Oil in injector housing?

[-=Jeff=-]

Originally Posted by -=Jeff=-

So B and C means you get a large amount of oil in the PCV system? In theory or was it tested on a Motor while it was being developed?

how much oil would you say that would be over engine running time (or miles).

What was the reason for the small holes to switch from the IH to the Head?

Would I also have to assume that the excessive oil would be seen out the exhaust as well?

Just curious and trying to understand it..

No input on this?

[LGAFF]

Jeff, oddly enough on my 90 I did not put the baffle plugs in and it was smoking a lot....was not doing that prior to the change...although my compression readings were low.

[-=Jeff=-]

Originally Posted by LGAFF

Jeff, oddly enough on my 90 I did not put the baffle plugs in and it was smoking a lot....was not doing that prior to the change...although my compression readings were low.

okay, mine has no plugs either and as far as I know it does not smoke that bad.. been this way since 2008..

if it is an issues I need to get the older IH back on it

[LGAFF]

What if you stuffed the Oil vapor galleys with Brillo pads(copper) would that reduce the flow enough...older European cars had that in their breathers...Jerry?

[A26B]

Originally Posted by -=Jeff=-

So B and C means you get a large amount of oil in the PCV system? In theory or was it tested on a Motor while it was being developed?

Yes. B&C is a no-no.

I'm sure it wasn't theoretical. There were significant problems with crancase pressure in the LT5 during development. As such, you see some unusual crankcase ventilation parts on the LT5, compared to a typical engine. The big holes in the 90MY heads were enough to precipitate a design change to install restrictor baffles (washers in the 90 model injector housings. Nothing theoretical about it, just too much oil in the intake via the PCV system.

how much oil would you say that would be over engine running time (or miles).

If it causes the engine to smoke, knock, foul plugs or not pass emissions, it's too much. Exactly how much would be subject to gross speculation, depending on how the engine was driven. The higher the rpm, the greater the crankcase pressure & the more oil to the PCV system and ultimately back through the intake & combustion process.

What was the reason for the small holes to switch from the IH to the Head?

1. The cylinder heads were originally cast with no ventilation opening

2. Originally (for 1990 MY), the heads were machined out to 3/4".

3. Testing resulted in too much oil in the PCV system,so restrictor/baffles were added to the 90MY injector housings as a fix.

4. Greg VanDeventer said " hey, why are we opening up a big hole in the cyl head and then making a small hole restrictor/baffle to install in the injector housing? Why not save a few unnecessary steps and some bucks by just opening the heads up with a small hole for ventilation & leave the injector housings alone, with no baffle? So, for 1991 & later, heads have small hole & it was not necessary to make & install baffle washers in the injector housings.

Would I also have to assume that the excessive oil would be seen out the exhaust as well?

Sure, everything that goes into the PCV system ends up going through combustion.

Just curious and trying to understand it.

[A26B]

Originally Posted by LGAFF

What if you stuffed the Oil vapor galleys with Brillo pads(copper) would that reduce the flow enough...older European cars had that in their breathers...Jerry?

My profession was oil & gas exploration & production. Fluid flow (includes gas) is a significant part of engineering design of well completion & production facilities. What is involved here is extraction of the liquid from a gas/liquid mixture at variable flow rates & differential pressures. The mist extraction itself can be relatively straight forward, much like what occurs in separating oil, gas & water during well production. The difference here, is that well production separation facilities are engineered with relatively steady-state conditions, whereas the LT5 during it operation will experience variable rate/differential pressure conditions.

The coalescing filter media (brillo pad) is going to hold quite a bit of oil under steady state condition of low rpm cruise, due to the large amount of surface area. At higher rpm, the velocity through the filter media is going to pick up a lot of that oil & carry it through to the PCV system.

The restrictor/baffle design (essentially an orfice), restricts flow rate with increasing back pressure as crankcase vapor volume builds during higher rpm conditions. Adding coalescing filter media (brillo pad) adds surface area & tortuosity for good extraction but would do little to impede flow volume as vapor volume increases.

Caveat: WAG requiring empirical test data to confirm or deny, highly theoretical opinion.

[-=Jeff=-]

Thanks Jerry.. now I understand I could plug the holes of my late IH too right? are all 3 open currently? your one pic blocks the 3rd. if I have to do that now is the time for me since it is winter and I need to pull the plenum to swap the AC compressor.. what is a few more bolts and a set of gaskets.

[A26B]

Originally Posted by -=Jeff=-

Thanks Jerry.. your one pic blocks the 3rd. if I have to do that now is the time for me since it is winter and I need to pull the plenum to swap the AC compressor.. what is a few more bolts and a set of gaskets.

Unless you know why you have late style inj hsngs on your engine, it would be prudent to check the heads too. If your heads happened to be 91 or later with the small hole, the would be no need.

now I understand I could plug the holes of my late IH too right? are all 3 open currently?

Yes. By "plug" I'm assuming you mean with the restrictor/baffle washer that has the hole in the middle.

[-=Jeff=-]

Originally Posted by A26B

Unless you know why you have late style inj hsngs on your engine, it would be prudent to check the heads too. If your heads happened to be 91 or later with the small hole, the would be no need.

Yeah I put them on not knowing about having to have the baffles

Originally Posted by A26B

Yes. By "plug" I'm assuming you mean with the restrictor/baffle washer that has the hole in the middle.

Yes by plug I mean restrictor/ Baffle although 2 are baffles 1 is a Plug correct?

[tomtom72]

Okay, I knew if I waited I would not have to start a thread about using late I/H's on 90 heads.

I've tried to find the correct diameter freeze plug that I could insert into the late I/H so I could duplicate the restrictor hole size on the 90 I/H's.....so far no joy in finding a plug that fits the opening.

My question would be would it be something that a machinist, Carter, could make from brass so we could drive it into the I/H opening? What size would it have to be?


I bought a plenum & I/H set from a 91 motor part out that were ported. I figured I could plug & play with that stuff on my 90 so I jumped.....I should have looked deeper as I didn't know about the PCV restrictor.....


Tom

Jeff, the hole that is completely "pluged" is the coolant passage in the I/H that exits coolant from the block thru the I/H and then into the tubes.