Intermittent LT1 Ticking?

[97Formula]

My car doesn't seem to tick all the time (but lately it has been ticking more often than not). When I hear ticking, I either hear it at idle (when fully warm), or around 1400-1500RPM (not noticeable at all around 1200-1300RPM, or anywhere above 1500RPM). The tick sounds like it could be coming from anywhere (most noticeable when I open my driver side door, sounds like coming from the bottom of the car). But when I open the hood it also sounds like it's coming from there too.

The car still runs strong with no SES light. No driveability issues, and no additional vibrations from the ticking. The engine oil has always been changed no more than 2000 miles each interval with Mobil 1 5w30, with 31500 miles on it now (magnetic drain plug didn't have any heavy metal chunks, just the normal metallic particle covering the tip of the plug).

Do all LT1's experience ticking? I had the car since new and it seems that I always had some kind of ticking (actually had the lifters replaced at 3500 miles because the dealer thought that was making the noise).

[sweetbmxrider]

Try probing around with a long screw driver and placing your ear to the end of it. This should help isolate and amplify the noise. It could be in the valvetrain or it could be a small exhaust leak, both happen on lt1s.

[97Formula]

Try probing around with a long screw driver and placing your ear to the end of it. This should help isolate and amplify the noise. It could be in the valvetrain or it could be a small exhaust leak, both happen on lt1s.

I think I'll have to try that. that's when I put the tip of the screwdriver on different parts of the engine, correct?

Also, I noticed that when the engine is cold it does not tick at all, or anytime during warmup. Once the engine reaches operating temps, the ticking returns.

Anyone know good shops in Central Jersey area that know LT1 engines really well (specifically in the Trenton/Hamilton/Robbinsville areas)?

[sweetbmxrider]

That's definitely strange its only when hot. Might be a tough one to diagnose over the internet. Yes its putting the tip of the screw driver on different things and listening through the handle. I cup my hand and put my ear in that.

[transmaro93]

could be a small exhaust leak that only starts when metal expands from heat... could also be a wrist pin knock on a piston but the car only has 31k on it? thats low miles for a wrist pin knock... my jeep has a wristpin noise with over 130k on it... prob most likely an edxhaust leak

[transmaro93]

ohh and if there is a harbor freight near you they sell a decent mechanic stethoscope for pretty cheap that works real well for listening for noises incase you dont want to use grandpaBMXers screwdriver method haha

[The Fixer]

I remember my LT1-powered Impala SS making a ticking noise similar to what you describe when the EGR valve died. It could be just the solenoid, or maybe the gasket, or the EGR itself. It's bolted to the backside of the intake manifold - probably a royal PITA to reach under the windshield cowl, but it was an easy job on my Impala.

[BonzoHansen]

long piece of heater hose works well as 'stethoscope' too

[JL8Jeff]

My old 93 always had a piston slap type tapping noise. It would get a little louder when the car wanted an oil change and would quiet back down with fresh oil. I was running a Powerdyne 4.5 lb supercharger on it and went with Mobil1 15W40 or 20W50. The car had 74K on it when I sold it and never had any real problems with the motor. What oil filter are you using?

[Anti_Rice_Guy]

The 'vert has always had a slight ticking around idle.

[Pampered-Z]

LT1s have lots of ticks, even the injectors can tick. How is the oil pressure? LT1 historically have low oil pressure, and some filters can actually cause a tick. If you not using a GM filter, switch to one next oil change.

Also check the exhaust, could be a leak at the join, and the 97s have that odd cat placement on the drivers side.

Also check under the hood in the dark, a bad wire can arc and tick and still not cause the car to run bad. I've seen this 2-3 times. The #3+5 and #6 cylinders like to burn wires over time.

[97Formula]

LT1s have lots of ticks, even the injectors can tick. How is the oil pressure? LT1 historically have low oil pressure, and some filters can actually cause a tick. If you not using a GM filter, switch to one next oil change.
Oil pressure is above 40 on cold startup and stays that way until warm. Once warm, it is 20-25 at idle, and at least 40 while driving. By GM filter, do you mean oil filter? If so, I'm using a K&N since the new GM filters are now half the size as they used to be.

Also check the exhaust, could be a leak at the join, and the 97s have that odd cat placement on the drivers side.

Also check under the hood in the dark, a bad wire can arc and tick and still not cause the car to run bad. I've seen this 2-3 times. The #3+5 and #6 cylinders like to burn wires over time.
I'll have to check that....still no SES, and still no ticking until warmed up to operating temps.

What oil filter are you using?
K&N HP2002

[z28camaro94]

my car make a similar noise, only upon deceleration from about 30mph down to 5mph then goes away, and only when warmed up...very strange i have yet to be able to trace it down..but sounds like coming from front wheels

[97Formula]

Also lately, I noticed that on occasion it sounds like "bells ringing" under the passenger side valve cover (lasts for a split second here and there)

[97Formula]

Also lately, I noticed that on occasion it sounds like "bells ringing" under the passenger side valve cover (lasts for a split second here and there)

Took it to a shop, they said nothing is physically wrong with the engine. But they told me the ticking is due to low oil pressure at idle and recommends a different oil (15w50 hot rod oil). Any thoughts on that???

[WildBillyT]

Took it to a shop, they said nothing is physically wrong with the engine. But they told me the ticking is due to low oil pressure at idle and recommends a different oil (15w50 hot rod oil). Any thoughts on that???

IMO- Nope. That type of thing will get your pressure up but it won't be right for the engine.

[97Formula]

IMO- Nope. That type of thing will get your pressure up but it won't be right for the engine.

Thanks for confirming, as I was extremely skeptical to jumping straight to an oil that thick (currently using M1 5w30). After doing some research, I decided to give M1 10w30 a try (since it rarely gets below 0*F around here). It did seem to quiet the car somewhat at hot idle (too early to tell). But I was also wondering about other oils in these viscosities (i.e. Penzoil Platinum, German Castrol, etc)...

EDIT - The car has never consumed oil between oil changes (dipstick reading is always the same as the day I put the oil in)

[sweetbmxrider]

How many miles are on the motor?

[97Formula]

How many miles are on the motor?

31500 miles

[Pampered-Z]

20-25PSI is actually good for an LT1, some see as lower at 15 (this is on the stock gauge). I would agree not to go to a 50W oil. Stay with what ou are using.

Switching from 5-30 to 10-30 adds nothing, once the oil is hot it the same 30W

If it's really bothering you can do a spring change on the oil pump to give you more pressure, You can do a search on this site about the GM white spring. It can be used to increase oil pressure. but that is allot of work for something I honestly don't think you need to be real concerned about.

[97Formula]

Just had it out tonight. I punched the gas at around 40-45MPH, and when it kicked into 2nd, I think I heard some ticking while under hard acceleration for a second (this was in the 3500-4500 RPM range). But when I slowed down to idle, the car wasn't really ticking at all.

EDIT -- I am now thinking that it was due to being close to a guardrail on a ramp (causing a "reverberating" effect). Tried a few times just now on different roads and was not able to reproduce the "ticking" sound I heard before on harder acceleration.

[greenformula92]

you have good idle oil presure for a LT1. Both I had had no more than 10PSI at operating temp. I think Alldata says LT1 idle oil presure is 7-10PSI or something like that.

by the way both my LT1's also had a idle tick when hot

[JL8Jeff]

I ran 15W40 or 20W50 in my old 93 and never had any problems. But you could usually tell when the oil was getting old, it would start to get louder with the ticking noises.

[97Formula]

Just had it out tonight. I punched the gas at around 40-45MPH, and when it kicked into 2nd, I think I heard some ticking while under hard acceleration for a second (this was in the 3500-4500 RPM range). But when I slowed down to idle, the car wasn't really ticking at all.

EDIT -- I am now thinking that it was due to being close to a guardrail on a ramp (causing a "reverberating" effect). Tried a few times just now on different roads and was not able to reproduce the "ticking" sound I heard before on harder acceleration.

Quick update to this particular post -- I am now worried that it was detonation I heard for that little bit:omg:! Reason I was thinking is I had my car at the dealer replacing the fuel pump since I was still trying to solve the "slow prime" issue and occasional slightly harder cold starts. They tested fuel pressure, which was 45PSI with key on engine off, and 35PSI when running. Was told that GM specs called for 55-60PSI, and after the new pump it showed 58PSI (and the car accelerated a bit stronger and smoother, so I guess I was gradually losing power along the way as the fuel pump started to go).

How would I know if I damaged the engine (since I did not know the fuel pump was really on its way out but still did WOT runs here and there)? I am perplexed that I did not get a SES light or even a trouble code all this time...

[sweetbmxrider]

Actually, your previous fuel pressures were correct. 55-60 is too high. GM specs 40-49 I believe Key On Engine Off and 10 psi less engine running. There is no fuel pressure sensor so the engine wouldn't throw a code for that ever.

[97Formula]

Actually, your previous fuel pressures were correct. 55-60 is too high. GM specs 40-49 I believe Key On Engine Off and 10 psi less engine running. There is no fuel pressure sensor so the engine wouldn't throw a code for that ever.

I wasn't expecting fuel pressure to throw a code.....was thinking that I should've had at least a trouble code or SES light for a LEAN fuel mixture, or a misfire, or something...

This was a GM dealer telling me where the specs should be for this car. Is there an issue with the fuel pressure being that high? And how would "the customer" (me) challenge the dealer mechanics what the correct fuel pressure should be? The engine runs better now than before the pump replacement (they also "power-cleaned" the injectors).

One other thing I noticed (after the fuel pump replacement).....after filling the tank, the gauge was between 3/4 and F (instead of 2mm beyond F). Took it back, they dropped the tank once again to test the sending unit (I am under the impression that GM sells the fuel pump kit with a new sending unit installed). They told me the new sending unit is at the correct spec (90-OHM), and my old sending unit was too high (103-OHM). They tried another fuel pump assembly unit with the same result, same reading, etc. Then they told me they manually tweaked the float arm (not sure how this is done, and they told me they did not bend it). It's a little closer to F but not quite there yet (not sure if this is because they did not put all the gas back in the tank when they lowered it a second time).

[sweetbmxrider]

Its a pretty known issue that these sending units were off from the factory. If your gauge is closer to F, you should brag about it at car shows :lol:

Ask them to show you in the service manual where it specifies the pressure they told you?

FUEL SYSTEM PRESSURE
Ignition ON Engine OFF 284-325 kPa (41-47 psi)
With Regulator Vacuum Applied [1] 3.0 - 10.0 psi less than Ignition ON Engine OFF

REMARKS:
[1] May be checked with either of the following methods.

With Pressure Regulator Vacuum Line Attached at normal idle speed.
Ignition ON Engine OFF with 10 Inches Of Vacuum Applied To The Pressure Regulator.

This is how AllData lists a 95's fuel pressure. They Only listed Key On pressure for 97.

There's a chance that cleaning the injectors helped the car out. If the extra fuel pressure is band aiding a problem, well you have to figure out what it is. The SES light will trigger for lean too only if the computer can no longer compensate for it. There is a chance that your Fuel Pressure Regulator is bad causing your higher pressure.

[97Formula]

Went back to the dealer, and turns out they did wind up referring to the 1998 shop manual for the fuel pressure :facepalm:. However, they ordered the parts based on the VIN number (so I should assume I have the fuel pump for my 1997 model).

I guess I will need to confirm the actual pressure on my own. Car still runs more awesome now than before the repairs. My only concern now is the fuel gauge.....


BTW -- I know the original thread was regarding ticking sounds (which I did ask the dealer to check while in the shop......they indicated on the bill "no unusual noises heard"). Car also doesn't sound as "stressed out" when I punch it and going towards the upper RPM range (instead it seems more willing at that range now).

One last thing -- before the repairs I noticed less "hissing" noises by the CAI filter (actually it was kinda intermittent, wondering if that was due to lack of fuel and the computer was constantly adjusting the fuel mixture to keep it going). Now, there is a "steady" hiss that is most noticeable at startup (which is how it should be)...