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1970 DeVille exhaust manifold

Started by cmwolf, November 08, 2015, 05:30:27 PM

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cmwolf

All,

I had an exhaust gasket blow out. All the bolts on the drivers side came out very easily. The passenger side bolts holding the manifold on won't move. Any suggestions to get these bolts out without snapping them off? I've been spraying them with PR Buster and Sea Foam lubricant for a couple days now.

Thanks,
Chris

chrisntam

These can be problematic.  When I pulled my engine apart, I recall two breaking off.  Some suggest trying to tighten them slightly, then loosen.  Some also say a quick loosening motion like from an impact wrench or good wollop from a large mallet on the wrench.  I understand the slow twisting motion isn't a good thing on cranky bolts.

Clean the threads really well, possibly new bolts and anti seize upon reassembly.

Hopefully, others will chime in with their magic potions!!

chris.
1970 Deville Convertible 
Dallas, Texas

Jeff Rosansky CLC #28373

50/50 mix of acetone and ATF. Let it soak for a few days and reapply often. Keep away from paint. Be sure you have a very good socket/wrench and be sure ot is square on the bolt. Uou mayneven need to undersize the socket with a metric one because asbthe bolts rusted over the years they have gotten smaller--_-- wish I could do that.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Tito Sobrinho

I used to go to a "junk yard" where they had 2 Cadillacs (1950-1952). From the '50 I got a harmonic balancer, exhaust manifold and other things using NAPA's Super Penetrating Oil on very rusty bolts. I was able to remove them with ease, but I don't know if they still manufacture it as my trips to that locale was 20 years ago.
Tito S.

1949 CCP 6267X  (First Series)

Thanks to Frank Hershey for its design and thanks to Harry Barr, Ed Cole, John Gordon and Byron Ellis for its engine.

savemy67

Hello all,

I have to remove the exhaust manifolds on my 429.  The bolts angle upward.  Capillary action may draw some of my penetrant up towards the threads in the cylinder head but I am not holding my breath.  On the 472, what is the angle of the exhaust manifold bolts relative to horizontal?

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

TJ Hopland

#5
Not sure what the reason or rhyme is to how stuck they get.   I have had cars that are so rusty you can reach through a rust hole in the body and they just spin out.   Have then had other cars that look new where every one is stuck.   Heck you even see that on the same engine,  a couple come out and others don't and you can't see any reason why some would be stuck. 

Problem with exhaust manifolds is they can be stuck in several places.  You could have the head stuck to the manifold.  You could have the stud part stuck in the hole in the manifold.   You could have the threads stuck in the head.   Most of the time you end up with a combination of all 3.    Problem with the threads is you can't really get any heat or lube where you need it because the manifold is in the way. 

The logic behind going tighter is that you have a better chance of getting some lube in there.  What you want to do is rock it back and fourth while adding the lube and ideally heat.   At first you get a tiny bit of movement (hopefully not the bolt starting to break) so you add more lube and heat and every cycle you get a little more movement till you finally are able to unscrew it.   

For sure the worst thing seems to be a 'breaker bar'.   That has always resulted in broken bolts for me. 

I have had some luck with my cheap worn out air impact or smaller battery powered impacts.  I just let it hammer away for a few seconds one way then the other way.  The big good impact usually seems to snap em off.   

If they don't seem like they are going to come out the best thing is to remove the heads from the bolts.  If you just break em most of the time they will break flush with the head which then is a real pain to get out because they have to be drilled which is usually very difficult or impossible in the car.  Sometimes you can weld a nut to them but that too can be difficult in the car.   If you remove the bolt heads you can usually pull the manifold off leaving the studs sticking out the cylinder head.  You now have access to get heat and lube at the threads and its a fairly easy proposition to get them out with a vice grip.  I have seen guys that can knock the heads off with an oxy acetylene torch with no damage to the manifolds.   I don't have that sort of skill with the torch so i usually end up grinding em off.   Sounds like a lot of work but I really think its less work than drilling.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

cmwolf

Thanks everyone for the help.  This will be my first main project on my new "Beast". 

The bolts seem to go upwards so it has been difficult for the lube to penetrate, it runs off. I also made the acetone/ATF concoction and put that on tonight. I will continue till the weekend. That is when I will work on it. I will keep you all updated.

This weekend if all goes well....
Pertronix ignitor II to replace points
oil change
trans fluid and filter change
plugs
wires
exhaust manifold gaskets
bleed all brake fluid and replace
Maybe find out what the clunking sound is in the front end when I stop fast
Gonna be busy

76eldo

Welcome to the CLC message board.

Best of luck with your repair.

Are the manifolds leaking badly and making a lot of noise?  I have replaced manifolds on a 76 Eldorado and it's not too much fun.

I have a 76 Eldorado that makes a slight ticking sound when cold due to some snapped off manifold bolts but it quiets down when warmed up.  If your is not really loud maybe let this go until you need to do more engine work?

I know that guys like the Pertronix in their cars but I run points in my 60 and 70.  Easy to maintain and I have no fear of an electronics malfunction.  Just my opinion.

1970 was a great year for Cadillac.  Have fun with yours!

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

TJ Hopland

Quote from: 76eldo on November 09, 2015, 11:14:43 PMIf your is not really loud maybe let this go until you need to do more engine work?

That is good advice for a car you just got.    May be other things that come up as you get to know the car. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

76eldo

I think these manifolds were originally installed without gaskets, just a metal to metal fit.  I never understood why either.

If the passenger side is NOT leaking Id leave it alone.  It's OK to just do the one side.  If the bolts came out easily I would assume it's been apart before.  These gaskets don't just blow.  Chances are your manifold may be warped and not getting a good seal.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

cmwolf

Well...It didn't go so great. One bolt head snapped off and the bolt is still sticking out of the head, one snapped off flush with the head, and one somehow snapped a 1/4 of an inch off deep inside the head. Jacked up the motor and removed the exhaust manifolds. Decided I'm going to have to take the heads off and have the valve job and have the guides replaced, plus remove the stuck bolts.

Oil changed
Transmission drained
Didn't touch the brakes
I did find out what might be making the clunking sound. Missing some rubber bushings on the front end.
I thought about sending off the carburetor and sending it off to be rebuilt, but I need this up and driving for the week of christmas. I'm think I'm going to wait for that


chrisntam

Well, crap, that sucks.  Sorry to hear.  Unfortunately, that happens when working on an old car.  Hopefully you can get it all back together by Christmas.  Is that about six weeks?
1970 Deville Convertible 
Dallas, Texas

cmwolf

Yes about 6 weeks. The whole reason was to take the Caddy down to Virginia Beach with all the kids in the back seat with blankets and see the Christmas lights. My kids are only in town from WI for the week of Xmas. They were with me when I test drove this over the summer, but have never been in it once I bought it. They loved riding in the back seat with the top down! I have to get the bolts out, but I think I will wait to pull the carb and send it out until after the new year.

Jeff Rosansky CLC #28373

Ouch.
Sorry to hear that.
Good Luck.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

WTL

I guess I will post here, to be helpful to people using the search feature.  It's not quite worth a new thread, but might be helpful. 

I just got both my manifolds off with no broken bolts. I had been worried about this job for quite some time, to the point of tolerating a leak I probably shouldnt have. 

3 quick points that seemed to help. 

1.  Take your time.  Don't be afraid to soak, and soak and soak.  Don't use a ton of torque, but rather focus on making the head of the bolt move.  Try tightening it a bit, then loosening it.

2.  As I said, soak...wd40, pb blaster, acetone/atf....but one that hardly ever gets mentioned is melting candlewax so it wicks in the threads.  It really seemed to help in breaking the seal of the rust. 

3.  I tried 9/16 ratchets, and every wrench I had, but it was still a knucklebusting experience until I happened on a Cromwell 14 mm wrench.  14 mm is a little tighter and it really helped.  I normally buy cheap tools, but maybe it's a little bit better than a harbor freight wrench.

TC

Good info.

Your use of a different size wrench reminds me of another issue with exhaust manifold bolts. I guess the high heat plus rust often makes the bolts heads smaller causing a loose fit with a wrench or socket wrench ending with a stripped bolt head. Nutcracker type sockets work well in these instances.