 2 yrs I've owned it.

I will say one thing - the valves clatter like a diesel - and I noticed how amazingly quiet everyone else's were at the metal dash event. makes me think they were way too loose for awhile.....

[daveb]

too loose generally jsut means less performance as the VE is reduced.

Some people se tthe exhaust valves a little loose so they spend more time closed. That means they spend more time in contact with the seating surafce in the head which fgives them time to dissipate their heat and stay cooler. thus reducing the chance of a burnt valve.

the oid volvo b18's gave a rang efor exhaust valve setting. of .018-.021 (I think) and we used to set the #4 to the maximum clearance for that reason.

this is on motors that have not been converted for unleaded.


ack! don't say that!! haha. I've barely gotten use out of this truck in the 2 yrs I've owned it.

I will say one thing - the valves clatter like a diesel - and I noticed how amazingly quiet everyone else's were at the metal dash event. makes me think they were way too loose for awhile.....

[Bostonian1976]

ugh - that brings up a point. I don't use lead additive. I wonder if that's my problem.

wow - I'm really winning points as 'the new guy' here....

[daveb]

I don't think many people do. use the additive. if you rebuild it, use hardened seats and valves and it won't be an issue anymore.



ugh - that brings up a point. I don't use lead additive. I wonder if that's my problem.

wow - I'm really winning points as 'the new guy' here....

[Bostonian1976]

thanks for all of your help, dave - I'll report back when I get compression readings (or lack of)

[daveb]

hey maybe you can trade one or both of those beaters for a new(er) motor...

or yank one out of said beater and use that...


thanks for all of your help, dave - I'll report back when I get compression readings (or lack of)

[Bostonian1976]

hey maybe you can trade one or both of those beaters for a new(er) motor...

or yank one out of said beater and use that...

haha well I hope to someday get those running again in their current bodies...otherwise I definitely would...

[Bostonian1976]

okay finally did a compression check - happy to report at least 130 psi in each cylinder. So my new thought about this leak is - could it be misadjusted valves? Mine tap pretty bad. Could pressure build up in the valve cover and push bits of oil through the breather?