425 NH/Transmission separation issues

Ok, so I nabbed that 425 from the junkyard the other day, and now both the engine and tranny are in the back of my truck. I figured the best way to get it out of the truck is to separate the two, then work them out individually. (No shop crane available) I pulled the starter, and all the bolts around the tranny, and all that is left are the inner tranny bolts. (Flexplate or whatever it's called) I cut all the belts, and tried turning the crank, but it's a no go. Any ideas? Thanks.[S

You're probably going to have to pull the engine apart and find out way it's stuck. If you're lucky it's just alittle rust in the cylinders and PB Blaster will free it up. Good luck!! Keep us informed with progress..[P

i have a boat that sits outside all winter although it is mild here, i dont want to damage it by just cranking it over. i spray a little bit of wd-40 in all the cylinders and let it sit for a day, the i turn it over by rotating the crank pulley. pb rust buster works well, too.

Engine disassembled

Well, spent the day getting to know my new friend. Pulled off the carb, intake manifold, valve covers, and heads. All the while vacuuming out all the rust, and rat nest stuff. One of the cylinders was full of water, the rest didn't seem too bad. At least from the top side, nothing seems damaged. All the push rods were straight, and the valves moved after a couple smacks with the rubber mallet. The carb will definitely need to be replaced, one of the aluminum throttle valves has disintegrated. Tomorrow after work I'll see about draining the oil, and taking the water pump, and other front stuff off. Also, I'll need to get that tool to remove the valve springs, so I can send the heads off for checking.

Question...

Well, I couldn't let it go, and decided to pull some more off of the Nailhead. I pulled the fan, and the water pump off. When I did though, a lot of white powdery stuff came out. I am hoping this is antifreeze residue... [S Any other possibilities? This isn't bad is it? Oh, and I'll need to find a new water pump, as one of the blades broke off.

Aparrantly your motor has been out in the weather and suffering from alot of corosion so you will need to strip it completely dowm and have the block and heads cleaned and magafluxed for cracks. But first you gotta get it apart. The cylinder full of rust and crud needs to be scraped and cleaned as best you can and soak it with penetrating oil [I like pb blaster]. Then try to rotate the crank in the direction that will cause the piston in the rough cylinder to go down so as to allow you to get all that crud out and free up the motor for dissasembly. This will be a great learning process for you. Be sure to save all the parts and organize them so you know how to put it back together. This is gonna be fun..[cl

I feel your pain. I have a 401 NH that's stuck on top of a scrap pile-about 10' in. Once I can manage to get it down and out I'll be following your same process. Mine has been resting on its side on the top of the pile since the early 70's. Everything was plugged (except that valve cover), but I'm not very optimistic about it ever running again. I still have hope though....



Just remember to loosen bolts slowly/a little at a time and try to follow the reverse torque sequence-especially on the heads. Diesel or PO1 also do a fine job of loosening up stuck pistons. I'm not planning on using the original trans, although it is still attached. I've heard from the previous owner that first gear never did work on this particular one.

Nailhead disassembly update

I finally got the 425 and tranny separated. Seems the cylinder with the water in it, was what was holding it up. Of course I only found this out after I removed all seven other pistons first, lol. I would have done that one sooner, but the nuts weren't very accessible at the time. Tonight I'll get some longer tranny bolts so I can put this thing on the engine stand, and clean it up before having it checked. Attached are some pics of the engine/parts and my wonderful "shop".

Sounds like you didn't have too much trouble getting everything apart, and that's a good thing. Hope it all checks out ok so you can start the rebuild. Your shop!! well I bet most of us have been there and done that? In the future when you have your dream garage built you'll look back on this project and smile and say how did I work under those conditions??..[cl

You may have already found this site, but V8Buick.com is a great wealth of knowledge about all things Buick. I was lucky enough to find a never-been-started 1979 Buick 350 and am learning about it every day. I would imagine there are tons of motors just like yours that they can tell you about there. Find a good machinist who knows Buicks--I'm told their tolerances are tighter than Chevys. You will become a good customer.