When it rains it POURS!!!

[C4Fanatic]

Took the car for a spin yesterday evening after getting the plenum pull finished and all buttoned up.

Seemed like the idle was still a little high...guess I need to check that primary throttle plate actuator like rhipsher has suggested I do.
So, I stop and blip the throttle, get it to idle down then decide to blow the cobs out a little. Nailed the throttle from a slow roll and before I could catch it, the back tires let loose and I hit the rev limiter...I think...tach flashed 8k. CRAP!
Drive the rest of the way home, no issues, but I think I hear something.
Go out today to drive it down the road and definitely hear something now.
Pop the hood and hear a clatter that seems to be coming from under the drivers side cam cover.........#$%)@((#&%*()&()#*@$&!!!!!!!!!!!!!!!!!

So, if you were to venture a guess...lifter...cam lobe??? I think I'm in the same boat as VetteMed...don't have the dinero's to pull the motor or to send the car to Mark or Corey right now. Is pulling the cam cover for a quick peek a big job that can handled in the garage?

CRAP CRAP CRAP...:mad::mad::mad:

[LGAFF]

PS is not bad, but not easya the bolts tend to stick alittle......a quick trip to 8K really should not do the motor in. the 8K failures I have heard of were more sustained speeds as you would at a track......but with aged pieces, who knows.

[C4Fanatic]

It was a VERY quick trip, but you know us old guys and our reaction times! Got off the throttle as quick as I could lift my foot. One of those "DAMN THAT WAS QUICK" moments.

I'm going to have a mechanic buddy come take a listen. I just noticed that the serpentine belt tensioner is bouncing around. The motor runs smooth and doesn't seem to have a miss like I would expect, so I'm still searching.

[USAFPILOT]

If you hit the rev limiter, shouldn't it have not spun beyond whatever the limiter is set at?

[VetteMed]

If you hit the rev limiter, shouldn't it have not spun beyond whatever the limiter is set at?

Correct, only way to over-rev is either due to an incorrect shift (meant to hit fifth, got third instead, or a poorly judged downshift (should have grabbed third, went for second instead). Either situation will not be prevented by a rev limiter in the ECM / PROM.

[C4Fanatic]

Actually it was just a hammer down acceleration in 1st that spun the tires and I saw the tach hit 8,000...come to think of it, it never even acted like it hit a rev limiter.

[Kevin]

if you hit 8k you either don't have a limiter on your chip or your tach is off. factory redline is just over 7, I know of a few 415's that are 7.5

[C4Fanatic]

I'm thinking the limiter has been E-limi-nated at some point in this cars life

[Kevin]

i can't imagine why someone would do that

[cvette98pacecar]

Dave, Sorry to hear the bad news. Guess you have to get another ZR-1 until you can get the car to Mark or Corey, Dont forget about Aaron (SGC). That is a beautiful car, Are you thinking 385 or 415?

[USAFPILOT]

i think the most likely situation is the tach is a little off. I've read numerous times that the tach will read high.

[RedRiderZR1]

Tach is off in my car. Logged it once and realized 7k actual is 8k on my tach. So I know its time to shift when the car tachs out. Thought it was odd I never hit the rev limiter at 7200. Not sure how to fix that. Heard something once about a "tach filter". Not sure what that is or if the car has one of those. But all I know is 7k is 8k on the tach.

[C4Fanatic]

i can't imagine why someone would do that

Me neither, hope I'm wrong and that, as others have said, the tach is reading low at the top end.

[C4Fanatic]

Dave, Sorry to hear the bad news. Guess you have to get another ZR-1 until you can get the car to Mark or Corey, Dont forget about Aaron (SGC). That is a beautiful car, Are you thinking 385 or 415?

Right now all I want to do is get it fixed and get it back on the road. Another beautiful, sunny 60* day here and the car is sitting in the garage again. :mad:

[Paul Workman]

Calibrating the tach is pretty straight forward, and can be done by anyone with average mechanical and some soldering skills. PM me for details.

P.

[rhipsher]

Dave mine is the same way. No limiter. After the top end porting I hit 8k so fast in first but it's only for a split second then its in 2nd gear. Two bit's of advice. Get an impact driver. If you have the original button head cam cover bolts you will have some that you will strip the torx pattern out of. They feel soft. The impact driver is like the Honey Badger. 'IT DON'T GIVE A CRAP." Those screws will come out no problem. Stripped head or not. And if you decide to go the brake booster removal rout, It takes a 13mm socket to remove the 4 bolts that hold the booster to the fire wall. You can remove three of them with a 3/8 drive extension and swivel. But that fourth one that is a pain can be easily removed using a 1/4 drive 13mm socket and extension with a swivel. 1/4 extension is the only one that will fit in between the wiring harnesses the steering column and that sheet metal piece. Done that job three times already

[tomtom72]

Okay, I'm no mechanic so this is fwiw.....from the dummy gallery!

Valves, springs, and cam is the only moving parts under a cam cover on our cars, right? Oh, forgot the cam drive gear and by extension the primary chain set up. My point is you make no mention of a dead miss? How about checking the P/S pump for bearing damage? Or even the W/P or any of the other driven accessories? My reasoning is that in the owner's manual our ECM's shut off the A/C compressor at 4k rpms automatically so no damage can happen due to over reving the compressor.

Remember when they put A/C in the old 72 LT-1 cars? GM had a rule back then, before electronics, no solid lifter motors could get factory A/C because two things would happen. Over reving = compressor damage & the belts were too long and at 6k they jumped off the pulley, unless you used 8 thousand series belts.:o I had one of those LT-1's and the owner's manual cautioned not to engage the A/C after 3500 rpms and / or not to use the A/C if sustained expected engine speed would exceed 3k rpms for any length of time. To prevent all that they used the tach face from an L48 motor to stop you going to 6.5k to shift!
Peace!
:cheers:
Tom

[Torchred96]

Having reduced all the harmonics (harmonies?) of injectors, ignition, flywheel, timing chain, etc., after I got done with my plenum pull, I was surprised to hear a soloist toward the front of my engine singing a capella. Turns out mine was a water pump.

To eliminate all the accessories as a culprit, with the engine running, I put a 1/2 in drive socket wrench (VERY CAREFULLY) into the serpentine belt tensioner and released tension on the belt until all the accessories stopped spinning, engine got very quiet.....soooo nice to hear the LT5 with no noise.
Anyway, Hope yours turns out well. Learning how to change a lifter (and while I'm in there timing chains) on my LT5 is nice to know, but I'd rather wait until I HAVE to know to learn about it.

Good luck with it.

[Kevin]

Dave mine is the same way. No limiter.

you may want to get the car retuned to fix that. who did the tune on your car?

[rhipsher]

you may want to get the car retuned to fix that. who did the tune on your car? I've had the car 5 years and never had it tuned. Who ever owned it before me had the 1-4 shift disabled. I never have to press the clutch down to start the car amongst other things. I know that the tac needs to be recalibrated because the first time I took the car to top speed to where it had no more to give in 5th gear my tac was sitting at 7100-7200 rpms. After top end porting I ran the car top speed all out again to 181 and the tac was at 8000. But both times the tac was always at 950 rpms at idle. But im getting ready to have corey do headers and all so he with tune the car where everything should be.

[C4Fanatic]

I've had the car 5 years and never had it tuned. Who ever owned it before me had the 1-4 shift disabled. I never have to press the clutch down to start the car amongst other things. I know that the tac needs to be recalibrated because the first time I took the car to top speed to where it had no more to give in 5th gear my tac was sitting at 7100-7200 rpms. After top end porting I ran the car top speed all out again to 181 and the tac was at 8000. But both times the tac was always at 950 rpms at idle. But im getting ready to have corey do headers and all so he with tune the car where everything should be.

This sounds almost like my car to a "T". No skip shift, no clutch in to start, and no rev limiter at 7200.

After more input from local folks and more searching, we are of the consensus that it is most likely a bearing in one of the auxiliaries, either power steering or water pump, alternator or the A/C.

There is no miss, even if you rev it. Idles smooth etc.
So, when I return home from Virginia I'm going to begin checking all the things I mentioned. And ONE OF THESE DAYS I'm going to get a tune and chip from Mark or Corey so I know exactly what's what in regards to all that chit.


"Anyway, Hope yours turns out well. Learning how to change a lifter (and while I'm in there timing chains) on my LT5 is nice to know, but I'd rather wait until I HAVE to know to learn about it."

AMEN BROTHER!!!

[cvette98pacecar]

Dave, Haven't heard from you in a couple of weeks. Hope your issue was a secondary bearing.

[Pete]

Put a stock chip in it go 1st gear WOT till rev limiter hits at 7200 and see what your tech reads.

My tech used to be off by 1500 rpm it would show past 8K when me rev limit hit.

You can not hurt this motor by overevving once.

Also the 1-4 skip shift anyone can disable just unplug the plug on the side of the trans.

PS
I totally doubt this but,you could've just bled down a lifter or 2 by either slapping a valve with a piston which in turn will bend a valve, if you only bled them down from overevving it will idle funny and clatter for a bit till they load back up once they load back up idle should be fine which means you just bled down the lifters from overevving.


Pete

[C4Fanatic]

Hey guys, sorry, been out on the east coast on business.

Had a couple folks listen to it, and here's what it seems to be.

On the headers are two air valves for the emissions system. At some time someone disconnected them and brazed them shut, but left the valves there. It seems that the guts of one of them is loose and clattering. The noise has actually gone nearly away.
I did a bunch of digging yesterday, removed the serpentine belt, no change. Put it back on, started the car and just let it sit and idle. As it warmed up, the clatter slowly went away, and was pretty much non-existent at idle.
Went ahead and drove the car yesterday to a local car show, no issues, pulls hard through the gears. Took it on a long drive today and she never missed a beat. So it seems all is well. When I get real motivated I'm going to have to drop the headers and have those things removed and the holes welded up.

[cvette98pacecar]

Glad to hear it is nothing major.

[C4Fanatic]

Glad to hear it is nothing major.

AMEN BROTHER!

[Paul Workman]

AMEN BROTHER!

Wow... It is easy to see how you could be lead to think something loose in the valve train, due to proximity. Glad it weren't nuttin impotunt, uh-huh!

I have one of those mechanic's stethoscopes with the metal probe and the diaphram. It has worked - so configured, but sometimes the sound gets transmitted through the block and everthing I touch sounds like (whatever). Marc Haibeck removed the probe and diaphram and used just the open tube as the probe to isolate what turned out to be a bearing on the water pump. I tried it too, and in that case there was a distinct amplitude change when the tube was near the cause.

Slick trick!! Thanks, Marc for the tip!

P.

[cvette98pacecar]

Wow... It is easy to see how you could be lead to think something loose in the valve train, due to proximity. Glad it weren't nuttin impotunt, uh-huh!

I have one of those mechanic's stethoscopes with the metal probe and the diaphram. It has worked - so configured, but sometimes the sound gets transmitted through the block and everthing I touch sounds like (whatever). Marc Haibeck removed the probe and diaphram and used just the open tube as the probe to isolate what turned out to be a bearing on the water pump. I tried it too, and in that case there was a distinct amplitude change when the tube was near the cause.

Slick trick!! Thanks, Marc for the tip!

P.

That is great idear, Okay I was watching Orange Country Choppers.

[Kevin]

no clutch in to start has nothing to do with your chip by the way