drumstixer

Hello all,
I'm fairly new to this board and I have a few questions about my L03.

Background first: I bought my 91 Firebird about a year and a half ago from a guy whose only modding experience had come from Need For Speed. The mods he did are as follows:
Straight Pipe (No Cat) with what appears to be a junk Glasspack welded on.
Open Air filter
A/C removed (almost)
??Racing Radiator?? (what I was told. It definitely isn't stock, but not sure what it is exactly)
Don't get me wrong, I'm all for these things...if done right. The exhaust work was poorly measured and the parts were poorly picked. The A/C components are gone (yay space) but all the climate control parts are trashed. The open air filter was great! Except when I bought it, the filter was almost black. The radiator works lovely, except the fan does not turn on. Not only that, but fluids (including oil) were all old, contaminated, and/or leaking (tranny and engine oil). Most of the basic things are fixed, such as fluids, plugs/wires, brakes, starter, water pump, basics.

Now for my issues. Ever since I got the car, the oil pressure levels are low when hot, like around 15-29 psi. The levels never reach 35-40. Also, I've been hearing a strange knocking sound on the passenger side of the engine and I'm afraid it's a rocker arm or rod....

My questions are:
What could cause this low oil pressure and how would I go about testing the issue?
Is it fixable and how?
Also, if the knocking sound does turn out to be the rockers or rods or some other internal part, is it fixable? Or is it worth the fix? OR is it just time for a rebuild?
Also off topic, I assume that when I remove the valve covers, there will most likely be a bunch of gunk from past abuse. How do you clean that?

Any and all help/advice/comments/wisdom would be great! I'm not exactly a novice, but I'm FAR from an expert.

Thanks much.

F Bomb

sounds like its time for a rebuild to me

bradley23150

iTrader: (10)

Try hooking up a mechanical oil pressure gauge up and see what that reads. Is the 'knocking sound' more of a "knock" or a "tick"? Is it coming from higher up on the motor, or lower?

steve87ta

iTrader: (4)

True... valve sounds are more click-tick, crank and rods have more of a bang-bang like a hammer.

The low when hot does not bother me as much as the never above 40 lbs.
Make sure you are getting accurate oil pressure readings if you are going to make decisions based on them. Senders get old and funny sometimes.


I bought a 91 bird for parts- it ran pretty shaky but did run on and off the trailer. When I stripped it I found what was left of two rods in the pan- the crank was empty on two journals! With two pistons still in the up position I could not believe it ran! I even toke it down the road to check the tranny!

High milage 305 do not have a good rep if not maintained. Well maintained they can last for more than 200,000.
I hope I helped you.


Valve stuff can be done with the motor in the car but rods and cranks are usually done with it out.

I am not saying you could not change the oil pump and get more oil pressure but it prob has too much clearance and that requires machine work-rebuild. Guy do slap rings and bearings in motors and some even get by with it.
Most get it or a rebuild if going to all the troulble but if you got more time than money....

TZFBird

How many miles are on the engine? If it's more than 150k you probably just have enough wear to make the pressure low. Another thing would be to check for some corrosion on the pressure sending unit behind the distributor. If you pull it off, the guage goes to 0. So if there is added resistance from corrosion or dirt, that would definately make the guage read lower than it really is. That also grounds through the block, so any extra resistance there would affect things as well.

As far as the knock, sounds can be decieving. You could be hearing the tick from the injectors(more apparent with an open element filter). Or it could be an exhaust leak. Lifters/rockers are also a clattery sound, but I think more of a description would be needed.
Such as specifics about the noise:
*At idle
*Just off idle
*Part throttle
*Is the car parked, or rolling
*How loud it is

I had detonation which sounded like rattling only when the engine was at operating temperature. This was caused by the ignition control module. I took it in and had it tested, which it tested out bad in the low RPM range. Picked up a used one and everything is running right again. Or you can get a new one for $20-$50 depending on brand.

drumstixer

Hey guys thanks for all the advice. as far as specifics, the engine only has 92,6** miles on it which is nice, but still. The sound is more of a click-click-click sound and seems to be coming from underneath the passenger side valve cover, although I guess that doesn't completely out rule an exhaust leak. The sound appears when idling and becomes a tad less apparent when warmed up, but then reappears when I am driving. I cannot tell if it is happening all of the time, but I know I can here it when i am stopped at a light or something...generally at low RPMs....this sound is slightly different. Kind of like a fast tick-tick-tick-tick sound and it is loud enough to hear over the sound of idle and music. As for the oil pressure sending unit, I will check that when I get a chance and let you guys know what's up with that when I get a chance. I plan on one day doing a rebuild on either my current 305 or a 350 (if I get my hands on one), but it may have to be sooner than later. Once again thanks for the help, I appreciate it. Anything else you need to know, or any info you can give me?

steve87ta

iTrader: (4)

If it was mine, I would pull the valve covers. You probably have a collapsed lifter or a flat lobe. It is probably fixable with the motor in the car. To change a lifter the intake must come off and to change the cam the water pump and timing chain, ballancer must come off. It maybe more than you want to do but is not that hard and a whole lot cheaper than paying a shop.

There are rocker arms that have locknuts on them under the valve covers and that is how you adjust the valvetrain.

Should be able to search "setting the valves" and find something. Or sometimes you can see the rocker that is loose. If you are lucky it is just the lifter but could be a pushrod and/or the cam is worn.

drumstixer

Okay thanks! I'll pull the cover and see whats up when I get some spare time. If it is just a lifter issue, would I have to change out the cam as well as all the lifters? I read somewhere that you should, but not so much for hydraulic lifters? Or if the issue is a loose rocker, would I have to reset the valve lash on them all??? Or am I even asking the right questions?

Fuzzman17

With roller lifters you need not change them unless they are damaged or worn. flat tappets need to be changed as they "wear in" to the lobe they are on.

If you have a rocker that has to much lash you first need to determine why. You may have a worn cam lobe, A lifter that is collapsed or a worn rocker. A bent push rod is another possibility. Check the hight of all the studs also to make sure one or more are not higher than the others.


What you find will determine what course you take.
as a rule rockers don't just go out of adjustment. Parts wear or are damaged.

To adjust your rockers make sure the lifter is on the cam base circle. Back the adjuster nut off till you have play in the rocker. Roll the pushrod back and forth between your thumb and index finger using a light pressure as you tighten the adjusting nut. When the push rod stops turning you are at zero lash. take the nut down from there to the specs for your engine.

drumstixer

It seems the general consensus is pretty much a valvetrain issue. Correct me if I'm wrong, but in order to avoid having to check for issues that may or may not (but probably more than likely) exist, what if I just replaced certain components? I'm talking cam, lifters, rods, valves, rockers, timing chain....pretty much anything I can get to. I've reading about the LT1 cam switch on the board and it seems to be pretty beneficial. I fI do this switch and change out most or all of the valvetrain components, would that be a mistake or would that fix the issue? Or am I just way over my head with this? Also would a switch like this be difficult with the engine in the car, minus the radiator and fan?

Help, help, help, advice, wisdom, anything....and thanks

steve87ta

iTrader: (4)

I guess if you can see the valve that is clacking and go from there. It would help to have someone that knows look at it once you get the valve covers off and maybe the intake too.

If you are willing to type it out, we will try to steer you in the right direction.

drumstixer

Cool I can do all of that. Will post again with what I find out down there. Thanks again for your help so far, people. I do appreciate it.

drumstixer

Update:

I finally had time to poke around the engine bay today. I initially planned on doing a quick oil change and checking the rockers, and I did, but I also did a Seafoam treatment (which worked fantastically). All was going well with the treatment until I noticed what could have been my problem all along: an exhaust leak. I noticed the white exhaust from the seafoam leaking out of what appears to be the passenger side manifold close to the firewall. I did check the rocker nuts and lifters after the treatment and I did indeed find a couple loose nuts. My buddy and I straightened that out, but the sound still persists. I'm almost certain that the sound is the leak. Tomorrow I will go under some more and tighten some bolts and maybe even just buy a new gasket and re-seal it. Any suggestions on gaskets? Sealers?

Also since this problem is here, it may be a great time to invest in some aftermarket headers. Any suggestions on headers? Preferably shorty's....

Last but not least, the oil pressure is now back to normal and I have been getting pressure readings between 30 and 40 all day. I did replace the oil pressure sending unit and used 5W-30 full synthetic this change and it is beautiful. I will never let a shop do my oil ever again, even if it's cold....

xX89RSXx

iTrader: (1)

Stock manifolds don't use a gasket, believe it or not. May just be a loose bolt.

drumstixer

No gaskets...definitely didn't know that...now I sound like an idiot. But I'll still check the bolts...

xX89RSXx

iTrader: (1)

Hey I didn't know it till I came across it on here at one point. If you didn't ask, you would never find out. But any header choice is better than the manifolds.