rockken_vette

my '94 LT1, w/ stock engine, 115K miles, has developed a tapping or ticking sound. My search of the threads suggested exhaust leak, or valvetrain noise, but this seems new, and I just changed the oil to Mobil 1 5W-30 (sorry, I just saw all those oil threads as well...). I had been using 10W-30 M1 previously, but it seemed cold out, so I figured it would not hurt.... Maybe I was wrong.

Anyway, the tapping or ticking, is much louder than the standard sewing machine LT1 valvetrain noise. I cannot seem to pinpoint location, though it seems equal from both sides of the engine. I would guess it was coming from the center of the engine, perhaps towards the front. It seems to be always present, though hard to hear over my exhaust (Flowmaster, no mufflers) when reving it up. Drivability and power seems fine SOTP, though I had been driving my 4-cyl for a week before I drove the Vette after the oil change. My oil pressure is good (60psi cold, 50psi warm at 2K RPM, and 20 to 40 (roughly) warm to hot idling. It has not changed since the oil change. Car starts every time.

My experience with cars is plentiful, I'm just a chicken to tear into things inside the engine of my daily driver- besides, I really want to spend the money on restoring my C2 and saving for my C6 or CTS-V. I have many tools, and have done brakes, clutch, coolant flush, water pump, opti was never replaced, custom exhaust work, seat track repairs, misc interior, and build a 4-cylinder Cosworth Vega Engine (10:1, forged crank, Crower rods, SS valves, tweaked cam timing, ARP throughout)

Could this be a lifter? A bad rocker arm? bent pushrod? About to fail timing chain?

So I see my options as (in order of complexity & cost):

1) leave it and live with it (scary)

2) add STP or something to oil, see if it goes away (pray)

3) change oil entirely, hope it goes away (pray)

4) take to Chevy dealer, see what they think it could be, decide what to do then (out diagnostic fee), how much could it cost? ( )

5) Pull valve covers, see If I can see anything loose, not right, attempt to adjust rockker arms (I've never done this - how difficult is getting covers off? I assume I will need new gaskets)

6) dig deeper it to engine, examine/replace lifters (how can I tell if a hydrualic lifter is bad?)

Gosh, if I am in there, roller rockers were always on my wish list.....

Any words of wisdom are appreciated....

Ken

DVNCI

I think the best thing to do for stuff like this is take a vid so we can hear it

illenema

Ive owned many older cars and my vette. May I suggest that the ticking noise is pry a lifter, that unless gets louder quicker isnt a major thing.
If its more like a clunking look at Rods/crank.
If you do open the engine up might be a good time to do a mild cam swap.
Try heaver oil.
Hows the engine temp normal? Take care good luck

Midnight 85

My opinion,,,,
1. NO!
2. NO!
3. maybe
4. NO! NO! NO!
5. a possibility
6. Not yet.
Now to clarify, the first thing that comes to mind is an injector clicking.
You can diagnose this with a length of hose. Touch one end to an injector then listen at the other end, do all the injectors. If it is indeed an injector then you can stop worrying, they all do it.
Second, and there will be those who disagree here, any car with the mileage yours has needs 10-30 oil. There is more clearance now between moving parts than there was when the car was new. Don't just rush out and change oil again until you try everything else. Get a can of Seafoam from any parts house or Walmart and dump it in the crankcase. If you have a sticky lifter this will possibly free it up again.
If you pull valve covers you will need new gaskets, I don't know how hard it is, I have an L98. Try all the freebie/cheap stuff first, then get a diagnosis from someone other than the dealership unless you are made of money.

94z07fx3

How long would you leave it in before an oil change?

Would you put the entire can in or just half?

BTW a Snap-On Stethoscope is only $20 and the $10 off brand ones work well too. Stethoscopes are much easier to use than a hose or a long screwdriver to the ear.

rockken_vette

As I looked for more Seafoam info, I cam across this post in the Saturn forum, about oil and additives - it was helpful.

http://www.saturnfans.com/forums/showthread.php?t=38696

So the Seafoam would clean out stuff that might be causing the lifter to operate improperly. What is the theory here?
a) lifter does not fill with oil
b) lifter bleeds out oil too fast

It seems that case (b) makes more sense, as I just added thinner oil than what I had been running.

Another lifter question.... When one doesn't pump up all the way, does it bang itself to pieces, or is it just noisy? I imagine clearances become too far open... can that damage the lifter, cam, pushrod, rocker, or valve?

I will listen more carefully with a hose to injectors, and try to get a vid or sound clip as well.

Thanks for the responses so far....

Midnight 85

It doesn't hurt to leave the Seafoam in until next oil change. I agree of the possibility of "case B" since the problem just showed up after the change to thinner oil, it's possible the thinner oil could have dislodged some tiny bit of whatever to clog the lifter, if this is the case the Seafoam would take care of that. You have a roller cam so if you have a lifter not acting proper it will not do as much damage but it still is something that needs attention. I still think you will find a noisy injector.

illenema

Hey there Hope you dont mind me asking how did you like that cosworth? I had one in 1975 # 1561. Pretty cool from the factory, At the time

rockken_vette

I get the thought of the Seafoam, if something is really stuck there, but won't that clear everything out and open up all tolerances that I might already be worn? Isn't it more likely that the thinner oil just is exaggerating a problem I might have already had? That's why I thought STP would get me back to a slightly heavier weight and would be a good idea.

Not trying to get off topic, but i still have Cosworth Vega #0257, and I just fabricated a mandrel bent/welded 2.5" exhaust on it with my Dad last weekend . Check out:
http://www.cosworthvega.com/
and make a post here to tell us about #1561
http://autos.groups.yahoo.com/group/cosworthvegas/

sexasomniac

Just from what you describe it sounds like a lifter. I had the same problem after I bought the car, changed the oil and it went away but you say you just changed the oil so I'm not really sure, haha.

rockken_vette

Okay, I took some video : let's see if I can link it in here....

Video 1 posted to youtube: Rockken_Vette_Tapping_1
http://www.youtube.com/v/lpGG29p75_Q

Video 2 posted to youtube: Rockken_Vette_Tapping_2b
http://www.youtube.com/v/wBEmbWC2If0

Video 3 posted to youtube: Rockken_Vette_Tapping_3
http://www.youtube.com/watch?v=-_TNcCp1zy0

When I took a hose to listen around, the Pass side seemed worse, and it also sounded worse under the throttle body, and on the Intake manifold at the bottom, between the ports....

What do you think?

GACELT4

Just a suggestion (it's free so why not), but make sure the plug wires are tight. Had a loose wire on my '96 that sounded very similar to an exhaust leak or noisy lifter.

Z06_BluByU

the deep sounding wot wot wot wot wot from the passenger side is normal LT1 noise.. these things tend to be noisy.. the higher pitched ticking i heard sounded like something was loose near the oil dipstick tube.. or front of the engine.. check the power steering pump line that routes under the front of the engine (from the resevior on the passenger side to the pump on the driver side).. it is anchored to the timing chain cover with a single bolt.. that could be loose causing it to clatter.. also check the air compressor bolts...

BTW: the deeper wot wot wot sound should go away as the car warms up..


As for the Lo oil temperature you have a bad sensor.. its located right above the oil fiter on the driver side back of the engine.. the harness is either bad, unplugged or the sensor is cracked.. this is cheap and easy to fix!

Good luck!

rockken_vette

Okay, notes on the videos....

These were taken just as the engine was started Cold (30 degrees F) here. The Oil temp guage works, and measures temp acurately once above 40 or 50 degrees. I was just trying to show 50 to 60psi oil pressure when cold at idle. Once everything does warm up, the noise still remains.

I did not notice anything loose on the side rear by the oil dipstick, but I did put the dipstick in 180 degrees from where it was to get a better fill reading. I'll flip that over.

I saw the PS hose mentioned, but I do not recall it being loose - I will check it again. (on an aside note, I saw that there was some fluid/oil on that line, like there was a small leak on it or above it, like either Front Main Seal or Power Steering Fluid from the reservoir or the pump or the line itself). I recall seeing a thread on the line changing design in maybe '95 to support it better?

Ken

DVNCI

It's hard to tell exactly but that sounds similar to a problem I just had on my 97' Silverado w/ 175K on it.

My truck would make a knocking sound during cold start, then the noise would finally go away after the truck got warm - though the noise sometimes would last a good while.

I'll tear into my Vette since it is not my daily driver but I didn't want to tear into my truck, so when I took it to my mechanic (who is VERY good) his explananation was that a lifter had "lost its prime".

They poured some additive in and had me change the oil after 200 miles or so. The problem went away completely after 150 miles of driving or so. It seems to slightly reappear every now and then but not to the extent it did originally.

I don't know what the additive was they added but I could probably find out if you are interested. Good luck!

RACER 1993

Buy yourself a mechanics stethoscope and listen to the motor. Touch exhaust manifold bolts, intake bolts and other places. You can hear discrete injector sounds and lifter noises and compare with your on ears. You will also be able to hear bearing noises, pulleys, etc.

You can use a brookstick, but a stethoscope makes you look more like a Vette Doctor.

You can compare one cylinder to another, and so on. Just keep the tip away from fans and such.

Z06_BluByU

i've scoped mine and all is normal inside the engine.. you'll be amazed at how loud things like the injectors etc.. are.. noise really bounces around in these engine compartments.. LT1's are noisy!

Lars87

My lt4 has that noise too, what is that??

sounds like the pass. side exhaust is leaking

Z06_BluByU

In my opinion its engine bay harmonics - the amplification of cold start piston slap (which is normal in all GM engines using Hyperutectic pistons (LTx, LSx, Vortec, etc..) due to the engine position and accostics in the engine bay area.. In mine its been there for 10 years and 100k miles (both on the original LT1 and the Stroker replacement).. It goes away when the engine warms up..

WW7

I agree with using the seafoam if it sounds like its a lifter, I used it in my truck and it cleaned it out and stopped the lifter noise , also if you want to check for a leaking exhaust gasket pull the hose off your brake booster and pour half a can of Seafoam slowly into the hose using a small funnel. If you have a exhaust leak smoke will come out of the leak and you can tell where it is , this will also clean your intake and valves which isn't a bad thing to do every now and then. WW