additional persuasion to remove studs

[skhorleb]

Hi Don,

I removed my cylinder head at your recommendation since I had some bubbling in my coolant expansion tank and persistant water in my oil. I did this while the engine was still in the boat and found that part of the remaining head gasket is a fibrous material...Hence, I think you were correct about it being asbestos....and probably original.

What a job! Removing the studs and pulling the head took me two evenings, my stud removal tool, incredible patience, many ounces of Kroil penetrating oil, lots of TLC and elbow grease, and I still snapped off 3 studs. Both thermostat housing studs snapped off flush with the top of the head and a third (middle front) snapped off flush with the block. I was eventually able to persuade the head off the block with the thermostat housing studs in place, but that took almost a whole evening's work. To make sure no hairline cracks resulted I am having the head magna-fluxed, resurfaced, and bead blasted.

After the head was pulled, I was still unable to remove the thermostat housing studs out of the block with vice grips. I let it sit overnight again (day 3) with another dose of Kroil soaking around the studs. I already have to drill out the middle front stud and hate the idea of drilling these other two as well, risking damage to the coarse threads in the block, requiring two additional repair studs, etc. As an alternative, is it worthwhile to apply some heat to those studs as additional persuasion to the vice grips, continued dousings of Kroil, and tapping on the sides of the exposed studs? I don't want to waste my time fighting windmills or start a fire.

Also, the screwdrivers I used to pry the head up scarred the front of the block surface a little...but I stayed clear of the values. When I reinstall the head, should I use any Permatex aviation sealer in addition to the two graphite gaskets or is that over compensating for the scratches in the head surface? Thanks.

[Don Moyer]

Steve:

Sorry to hear of your difficulty. If it's any consolation, the degree to which these studs are resisting coming out of the block is good evidence that the threads remaining in the block are in excellent condition.

I have never resorted to applying heat, but I do recommend investing in a small factory fresh pipe wrench (a 12" works well). It will grip as well as a vise grip and give you a bit more leverage on the thermostat housing studs. In terms of predicting the outcome, I don't recall ever having a stud fail once the head has been removed, so support the jaw end of the wrench and apply as much muscle as you can, and my guess is that the thermostat housing studs will yield. For what it's worth, the reason those two studs are so stubborn is that their threads are approximately three threads deeper than the rest. Even the lifting eye stud holes are not quite as deep.

For the stud that presumably failed flush with the top of the block, use a flat file to smooth the top of the failed stud if possible, then make a good center punch mark, then use a factory fresh 1/8" bit, then a 1/4" bit, and finally a 5/16" bit. If you were lucky and got the 1/8" bit in the center of the stud, you should be able to see faint signs of threads around most of the circumference of the 5/16" hole. You can then take an ice pick and clean out much of the remaining thin pieces of stud and finish the job by running a 3/8" coarse-threaded tap into the hole. If you were slightly off center (which you should pick up after using the 1/4" bit), you could demonstrate great finesse by picking up a 19/64" drill bit to use rather than the 5/16" bit so as not to damage the threads along one side of the hole. In this case, you should be able to take the ice pick and tap the thin sliver of stud away from the side of the hole and out. Again, finish the job by running a 3/8" tap into the hole.

Good luck,

Don

[skhorleb]

Head and studs fixed

Don,

'Just a follow up to confirm that the pipe wrench idea you proposed worked great. Using a 12" pipe wrench, both thermostat studs came out without further incident. While the head was off, I scraped the carbon build up from the block surface. A number of the oil and water ports in the block were quite cruddy, two were completely clogged, so by hand I ran a 1/4" drill bit (I think) through them to clear them.

The machine shop gave the head an acid bath which really cleaned up the head's cooling and oil system ports. Magna-fluxing the head showed no cracks. The machine shop took .012" off the head to get it right. All of their work cost me only $95. Just to pamper the head some more, I gave it 2 fresh coats of engine paint.

The front middle stud, which had to be drilled out, involved a big mistake--I tried drilling out the old stud in the block while the head was at the machine shop. In the confined space I guided the drill slightly crooked. I should have remounted the head BEFORE going to a bit larger than 1/4". This would have assured the final passes with the 9/32" and 5/16" drill bits would be straight before tapping the block threads to 3/8". Hopefully others will benefit and not make the same mistake.

Nevertheless, I was able to recover from my mistake with a repair stud. To compensate I temporarily put the head back on the block, bolted it down with a handful of fresh studs in the surrounding holes. Using the hole in the head as a guide, I drilled the hole in the block up to a 23/64". I removed the head again, and drilled out the head to 7/16" so the tap would fit through the head and the head would guide the 7/16" tap straight. 'Installed the head again and finally tapped the block for the 7/16" repair stud. JB Weld was applied to the threads before installing the repair stud. The front center stud was fine after this detour.

All head studs and manifold studs are now new! I used red locktite on the other new studs, used two new graphite head gaskets, and installed the head without incident. 'Torged all of the other head nuts up to 35 lbs and let the JB Weld dry overnight. Before starting the engine I changed the oil again, torged the repair stud up to 35 lbs, and filled my coolant expansion tank about 3/4 full.

When I started the engine, no more bubbling in my coolant expansion tank, no white smoke in the exhaust, no detectable loss of coolant, and no more water in my oil! After the engine warmed up, I re-torged the head again, and then ran the boat under load for about an hour. It runs very smooth, temperature varies between 175 - 180 degrees, depending on the RPM. I re-torged the nuts a third time, and believe the ole' A4 is about as good as new!

Next week I will run a compression test to see how my compression numbers compare against earlier stats and will report on that.

Thanks again for all of your help and advise. Your wisdom is keeping guys like me sane!

[Don Moyer]

Steve:

So glad to hear that things worked out well for you. It sounds like you should be ready for a good season.

Don