service main and rod bearings in car?

[TheBirdistheWord]

Did a search to no avail, and I have purchased a few books on the subject.  Everything I have seen shows or explains having the block out of the car and upside down to perform any kind of service on the crank bearings.  Assuming the crank is fine and bearing journals arent to badly scared, if at all.  Can I get away with verifying mains have proper clearance and just replace the rod bearings, hone, and re ring in order to keep the motor in the car?

 

also, can I do this while maneuvering around the crossmember?

 

thanks for reading! and any input, have a good day!

[hang_510]

only a masochist would attempt it. :D

it could be done in half the time with the motor out... ASSUMING nothing is wrong.

[Stoffregen Motorsports]

You can do it in the car, but unless you're pulling the trans too, getting the main bearings out and then back in requires finesse. If you screw this up, you'll scratch the mains or even put dings in them...NOT GOOD! And you're planning on pulling the head right? If not, that's another can of worms.

 

Just pull the motor and do it on a stand. Doing it on a piece of cardbaord in the driveway would be easier.

[TheBirdistheWord]

If the mains visually look alright and have adequate clearance, it is possible to just get to the rod bearings for service?

 

Don't have a driveway to do this in, I have been trying to find some place to do it, no luck though. So for now the street is my garage! It really does look straight forward if you have it on a stand.

[EricJB]

What are you trying to remedy?

I have done it on a sbc in a 4x4 out of desperation, and also rings and rod bearings in a rabbit pickup with the head off. Not pleasant. Not clean. Not right. Dont do it. Wait till you have the facilities to do the job correctly, if you can.

[TheBirdistheWord]

I have a stock rebuilt replacement A87 head ready to go on, 

 

leak at the head on the passenger side adjacent to cylinder 3. low compression on that cylinder as well, excessive blowby out of the valve cover.  There is a valve train noise as well as what sounds like rod knock, that is the reason I got the head.  Car had power until about two weeks ago, and the knock has become more definitive and louder.  That is what lead me to believe the bearings are worn, I thought both noises were the same noise.

 

I installed a motor with an unknown history out of desperation.  Out of lazyness and fear I didnt inspect it because it "looked" rebuilt..... I am suffering the consequences of that mistake now.

 

I am basically trying get away with a re ring hone and rod bearings.  I am aware that the main bearings might be suspect, if they are it means the crank will need work, and the block will come out, correct?

[datsunaholic]

You hone it in-car, without taking the crank out, how are you going to clean all the hone dust out?  You'd never get it all with a rag.  Since you can't take the crank out without taking the transmission off, it will have hone dust (metal and the hone material) which will go nicely through the oil system, and then you'll be back to square one.

 

If you have a rod knock, the crank will likely need to be turned anyway and an undersized bearing used on that journal.

[TheBirdistheWord]

it was my understanding that most of that could be washed out or averted by covering the crank, or both.

 

If new std bearings are used and I smooth the journal by hand couldn't that bring it close to spec?

 

Do I have to open the motor up and see how bad the damage is before I can answer that?

[datsunaholic]

it was my understanding that most of that could be washed out or averted by covering the crank, or both.

 

You trust rags that well?  How would you wash it out on the street?  You also want to get all the cleaning agents out too, you think they'll just evaporate?  Crank has oil passages.  Any cleaning agents are gonna get in there, some still trapping hone leftovers.  Nice way to add 10,000 miles wear right from the get go.

 

If new std bearings are used and I smooth the journal by hand couldn't that bring it close to spec?

 

No.  You don't want it close.  You want it within tolerance, or you'll just pound the next bearing out.  Sure, if it's within tolerance you can clean it up and it'll be OK, but do you have a micrometer to measure it?  How much money and time are you going to spend doing this the wrong way? 

 

 

Do I have to open the motor up and see how bad the damage is before I can answer that?

 

Not all damage is visible.  Have to measure it.  You don't know if the journal is out of round.  No amount of hand smoothing will fix that,

[TheBirdistheWord]

You trust rags that well?  How would you wash it out on the street?  You also want to get all the cleaning agents out too, you think they'll just evaporate?  Crank has oil passages.  Any cleaning agents are gonna get in there, some still trapping hone leftovers.  Nice way to add 10,000 miles wear right from the get go.

 

 

isnt this a bit exaggerated? wouldnt anything left behind be negligible in comparison to the amount of oil you put in and changing the oil so frequently per part of the break in process?

 

EDIt: in fact isnt that one of the main reasons you change the oil so frequently after a motor build?

[EricJB]

Most of the motors I have torn down with a suspected rod noise were not repairable with a bearing swap.

 

If you can hear it, it's usually too late. When it comes to the crank journal and the roundness of the rod end, were talking about a thousandth of an inch of tolerance. Sorry my friend, but I think it's over.

[Stoffregen Motorsports]

isnt this a bit exaggerated? wouldnt anything left behind be negligible in comparison to the amount of oil you put in and changing the oil so frequently per part of the break in process?

 

EDIt: in fact isnt that one of the main reasons you change the oil so frequently after a motor build?

It has to be taken into context. If you're dying to get your hands in there and work on it, go ahead. I have done it myself that way a few times, but datsunahloic is right, you will never get ALL of the debris out. But you could get it clean enough.

 

Measuring the bearings is critical, and if it in fact has a rod knock, installing a new crank will require measurments of some kind, but if the bearings look good, leave them. If they look bad but are still running and the crank has no discernible marks on it, buy the best bearings you can find and try replacing them. If they are too tight, they will lock up. If they are too loose, your oil pressure will be shit. Both cause premature failure.

 

If you want to try, go ahead and try. Don't let the overly cautious keep you from having the firsthand experience. But for our sake, document it here in a thread so we can see too.

[EricJB]

Yes, by all means, dont stop because of my comments. I did the chevy 4x4 in a foot of snow so I could get to work, and I did the mains too. That was 4 years ago and it still runs. Desperate times call for desperate measures.

[datsunaholic]

isnt this a bit exaggerated? wouldnt anything left behind be negligible in comparison to the amount of oil you put in and changing the oil so frequently per part of the break in process?

 

EDIt: in fact isnt that one of the main reasons you change the oil so frequently after a motor build?

 

Well, it's up to you if you want to risk it.  Having a vehicle out on the street with the oil pan off, having any wind blow dirt and crap up into the crankcase, having to worry if it will rain at any time when the crank is exposed.   I am not saying it can't be done.    Just that it shouldn't be done.  I changed mains without removing the crank once.  Or even the timing cover.  But I had the engine out and upside down, with the transmission off.

 

All it's going to cost you at this point is a gasket set and a set of bearings, and time.  If it works, great.  If it doesn't, well, you have to buy all those parts all over again (or another engine), and then you'll HAVE to find a place to pull the engine, since you'll have totally toasted the crank by then (if it isn't already gone, which I suspect it is).  Hopefully the car doesn't get towed for sitting on the street inoperative by then.

[TheBirdistheWord]

well, it seems this is probably one of those "do it right the first time" deals, as I should have already learned from throwing this motor in.  I already have most of the parts for a rebuild, I started this thread to help justify if it was worth doing. Probably going to keep on looking for a short block to build or a complete motor....  

 

I appreciate every ones input very much.

[lostforawhile]

if you dont have a garage, why not rent a storage building for a month, buy or borrow a cheap engine hoist and stand, at least if you run into problems, you can shut the door and take a break. it's a can of worms trying to do this by pulling the crank from the bottom, the engine needs to be CLEAN, much cleaner then wiping it with rags. not only will you have hone dust, you will have metal from reaming out the ridge at the top of the cylinder,so the pistons can come out.

[Stoffregen Motorsports]

if you dont have a garage, why not rent a storage building for a month, buy or borrow a cheap engine hoist and stand, at least if you run into problems, you can shut the door and take a break. it's a can of worms trying to do this by pulling the crank from the bottom, the engine needs to be CLEAN, much cleaner then wiping it with rags. not only will you have hone dust, you will have metal from reaming out the ridge at the top of the cylinder,so the pistons can come out.

For the record, Datsuns never have a ridge. The metal in the block is far superior to other brands (like Chevy of Ford). In all my years building Datsun motors, I can count on one hand the times I've seen a ridge.

[lostforawhile]

For the record, Datsuns never have a ridge. The metal in the block is far superior to other brands (like Chevy of Ford). In all my years building Datsun motors, I can count on one hand the times I've seen a ridge.

it depends on how many miles, the top ring never goes all the way to the top of the block, so there is always going to be a difference between the unworn cylinder wall and the worn cylinder wall, wherever that rings top point is, there can be a ridge, it doesnt have to be much to snag a ring, you just get one of those simple ridge reamer tools and it takes a second to remove it

[Stoffregen Motorsports]

it depends on how many miles, the top ring never goes all the way to the top of the block, so there is always going to be a difference between the unworn cylinder wall and the worn cylinder wall, wherever that rings top point is, there can be a ridge, it doesnt have to be much to snag a ring, you just get one of those simple ridge reamer tools and it takes a second to remove it

Understood, but let me put it another way, have you ever seen a ridge in a Datsun block?

[datzenmike]

I have, but very very slight (a visible line really) and certainly not enough to stop the pistons being pushed out easily. A better question would be, did you ever hear of someone having to use a ridge reamer to get Datsun pistons out? I have or had KA, Z20 x2, Z22 x2, Z24 x2 L20B x3? sets of pistons pulled from blocks and not a one didn't just pop out. I have to admit reaming ridges by hand on my 64 Dodge and a 283 gets old real quick and no way the pistons would come out past that lip.

[lostforawhile]

Understood, but let me put it another way, have you ever seen a ridge in a Datsun block?

my 310 had one on one cylinder, it wasnt bad but it had to come out before the piston would come out, the point on this thread though, is do this with the engine out, find somewhere you can work with a roof over it, trying to do this bass ackwards and in a hurry because you are outside is just inviting a mistake, Working as a machinist for a living, It would be a pain in the ass for me to even have to measure the journals at two points, while upside down laying in the street, how are th new bearing caps going to stay in place upside down while the crank is pushed back up against them? it just seems like it would take a lot less time to do it right 

[Stoffregen Motorsports]

my 310 had one on one cylinder, it wasnt bad but it had to come out before the piston would come out, the point on this thread though, is do this with the engine out, find somewhere you can work with a roof over it, trying to do this bass ackwards and in a hurry because you are outside is just inviting a mistake, Working as a machinist for a living, It would be a pain in the ass for me to even have to measure the journals at two points, while upside down laying in the street, how are th new bearing caps going to stay in place upside down while the crank is pushed back up against them? it just seems like it would take a lot less time to do it right 

You could use a bottle jack to hold the crank in place while you install the main caps!!!

 

And you and I agree that a ridge in a Datsun block is very rare.

[kelowg]

i have done rod bearings and reringed one before. that was 7 yrs ago in my carport and homemade ring compressor, no problems as of yet.

[72240z]

You guys have a lot of patience to explain comon sense and proper procedure so many times... I would just say to pick up a book.

I have seen a ridge on a few L6's but more a visible line, nothing that interfered with removing the pistons. Nothing like on a domestic either where you really do have trouble with them. 

[lostforawhile]

you could get one of those car roterriseries and just roll the entire thing upside down   :w00t: