Main Caps Wrong way - Now What
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 56
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Main Caps Wrong way - Now What Well I'm a douche. I put the main caps on the wrong way, meaning 1 was at the rear and 5 was at the front. I built the motor and it ran just fine with great oil pressure. When I was tunning it I noticed the oile pressure started to slowly drop. I got to 12 psi at hot idle, I changed the oil and it then it was basically at 0 when I started it so I just shut her off. She was never run with any load as the ecu was never tuned. The motor ran for about 2 hours total. SO my question is, can I just change the main bearings and put the caps on right or is there something else I need to do? Can I this with the pistons in and rods connected to crank or do I need to take the rods off too?
Thanks,
Adam
PS - I'm an idiot. LOL
Thanks,
Adam
PS - I'm an idiot. LOL
**** happens. dont worry. unfortunately it sounds like you came close or actully did spin a bearing. good thing you was watching oil pressure. i wouldnt just do main bearings, ill bet the caps and what not are out of round now, so i would do an align hone, and have the crank polished. then install the new bearings. sorry bout your mishap. i've had plenty.
That engine needs to come apart....
You inadvertently just ran a lot of bearing material thru most of the crank rod and main journals, cam journals, etc. All that small debris will have likely scored and possibly ruined a number of various components. Crank will need to definitely be turned down (highly likely) and you will probably need to replace cam bearings and possibly even the cam if its scored badly enough.
Rookie mistake....it happens....but I bet it wont happen to you again!
Get the hoist out and yank that thing....the only right way to rectify what happened is basically another freshen up.
Good luck on the next go around
Regards,
Tony
You inadvertently just ran a lot of bearing material thru most of the crank rod and main journals, cam journals, etc. All that small debris will have likely scored and possibly ruined a number of various components. Crank will need to definitely be turned down (highly likely) and you will probably need to replace cam bearings and possibly even the cam if its scored badly enough.
Rookie mistake....it happens....but I bet it wont happen to you again!
Get the hoist out and yank that thing....the only right way to rectify what happened is basically another freshen up.
Good luck on the next go around
Regards,
Tony
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 56
Likes: 0
Ok, well I took off the main caps and this is what I found. The engine was never run under any load so I think I got off pretty lucky. I didn't spin any bearings but this is how they look. They are obviously shot but would this be enough to cause the oil pressure to drop so much?
I also took a look at the crank and all the journals except the middle one seems to be perfect. I took a picture of it for you guys too. You can't feel the score with your finger but you can feel it with your fingernail. I don't know much but I think I need to get the crank to a machine shop to let them polish or turn it depending on what they think. Does this sound about right?
How should a cam bearing look. I'm assuming there should be pretty much no signs of wear at all?
Thanks,
Adam
I also took a look at the crank and all the journals except the middle one seems to be perfect. I took a picture of it for you guys too. You can't feel the score with your finger but you can feel it with your fingernail. I don't know much but I think I need to get the crank to a machine shop to let them polish or turn it depending on what they think. Does this sound about right?
How should a cam bearing look. I'm assuming there should be pretty much no signs of wear at all?
Thanks,
Adam
Ok, well I took off the main caps and this is what I found. The engine was never run under any load so I think I got off pretty lucky. I didn't spin any bearings but this is how they look. They are obviously shot but would this be enough to cause the oil pressure to drop so much?
I also took a look at the crank and all the journals except the middle one seems to be perfect. I took a picture of it for you guys too. You can't feel the score with your finger but you can feel it with your fingernail. I don't know much but I think I need to get the crank to a machine shop to let them polish or turn it depending on what they think. Does this sound about right?
How should a cam bearing look. I'm assuming there should be pretty much no signs of wear at all?
Thanks,
Adam
I also took a look at the crank and all the journals except the middle one seems to be perfect. I took a picture of it for you guys too. You can't feel the score with your finger but you can feel it with your fingernail. I don't know much but I think I need to get the crank to a machine shop to let them polish or turn it depending on what they think. Does this sound about right?
How should a cam bearing look. I'm assuming there should be pretty much no signs of wear at all?
Thanks,
Adam
Ive seen bearings that were a lot worse than that ,(into the copper) and steal have oil pressure. Looks like to me you just scuff the Babbitt off the bearings. I would change the bearings and put the caps in there right places and start looking for the real pressure drop. Ive seen bearing clearances with .0035" -.004" and steal hold oil pressure .Plastic gauge and see what your clearance are on the old bearings. My main bearings are set at .0025" and have 60psi at hot idle. Dont get me wrong your cap were in the wrong place, but i would also check the oil pump (O) ring ,the trust plate behind the timing gear , the check valve in the oil pump , rod bearing clearances, cam bearings, and even the oil sending unit !! Did the motor rattle or sound like a sowing machine ? if the lifters and rockers dont get any oil ,the lifters will collapse and make the rocker loose and will make a loud rattle. Just trying to give you some options to look at.
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If you can feel any scoring on the crank itself with you fingernail it needs to be turned no doubt about it. To be safe do all the cam and associated crank bearings and have the machine shops check your main caps also.
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Staging Lane
Joined: Mar 2006
Posts: 56
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Randy,
You have a good point. I shoudl check the main bearing clearance and start looking for another point of lost pressure. The oring looked good and was in place. I doubt that was the issue. I'm going to pull the pump and take a look at it. It was brand new so I hope that wasn't the issue. The cam retainer plate is also a suspect but we will see as it was new. The engine held 12psi at hot idle. I changed the oil and started it up and didn't get any pressure so I shut it off. It probablly ran all of 3 seconds. I even started to second guess myself if I let it run long enough to even build pressure. So the motors was never really run without oil pressure.
My rod side clearance was .029", .025", .026", .025" which is larger then stock but they are aftermarket rods and to my understanding that should be fine. I will check out the cam bearings to see if they also caused an issue.
I think the damage was so minimal as the engine was never run with load so the most it did was just lightly scuff the mains. If it had run hard then I'm sure the damage wouldn't have been worse. I have an autometer gauge and sender so I know it works well. The motor NEVER rattled or sounded bad at all. No ticks or anything like that. I know it is a loud motor but you can usually hear a high pitched tap or tick. When I pull the heads off I'll check out the lifters as well but I would bet that they are ok. We'll find out soon.
Thanks,
Adam
You have a good point. I shoudl check the main bearing clearance and start looking for another point of lost pressure. The oring looked good and was in place. I doubt that was the issue. I'm going to pull the pump and take a look at it. It was brand new so I hope that wasn't the issue. The cam retainer plate is also a suspect but we will see as it was new. The engine held 12psi at hot idle. I changed the oil and started it up and didn't get any pressure so I shut it off. It probablly ran all of 3 seconds. I even started to second guess myself if I let it run long enough to even build pressure. So the motors was never really run without oil pressure.
My rod side clearance was .029", .025", .026", .025" which is larger then stock but they are aftermarket rods and to my understanding that should be fine. I will check out the cam bearings to see if they also caused an issue.
I think the damage was so minimal as the engine was never run with load so the most it did was just lightly scuff the mains. If it had run hard then I'm sure the damage wouldn't have been worse. I have an autometer gauge and sender so I know it works well. The motor NEVER rattled or sounded bad at all. No ticks or anything like that. I know it is a loud motor but you can usually hear a high pitched tap or tick. When I pull the heads off I'll check out the lifters as well but I would bet that they are ok. We'll find out soon.
Thanks,
Adam
And make shore the oil restricter plug is in place in the back of the block ,behind the rear cover in the oil galley and make shore the (O) ring is on the restrictor. and also check and make shore the small freeze plug is in the front of the block behind the timing cover on the driver side.
Last edited by Randy WS6; Aug 20, 2008 at 01:41 PM.
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 56
Likes: 0
Well I broke the motor down completely and found the problem. I noticed the main and rod bearinsg are all shot but not bad. Not reusable obviously but not enough to make the oil pressure drop. So after taking out the cam and noticed that the cam bearings are better but still probablly need to be replaced I noticed one started to come out of its bore. The guy at the machine shop said that with AL blocks it is not totally uncommon for them to walk out when the block gets up to temperature. His two suggestions were to either epoxy it in there or use a set screw depending on the condition and size of the bore after they check it out. Since the bearing slid halfway out of its hole, it exposed the oil hole and the oil just poured out of it and that is why I started to loose pressure slowly and pretty much had only a few pounds in the end. The lifter managed to grind away at the cam bearing as it worked out of its hole. The lifter guide seems fine and so does the lifter but I will probablly get a new lifter as they are cheap. The guy at the machine shop also said that nothing was too bad and that the crank probablly just needed to be polished. I won't know until they get to work on it and see what the measurements are at the end of the day. So hopefully this will turn out to be a very cheap fix (<$200 for everything), but we will see at the end of the day what the actual number is. The guy also mentioned that needing to re-hone the cylinder walls after taking the pistons out of the bore is bullshit. So i'm going to go with his advice. We will see where that takes me. lol
Well I broke the motor down completely and found the problem. I noticed the main and rod bearinsg are all shot but not bad. Not reusable obviously but not enough to make the oil pressure drop. So after taking out the cam and noticed that the cam bearings are better but still probablly need to be replaced I noticed one started to come out of its bore. The guy at the machine shop said that with AL blocks it is not totally uncommon for them to walk out when the block gets up to temperature. His two suggestions were to either epoxy it in there or use a set screw depending on the condition and size of the bore after they check it out. Since the bearing slid halfway out of its hole, it exposed the oil hole and the oil just poured out of it and that is why I started to loose pressure slowly and pretty much had only a few pounds in the end. The lifter managed to grind away at the cam bearing as it worked out of its hole. The lifter guide seems fine and so does the lifter but I will probablly get a new lifter as they are cheap. The guy at the machine shop also said that nothing was too bad and that the crank probablly just needed to be polished. I won't know until they get to work on it and see what the measurements are at the end of the day. So hopefully this will turn out to be a very cheap fix (<$200 for everything), but we will see at the end of the day what the actual number is. The guy also mentioned that needing to re-hone the cylinder walls after taking the pistons out of the bore is bullshit. So i'm going to go with his advice. We will see where that takes me. lol
if your main caps are shot good luck finding new ones as GM won't just sell the main caps. You have to buy the block and the mains come with it. I had to pick up a used set that had little to no mileage on them and then take it to the maching shop. What a pain.
You can have the mains line bored if the bearings didn't spin, But it you need a use set i have them. You do need to re hone the cylinders to seat the rings ,and you need to put new rings in to, if you don't you may have excessive blow by.Your cam bearing journals need to be clean from any oil and dry, and put a very thin coat of red or green loctite on the bearing ,and make shore they start in the bore straight to keep from galling or piling,if the bearing starts to gall you are loosing the tolerance for the press fit ,and the bearing will be loose in the bore. the cam bearings is real teagues and need special attention when installing them ,and are numbered for each journal and must go in the appropriate place
