What are the odds of successfully getting the manifold screws out of a 1992 with 260k miles?

Erik the Awful

Supporting Member
Supporting Member
Joined
Aug 9, 2019
Messages
3,860
Reaction score
7,084
Location
Choctaw, OK
While you're backing those bolts out, if one tightens back up as you remove it, take a moment and run it back in one thread, and then start backing it out again. If the threads are binding up on rust, running it back in a little smooths things out. You also need a feel for whether the bolt is turning or if it's stretching, and that's a hard "feel" to teach over the internet.
 

351FUN

Supporting Member
Supporting Member
Joined
Aug 24, 2020
Messages
389
Reaction score
486
Location
US
If you are referring to the exhaust manifold bolts there is a tool that is placed between the front exhaust port and the middle exhaust port on the manifold that spreads the manifold open slightly to take the side load off from the bolts to ease their removal. GM put out a service bulletin on this years ago when these trucks first came out.
Snapon used to offer the tool.

Yeah, years of working industrial has me pedantic about screw vs bolt lol. I'll definitely look at that tool though, that seems like a neat trick.
There are some engine families where the exhaust manifold bolt holes in the cylinder head are open-ended, you can spray penetrating oil on the back side, directly onto the threaded part of the bolt. You stand a chance of having the oil actually wick into the threads and do some good.

On a SBC, none of the holes are open on the back side. The penetrating oil would have to get between the underside of the bolt head and the iron manifold. This is practically impossible. Then the oil has to travel down the un-threaded shank of the bolt to even reach the threads.

Penetrating oil will make a lovely but useless puddle on the ground.

You underestimate how well kroil can seep in. It'll work it's way in eventually.
 

Jsiff

Newbie
Joined
Jun 23, 2021
Messages
3
Reaction score
3
Location
North Carolina
Yeah I definitely want to start soaking them in kroil for a while. The cold shock is a good idea.
yupppp. best thing to do. I swapped mine out on my 99 that has 218k and soaking and soaking with penetrating oil was my best friend. started weeks in advance.
 

tinfoil_hat

I'm Awesome
Joined
Nov 18, 2016
Messages
251
Reaction score
97
Location
Sparks, NV
I would spray the bolts with PB Blaster at least once a day until you are ready to make the attempt. It's very heat tolerant if you choose to heat them up with a torch. I got a 26 year old o2 sensor red hot before the PB Blast boiled off. It's evil smelling stuff but it works well.
 

Nad_Yvalhosert

I'm Awesome
Joined
Oct 11, 2016
Messages
1,017
Reaction score
1,245
Location
Rochester, NY
I put shorty headers on my 135,000 mile 1995 C2500 New Yuck state vehicle in February. Every bolt unscrewed with no heat, no lube, no problems.
Maybe I'm just lucky, but I've never broken a 3/8 exhaust bolt upon removal. Not like the tiny, weak 8mm Ford or Chevy LS.
 

HotrodZ06

OBS Enthusiast
Joined
Apr 30, 2016
Messages
75
Reaction score
78
Location
Oklahoma
I haven't on a Gen1 Small Block either and usually just use a 3/8 impact to spin them out. Fords manifold bolts are horrible though had to heli-coil 16 of 20 on my v10.
 
Top