Measuring Crankcase Pressure? (1 Viewer)

[Stone]

I was wondering if anyone has a method of measuring crankcase pressure for Toyota diesels as a method for gauging blowby? I'd like to do this for my 12H-T, but I can't find anything online, and don't remember seeing anything about it in my FSM...though I haven't looked at that section in depth.

Found lots of stuff pertaining to Cummins, but nothing Toyota.

Thanks!

 

[Adam B]

Hey Stone,

I can't answer your question directly but as an alternative how about an oil analysis? Did you do a compression test when you swapped engines?

 

[Stone]

Hey Adam...I just performed an oil change and have a sample ready to send to CAT/Finning for a UOA. Unfortunately, I didn't have the foresight to do a compression test back then. I think it was done when the engine originaly went into the rustbucket FJ60, but I don't know if there will be a way for me to track down the numbers or not. I will need to send in my injectors sometime soon to be checked and serviced if needed...so that will present a good time to do a compression test.

In the meanwhile, if someone has done the crankcase pressure test and has some data on how it's done and the numbers to look for, I was just thinking that it would be an easy way of infering compression and blowby.

 

[lostmarbles]

Easy enough to measure ... but I doubt you'll find any reference figures on what's acceptable Stone (because I doubt anyone has done it before).

"Inches of water" are usually used to measure small pressures like this.

So you could just hook up some clear hose (say 5/16" or 3/8") into a "U" shape, add some dyed water, and fit a tape measure in the middle of the "U".

Then seal one end of the hose into your oil filler plughole and leave the other end open to the atmosphere.

The differences between the levels (in either side of the "U") is now the pressure in "inches water gauge".



(Or millimetres rather than inches depending on where you live.)

 

[amaurer]

I could have sworn someone here did what Tom describes by hooking such a U-tube right to the dipstick tube.

I thought there was a Toyota spec for it as well? Am I crazy?

 

[RufusTheDufus]

Do you have to plug the crankcase vent tube that routes into the intake for a test like this?

Edited to add:

http://www.eng-tips.com/viewthread.cfm?qid=150178

Suggests that the turbo oil drain should be isolated since it's a source of pressure. One person suggests that a natural gas meter (the kind that measures flow into your house) would be a good source to measure the amount of blowby volume.

 

[RufusTheDufus]

Simple home-built manometer example:
Manometer

However, I don't think it will be helpful for measuring blowby pressure. I tend to think that an un-vented crankcase will simply build pressure to the point that it blows bubbles through the manometer.

 

[dousty]

The problem with measuring blowby is the lack of reference. If you could take a measurement from a healthly engine then you could be on your way. Cummins take the measurement from the engine breather but use different sized restrictors based on engine model. Again your measurment is useless unless you have a reference point, Cummins provides these in their service manuals.

 

[eleblanc]

I used a simple magnehelic gauge, with a 1/4" rubber hose into the dipstick. Can't remember what i got but it was low and under what i was told it should not exceed. I beleive i was told not to exceed 5" of water.

I was wondering if anyone has a method of measuring crankcase pressure for Toyota diesels as a method for gauging blowby? I'd like to do this for my 12H-T, but I can't find anything online, and don't remember seeing anything about it in my FSM...though I haven't looked at that section in depth.

Found lots of stuff pertaining to Cummins, but nothing Toyota.

Thanks!

 

[lostmarbles]

I never thought of using the dipstick tube .... That's a great idea.

And you wouldn't want to block off the normal vent tube (or alter it in any way) because that would certainly increase the crankcase pressure to blow all the water out of your manometer tube.

This thread supports the opinion that the limit should be around 4 inches So that sounds like a good starting point:

http://www.mechanicshub.com/heavy-e...-and-engines/806-3116-crankcase-pressure.html

 

[RufusTheDufus]

I'm thinking about how it could be done on a B or H/2H that are vented directly to the atmosphere. I doubt it would work with a manometer.

 

[lostmarbles]

I'm thinking about how it could be done on a B or H/2H that are vented directly to the atmosphere. I doubt it would work with a manometer.

Well I am already thinking of these old diesels (like mine) that have nothing in the way of emission controls and vent directly to the atmosphere.

I wouldn't expect to record more than 4 inches of water gauge from my dipstick.

You'd have to specify an RPM figure too. (Say 2000 rpm?).



(But don't ask me to do it because I couldn't justify spending the time.)

 

[PERUVIAN]

Let me tell you boys how its done..
First.. you cannot block off any of the openings.. as then you aren't measuring the actual pressure.. you want to measure pressure as it's producing it.. if you block the vent.. you will blow your manometer.. or at least make a big mess.. ( good call rufus ) and not have a real reference..
Second.. We do this in aviation.. we say that anything above 4" of water is to much.. these are on large bore high HP turbocharged engines.. When we do it.. we place a fitting in the oil cap ( welded fitting with a cap ) and then measure it with the manometer.. you can use a pressure gauge as well.. but it will be a very small measurement.. almost unnoticeable rise.. I actually just did this a week ago.. then run the engine at redline.. for real.. redline.. for 15 seconds- then measure- Your crankcase vent should eliminate ALMOST ALL of the pressure-
Good luck-
Todd

 

[Stone]

Thanks, folks! I knew I'd get some info here.

I was planning on building a manometer similar to what Lostmarbles and Rufus mentioned. Will try and do it this weekend when I have some time and update with any results. Planning on measuring at 1k, 2k, 2.5k, and 3k RPM's.

For comparison, I could probably see if we can do the same for Petra's HJ61 when I see GregB next.

 

[PERUVIAN]

for a reference point.. 4" of Water = .15 PSI... thats POINT ONE FIVE PSI.. less than a quarter of one PSI.. which makes sense as there is a 3/4 hole in the head which vents air to the atmosphere-

 

[RufusTheDufus]

It would be interesting to compare leakdown % numbers with crankcase pressure readings.

 

[dousty]

Let me tell you boys how its done..
First.. you cannot block off any of the openings.. as then you aren't measuring the actual pressure.. you want to measure pressure as it's producing it.. if you block the vent.. you will blow your manometer.. or at least make a big mess.. ( good call rufus ) and not have a real reference..
Second.. We do this in aviation.. we say that anything above 4" of water is to much.. these are on large bore high HP turbocharged engines.. When we do it.. we place a fitting in the oil cap ( welded fitting with a cap ) and then measure it with the manometer.. you can use a pressure gauge as well.. but it will be a very small measurement.. almost unnoticeable rise.. I actually just did this a week ago.. then run the engine at redline.. for real.. redline.. for 15 seconds- then measure- Your crankcase vent should eliminate ALMOST ALL of the pressure-
Good luck-
Todd

Engine will need to be underload to achieve maximium cylinder pressures and hence blowby reading. Peak torque, peak load aka working it's arse off. Find a big hill that will cause your engine to die even with full throttle and hit it at high rpm's, then watch the manomoter as your engine drops right back through the rev range at 100% throttle.

 

[eleblanc]

I'd did my test under load. So with the 1/4" tube i went through the hoods vents, through the window and in the gauge on the passenger seat. Then i went for a ride!

I was told this must be done under load

Thanks, folks! I knew I'd get some info here.

I was planning on building a manometer similar to what Lostmarbles and Rufus mentioned. Will try and do it this weekend when I have some time and update with any results. Planning on measuring at 1k, 2k, 2.5k, and 3k RPM's.

For comparison, I could probably see if we can do the same for Petra's HJ61 when I see GregB next.

 

[Stone]

Okay...I just got those RPM's from a Cummins site, and thought that the RPM range jived with where my 12HT is usually sitting at when driving.

I'll try and figure out how to do the test while driving also...although I guess a manometer will qualify as a handheld device in BC...LOL. Wonder what the cop will write on the ticket if he pulls me over because I'm trying to mark water levels on that thing?

 

[eleblanc]

Just get one of those screwed to your dash

http://images.drillspot.com/pimages/3323/332392_300.jpg

Okay...I just got those RPM's from a Cummins site, and thought that the RPM range jived with where my 12HT is usually sitting at when driving.

I'll try and figure out how to do the test while driving also...although I guess a manometer will qualify as a handheld device in BC...LOL. Wonder what the cop will write on the ticket if he pulls me over because I'm trying to mark water levels on that thing?