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SaxMan's Cylinder Head Overhaul / Head Gasket Replacement Thread

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If your thermostat doesn't have the little bypass valve or a small vent hole you can indeed have problems with an air lock when you are first trying to get the car going. Thermostat's are designed to sense water temp not air temp so it is possible to do some damage if an air bubble exists below the thermostat. Not likely but possible.

Kurt.
 
Open the heater valve. The air in the engine vents out to the radiator through the heater return hose and the lower radiator hose. Works every time. Don't know about them funny 1500s, though.
 
Hmmm....Don't know why I didn't think of that, Tom. Guess its just been a habit to always make sure air can vent past the thermostat since I started working on engines.

Kurt.
 
I picked up the cylinder head today from the machine shop. It is a thing of beauty. I'm not crazy about the grey finish, but I'll deal with the aesthetics another time:

DSC_1508 by onyxsax, on Flickr

Bottom with the blanking plug repair, per Hap's instructions:

DSC_1511 by onyxsax, on Flickr

Head back where it belongs. Unfortunately, on cylinder 2, one of the studs sheared in two when I was torquing it down...nothing crazy, just to factory specs.

DSC_1514 by onyxsax, on Flickr

Another view of the sheared stud. Fortunately, if I pull the rocker arms, there is plenty of stud above the head that removal will not be a problem. I presuming I should loosen all cylinder head bolts when repairing this? I torqued all the bolts down to see if I had any other problems. The small bolt on cylinder #4 was also having issues, but it didn't shear so I'll replace it, too. I recycled the hardware for the head, but I'm thinking I should have gone with new stuff.

DSC_1515 by onyxsax, on Flickr

I feel like Burgess Meredith in the Twilight Zone episode. I was getting ready to hunker down for a couple of days because of the snow and get a lot knocked out on Baby Blue, but now I'm stopped dead in my tracks until I can get replacement studs.
 
While I'm waiting for parts, would it screw anything up if I reattached the exhaust manifold and hung the exhaust piping, or is it better to wait on the new studs before proceeding further?
 
This is why is pays to go to high priced head studs........just to eliminate all the old stuff from 50 years ago.
there are many ways to go when restoring a car........usually a fight left and right....just as you have. The secret is eliminating as many of the hiccups in advance...and one is to only use the best bolts, head, crankshaft, and rods....good luck...Scott in CA PICT0005a.jpg
 
X2 Scott. I would order good quality studs, ARP for me, but use what you are confident in. Wait until you get the head on and torqued down before adding the manifolds. The prep work I would do at this point would be to make sure ALL of the studs will come out and then leave them in place until your new ones arrive.
Rut
 
While waiting for the parts, I ran a leakdown test on the engine tonight (other than the broken stud, the cylinder head was torqued down and the valves adjusted). Results were encouraging: I was showing a 35% leakdown consistent across all four cylinders. While that might sound high, it was still in the "Good" range on the tester, and the consistency between all cylinders was a far cry from the 30/70/60/40 result I had before I pulled the head. (BTW - Now that I know how to use it properly, the leakdown tester is the coolest tool in my garage!)

With the head gasket and valvetrain replaced, the remaining leakage is probably through wear on the piston rings. So long as we stay in the "good" range, I probably won't worry about rebuilding the bottom half in the near future, but I know that day will eventually come.
 
Parts came in and I was ready to work again. Loosened up the torque on the cylinder head, put in the new studs and everything went back together with only a few minor hiccups. Reattached the heater core line to the head and began putting some antifreeze through the thermostat hole, and I immediately heard splashing on the ground. Tried again, more splashing. I then realized that I forgot to put the water temperature sensor back into the head. Oops. Was able to refill the antifreeze without further incident until...

I poked around the motor after I cleaned up and noticed some antifreeze leaking around the thermostat housing, so I decided to torque down the bolts a bit more, and I'll be darned if I didn't snap another stud...this time on the thermostat housing. Lesson learned: Replace ALL hardware. At least with this one, I can still go ahead and hang the intake & exhaust manifolds while I'm waiting on parts again. I was trying for about 40 ft pounds when it snapped. I didn't think that was an outrageous amount of torque to use, but perhaps I'm wrong.
 
Yes, on those little studs that is too much. I'd imagine that you can Google up the standard torque necessary for standard bolts. Don't think it's listed in your manual's other than for major components.

Kurt
 
I think I'll go back to the "manual" way of setting torque on the smaller bolts...just by feel with a 3/8ths drive ratchet.
 
I almost always replace the thermostat studs when the cover is removed. They are so prone to corrosion that it only makes sense. I've never used a torque wrench on such things. I've worked on engines/cars/tractors since I was 6 years old so I have a basic feel for how much to tighten non critical fasteners. But the ones that are important for safety or major mechanical failure I like the comfort of a calibrated torque wrench.
 
I'm with Trevor, rather than a torque wrench I just wait till my elbow click's!:highly_amused:

If you are unfamiliar with how tight a bolt should be, though, I imagine there are standard torque's listed somewhere. I have an old mechanical engineering manual that has that information in it.

Kurt.
 
I got a fair amount done this evening: Intake and Exhaust manifolds reattached, Exhaust pipe attached to the manifold. I didn't finish hanging the rest of the exhaust, so I put boxes, bricks, etc., to keep the pipe from sagging until I can finish hanging it....hopefully tomorrow evening. I also placed the heat shield and carbs back on, but haven't tightened them down or hooked them up yet. The only ziplock bag I have left is the carb parts. I might have the car ready to fire up by next week.
 
The factory thermostat studs on these cars are junk , one the softest fasteners I've ever seen. I have developed a way to get them out when they break off in the head, I flush them to the head with flap wheel on a side grinder, then put them on the milling machine and use a 5/16" end mill and just plunge cut them out, then drill and tap for 5/16" heli coil. Now that fact that I can even do this is somewhat amazing, any other type of fastener, grade 3, grade 5, or grade 8 would simply just destroy the end mill, but these things cut like butter. I think this factory thermostat studs are slightly harder than a wet pretzel. :smile: What I do if I get em out successfully, or have to do my helicoil repair, is I go back with bolts, bolts don't snap off when you try to remove them.


I was going to post a picture of this, but this site won't let me, it seems I can no longer post a pic here, oh well see ya later.
 
Thanks Hap. If you follow this thread, I did have my machine shop follow your instructions on the blanking plug repair to a T, which will undoubtedly save me a lot of headaches down the road. I think I get what you're saying with the thermostat. I also don't feel as bad as I had about snapping studs...I guess this is a fairly common occurrence.
 
A little bit more work done tonight on the exhaust. I got the front and rear exhaust hangers rigged up. The old parts on the rear hanger were a bit stubborn to remove, but some PB Blaster took care of that. I didn't have enough time to get the muffler and muffler hanger on, so the pipe ends just past the rear axle for now, but at least it is all hooked up. I can see the light at the end of the tunnel. The Sprite is looking more and more like a complete car again.
 
Muffler went on last night and tonight I replaced the thermostat studs, put all the carb parts back in tonight and hooked up the throttle cable. I still need to hook up the fuel line and the choke cable. I learned the value of taking lots of pictures, because when I went to put the linkages between the front and rear carbs back together, I wasn't sure if I had things upside down or right side up. Going back to my pictures gave me a reference of how things were supposed to be hooked up. Inching closer and closer to completion!
 
At 9:45 PM this evening, Baby Blue came back to life. It took a little bit of cranking, but she turned over and was idling without any choke (maybe carbs too rich?). The motor woke my daughter up and she became VERY excited when she heard the car's motor going again.

It wasn't 100% smooth. I was getting some bizarre readings when I ran a compression test and the results were not consistent when I the test on the same cylinder. I'm thinking that I still have to do some adjusting to the valves possibly. By bizarre, they were either high, such as 160 psi in the #3 cylinder, when the p.o. had a max of 150, and then only reading 90 psi in cylinder 1, which was the "good" cylinder. It's possible this may be user error. I'm also thinking the the valves may still need some adjusting.

I also realized that I forgot to order the cable pinch bolt for the choke cable, and I had lost the original when it fell, hit the floor and disappeared. I wasn't going to be denied. I quickly discovered that a pinch bolt from a set of cantilever bicycle brakes that I had lying around would fit the carburetor perfectly. Yes, I will get the proper bolt the next time I have to order parts, but for now, it works.

I do plan on changing the air filters, but for the life of me, I can't figure out how to get to them. I'm guessing you need to take the center bolt off? I also still need to check the timing, recheck the valves, reset the carburetor, and of course, put the hood back on, but the engine is running!

There are no words that can adequately express my gratitude to everyone's helpful hints and advice. Thank you, thank you, thank you!
 
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