RPMs increase but power doesn't - Team Camaro Tech
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post #1 of 20 (permalink) Old Jun 22nd, 09, 11:31 PM Thread Starter
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Brian
 
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RPMs increase but power doesn't

I am having a problem which I thought might have been a carb accelerator pump issue, but now I'm wondering if it is a transmission problem.

When the car is warm, if I accelerate, it seems like more often than not, the engine RPMs will increase, but I don't feel any additional power or acceleration. If I slowly hit the gas, then I do accelerate slowly, but if I am slightly aggressive or want to really accelerate to pass a car, the RPMs increase but the car doesn't go any faster. I'm pretty sure it's not the accelerator pump anymore, because I'm pretty sure it's not a hesitation or bog.

Does this sound like a transmission issue? If you need more info, I'll tell you all I can, but I'm not sure what direction to go in so I don't know what other signs or symptoms I need to look for.

I bought this car early this year and it hasn't always done this. The transmission looks clean so I thought it would have been a recent rebuild, but I know the previous owner put in a new engine after blowing the last one so who knows what kind of damage has been done to the transmission.

Should also mention that the transmission leaks but I'm not sure from where (fluid looks good though)... it's always leaked but it seems like it's leaking more now than it did before. I'm thinking I might need to hurry up and swap in the 700r4 I was planning on...


I also think I may have answered my own question....
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post #2 of 20 (permalink) Old Jun 23rd, 09, 05:38 AM
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Charlie
 
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Re: RPMs increase but power doesn't

To be honest, it sounds like the tranny is worn out. You mentioned that the tranny leaks. Before you try your hard power accelerating, are you making sure that the tranny fluid is where it's supposed to be? Low fluid levels will make for a slipping tranny. If the fluid levels are correct and you still get the slipping, then it more than likely indicates a tranny where the clutch packs are worn to the point of needing a rebuild. I was close to this point. My original 67 Powerglide would leave hard and pull, but shifting from low to high it would take some time. I went to the next level and ditched the PG and went to a TKO 600. I run 4.10's and wanted to be able to drive the car on the highway. The reason for going to the manual is I was bored of just puting it in gear and going. It sounds like it's time for either a new tranny or to rebuild this one. Find yourself a GOOD tranny shop. They have gauges they can hook to the input and output ports of the tranny and gauge what condition the tranny is in. Hope this helps.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #3 of 20 (permalink) Old Jun 23rd, 09, 11:16 AM Thread Starter
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Brian
 
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Re: RPMs increase but power doesn't

Yeah, I filled up the tranny with fluid before I drove it. It seems to shift fine but once I'm in third (which is at around 30-40 mph thanks to 4.11 gears), and I need to accelerate faster than a grandma, I hit the gas and the RPMs increase but the car doesn't speed up.

I already got a 700r4 sitting in my garage (and the best tranny shop in town). I was planning on waiting until after I moved in to my new house to spend 2 grand beefing it up and swapping it in, but stuff happens...
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post #4 of 20 (permalink) Old Jun 24th, 09, 03:31 PM
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Bill
 
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Re: RPMs increase but power doesn't

Sounds like you cooked your trans with low fluid level. Quick, temporary fix; fill it with power steering fluid. It will swell the internal seals. ..... P.S. This solution might work for hours or years. Depends how bad it is and how hard you beat on it.
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post #5 of 20 (permalink) Old Jun 24th, 09, 03:35 PM Thread Starter
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Brian
 
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Re: RPMs increase but power doesn't

And run the transmission with the power steering fluid? Is this safe?

If it doesn't help, would it have been safer to just stick with transmission fluid? I mean, could it cause any problems?
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post #6 of 20 (permalink) Old Jun 24th, 09, 04:31 PM
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John
 
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Re: RPMs increase but power doesn't

What kind of car do you have, could it be a stopped up cat conv, bad exhaust system?
Could be trans, or other things?
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post #7 of 20 (permalink) Old Jun 24th, 09, 04:56 PM Thread Starter
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Brian
 
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Re: RPMs increase but power doesn't

It's a 68 Camaro. The transmission is a TH350 w/ shift kit. I have brand new Magnaflow exhaust behind brand new headers and no cats. I have a feeling it's the transmission. I'm going to go drive it today and see how it does if I get some wiring done, but I'm pretty sure I'm just going to have to put in the 700r4 sooner than I had hoped.
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post #8 of 20 (permalink) Old Jun 26th, 09, 03:27 PM
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Bill
 
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Re: RPMs increase but power doesn't

You are not running straight p/s fluid, just filling the trans. So it will be a mix of trans fluid and p/s fluid. Is it safe? Yes, it wont blow up or anything. Could it cause problems? Yes, but again, if the trans is cooked, which it sounds like it is, what do you have to lose? I got this whole thing from an article I read years ago which basically said that "Transmision overhaul in a can is basically just power steering fluid." I know it works because I put it in a slipping trans I had and it immediately worked better and lasted until I sold the car (months later). Feel free to get other opinions on the topic. Good luck.
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post #9 of 20 (permalink) Old Jun 26th, 09, 05:46 PM
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Re: RPMs increase but power doesn't

When I had my TH350 in my 68, I had the exact same problem. I knew it was the tranny. Got to the point where I would only drive on side streets as anything over 40 mph would do what you just described. Then the reverse went out so I could not backup against any slope but would have just enough pull on level ground. I kept driving it just had to make sure I would never get myself in a position where I had to backup against a slope. Then one day the big D went out as in "Drive". I got a stage-3 700R4 now and it's all happiness again.

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post #10 of 20 (permalink) Old Jun 27th, 09, 12:12 PM Thread Starter
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Brian
 
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Re: RPMs increase but power doesn't

Ok, so I drove the car today and got a better feel for the symptoms.

I start out in first, and the engine seems to rev up much faster than the car is actually moving forward.

Then I shift into second and it shifts fast and jerks into gear (has a shift kit).

Again in second, the engine seems to spin up fast but not much increase in speed, and again I shift and it jerks into third.

Once I'm in third, I think it normally accelerated alright, but I wasn't really pushing it at all today... just nice smooth throttle adjustments.

So the actual shifts are tight... does this shed any new light or just reinforce what you guys already thought?
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post #11 of 20 (permalink) Old Jun 27th, 09, 02:55 PM
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Re: RPMs increase but power doesn't

Could be a bad sprag in the torque convertor. The sprag holds the stator inside the convertor still under load but allows it to free wheel a bit when cruising. When the sprag fails, the stator won't redirect fluid in the torque convertor properly which will make it feel soft.

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post #12 of 20 (permalink) Old Jun 27th, 09, 04:52 PM
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Re: RPMs increase but power doesn't

I'm betting on a toasted trans. The higher the speed, the greater the load - air friction.

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post #13 of 20 (permalink) Old Jun 29th, 09, 08:09 AM
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Re: RPMs increase but power doesn't

Like I said in my 1st reply, take it to a tranny shop. They have gauges they can hook to it and tell you if it's producing the correct pressures or not.

Charlie Knudsen 67 Camaro RS/SS 350 TKO 600, 4.10's, AFR 195 Street Heads, Comp 270H, Rhoads Lifters, Crane Ignition, Pertronix Dizzy, Performer RPM Q-Jet, Heavily Modified Q-Jet, Hooker Comp Headers, MagnaFlow 2 1/2", 144 Decibles(Alpine CDA-7998 Head Unit, RF X7 and RF 750X Amps, MB Quart Mid's & High's, Kicker L7 12" Solo Barics)
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post #14 of 20 (permalink) Old Jun 29th, 09, 10:34 PM
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Re: RPMs increase but power doesn't

I had a 700R4 that did the same thing when the trans went out. An auto still has clutch packs in it and what you're seeing is slippage. It may be the pump but it doesn't take much driving one around with one bad part to take out all the rest. If it doesn't have a manual valvebody and won't upshift in drive, that's a sure sign. That's what mine did and it wouldn't accelerate in third, only rev.

When I had mine rebuilt, the pump they put in failed and it puked fluid out and wouldn't even move.

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post #15 of 20 (permalink) Old Jun 29th, 09, 10:46 PM Thread Starter
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Brian
 
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Re: RPMs increase but power doesn't

Alright, since this definately isn't looking like an easy fix, I finally decided to go for a 2004r (instead of the 700r4 I picked up). Going to get this in there asap rather than attempting to fix the th350. Thanks for the insight everyone, it cemented my decision to swap in a new trans instead of waiting.
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