HLA Problems, Input?

[skid542]

So my 96' OBW has been having some HLA issues starting about a week ago. (Before anyone says 96's don't have HLA's - mine does. Single port exhaust, roller cam followers, and HLA's - it's unique i know )

There's always been a little bit of typical llifter noise but about a week ago it got signficantly worse to the point I felt I needed to do something about it. My valve cover seals needed replaced anyways so I figured, okay, lets just do it and be done.

The first thing I did was replace the oil. I knew I was overdue (around 5k, I know...) and it'd gotten a little low (about a qt, again, I know...). So I put in nice new oil, made sure it was topped off, and went out for a bit - no change in noise.

So, last night I took the valve cover off the driver's side (where the noise is coming from) and I could push in every lifter on the intake valves. The exhaust valves were nice and firm like they should be. The passenger side seemed to be just fine with everything being firm - I replaced the valve cover gasket and called that side done.

It threw a little bit of a flag that all the intake HLA's were bad, but stranger things have happened I figured. I took off the rocker assembly and replaced all the intake HLA's with HLA's that were good when I pulled them (4 years or so ago). The ones I put in were firm and if pushed really hard (i.e. channel locks) they'd squirt a little oil.

So this morning I finished the job and started the car up. Nice and quiet. Then it started tapping just a little. Now it's back to really tapping like I didn't replace the HLA's at all.

Thinking that maybe I had a little gunk in an oil passage or something I put 1/4 - 1/3 bottle of seafoam in the oil and went on a 40mi. interstate trip to run some errands. This got the RPM's up to around 3.3k.

Granted I only have 40mi with the seafoam in the oil, which I plan on changing in 200mi, but I should have had decent oil pressure with the RPM's up and still no positive progress.

I'm at a little bit of a loss. I can't figure out why just the intake bank went dry to start with and why now it doesn't seem to be keeping them wet. Best I can tell the shaft the rocker arms pivot on only has a single oil inlet from the head. This must be pushing oil if the exhaust HLA's were fine. What I don't understand then is what could be clogged that would cause only the intake HLA's to be dry. Do that shaft have two oil galleys that feed the intake and exhaust banks seperately?


The Outback is my primary winter vehicle and I would like to fix this issue as it's driving me nuts.

So, I'm looking for any comments, suggestions, etc. on the situation. Both in terms of how to fix it and how much damage am I going to do if I let it ride for a little while.


Many thanks in advance



P.S. Thanks Josh and Todd for answering my last post - I haven't forgotten, just haven't had my SS out much with the weather being what it has been here in north Idaho.

[Legacy777]

Lee,

First, I would not recommend leaving the seafoam in the oil any longer. The seafoam is going to breakdown the oil a little bit or inhibit its protection. So if it were me, I'd change it.

Secondly, on the HLA's. The rocker shaft should only have one oil gallery to feed both intake & exhaust rockers/lifters. I'm not sure why the intakes are all causing problems, other than you got some junk in them. It may just be how they are positioned. I'd suggest pulling the rocker assembly off again, and disassembling and cleaning the individual rocker assemblies and rocker shaft. Use compressed air to blow out/through the oil passageways after they have been cleaned/soaked in mineral spirits and/or brake cleaner. Brake cleaner is a good cleaning solution since you can put the red extension on and squirt it into the oil passangeways.

[skid542]

Josh,

Thanks for the reply. I do agree with you on the seafoam degrading the oil's performance a little. That is one of the reasons I only leave it in for 200mi or so. I've done this before and others on the BBS have done it as well. But, I do agree that not a long term oil mix.

I'm glad to know you also think there is only one oil passage way down the shaft. I didn't think there was two but would have explained why only the intake's went out, and seems to have gone out again.

It hasn't gotten any better today so I think you're right that I need to break down the rocker assembly and clean each one. I need to review the FSM, I assume my rocker assembly isn't really any different than the 90-94 heads. Do you know off hand if this requires any special tools other than a small torque wrench?

Finally, how damaging do you think a dry lifter really is? I'm working on a wood project in the garage and would prefere to not get it all wet again from melting snow until I'm done with the project this weekend. At latest I'd be working on it next week but there's places I need to go before then.

Again, thanks for the help Josh.

BTW, and off topic - how's your re-rebuild going after the deck scratch and such? You get the motor back in the car yet?

[Legacy777]

I would assume the rocker assembly should be the same/similar to the 90-94's. It may be a little different due to the roller followers, but can't be that different. Just make sure you make note of the alignment of all the rockers and shims/springs. I don't even think a torque wrench is really necessary.

As for how "damaging" a dry lifter is.....I don't know how damaging it is, the lifter is just not providing the proper valve clearance, which over time may cause some wear on the valve and poor engine performance, but if you have to wait anohter week I don't think it'd be a big deal.


My project, motor is mostly ready to go back in the car, but I just haven't had much time to work on things. The month of December is pretty busy with the holidays and such, so we'll see how things go. I'm hoping to take that last week off from work in December and work on the car.

[skid542]

Well I found the problem. Some little piece of sealant or silicone (small, flatish, squishy, rubbery) got between the shaft support and the rocker shaft. There is a little flat on the rocker shaft on the front end where the oil inlet into the shaft is and that little piece of sealant got in that little flat plugging oil entry into the shaft.

The rocker shaft itself is hollow with one end plugged and one end having a pressure relief valve built into it. Then there are simply holes drilled through the shaft to feed the HLA's and bushing surfaces. The wall thickness looked around 0.10" or so. The holes that feed the HLA's and bushing surfaces are larger than the hole that permits oil into the shaft.

So I figure since the exhaust HLA's are oriented down, they stayed full of oil while the intake HLA's just dried up without the shaft getting oil.

Cleaned it all up, put it back together and 5mi later (with a few redlines for good measure) it's running like a top again. Ticking is gone and it's got some power back - you could definately tell the intake valves were opening late and not allowing as much as in.

Thank you for the help as always Josh!!

[skid542]

And I'm glad the motor rebuild is going well. It's amazing how busy life gets and how quickly it can distract you from the fun projects but mad props to you for being patient and continueing to do it right.

You're going to have a bullet proof motor. Can't wait to see more dyno charts come spring .

[Legacy777]

Lee,

Glad to hear you got it fixed up.