Vintage Mustang Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
123 Posts
Discussion Starter #1
in my 67 i have a i6 with a c4 trans, i posted earlier about my engine knocking at about 60mph, the trans has leaks, when i changed the radiator about two drops came out of the trans lines. im wondering if the transmission is low on fluid will it cause a knock?
 
G

·
Guest
Joined
·
0 Posts
Being low on transmission fluid won't cause a knock in your engine. Try using Supreme gas. If that doesn't help, then get back and describe the knock.
 

·
Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
Joined
·
20,827 Posts
When you change radiators out it's normal to lose very little ATF fluid from the open fittings. It tends to run back into the transmission unless the lines are actually on the floor or something, then you'll have a flood.
 

·
Registered
Joined
·
3,595 Posts
Anthony,

Make sure the ATF is warm in your C4 before checking the fluid with the dipstick, and make sure the car is sitting level. Check with the engine running and the transmission in "Park". To add oil, get a small funnel and put it into the dipstick tube, just a few ounces at a time. Do NOT overfill the tranny!

We need more information. "my engine knocking at about 60mph" isn't very descriptive. As I recall in your previous post, you were coasting down a hill and heard a noise you described as "knocking". The noise went away when you applied your brakes. This doesn't sound to me like it has anything to do with the engine, so if you leap to that conclusion, any suggestions you get from the group here will be flawed.

So, I understand you heard a knocking noise, but how do you know it was coming from the engine? There are a lot of things that cause noises. Do you hear any "knocking" noise when you first start the car after it has been setting? Do you hear anything when you are lugging the engine at 30 mph in high gear? Do you hear anything when you are just cruising at 60 mph on the level and let off the gas? What is your oil pressure at cold idle, and at hot idle?

What things have you checked out under the car? I would suggest jacking the front end up an secure it with jackstands. Then, check each wheel for slack top/bottom, and side/side. If you feel slack, try to determine where it is coming from. Visually inspect everything under the front end to see if looks like it's loose and could be flopping in the breeze at 60 mph. Turn the wheels and see if you hear any kind of noise, and if you do, try to describe the noise to us.

A good description of the problem is essential to make suggestions regarding the cause. See if you can replicate the sound you heard. Have you heard it only once? Is it a clunking sound, clicking, rattle, pinging, is there an associated vibration, etc?????? Does it do it when accelerating, or just when decelerating down a steep hill? It could be any number of things other than an engine knock.

Keep us posted with good information and what things you have done to isolate the problem, and someone will be able to help you with it.
 

·
Registered
Joined
·
3,595 Posts
i just guessed that it was the transmission, i dont know if it is or not. it makes a clunking sound, and it clunks at 60 weather im coasting or decelerating or accelerating. i also think its the trans because when i start it up it makes a clunking sound, when i put it in reverse the car jumps and then clunks, but in 2,1 or drive it doesnt make that sound only at 60. the car also vibrates i dont know how to describe it when i get to about 50 it makes a woom woom woom woom sound while its vibrating. i dont know what the oil pressure looks like whn cold or hot but i will get back to you on that. thanks
Anthony,

OK, now we're getting someplace. I'm posting this on the forum to get more input, instead of just my humble opinion.

With your description above, I would now suspect the U-joints are shot. Most of the symptoms you describe are classic U-joint. I would drop the driveshaft by taking the u-bolts loose from the differential, and then it will just slide out of the tranny. Get it out to where you can really check the u-joints for play in them. Any play at all will indicate they are shot. While the driveshaft is out, I would suggest replacing them anyway, unless they are new.

If it's the u-joints making the vibration, and you don't fix them ASAP, you are going to lose the driveshaft while driving down the road. Not a fun thing. You haven't heard any noises yet till you experience the driveshaft turned loose under the car while spinning wildly! ::
 
1 - 5 of 5 Posts
Top