leak down test

[juvie_99]

hey carlos i am getting ready to do a leak down test on my motor and i was wondering what do you guys use to block off the exhaust and intake to do the leak down on the motor and when you do a leak down on the cooling system were do you tap into and how much pressuree do you send through the cooling system this is very vital to me now that there are possible exhaust flange bolts tapped all the way through last thing i need is coolant in the cylinder on a new build . if ya could id really appreciate it ,thanks,,,,,,,,,,,,,,,,,,,,josh

[acecarlos]

We use a block off plate with a rubber seal. You can go to the local Hardware or Auto Parts store and pick up a rubber plug with steel expanding nut that fits the exhaust. We use a similar rubber plug for the intake boot, execpt we have a hole drilled for the air pressure to come in at. Use 8 PSI @ 10 minutes for the crankcase leak down...a loss of 1 PSI (or less) over 10 minutes is acceptable since the seals will weep a bit of air.

For the coolant system leak down test; we plug up the coolant nipple on top of the engine head with a piece of coolant engine hose, clamped on the nipple and plugged at its end. We pressurize from the Water Pump (Clutch Cover) nipple, the one that leads into the right lower radiator hose. Use 10 PSI @ 10 minutes for the coolant leak down test...the coolant system should not show any leaks, however; a loss of 1/2 (.5) PSI max over 10 minutes is accpetable.

Carlos.

[juvie_99]

thanks for the answer carlos,,,,, your one hell of a helping hand,,,,thanks

[acecarlos]

Anytime; my pleasure...!

Carlos.

[juvie_99]

ok im back did a leak down test on the motor everything was good didnt leak then i moved to the cooling system and what do ya know someone tapped the top exhaust bolt hole too deep leakin air like a siv but i also had air coming out of my weep hole as well wheni rebuilt it i changed the seal seperating the clutch case to the water pump but reused the mechanical seal and the spring and seal on it. Im thinking im gonna have to rip it apart to change these? whats your thoughts on this. thanks again on the heads up on the exhaust bolt savd me alot of trouble in the long run.,,,,,,,,,,,,,,,,,,,,,,,josh

[C-Leigh Racing]

Carlos,
When the cooling system is pressure checked, if no fluid was in the system, specially in the water pump, could it be possible that mechanical seal could leak air under pressure but not leak fluid if some was in the pump area.

Many years ago helping do plumbing work, working on water pumps & such, while rebuilding house water pumps, they have a mechanical seal just like in the R engines & I was always told not to put anything between the white ceramic piece & inner part of the seal, any type of lube or anything & I thought at that time, thats the stupidest thing I've heard cause those two pieces going to be rubbing each other like crazy & what is going to keep it from being damaged.
Well, I lubed one, you know the I know better deal, guess who was pulling that pump down the next day replacing that seal & at no pay I might add.

What I learned, those two pieces of that mechanical seal got to rub against each other with nothing in between, so that they can imbed themself into each other to create a seal that fluid cant pass by.
They dont need to or suppose to be ran dry, but could be for like a few seconds on a fresh build just to seat them.
If a lot of care is used while installing that mechanical seal, do it perfect as can be done, that seal will last many many years.
Neil

[juvie_99]

i too was wondering about the mech. seal and if theres no coolant in the system how does the system seal all the way up with no help from the coolant.

[juvie_99]

bump,,,,,

[acecarlos]

Josh:

Sorry for the late reply; did not see the post. The Mech Seal seals up just fine without Coolant in the system. Now (Yup Neil); we always coat the lip of the Mech Seal and the Ceramic washer with White Gease to prevent Seal damage (two dry surfaces rubbing against each other) or Dry-out from sitting around.

We test every single WP-Clutch Cover assembly after rebuild, and we test every single engine we build without fluids for Coolant system leaks...the Mech Seals work and seal up without issues.

FYI...it has happened to us before; a new Mech Seal sometimes is bad or goes bad during assembly...they are more finicky than you would think. This is one of the reasons we perform a Full Coolant leak down test; never know if the Mech Seal is good unless you check...we can't afford to ship a Clutch-WP cover assembly or a new re-built engine with ANY leaks.

Carlos.