Accelerating at freeway speeds

[chevychic]

Now that I've been driving my truck 70 miles 2 days a week on the freeway, I'm finding other problems.

If I'm cruisin along at 65 and try to accelerate to pass someone, I start hearing a noise kind of like an exhaust leak (I think) accompanied with a metal ticking noise (like a fan). It's coming from the engine area and I'm not positive, but I THINK it's coming from the passenger side. Kind of hard to tell with all the freeway noise and rattles my truck has. The metal ticking and the air noise may be 2 seperate things but they both happen at the same time. That's the best I can describe the noise so if you need more details just ask and I'll do the best I can.
Once I back off the accelerator, the noise stops and I can cruise along comfortably. It's just on acceleration that I'm getting the noise.
I played around today and found that I don't always have to be at freeway speeds for this to happen. Once my 700r4 shifts into 4th gear and I try to accelerate I hear the noise(s).
As far as performance goes, it seems to bog down a bit when this happens. Not incredibly, because I can still increase my speed but enough for me to know that I'm missing quite a bit of power that could be there.

Just a couple of notes to help you guys out...
I did have a different metal ticking noise that ended up being a couple of loose bolts from my flexplate to tc. Tightened those up and that noise is now gone. (Although I do need to shim my starter now)

Any ideas?

[1974ChevyC10]

im kinda having the same problem-i wonder if my starter needs shimmed?ive never had to shim a starter in a vehicle before however-why would you need to do that?i had my starter out a couple weeks ago having it rebuilt and ever since it has been out my truck has been making a ticking noise as well.i hope this is the cause and not the flywheel since i have nowhere to take out the flywheel and im moving so i need my truck and cant afford to have it down for long periods of time

[mike reeh]

Originally posted by chevychic
Now that I've been driving my truck 70 miles 2 days a week on the freeway, I'm finding other problems.

If I'm cruisin along at 65 and try to accelerate to pass someone, I start hearing a noise kind of like an exhaust leak (I think) accompanied with a metal ticking noise (like a fan). It's coming from the engine area and I'm not positive, but I THINK it's coming from the passenger side. Kind of hard to tell with all the freeway noise and rattles my truck has. The metal ticking and the air noise may be 2 seperate things but they both happen at the same time. That's the best I can describe the noise so if you need more details just ask and I'll do the best I can.
Once I back off the accelerator, the noise stops and I can cruise along comfortably. It's just on acceleration that I'm getting the noise.
I played around today and found that I don't always have to be at freeway speeds for this to happen. Once my 700r4 shifts into 4th gear and I try to accelerate I hear the noise(s).
As far as performance goes, it seems to bog down a bit when this happens. Not incredibly, because I can still increase my speed but enough for me to know that I'm missing quite a bit of power that could be there.

Just a couple of notes to help you guys out...
I did have a different metal ticking noise that ended up being a couple of loose bolts from my flexplate to tc. Tightened those up and that noise is now gone. (Although I do need to shim my starter now)

Any ideas?

man heather Ill be damned if youre no describing engine pinging. does it sound like marbles in the motor?

try retarding your timing a bit OR better yet run some real high grade gas for a tank (or 1/2 tank) and see if it improves.

mike

[1974ChevyC10]

Originally posted by mike reeh


man heather Ill be damned if youre no describing engine pinging. does it sound like marbles in the motor?

try retarding your timing a bit OR better yet run some real high grade gas for a tank (or 1/2 tank) and see if it improves.

mike

now im wondering if that could be my problem is the quality of gas in my truck.maybe i should run some premium in it to see what happens.sorry to steal your thread heather but i seem to be having the same issues as well.

[chevychic]

Thanks Mike, I'll give the gas a try and see how it does.

Hey, where's your avatard? You have 107 posts!

[85 K5]

If it is pinging, and since you've just rebuilt your carb, did you vacuum guage tune your air fuel mixture screws? Lean conditions on these adjustments will definitely cause pinging during the conditions you describe.
Make sure it is fully warmed up, drive a few miles then connect the guage to manifold vacuum and adjust for maximum. It is hard to go overrich unless you have drilled out the discharge ports as described in Swervin's / Damon's article.

Doug

[chevychic]

When I rebuilt my carb, I didn't change any settings. Everything went back to the way it was.
The truck did this before I rebuilt my carb but I didn't drive it enough on the freeway to be concerned or to even remember to ask about it.

I'll try premium for a bit. Is there a gas additive I can get that might help?

[Tom]

If the tranny dosent shift out of 4th and lockup at highway speeds [like my 2004R, Ill be damed if that thing will ever kick down out of 4th gear] then the engine cold be lugging. This would make any exaust leak very apparent, and load the engine to the point pinging could start.

[PHOENIX]

When my air injection tubes were leaking at first, they came and went and sounds kinda weird. Just to eliminate them, idle your truck in your driveway and give each tube a little tug and see if you get any noise. If you dont, then try something else. Just one more little thing to check. I know when my problem first started (both times) it sounded like a metal sound, not an exhuast leak. Well as it got worse, so did the noise. Does the sound only happen at a certain rpm?

[MylilBowTie]

Im not sure if you have any Sunoco Filling Stations where you live but thats the only thing I have found that my truck likes. 89 with it being as cold as it has been and 94 in the summer. They put more stuff in the gas mix than some others.

[PHOENIX]

I like Chevron gas. Ever since the 350 has been installed in my truck, it always gets Chevron. I have only put onthers in when I absolutely had to (10 times max in almost 4 years). I also only put in distilled water for the cooling system, helps to keep it real clean.

[chevychic]

We don't have a sunoco here but I do use Chevron. I'll either go to them or Texaco only.
What octane are you guys using?

[TODDS 72]

heather
if your engins mostly stock than you should be able to run 87 octane,try adjusting your timing by ear a little sometimes the timing lights lie..lol have you checked to see if the weights are moving in the dizzy,is there vacume there,sometimes the ports can get a piece of carbon in them,i know some guys think you should run higher octane but in 1986 this truck was made to run on cheap stuff,plus the lower the octane the more gas per gallon
the higher octane has more cemicals in it to raise the octane,i'd really try the timing adjustment things wear,it help my 86 stop pinging,and i run 87 in all the time.
good luck

[Chevy87blazer]

Hey, where's your avatard? You have 107 posts!

?????

[Prerunner1982]

what chevy87blazer? what are you confused about?

[racedvl]

My 86 GMC 305 is pinging. It does the same thing you decribed. I have tried retarding, and high octain, witch have helped, but it's still there. SoI am planning on pulling the heads and wire wheeling the carbon off my valves. When I did the intake last weekend I looked down the intake ports and saw the carbon on the intake valves, and I'm sure it's on the exhaust as well. I'm also thinking that it will be a good time to slip a RV cam in it, and some new lifters. . . I would really like to find some Vortec 305 heads, but now it seems that I can't find any used ones now. .

[chevychic]

Originally posted by racedvl
My 86 GMC 305 is pinging. It does the same thing you decribed. I have tried retarding, and high octain, witch have helped, but it's still there. SoI am planning on pulling the heads and wire wheeling the carbon off my valves. When I did the intake last weekend I looked down the intake ports and saw the carbon on the intake valves, and I'm sure it's on the exhaust as well. I'm also thinking that it will be a good time to slip a RV cam in it, and some new lifters. . . I would really like to find some Vortec 305 heads, but now it seems that I can't find any used ones now. .

When you get done with yours, wanna come do mine?

LOL

[79BIG10]

Heather have you tried the tranny fluid down the carb yet? That worked for my old engine. Much safer than the water trick.

[racedvl]

Maybe, for a nice turkey dinner. . .

[mike reeh]

avatar will be arriving shortly! dont think I havent been thinking about it

mike

[monypit]

it might just be a small exhaust leak at the collector the lead doughnut might have wore out or the bolts come loose sometimes. You would notice pinging on acceleration in any gear and you said it only seems to happen in 4 so i would bet that it is just an exhaust leak. I had the same thing happen to me on my other blazer and my brothers at the same time. 4.96 for a new doughnut and it was all better

[CustomChevy]

For diagnostic sake, try manually keeping your tranny in 3rd, 2nd, and 1st gear. find out if it does this in each individual gearset. if it is only doing this in 4th gear, there is more likely a prob with your tranny.

you did say your flexplate was loose, but i doubt that the starter was being affected because the starter gear moves back in after starting.

also, have you checked your lifters? common problem on accleration if the nuts are not adjusted properly.

your exhaust leak could be just that, a leak possibly at your manifold-to-pipe connection. see if any of these bolts are loose and tighten as necessary. it could also be the cause of the tick noise. also check manifold-to-head connection.

hope this helps out!

[82 Silverado 4X]

Didn't 1982's and up have Electronic Spark Control and a Knock Sensor that tied into the computer to retard the timing to prevent pinging? Could be a bad sensor if you've exhausted all other solutions.

[apstguy]

Mine has the same described metal tick - except mine happens at 20 mph. It has always done it so I don't worry about it.