Small block C6 questions

Cougar Community Classic Cougar Maintenance Restoration and Repair
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Hey all, I’ve got a small block c6 in my 69 that was put in about 15 years ago. Shortly after the install the car went into storage for 10 or so years so it’s got less than 1k miles on it. I have a couple problems I was hoping to get some feedback on.

The tranny has 2.8 to 3k stall converter, e4od first gear, redline clutches, and might be rollerized. All I remember is telling him I was worried about the c6 eating so much HP but he said “not the way I build them” :slight_smile: Oh and the tag is gone but the casting number is D4OP-7006-BA making it a 74. Runs good, changes gears smooth.

The first problem is that I remember the builder saying to use the ATF on the dipstick tube. Well I had a cooler line start leaking and lost some fluid, I went to replace it and realized that the dipstick tube isn’t from a ford. The part number on the dipstick is 1387568 which is a GM turbo 400 and says Dexron so that’s prolly whats in it. 74 c6 should have type F right?

Second problem is it whines like mad in park and neutral but not in any gear. I’m not sure if the wrong fluid could cause this or possibly the wrong fill line since the dipstick is not made for the c6. It’s done it since it was rebuilt. You can hear it on this video that my exhaust guy posted on his Facebook page:

https://www.facebook.com/muscletonesexhaust/videos/635602333445650/

Sorry for the long post, I really really hate that whining, it’s embarrassing when your sitting at a show! Do you guys think it could be fluid related?
Charles

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You can use either Type F or Dexron/Mercon 3 in the C-6. I’d look for the correct dipstick tube and stick. It’s possible this GM stick is the right length, but to find out, you’d have to remove the tube from the car. Put the stick in the tube and note where the crosshatch area is on the stick in relation to the bump on the tube. I’d rather have a part that says Ford. But if the GM stick happens to be correct and doesn’t bother you, then leave well enough alone.

Switching between type F and DM3 isn’t going to make the trans whine. Sucking air because of low fluid level could make the pump whine. But, it would continue to whine when put in gear too. Or, if it whines in P or N then goes silent in D or R, it could be a bearing making noise. Does the whine occur when you start rolling in 1st or 2nd gear then go away in 3rd? If so, I’d look towards a bearing in the forward drum area.

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Thanks for the input. It stops whining immediately as soon as you drop it into gear so it seems to be only when in a low pressure mode. There is no whine in any forward or reverse gear.

I read somewhere that DM3 was a 5W oil and F was a 10W (I don’t know of this is true or not). It’s what got me thinking that a heavier oil might quiet down the front pump.

I think I might drop the pan to have a look and make sure the filter and bottom of the pan is clear of debris. If I decide to put type F it will be a mix since I can’t drain the converter (no drain plug) Hopefully that doesn’t cause problems.