Check Valves again

[bobk]

I just noticed that the turbos on my 6V92 TA's (425 HP) have what look like check valves on the drain lines. Do these need regular service like those on the air box drains?

Bobk
1981 48MY
Chateau de Mer

 

[Genesis]

Picture please.

 

[bobk]

Picture please.

Karl, When I went to get a picture I realized I described it wrong. This is from the Air Sep filter housing. Getting to the inboard valves will be easy, outboard if necessary will require a mechanic because I can't bent that way anymore. Do they need periodic cleaning?

 

[captddis]

Those are for the air seps. Normally no service needed. They are supposed to be installed vertically though!!

 

[Genesis]

The rules for the airsep check valves to the drains at the oil pan are that they should be just above the level of the oil in the pan AND they should be vertical (they don't work right if horizontal.) Those typically do not require frequent cleaning but they should be checked annually.

The better choice than taking them to the oil pan is to route them to a crap can instead, as with the airbox drains. Put the check valves right on the top of the crap-can entrance and vertical. This also makes the risk of them failing to seal a non-event. Since you should route the airbox drains to a crap-can instead of the oil pan anyway, you should already have a convenient place for them. This also makes their maintenance easy since you can put the crap can and the check valves where they're accessible.

In addition that blanket (I assume that's on the hotpipe) looks to be in terrible shape; that pipe is 1,000F under there when under load and that's an oil hose right under it -- replace that!

 

[bobk]

I think my crap cans are made by Air Sep too based on their small filters. They only have two inlet pipes now for the right and left side air box drains. Should I try to fit some sort of Tee or Y on top of it to accomodate the two extra lines? That might make it difficult to maintain a verticle orientation.

I'll have a better look at the blanket and report back. It seemed to me only the outer wrap has some fraying.

Bobk
1981 48MY

 

[Boatnut]

I am not expert on air seps by any means.

I have allways been under the impression on of the purposes the air seps were designed for is speratate the oil and residue and return the oil to the cranks case, therefore eliminating the oily vapor in the bilge. Wouldn't opening up this line defeat that purpose?

 

[bobk]

I think my crap cans are made by Air Sep too based on their small filters. They only have two inlet pipes now for the right and left side air box drains. Should I try to fit some sort of Tee or Y on top of it to accomodate the two extra lines? That might make it difficult to maintain a verticle orientation.

I'll have a better look at the blanket and report back. It seemed to me only the outer wrap has some fraying.

Bobk
1981 48MY

I opened and cleaned the two inboard check valves. There was no oil accumulation, just a film on the surfaces. They appear to have been working OK. Again a PITA to break the hoses off, but the film rinsed right off with mineral spirits. These had nothing like the grunge from the air box drains. I guess I'll run north next week and have my Baltimore guy clean the outboard valves when I have him onboard for other stuff.

The fraying on the exhaust blanket was just a bit of loose threads at the end of a seam in the outer cover. The cover itself and the insulation behind it look great.

The last 'chore' prior to starting north will be to replace the port 8D batteries. They are struggling to start that motor. I replaced the starboard batts a couple of months ago. These were the best from NAPA and I only got 40 months out of them. Never ran low etc.

Once again, thanks for the guidance and help. The members here are great.

Bobk
1981 48MY
Chateau de Mer

 

[davidwigler]

"The rules for the airsep check valves to the drains at the oil pan are that they should be just above the level of the oil in the pan AND they should be vertical (they don't work right if horizontal.) Those typically do not require frequent cleaning but they should be checked annually.

The better choice than taking them to the oil pan is to route them to a crap can instead, as with the airbox drains. Put the check valves right on the top of the crap-can entrance and vertical. This also makes the risk of them failing to seal a non-event. Since you should route the airbox drains to a crap-can instead of the oil pan anyway, you should already have a convenient place for them. This also makes their maintenance easy since you can put the crap can and the check valves where they're accessible. "

I do like the idea of installing the check valves on the crap can, but I'm curious, are the check valves designed for the airbox drains the same as for the airseps? It seems that the ones for the airseps are designed to pass oil through from the top but close under crankcase pressure from the bottom? The ones for the airbox are designed to pass oil/crap through from the top but close under pressure from the top? Seems they might be a different mechanism? Are they interchangeable?

 

[Genesis]

They are not the same; the airbox drain valves are open normally and close under pressure. The intent is that when there is little pressure in the airbox (just the blower's positive pressure used for scavenging) the accumulated gunk (presumably mostly oil that passes the turbo and blower seals along with any carried up past the oil control rings) drains out but under boost they close so the boost isn't drained off and, if routed back to the crankcase as is the default, you don't put full boost pressure into the crankcase (that would be bad!)

The Airsep drains must close under vacuum (as opposed to pressure) or the Airsep could draw oil up into the intake -- that would have the potential to cause a runaway.

 

[davidwigler]

Thanks, Karl for clarifying this old post.

So if both systems are set up to drain to the crap cans through a T, the airbox check valves (really not a check valve) can be mounted on both sides of the crap can, but the airsep check valves must still be installed somewhere in the lines for safety.

Or, I suppose the airbox drains could be joined together to an airbox check valve on one side of the crap can, and the airseps tied together to the proper check valve on the other side.

Regardless, the check valves should be properly labeled and I need to remember not to switch them.

 

[Genesis]

What I did on my boat was run the airbox drains together and then install one check valve. I got rid of my airseps and replaced them with the Racor CCV which IMHO does a much better job of preventing oil vapor pullover but airseps need the check valves on each Airsep's line because while in theory the vacuum in each should be equal, in practice you definitely don't want to pull oil drained from one back into the other.

IMHO it's more important to get the airbox check valves out where you can service them regularly (which is definitely not the case on 6v92s as-shipped from the factory) than exactly how you configure them.