Datsun Roadster Forum-311s.org

Need to put a new head gasket on my 1970 1600 but one of the head bolts will not budge. Started with a 1/2 ratchet, moved to a breaker bar, then a piece of pipe on the breaker bar. That caused the head to turn but the threads did not break loose. Not wanting to break the bolt I moved on to hitting the bold with a punch, both as it sat and with the breaker bar turning it. Nothing. Soaked it in kroil. Nothing. I don't want to have to drill it out. Any other ideas that won't cause me more problems?

"Every 20 minute job is just one broken bolt away from becoming a nightmare."

Not sure how I posted this 3 times but I guess I REALLY want some help

Heat? I have read on more than one occasion to try to slightly tighten the bolt, then loosen it. I'll let more experienced Wrenchers chime in if this is an area to try that technique.

Heat it up dull red may work I know long way from the threads but
Although let it cool some, an 1/2 impact gun
Not to strong is the way it's usually done
VW Tech on diesels do it this way most of the time they are terrible for seizing
3/4 " breaker bar too

redroadster wrote: Wed Jul 21, 2021 4:29 pm Heat it up dull red may work I know long way from the threads but
Although let it cool some, an 1/2 impact gun
Not to strong is the way it's usually done
VW Tech on diesels do it this way most of the time they are terrible for seizing
3/4 " breaker bar too

Is there a risk of warping the head by heating up the bolt?

Why not just try an impact both ways and if it snaps at least you’ll be able to slide the head off. Then at least you are closer to the threads in the block. Then plan another attack at the block. If it snaps just above the block then drill out and collapse the head bolt within and hellicoil.

"Soaked it in kroil."

Project Farm on YouTube did a test (yes not the be all and end all) but Kroil wasn't all that great in there head to head. Actually the most expensive and worst performing. Liquid Wrench "penetrating oil" and ATF with Acetone did the best. Well actually heat came out in first place.

https://www.bing.com/videos/search?q=Be ... M%3DVDMHRS

Rob1704 wrote: Wed Jul 21, 2021 4:39 pm

redroadster wrote: Wed Jul 21, 2021 4:29 pm Heat it up dull red may work I know long way from the threads but
Although let it cool some, an 1/2 impact gun
Not to strong is the way it's usually done
VW Tech on diesels do it this way most of the time they are terrible for seizing
3/4 " breaker bar too

Is there a risk of warping the head by heating up the bolt?

Not if it has coolant in it and keep it on the bolt but try the others 1st . the threads likely have rusted and expanded and so has the bolt removing all clearance ..diesels wear ridges and jam the threads .I have tried muratic acid on old junk engines it dissolves rust .
The trouble if it breaks is the bolts hardened nearly as much as the drill bit
Walmarts new penatrating spray has worked good for me
Another trick with the sliding type breaker bar head
( which has a flat up side ) pull pressure while another vibrates the B bar with a muffler gun and hammer bit
( we took siezed bolt problems to a very good machine shop they would use this Technic and kept it secret ...until we went early to get the car once and saw the setup)

Sorry Rob, If the head of the bolt already turned a bit it will probably shear and you will have to try something else. You could weld a head on the top of the bolt and start over with kroil and a bit of heat but I wouldn't try to move it without when it's been such PITA

Topics combined into one post.

If and when you break it and get the head out of the way you have a bunch more possibilities such as higher heat and parts loosener actually getting to the threads, and left handed drill bits, which are magic.

Just a thought,....that if it appears the head of the bolt is turning a little bit, and there appears to be the possibility of shearing the head of the bolt completely off, might it also be possible that it's not the head of the bolt that's likely to shear off, but more likely to shear at the threaded portion of the bolt where it enters the block. If that would be the case, then drilling the broken remainder might need to be done....

As mentioned, typically tightening a teeny bit is often good to break the relationship to the rust and its surroundings. It introduces new metal to the equation and almost always works. A friend of mine who used to restore Rolls/Bentleys told me that he rarely lost the battle.

But the bolt is going to shear its at at the block, so it it does you will have to deal with reverse drilling. Is this a bolt that runs exposed through the water jacket - at the front?? Perhaps removing the water pump might give you acess to it at its bases.

Any update ?
The head bolts heads are easy to access with the rockers off ....you would be better to grind off the head with a 4 " hf grinder , then lift the head off - up , to heat the bolt and pipe wrench it out
Nothing can hold a very hot bolt
If it has broken at the head ...a portable drill that has an electro magnetic base is best they are rentable

Carefully cut the head off the bolt, pull the head then deal with the bolt when it’s not engaged and it should pull out. Also if it will not tread out you could put heat directly at the point where the threads are frozen.