oil/air separator for vacuum pump

[sverbus]

Here's an interesting issue for you guys. I've got a GZ Motorsports vacuum with the '10an port coming out the very front of the drivers side valve cover. The separator is mounted to the core support on the drivers side next to the radiator. The separator has a breather on the top of it and it's not full of oil, I check by taking the breather off.

But, when cruising down the road i get TONS of blowby! So bad that It's all over the inner fender and the fender well and the front part of the frame and even back on the master cylinder and firewall on drivers side.

I don't know why it's so bad, i've drained it through the valve on teh bottom of the separator and I normally only get about half a paint can cap full.

There's about 11" of hose from the valve cover to the pump, and about 10" or so of line from the pump to the separator.

Any thoughts guys? Thanks!

Scott

[John_Heard]

It doesn't sound like it's getting a bunch of oil into the seperator but the blowing oil all over the place doesn't sound good. How much blow by at idle and when you rev it up do you have if you unhook the pump hose going into the inlet of the pump? Is it a lot? It sounds like the pump may be moving a lot of air and along with it oil. What kind of crankcase vacuum are you seeing at idle and running down the road?

[sverbus]

I'm getting only about 2" of vacuum at idle but when cruising down the highway at 3000+ rpm I'm getting about 11-12" of vacuum.

So you saying to take the hose off of the valve cover and then see if I'm getting alot of oil hitting into that hose which would be the cause that I'm getting alot of oil into the pump. but what the heck is causing the oil to come out of the breather on the separator? I know that's why it's coming from cause it's soaked in oil ALL the time.

[John_Heard]

You don't get oil without air flow, as the air is traveling through the pump and into the puke tank and out of the breather it's carrying oil mist with it.

There are two reasons that it might be doing this that come to mind. The first is that the engine has an excessive amount of blow by. The pump is keeping up with it but at the same time it's moving a lot of air/oil through it and the vent.

The other reason would be there is a leak somewhere in your crankcase system allowing more air through the motor into the pump. For example say your engine was not running and it was sealed up super tight - no leaks - and say the pump is spinning, In a situation like that It'll make a lot of vacuum but very little air flowing through the pump. You would have zero oil getting into the puke tank or out the breather, but a high vacuum level in the crankcase.

Ring blow by or seal leakage will increase the airflow through the pump and along with it oil in suspension in that air flow.

So if you unhook the line at the valve cover and start the engine and don't have much air flow out that engine fitting I would say it's a leak somewhere. If you do have a bunch of air - it's puffing out the hole, then it might be a ring seal issue causing a lot of blowby. It would be time to do a compression test / leak down test to see if there is a bad hole.

[sverbus]

Ok, so I took the line off of the valve cover and started the car up. Idling, with my hand about 1/2" away from the AN fitting in the valve cover it was blowing my hand. as I revved the car up the pressure of teh air coming out of the fitting increased.

So, guessing we got a ring seal issue ((*&DF(*&F'ing figures with the bonehead that built this motor)

Ok, got that out of my system, so what's the best way to do the compression test / leak down test?

Thanks guys, everyones always a huge help!

Scott

[sunsation540]

leak down will show the most but it really won't matter it needs to come down any way the 434 has a tight and high ring pack and not knowing what block this is in .will have alot of piston rock not helping ring seal get torn down take to good machine shop and let them freshen up the short block ck springs and freshen heads oil in the breather like you described also means contimanated combustion chambers that means loss of HP>>>

[sverbus]

This is a Dart Little M block and the springs are only 1 year old and have no visible cracks and are well over strong enough for the cam lift we have. But, I agree the pistons don't have alot of room for rings, and we aren't getting "that" much oil in the combustion chambers cause we don't get any blue or colored smoke other than the smoke we get after driving a bit and it's all loaded up.

Im going to do a compression check, and then a leak down test. If they are all equal and not HORRID on the leak down, Im going to leave it alone and rip the motor down next winter.

[1nicenova]

I have the same problem with my GZ motorsports pump. I am using a breather puke tank as well, moroso brand. Had it hooked to valve cover as an external breather before getting the v-pump & kept it to use when I added the vacuum pump. I have discovered that some of these breather tanks are listed as not for use with a v-pump. I think this one I have and you probably have the same one dont have the correct seperator in them. It was fine for a while until the breather got saturated. When I bought my pump from GZ I told him I already had a breather tank & he suggested that I buy his that was specially designed to be used with the v-pump as this would probably happen with the tank that I have. If you clean and dry the filter the problem will go away for a little while. I checked compression on mine when it started blowing oil out of the top & it checked out fine. I have mine torn down right now to check it out inside while my headers are out for coating & to switch to hellfire rings & everthing looks like new inside as it should with only 5 passes & around 300 street miles. I'm either going to get the GZ seperator tank or the moroso one that is specifically for a v-pump. I'm wondering if the pressure your seeing out of the valve cover is just excessive windage.