1959 1/2 ton Apache with a 261 engine, Last year I changed one on the drivers side of the engine. Today the second one on the same side is leaking, so I removed the manifolds and will install a new one tomorrow. Here's the million dollar question, It's been 14 yrs since the engine was built, should I pull the transmission, flywheel and bell housing and replace the one behind the bell housing? I'm thinking it would be in my best interest to do that, I know it will entail a lot of work but I do drive this thing a lot and would not want to spring a leak out on the road. Question number 2 is, the plug kit that I have has 2 concave plugs and one regular looking plug that look to be the same size, they are all larger than the ones on the side of the engine. I know I'm assuming the regular looking one, goes behind the camshaft. So that would mean the concave one would be the freeze plug for the center of the block. Am I correct with my assumption? Any words of wisdom?
Don't break it by fixing something. That's how I roll. The freeze plugs you are talking about are hard to get to. Leave them alone until they start weeping. Its not like they are going to blow out and spew all of your antifreeze all at once.
I am not a big fan of Stop-leak, but if one of those hard to get to plugs began to weep, I would use it. Especially if a rebuild was likely to be done in the next 5-10 years. That would be a better time to change them.
Bottom line? Drive it and check everything as you normally would.
I am definitely with Carl here. Also you can use those expanding rubber plugs for the freeze plugs you can see and reach. They're cheap and quick. They won't pop out if it freezes, but in Metairie I never saw many hard freezes. I once drove a GMC 228 for 2 years + with one of those expanding rubber plugs where the one in the front of the engine used to be.
Carl and Jon,
Thanks for the response. I really don't want to change the one behind the bell housing, and I do not use stop leak. This engine was rebuilt 14 yrs ago and won't be done again. I will probably go over to the DARK SIDE" small block" before another rebuild. I have used the expandable rubber plugs before, and it doesn't ever get that cold here in Metairie. So I guess I will think about it for a day. It's a lot of work to get to the one behind the bell housing.
It may be worth your effort to find brass freeze plugs while you are doing this. They tend to hold up better over time than the steel. Just my thoughts.
Core Plugs, Welch Plugs and Freeze Plugs are what we call the plugs in the side of our engines, these plugs have nothing to do with freeze protection. These openings in the water passage are there to allow the sand from the casting process a place to exit. After the block is cast it goes onto a shaker that shakes it hard enough to break the sand out of the internal passages via these plug openings. After the sand is all out the plug is installed to seal the opening. If your block was to freeze it would break all the way at the bottom of the water jacket way before it would ever pop the plugs...
Yes, the concave plug, should be 2 inches, is for the back of the block, the large cupped plug is for the cam.
Thank You for all the responses. I will get further into this sometime over this weekend.
I'm back, the plug behind the bell housing isn't leaking (yay). So that will be left for another day hopefully no time soon. I was wondering when I put the intake manifold back on do I really need to use the alignment rings? My concern is, when the head was rebuilt a few years ago the machine shop made a cleanup cut on the head to block surface and the manifold surface. So I'm wondering if the rings would keep the intake from seating properly. Any thoughts?
This recently came up in another post, and Tim Lederman expressed this same issue or concern. Tim indicated that those rings can prevent a solid or tight fit under these circumstances and the rings would need to be cut or ground down.
The rings are for alignment of the manifold to the head, and they're essential for a good gasket seal. The rings don't seal vacuum but they do allow the manifold and the head to mate at the proper position. Just measure the depth of the counterbores in both items, and adjust the thickness of the rings accordingly. "Measure twice- - - -cut once!"
Tom and Jerry, thanks for responding. That is what I was thinking, maybe use a sharpening stone like used for sharpening a knife. Measure the rings and take a little off of them. I'm thinking with the rings installed the manifold and head should be flush against one another.
New rings are easily made, obtain a slightly larger exhaust pipe, cut pieces off of the correct length with a cutoff tool in a lathe if possible. Slit the new rings to the correct size and install them.
Measure the thickness of the ring. Press the ring in the head and seat it. Measure how much is sticking out. Press the ring into the intake manifold, measure what is sticking out and subtract from the ring thickness. If what is sticking out of the head is less then you are good to go.