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Old 08-09-2018, 11:05 PM   #1
Tkrysl
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Engine Revs Up but doesn't move truck any quicker

Total newbie to my truck but I'm learning everything I can.

72 C15 250inline.

Finally got her rolling and licensed! When I am driving down the road, she rides and drives great BUT when I get on the gas pedal good, the truck sounds as if it is revving up to take off but doesn't.

I'm assuming this isn't normal? Apologize in advance for ignorance!

Thanks,
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Old 08-09-2018, 11:08 PM   #2
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Re: Engine Revs Up but doesn't move truck any quicker

If manual trans, is your clutch slipping?
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Old 08-09-2018, 11:10 PM   #3
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Re: Engine Revs Up but doesn't move truck any quicker

Sorry. It is a 3speed manual. I can't answer the question I guess because I wouldn't know what a clutch slip felt like?

Nothing seems out of the ordinary except the reving.
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Old 08-09-2018, 11:14 PM   #4
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Re: Engine Revs Up but doesn't move truck any quicker

On a manual transmission the engine speed and the transmission output (vehicle speed) are directly related. If the engine revs and the speed doesn't increase it means your clutch is slipping. You may be able to adjust it if it's not too worn.
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Old 08-09-2018, 11:16 PM   #5
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Re: Engine Revs Up but doesn't move truck any quicker

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Originally Posted by Tkrysl View Post
Sorry. It is a 3speed manual. I can't answer the question I guess because I wouldn't know what a clutch slip felt like?

Nothing seems out of the ordinary except the reving.
Clutch slipping is exactly what you are feeling. It may be adjustable, if not you will need a new clutch. Take it to a good mechanic and get his opinion....

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Old 08-09-2018, 11:18 PM   #6
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Re: Engine Revs Up but doesn't move truck any quicker

Gotcha. Assuming a clutch adjustment isn't for the shade tree mechanic?
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Old 08-09-2018, 11:18 PM   #7
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Re: Engine Revs Up but doesn't move truck any quicker

I don't have any pics of the clutch linkage and throwout fork to show you what to look for. Someone will help out soon. If you do a search for "clutch adjustment" that should head you in the right direction.
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Old 08-10-2018, 01:00 AM   #8
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Smile Re: Engine Revs Up but doesn't move truck any quicker

If might be your clutch is slipping.
.....or did you buy a Ford by mistake?...recheck the registration.

all good
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Old 08-10-2018, 06:51 AM   #9
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Re: Engine Revs Up but doesn't move truck any quicker

Easy clutch check .

In a safe parking spot start your engine and set the emergency brake and keep your foot on the brake ,with the truck idling shift to 3rd gear and slowly release the clutch . If the truck continues to run you need clutch repair or replacement if the truck stalls you likely just need an adjustment
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Old 08-10-2018, 07:40 AM   #10
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Re: Engine Revs Up but doesn't move truck any quicker

clutch adjustment is relatively easy....clutch replacement....not so much.
If you aren't too mechanically inclined...take it to a mechanic that you trust...
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Old 08-10-2018, 08:10 AM   #11
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Re: Engine Revs Up but doesn't move truck any quicker

I think Loc Doc suggested having it looked at by a shop because it sounds like you need someone more familiar with mechanical operations to evaluate. We are only guessing by what you describe. Also, a slipping clutch doesn't happen overnight. If that is what the problem is, we need to know how long it was slipping. The long it is allowed to slip the more damage done. The clutch surface could be glazed or worse, material worn away. Once the surface gets glazed you will not get proper clutch performance even after the simple process of adjusting the clutch.
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Old 08-10-2018, 09:00 AM   #12
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Re: Engine Revs Up but doesn't move truck any quicker

I'll get it up on the rack and have a look. It's at 64k but I just got it. Sat in a barn since 1993.
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Old 08-10-2018, 09:21 AM   #13
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Re: Engine Revs Up but doesn't move truck any quicker

Where does the clutch grab when pushing the pedal down? Top or bottom?
If it grabs at the bottom, you may just need to adjust it to grab higher to get more engagement with the clutch. This is very simple to do and remember, a few turns makes a huge difference in the pedal.

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Old 08-10-2018, 09:27 AM   #14
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Re: Engine Revs Up but doesn't move truck any quicker

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I'll get it up on the rack and have a look. It's at 64k but I just got it. Sat in a barn since 1993.
check the linkage to be sure it moves freely....sitting that long...it could be a bit sticky....have someone push the pedal down and watch the fork on the bellhousing to see if it's moving freely back and forth...
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Old 08-10-2018, 12:04 PM   #15
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Re: Engine Revs Up but doesn't move truck any quicker

Another possibility is the rear main is leaking from sitting and you have a wet clutch. You'll see the mess before going into it. Depends on how much it's been run since sitting. You have the inspection pan for visual inspection.
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Old 08-11-2018, 02:18 AM   #16
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Re: Engine Revs Up but doesn't move truck any quicker

I remember when Motor Trend did a report on a 72 vega with an automatic. They also said that when you stepped on the gas to accelerate it made more noise but didn't move any faster. I drove one for 3 years and that is very much the truth.

but when a clutch slips there is also an unmistakable smell. like very hot brakes. dead give away. If the cause is related to oil on the disc, then you will smell hot brakes smell and burning oil smell too.

dont play around with it too much or you could ruin the flywheel too.
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Old 08-11-2018, 10:31 AM   #17
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Re: Engine Revs Up but doesn't move truck any quicker

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Originally Posted by mike16 View Post
I remember when Motor Trend did a report on a 72 vega with an automatic. They also said that when you stepped on the gas to accelerate it made more noise but didn't move any faster. I drove one for 3 years and that is very much the truth.

but when a clutch slips there is also an unmistakable smell. like very hot brakes. dead give away. If the cause is related to oil on the disc, then you will smell hot brakes smell and burning oil smell too.

dont play around with it too much or you could ruin the flywheel too.
I don't smell anything. Here is a picture of what I believe is the adjustment rod. My manual doesn't say to tighten or loosen. Any advice?
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Old 08-11-2018, 04:04 PM   #18
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Re: Engine Revs Up but doesn't move truck any quicker

Sorry. Here's the pic.
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Old 08-11-2018, 04:05 PM   #19
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Re: Engine Revs Up but doesn't move truck any quicker

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Originally Posted by Grumpy old man View Post
Easy clutch check .

In a safe parking spot start your engine and set the emergency brake and keep your foot on the brake ,with the truck idling shift to 3rd gear and slowly release the clutch . If the truck continues to run you need clutch repair or replacement if the truck stalls you likely just need an adjustment
Ok thanks. It died.
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