This stock 87 TransAm 305 TPI sat for seven years. 94,xxx miles on it. Skipping some of the story it's now running but I've got a lot of valve train noise. "Book" says these would be roller lifters. Oil pressure seems somewhat low to me with 5W-30 and a quart of Rislone in it I get about 30psi cold, drops to maybe 15 hot at idle of about 750 RPM. At driving speeds/rpms it seems to hold just under 30 psi. Is there a easy way to determine if this is stuck lifters or springs that have been weakened by sitting compressed for 7 years?

Lacking any better ideas I'm guessing one way would be to remove the rocker covers and test the springs with some tool made to do that job "in place"??

What are the chances of doing damage by running it lightlly (<2000RPM) around town for a little while to see if lifters (if stuck) will loosen up?

TJ Baker

 

first thing i'd do is put a mechanical gauge on it and see what you really have. is the tune up good? i'd not be thinking lifter or valve spring if you have a lot of "valve train noise".

 

ede,

Thanks for the reply,

I called it valve train noise because I don't know precisely what it is. I do know that it sounds just like the noise you'd get from lifters that are not 'pumped up' or too much valve lash (improper adjustment). My terminology may not be the best, but we all know that sound. If we could post a wav file here I'd let you hear it!!


""i'd not be thinking lifter or valve spring"" <- Does this mean you think it unlikely that some springs have been weakened by seven years of sitting in the same compressed position?? I have little to no experience in these matters myself.

TJ Baker

 

no i'm sure the springs need replaced if they're from gm. the point is i'd suspect timing, grade of fuel, plugs or other tune up related parts and adjustments is where your problem is not the springs or lifters.

 

First put a mechanical gauge and see what you've got. Second I would run through and check the valve adjustment. I would definitely replace the springs. It wouldn't be unlikely for a lifter to have collapsed after sitting with full spring pressure on it (whichever valves were open while sitting). Maybe the motor just hasn't got enough pressure to pump the tired lifters up.

 

Thanks again for the quick replies,

ede and Dialed_in - you both mention a "mechanical gauge". Can you be more specific? Is this a device to measure spring tension while the springs are installed?

TJ Baker

 

mechanical oil pressure gauge. Factory gauges are notoriously inaccurate.

 

I just picked up a 6 dollar one at wal mart.

 

Once again, questionable accuracy. My Snap On gauge agrees with my Autometer within 2 psi. while my factory gauge reads 12 psi higher and I tested a friends SunPro gauge and it read 9 psi higher than my Snap On gauge.

 

OH!

Mechanical Oil pressure gauge!!

Already did that. A borrowed mechanical gauge agreed with the indash gauge. That was some of the story I skipped. Agreed, I do not know how accurate the borrowed gauge might be.

TJ Baker

 

Well 30 psi cruising doesn't seem too low. Not great, but the lifters shoul pump up within a couple minutes at the most. Is the oil new? I would try driving it around lightly and see what happens. If you've got a dead lifter or broke spring you're not going to do anymore damage.

 

Not exactly true, i wouldn;t drive the car at all until you find out whats going on.

I ruined my old 305 by driving it with a collapsed lifter for a few days, the excess metal got into my mains and rods and litterally ruined what little metal was left. Spun both a rod and main bearing in just a couple days of driving to and from work.

After wards i tore down that motor and discovered it was actually a collapsed lifter, and when i took the bottom end apart, well, the consequences made me upgrade to a 350.

 

Oil is fresh. Drove it quite a bit today, no change in lifter noise. And this doesn't seem like the sound of just one lifter I'm hearing. Seems more like several. I guess tomorrow evening I'll get into the driver side rocker cover since it's the easier one and see what I find there for valve adjustment and such.

Rest of the story. Got the car last weekend. So far I've replaced;

Battery
Fuel pump
Fuel Filter
Spark Plugs
Oil & Filter
Coolant
Thermostat
Rear Shocks
Tie Rod Ends

Also repaired headlight motors, A/C control, etc., etc.......

Haven't had this much fun in ages!!

TJ Baker

 

Pull the valve covers, change the springs for sure. They've got to be shot. Check for bent pushrods while you're at it. Before you take the rockers off though, check the adjustment. Could be a couple loose valves making the noise. If you don't find anything, it may be wise to pull the intake and replace the lifters. If you decide to go that route, let me know. I have a couple sets of new lifters laying around.

 

OK, so I'm at the shop, got one rocker cover off (the easier one of course) and found two loose valves. #1 Exhaust had .022 clearance (nearly cold) when checked with a feeler gauge and #7 Intake had .032 clearance.

Rotating the pushrods of these two while pulling slightly up wards against the rocker I felt a little snag so I pulled one rocker and had a look. The top end of the rod has a small bump on it the size of the oil hole on the rocker arm. I'm guessing that the pushrods are supposed to rotate and maybe these lifters are stuck?

Anyway. made a splash guard from clean sheet metal (I'm a HVAC man by trade) and did the old school engine running valve lash adjustment that I'd learned in high school auto shop some 30 years ago just to see what I'd find. Things of course have quieted down some. I verified that oil IS being delivered to all rockers on this side at least, whatever that tells me.

I'm going to see about pulling off the other (passenger) side now. I expect to find more of the same.

It looks to me like at a minimum I'll need to replace the springs, and damaged pushrods and rockers. I'm still thinking that some of these lifters are stuck and I'll need to replace the set.

Any thoughts??

TJ Baker

 

Are you sure you have not wiped a cam lobe? I would also check your old oil filter for metal shavings just to be safe.

 

I do not have the experience to know how to tell. I suppose there are ways to measure the travel of the pushrods or rockers?? From what I can see the valves all appear to be traveling similar amounts, but that is only as the naked eye sees it.

As my posts state I just got this vehicle so the 'old oil filter' would be the one that it sat with for seven years. It's laying in the drain tank but I don't think that one would tell me much. I guess I could look at the one I just put in a few days ago before starting the vehicle for the first time in seven years.

Having now removed the passenger side rocker cover I have found a few more valves/pushrods in the same or similar state. I am currently thinking that the pushrod damage I am seeing is due to my running the car a few hours with the lifters collapsed or stuck to see if they would free up. Instead of freeing up the lifters, the looseness has damaged the pushrods where they've been pounding into the rocker arms??

TJ Baker

 

So now I've pulled the manifold and had my first look at these lifters I've been thinking were stuck. Didn't see anything that didn't look right. Plungers of the those at rest were right up to the retainers where they belong. Pulled out one of the ones that had clearance at the valve stem for a closer look. Cleaned it up a bit, checked for plunger motion. Seems fine to me.

I did notice something else though that I should have realized earlier. When I pulled a pushrod (one with damage to the top ball end) yesterday evening I noted that where the rod passes through the head the pushrod was clean on just part of one side where it had rubbed against the oil deposits built up around the hole. The rest of the rod was filthy. Tonight I pulled another rod from an adjacent valve that was behaving correctly. That rod was clean all the way around the same area as is normally seen on dirty old teardowns. It then dawned on me that the first pushrod, a damaged one, hadn't been rotating for a long long time, not just since I started the engine back up after a its' seven year sleep.

So now it would seem to me that the motor had this valve tapping noise long before the previous owner parked it for seven years. The one damaged pushrod/rocker arm that I have pulled out and looked closely at looks like the rocker arm socket where the pushrod goes into has enough galling/pitting/wear to be the cause of the excessive clearance. I don't know how many of them are damaged this way yet, I haven't pulled but two pushrod/rocker arms yet. I can't think of anything other than a lack of lubrication that would have caused this kind of damage.

The previous owner must have run out of oil sometime!?

TJ Baker

 

sounds like that rocker backed off somehow and got loose causing the pushrod to bounce around in the locating cup and beat up the rocker. That would account for the damage to the rocker and the noise you heard.

 

Thanks for the reply!

But what's the chance of that happening to five or more of them?? Maybe someone did a bad job of adjusting them at some point.

At any rate, I'll pull and clean everything up tomorrow and have a real close examination, lifters, pushrods, rocker arms and so on.

Thanks again

 

Take the lifters out of there bores and check the bottom of them if its flat and the lifter can spin in the bore you are good. Also remember each lifter has to go back in its original bore. If all is good there look at your rocker studs see if any are higher than the rest of the studs indicating the studs are pulling out of the heads. Next check your valve springs try and see if any are lower than than the rest of them. I would use a level the bottom has a nice stright portion to use.

 

ross, Thanks for the suggestions.

This is a stock 87 305 = Roller Lifters. I've got them out soaking in solvent now. (Identities kept)
Will do
All new springs will be installed since the car sat motionless for such a long time.

As it turns out all but 4 of the pushrods/rocker arms are scarred/pitted/etc. So I'm looking at all new pushrods/rocker arms/springs so far.

TJ Baker