Help with engine rebuild
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500, 472, 425, 368 Discussion, Help with engine rebuild in Cadillac Engine Technical Discussion; Hello all, I am in need of a little direction as this is my first engine rebuild ever. This may ...
  1. #1
    crucialjp is offline Cadillac Owners Member
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    Help with engine rebuild

    Hello all, I am in need of a little direction as this is my first engine rebuild ever. This may take a little to read but please bear with me.

    I have a 472 from a 72 cdv that is going in my 80 cdv. It was running before I did the swap. It took a while to complete due to neighbor complaints and not having a garage to work in but after getting my exhaust ran I cranked it back up for the first time and let it run a few minutes. I had it towed back home and everything seemed fine but the 3rd time I went to crank it when I got it home it wouldn't start. After looking around and checking the timing I discovered the gears on the distributor had chipped and some where broken off. I went and bought a new one to replace it only to find my engine was locked up and couldn't be turned over with a flywheel wrench.

    I pulled the engine and took of the intake, heads, I found 1 bent push rod and still couldn't get it to rotate. I started pulling the pistons and found 3 of them were stuck in the block. After some PB blast and time I finally was able to knock them out. The piston bores look good and I didn't find any visible cracks.

    So that's where I am now the only thing still in the block now is the cam. I was told by someone that I need to replace the main and rod bearings, and to take it to a machine shop. The problem is I have no idea what to ask for or have checked at the machine shop. I'm thinking about getting a rebuild kit but I don't know what to get there also. So if anyone can point me in the right direction I would greatly appreciate it

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  3. #2
    drmenard is offline Cadillac Owners Enthusiast
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    Re: Help with engine rebuild

    What did you put new into the motor? rings , bearings? Did you change the cam? Could you find out why the pistons were stuck? what else was broke? Something here sure don't sound right. Tell us more of what you found..

  4. #3
    crucialjp is offline Cadillac Owners Member
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    Re: Help with engine rebuild

    I haven't replaced anything yet. And I couldn't tell why the pistons were stuck but when I took the heads off I found 1 bent push rod. I was expecting to find some metal or debris in the bore where pistons where stuck because I found some in the oil pan from the distributor gear teeth but I don't even see any scratches.

    Today I was trying to think of what could have went wrong and the only thing I can think of was maybe I should have re-primed the oil pump b4 I tried to start it, or maybe the oil pickup wasn't adjusted right. During the inital swap I switched over all the parts I needed to complete the swap, put it in the car and primed the oil pump but the car sat for a few months before I got the exhaust ran. The first time it was started was while at the exhaust shop so they could check for leaks there was a little tapping but I figure it was bc it was cold and needed to warm up. It only ran a few minutes that time. The second time I started it I noticed the tapping once again it only ran for maybe 1 minute before I shut it down. My fluid levels were ok when I checked them. A few days later was when I tried it again and it wouldn't crank. I thought it was the timing which led me to find the broken teeth on the distributor, then after that the engine was locked. From that point the car sat from spring till now while I moved to a new location with a garage.

    I'm not sure what to replace internally since everything looks good. I thought maybe a machine shop can tell me but I don't know what to ask them to check for I don't want to be taken advantage of since this is my first re-build

  5. #4
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Help with engine rebuild

    From what you have described, it sounds as if your timing set jumped time and you kissed a couple valves, although I've never seen this in one of these engines. The other possiblity is that some debris got past your pick-up screen and got into the oil pump and when it locked up, your distributor stopped turning and that is how your distributor gear sheared. Did your oil light come on?
    Pull the front off the engine and find out what is going on in there. Pull the cover off the oil pump and see if you have anything in there that shouldn't be there.
    You obviously dropped the pan. Did you have a lot of metal in there? Was your oil pick-up screen comprimised?
    This being your first time attempting engine work, you should find someone with some experience to give you a hand, because there are several things an experienced eye can spot to determine the proper proceedures you should take to repair this engine.
    Let us know what you find. There are several qualified people on this site who can guide you through this.

  6. #5
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Help with engine rebuild

    Today I was trying to think of what could have went wrong and the only thing I can think of was maybe I should have re-primed the oil pump b4 I tried to start it, or maybe the oil pickup wasn't adjusted right.

    Had this engine sat without running for a long time?
    Were you in the bottom end of the engine? What did you do there?



    During the inital swap I switched over all the parts I needed to complete the swap, put it in the car and primed the oil pump but the car sat for a few months before I got the exhaust ran.

    How did you prime the pump? How long did you run it after this initial prime? If you only let it run for a short period of time, you may not have gotten all the air out of the passages.
    What grade of oil did you use?




    The first time it was started was while at the exhaust shop so they could check for leaks there was a little tapping but I figure it was bc it was cold and needed to warm up. It only ran a few minutes that time. The second time I started it I noticed the tapping once again it only ran for maybe 1 minute before I shut it down.

    It is possible you had a spun bearing from the git go and you got some metal through to the oil pump.



    I'm not sure what to replace internally since everything looks good. I thought maybe a machine shop can tell me but I don't know what to ask them to check for I don't want to be taken advantage of since this is my first re-build[/quote]

    What did your rod bearing halves look like? Pics will help here.
    Take a close look at your crank journals. If any are chewed or scoured, you will need a regrind or another crank.

  7. #6
    drmenard is offline Cadillac Owners Enthusiast
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    Re: Help with engine rebuild

    This being a 72 motor it has small chamber 77cc heads.. this does mean that is it did jump timing your valves will hit the pistons .. and if this happen and you had a bent push rod or you also have bent valves. there might be some other push rods bent a little....look at the valves that had the bent push rod.. does the piston have a mark in it where it hit the valve...you could have a valve got stuck open...next thing to take apart is the timing case cover to see what your timing chain and gears look like..

  8. #7
    crucialjp is offline Cadillac Owners Member
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    Re: Help with engine rebuild

    I'll try my best to answer everyone's questions

    drmenard:

    I don't recall the oil light coming on, but I will take a look at the the inside of the oil pump today and a closer look inside the block and the piston to see if I can find anything.

    deVille 33:

    I bought the donor car in March and drove it 3 different times. I didn't go far just around the block with it. When I pulled it to do the swap I had to pull the heads because I had some exhaust manifold bolts broken off. So I took it to a machine shop to have them removed. Also at that time I now remember that there was 1 bent pushrod that I found and replaced with a pushrod from my other 472 I had laying around. Maybe that was a bad idea and I should have bought all new ones. I will take a look today because I think it was the same one I found bent again. The only other thing I did was swap the oil pan and pickup from my old 368, changed the oil pump, rebuilt it before I put it in, and put on a new fuel pump.

    I used 10w-30 primed it with a drill and old flat head screwdriver, It set a few months after that. The first time it ran was at the muffler shop but that was maybe for 5-10 minutes max.

    I had a guy come take a look at the engine and he said the rod and main bearings didn't look bad but that I may want to replace them. Today I will take extensive pictures of everything and see if that helps.

    I would love to find someone experienced in building caddy engines locally. I think I'll post a craigslist ad and see if someone responds who would be willing to give advise or help. The guy who came by is the one who gave me the idea of the 472 swap, but he also sold me my first 500 which I later found was a 472. So I don't trust him that much for that and other reasons but he's the only person I know that knows something about Caddy big blocks. He always mentions that Chevy guys wouldn't know how to rebuild them and that he's the only one around that does. But he's never available when I need him and rarely comes by when he says he will. So is it really that much of a difference between gm and caddy engine builders?

    I will update this post when I get home with my findings and pictures of everything. Thanks all for the help

  9. #8
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Help with engine rebuild

    deVille 33:

    I bought the donor car in March and drove it 3 different times. I didn't go far just around the block with it. When I pulled it to do the swap I had to pull the heads because I had some exhaust manifold bolts broken off. So I took it to a machine shop to have them removed. Also at that time I now remember that there was 1 bent pushrod that I found and replaced with a pushrod from my other 472 I had laying around.

    Bent pushrod suggests there is a problem with your engine timing.
    You probably need a new timing set.



    Maybe that was a bad idea and I should have bought all new ones.

    Not a bad idea. In fact, if you still have that engine, you can use other pushrods to replace the ones that bent this time.

    I will take a look today because I think it was the same one I found bent again. The only other thing I did was swap the oil pan and pickup from my old 368, changed the oil pump, rebuilt it before I put it in, and put on a new fuel pump.

    Was the 472 pan too big for clearance? Check the tube to ensure it isn't clogged with something.


    I used 10w-30 primed it with a drill and old flat head screwdriver, It set a few months after that.

    Due to the distance between the pick-up screen and the pump, it is a common practice to pack the pump with petroleum jelly on these engines.




    I had a guy come take a look at the engine and he said the rod and main bearings didn't look bad but that I may want to replace them. Today I will take extensive pictures of everything and see if that helps.

    Pics will help. Take pics of the connecting rod large end and the bearing shells.

    I would love to find someone experienced in building caddy engines locally. I think I'll post a craigslist ad and see if someone responds who would be willing to give advise or help. The guy who came by is the one who gave me the idea of the 472 swap, but he also sold me my first 500 which I later found was a 472. So I don't trust him that much for that and other reasons but he's the only person I know that knows something about Caddy big blocks. He always mentions that Chevy guys wouldn't know how to rebuild them and that he's the only one around that does. So is it really that much of a difference between gm and caddy engine builders?


    While it is true that Chevy enthusiasts will have a problem if they are purists, anyone with engine building skills can rebuild a Cadillac engine, if they have a Cadillac shop manual. You need one for 1972. You will find a wealth of information in there that will be worth every cent you paid for it. You should be able to find one on ebay.

    I will update this post when I get home with my findings and pictures of everything. Thanks all for the help[/quote]

  10. #9
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Help with engine rebuild

    You could also go to the top of this site to Big Block Engine Assembly Guide and download the PDF file which is for a '70 - '75 472.
    It is a general file, but a lot of the info is relative to your engine.

  11. #10
    crucialjp is offline Cadillac Owners Member
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    Re: Help with engine rebuild

    Quote Originally Posted by deVille33 View Post
    deVille 33:

    Bent pushrod suggests there is a problem with your engine timing.
    You probably need a new timing set.

    I took a look at the timing gear and chain and it looked good, but I will look into replacing it

    Not a bad idea. In fact, if you still have that engine, you can use other pushrods to replace the ones that bent this time.

    I will do that

    Was the 472 pan too big for clearance? Check the tube to ensure it isn't clogged with something.

    THe 472 pan is front sump and the 80 CDV requires a rear sump. I'll check the tube

    Due to the distance between the pick-up screen and the pump, it is a common practice to pack the pump with petroleum jelly on these engines.

    I packed it with vaseline before installing it.


    Pics will help. Take pics of the connecting rod large end and the bearing shells.

    I had pics but my hard drive died Friday so I lost all my pictures including alot of my build up, I will take some more and post them when I get my home PC back up and runnning.

    While it is true that Chevy enthusiasts will have a problem if they are purists, anyone with engine building skills can rebuild a Cadillac engine, if they have a Cadillac shop manual. You need one for 1972. You will find a wealth of information in there that will be worth every cent you paid for it. You should be able to find one on ebay.
    A few things I noticed when looking at everything the other day; On each of the three pistons that where stuck in the block the rings are still compressed and are flush with the side of the piston. By that I mean on all the other ones that are out of the block the rings stick out from the piston. I also noticed on the middle bearing that the crank sits on the metal is coming off in thin strips. I'll take a few pics of both of these items and post them once I get my home computer back up.

  12. #11
    deVille33 is offline Cadillac Owners Connoisseur
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    Re: Help with engine rebuild

    Quote Originally Posted by crucialjp View Post
    A few things I noticed when looking at everything the other day; On each of the three pistons that where stuck in the block the rings are still compressed and are flush with the side of the piston. By that I mean on all the other ones that are out of the block the rings stick out from the piston. I also noticed on the middle bearing that the crank sits on the metal is coming off in thin strips. I'll take a few pics of both of these items and post them once I get my home computer back up.

    Are the rings free in the grooves? Can you spin the rings around in the grooves?

    Check the center main bearing surface of the crank. What you describe suggests that the center bearing wasn't getting oil.

  13. #12
    crucialjp is offline Cadillac Owners Member
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    Re: Help with engine rebuild

    Quote Originally Posted by deVille33 View Post
    Are the rings free in the grooves? Can you spin the rings around in the grooves?

    Check the center main bearing surface of the crank. What you describe suggests that the center bearing wasn't getting oil.
    Sorry it took so long to respond but my home pc is still not fixed so I can only get on here at work when I have free time.

    I decided to just go ahead and take everything to a machine shop in a few weeks and have it all checked. Hopefully it's not too bad off. I'll post back what they found when I get it back. Thanks everyone for your help.

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