coolant leak from exhaust manifold bolt?

[ultimatejay]

Hi everyone, new member here. Just bought a clean 1970 Duster with a 225. This is my first Plymouth coming over from Chevy so I dont know a lot about this engine. The engine runs amazing, crazy how smooth this engine runs. its smoother than my fuel injection engines. Anyways, i noticed a little smoke coming from the rear of the cylinder head. Upon closer inspection there was a tiny tiny leak coming from the upper rear exhaust manifold bolt- the one closest to the firewall. The previous owner just replaced the exhaust manifold because it was cracked and the bolt was slightly loose. i tightened the bolt and the leak is now gone. There is no smoke coming out of the exhaust and engine runs perfect like i said. Question is there a coolant passage behind that bolt?

 

[Rmoore]

I know the big block do ! Not sure on the slant ! Odds are it does though

 

[66 Valiant wagon]

Hmmm. I have a 66 slant 225 and I did not have a coolant passage there?
Also don't snug those bolts up too much, they pretty much float there, <10 ftlbs. Too tight and you'll end up cracking that new manifold.

 

[MoparMike1974]

Not sure about the slant but small blocks have studs on each end of the manifolds because they go into the water jacket. I use indian head gasket shellac on the threads and never had a leak.

 

[70dart340]

Rusty Rat Rod will answer your question soon. He's presently tied up at the Oracle of Delphi......

 

[RustyRatRod]

Yes. The two end most fasteners go through to the water jacket. Also, they are not supposed to be bolts, but studs. All of them. They are notorious for breaking off when removing the nuts. Whenever I service one, I now use one of the high end ceramic based brake paste lubricants. Permatex makes a nice one. Just paint the threads good and install them. On the two end most studs, I use Permatex red high temp RTV to seal them from leaking. Rest assured, if you have bolts there, and not studs, it IS still leaking, just not enough to see. There are also special washers and nuts that accompany the manifolds studs. All of that is very important, as since the two manifolds are separate entities bolted together, they expand anc contract at different rates. They must be allowed to "move" a little so that they can expand and contract. If you take some pictures of what you have, we can help you get it right, if it's missing anything important.

 

[RustyRatRod]

Rusty Rat Rod will answer your question soon. He's presently tied up at the Oracle of Delphi......

I'm sorry. That was absolutely hilarious. Thanks for the laugh. I really needed that one. lol

 

[70dart340]

I have a 30 round magazine full of 'em. Heading your way in the next year. Smart *** PM sent, Georgia.

 

[RustyRatRod]

I have a 30 round magazine full of 'em. Heading your way in the next year. Smart *** PM sent, Georgia.

LOL Good. Maybe we can meet up on your way down. That would be cool.

 

[ultimatejay]

Yes. The two end most fasteners go through to the water jacket. Also, they are not supposed to be bolts, but studs. All of them. They are notorious for breaking off when removing the nuts. Whenever I service one, I now use one of the high end ceramic based brake paste lubricants. Permatex makes a nice one. Just paint the threads good and install them. On the two end most studs, I use Permatex red high temp RTV to seal them from leaking. Rest assured, if you have bolts there, and not studs, it IS still leaking, just not enough to see. There are also special washers and nuts that accompany the manifolds studs. All of that is very important, as since the two manifolds are separate entities bolted together, they expand anc contract at different rates. They must be allowed to "move" a little so that they can expand and contract. If you take some pictures of what you have, we can help you get it right, if it's missing anything important.

THANK YOU SIR

 

[BillGrissom]

The rear exhaust manifold stud in my 1969 Dart 225 was leaking coolant. But, that was after the stud broke off and I hand-drilled and tapped it for a slightly larger stud. If it wasn't already into the water jacket, it was after that. I also had to drill the hole in the manifold larger to match (plus slightly offset). Anyway, I fixed 'er by wrapping the stud end with Teflon tape. Today, I would probably coat the threads w/ Peramatex Gasket Sealant, a purple goo which might be mostly butyl rubber. I've used it on water pump bolts in tapped holes which reach a coolant passage or crankcase. It stays gooey, and cleans up easy w/ ethanol.

 

[67belevdere/225]

I just used the liquid pst on mine
Permatex® High Temperature 592 Thread Sealant
, and it worked for me, depending if the threads in the head are really worn
you could use Loctite Form-A-Thread Stripped Thread Repair Kit 236382