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Vacuum problems??

5K views 45 replies 10 participants last post by  Winch 
#1 ·
I've been diagnosing various problems that seem vacuum related with my 68 factory A/C system. Yesterday it acted really strange. The automatic trans kept slipping out of gear, forward or reverse. I could put it in neutral, rev it a bit, drop back into gear and it would usually catch. Then I also noticed the power brakes were super sensitive. I only had it running for a minute while I moved it from one garage bay to another. Sound like a vacuum issue? A few days earlier I noticed a back leak from the A/C reservoir canister (i.e it wouldn't hold it's vacuum when the engine is revved or after it is shut off) so I installed an inline check valve in the hose supplying vacuum to the canister. That seemed to fix the back leak. Could it be a culprit?
 
#3 ·
What is the proper way to check trans fluid level? The Shop Manual doesn't go into that, at least not in the auto trans section. I kinda remember to check some old trans you had to have it in drive gear at idle.
 
#5 · (Edited)
Doh, Checked it like you said and nothing shows up on the stick! I also found I have an exhaust leak at the rear most port. I got my finger close enough to feel the hot exhaust pulsating out from there. I guess I have more work to do on this old thing.

Forgot to ask: is there a modern equivalent to the type ATF listed in the old Shop Manual? Seems like I can never find the type listed for these old cars.
 
#6 · (Edited)
C4s are kinda leak-prone, especially if they sit too much.
I would STAY AWAY from stop-leaks.

The exhaust leak may be "cured" with getting the bolts to the right torque, but don't overdo it, you may hafta RnR it. Be sure you aren't feeling exhaust coming from a heat riser tube port that has no tube in it.

Type F is still available, I have gotten it at Wallet-Mart, AutoZane, O'Really's, Adverse Auto (haha) and is what yours was designed to use. You can use the Mercon Dexron type in a new build but I wouldn't mix the two for a top-off.
 
#8 ·
here's where I feel the exhaust leak. Looks like the gasket has burned through. Looking at this again I remember what a bear that A/C compressor was and it appears it has to be moved to get at the front bolts. I might put this one off for a bit.
 

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#10 ·
Put a quart and a half of type F in it. Seems to have fixed that problem. I got it a little over the full mark. So far I haven't seem any foaming. Do I need to worry about that?

Now back to that exhaust manifold gasket. It definitely needs replaced. I'm having a problem getting a socket on any of the bolts. I'm sure they are 1/2 inch but I can't get either 6 point or 12 point on any of them. I've wire brushed one and used PB Blaster with no luck yet. I tried a 14 mm on one but it started to round off the edges and of course 13 mm won't go on either. Any tips?
 
#11 · (Edited)
The bolt heads are probably rusted to the point that they are "in between" sizes. IIRC, all the Ford exhaust manifold bolts are 3/8-16 and should have a 9/16" head. 14mm is only .012" smaller than 9/16. It might grab it if you use a good 6 point socket.

Be very careful when removing the bolts. Crack it loose, then tighten again, loosen 1/8 turn, tighten. You want to go maybe 1/8 turn more at a time. Keep hosing it with Blaster until it starts to come out easily. If you feel resistance, stop, spray it, and turn it back in a couple turns.
 
#12 ·
I just ordered a 17/32 socket from Home Depot. It's 12 point and for a 3/8 drive so it might not work. I did see a 1/2 drive 6 point 17/32 on Amazon which I might have to try if the 3/8 drive doesn't work.
 
#13 ·
Take Hemikillers advice..all of it!
Especially..the use a 6 point socket. TOO easy to round a rusted bolt with 12pt..
Good luck.. and take your time..allow the penetrant time to work.. you won't want to spend your time removing broken manifold bolts from your engine.

Sent from my SM-G950F using Tapatalk
 
#14 ·
Looks like there are 2 brands of exhaust manifold gaskets available, Fel-Pro and Mahle. Is either better? It's interesting that Fel-Pro costs more at O'Reilly's but half the cost of Mahle at Rock Auto.
 
#15 ·
Keep in mind that sometimes the easiest way to gain access to a nut or bolt is from a different vantage point. For example, on a big block motor some of the lower exhaust manifold bolts are best reached from below the car using extensions, and universal joints to get around obstacles. Also start several days early with PB Blaster (penetrating oil) on all the nuts and bolts reapplying it several times. Rusted nuts and bolts are prone to breaking off if forced. Too much force can lead to broken bolt extractions and they are usually time consuming and a PITA. Be patient. If nothing works, look into heat (a torch) to take advantage of expansion and contraction of the rusted metal. Lastly, once the exhaust manifold is off the engine, have it checked for warpage of the mating surface. A machine shop can true up that surface by re-surfacing the mating surface if needed.
 
#17 ·
I wonder if my problem has to do with locking tabs on the exhaust manifold bolts. The Shop Manual says to bend them back before removing the bolts. I can't tell if I have them on there or not. Of they are, then they are all under where I can't see them. I think maybe I can feel one on the one bolt I've been trying to loosen but I can't get a very small screw driver to catch it to bend it back.

I got a 17/32 3/8 drive 12 point and tried it this morning. It fit on pretty well but rounded it off when I gave it some torque. I guess I should have waited to find a 6 point. I'm about to give this up or find someone who will take it on. Anyone know of a shop that would attempt it in the St. Louis area?
 
#18 ·
I'm not sure if Ford used a gasket there, originally, or not. After removal, give it a good hard look over.

FWIW, when faced with the possibility of snapping a bolt off in the head (with my luck, usually either flush or worse), I've resorted to lopping the heads off the bolts, removing the manifold, then using heat and my stud remover to get the remainder of the bolt(s) out in one piece.

 
#19 ·
I'm starting to look at new manifolds if need be. I see Summit has one for 200 CID 6 cyl but the years of application listed are for 1964-67. Is the 68 manifold different?
 
#20 ·
Here is a pic of a 6 cyl bolt set. I don't see any locking tabs like for a V8 in the 2nd pic. Can I assume a 6 cyl didn't have them?

Also if I apply heat, using a propane torch like I use for sweating copper pipe, where would I direct the flame? Onto the manifold or where the manifold meets the head?
 

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#24 ·
How good are those bolt extractor sockets? I've been watching uTubes on them. I'm going to try to wire wheel the heads I can get to today and see if I can't get a 1/2 inch 6 point on them but if not maybe I'll try those extractors.
 
#25 ·
Don't be afraid to hammer a socket onto the bolt head. Usually a 12 point works best for this. Maybe a 13mm 12 point would get you there. Go down to your local hardware or home improvement store and pick up a couple varieties of socket around that range. I find that sometimes one socket will work, but the identical size in another brand won't. Once you have the bolt out, you can clamp it in a vice and lever the socket off.
 
#26 ·
Well it's off. 5 Bolts broke off. Three I think are long enough to get out but one is only about 1/8 inch out and one is flush. I'll try an easy out with those. Worse case scenario I'll have to drill and tap. What is best way to get the studs out that stick out a bit? One is 2 inches, one is 3/4 inch, and one is about 1/4 inch out. I've doped them all up with more Liquid Wrench now that I can get to them better.

The manifold looks pretty good still but probably will need resurfacing and truing up.
 

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#31 ·
I'm afraid of doing damage to the head if I try to weld a nut on. Especially to the ones that are flush. I don't see how to do that and I expect my weld wouldn't hold anyway. I have broken off an easy-out before and that is a pain. I'm finding the ones long enough to grab with a pipe wrench are still not coming out easily. I haven't put enough pressure on it yet to snap off the remaining bolt. I keep dowsing them in penetrating oil and maybe I'll try heat next.

Once I'm ready to reassemble, can I use grade 5 bolts from the hardware store or should I stick with a set of manifold bolts? I don't think the ones from CJ in this pic are exactly like I need. The six 1 inch ones are correct but I have five 2 1/2 but the ones in this pic look like three 1 3/4? and 2 odd longer ones. I'm sure those are for some accessory I don't have.
 

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#32 ·
You weld through the center of the nut. You can also weld through the center of a large fender washer, then weld a nut to the fender washer.

I'd use the proper manifold bolts vs. trying to match up what would end up as a bolt too short or too long for the application. Make sure you chase the threads and clean out the holes of any debris before putting new bolts in.
 
#33 ·
I just went to the machine shop and he said my manifold is beyond repair. The end that had the leak has burned the metal away to the point he said he would not be able to machine it off enough. So I guess I'm in the market for a new one. Oh well that will give me time to play with getting the broken bolts out. Fortunately this is my wife's car and she seldom drives it.
 
#34 ·
I'm going to try welding nuts on. At least onto the shot stubs sticking out. Do I need to do anything else like remove the carburetor or make sure there is no fuel close by?

And if I try to weld onto the flush studs, how do I hold the nut or washer on there? Magnet? I don't see any way to clamp it down.
 
#35 ·
Welding nuts on was a bust. I could not get the stud to melt. I guess my little 110v Miller doesn't get hot enough. It melted the nut fine but never would fuse to the stud properly. I think it would have just twisted the stud off anyway. I think I'm going to have to drill them out and re-tap.
 
#37 ·
Since your welder doesn't get hot enough to weld to the broken bolt a way to remove them is to heat the bolt to orange color just before it melts and let it cool. Heat again and cool. This breaks the rust bond between the head and the bolt. A propane torch won't do it- you need an acetylene torch.


I wouldn't try to drill out the broken bolts that are flush with the head on the engine. The bit will "walk" off to one side and you'll ruin the drilled and tapped hole in the head. Just remove the head and take it to the machine shop if necessary.
 
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