ZCar Forum banner

Status
Not open for further replies.
1 - 9 of 9 Posts

·
Registered
Joined
·
107,695 Posts
Discussion Starter #1
Is it possible to remove a piston & rod from an L28 engine from the bottom, without having to remove the head and/or remove the engine?

I haven't put the car on a lift yet to check this myself, and my car is 25 miles from me, parked at an auto hobby shop, so I can't get to it for a few days to find out.

But I'm hoping that I might be able to put it on a lift, loosen the engine mounts, jack the engine up an inch or two, remove the oil pan, and then be able to disconnect the piston rod from the crankshaft and maneuver the rod + piston out of the block from the bottom. Also hope to be able to reverse the procedure after replacing the rod.

Any advice?

-Rob
 

·
Registered
Joined
·
1,826 Posts
Re: Nope, won't work.

> Is it possible to remove a piston & rod
> from an L28 engine from the bottom, without
> having to remove the head and/or remove the
> engine?

The pistons won't clear the main bearing caps. Physically impossible. Plus you still have to remove the front cover to get the crank out due to the timing chain. Not that it matter, but you would also never be able to compress the piston rings without putting them in through the top. My suggestion is to pull the whole motor out. Since it's fuel injected I would probably go as far as to even disconnect the harness at the ECM and pull all the motor wiring along with the motor. Once it is out the task is much easier of tearing down the motor. Also much easier to reassemble. Only disconnect what is necessary to pull the motor out of the car, then do the other stuff after the motor is out.
greg
71 240z
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter #3
Re: Nope, won't work.

> The pistons won't clear the main bearing
> caps. Physically impossible.

Thanks, Greg. Had my fingers crossed.

Can I remove the oil pan at least without having to pull the engine?

Problem is, I only have about an hour or so tonight or Friday, not enough time to pull the whole engine. I'm dying to look inside to see what the heck is broke. Only after I see what's broke can I have a clear idea which direction I'll go (repair, rebuild, replace, etc...).

-Rob
 

·
Registered
Joined
·
1,826 Posts
Re: Nope, won't work.

> Thanks, Greg. Had my fingers crossed.

> Can I remove the oil pan at least without
> having to pull the engine?

> Problem is, I only have about an hour or so
> tonight or Friday, not enough time to pull
> the whole engine. I'm dying to look inside
> to see what the heck is broke. Only after I
> see what's broke can I have a clear idea
> which direction I'll go (repair, rebuild,
> replace, etc...).

> -Rob

I'm pretty sure you can remove the pan, but you will still have to lift the engine alittle bit. You will also probably have to turn the motor over by hand as you try to pull the pan so all the crank counterweights can rotate out of the way as you pull the pan. Also, dropping the oil pickup in the pan will help. What went wrong? The only thing you could tell by pulling the pan that you couldn't tell by a compression check or visual methods is condtion of each bearing. Dropped valves, broken pistons/rods, broken timing chain, etc. can all be done without diassembling the motor. Tell us what happened. Was the car running and something happened, has it been sitting for a long time, history unknown, etc? A good compression or leakdown test will tell you all you need to know. Then you can plan from there.
greg
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter #5
Pan can come off.....

You can pull the oil pan off the motor without removing anything else. I just jacked mine up and set it on stands, then unbolted it. It has about 25 or so bolts. To put it back together you will need a new gasket and a SMALL amount of gasket sealer to seal the pan. You also might need a rubber hammer to break it loose. But as listed above, why are you taking this down. If something is off in the pan you are in trouble, same boat as me... :p
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter #6
Re: Pan can come off.....

>.. as
> listed above, why are you taking this down.
> If something is off in the pan you are in
> trouble, same boat as me... :p

I'm taking it off because there's a horrible knocking inside, and I suspect a broken piston ring. If that's true there's probably a lot of other wear and maybe damage too, and I want to get a look-see before I start figuring out what to do (replace, repair, give up, etc...)

Thanks for the advice: I'm headed off now (after work) to try to pull that pan.

-Rob
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter #7
Re: Nope, won't work.

Dropped valves, broken pistons/rods, broken
> timing chain, etc. can all be done without
> diassembling the motor. Tell us what
> happened. Was the car running and something
> happened, has it been sitting for a long
> time, history unknown, etc? A good
> compression or leakdown test will tell you
> all you need to know. Then you can plan from
> there.
> greg

I bought the car this past Saturday night without ever starting it. I basically bought it because the body is in great shape, and I figured the engine might or might not be repairable.

The previous owner said it suddenly developed a very bad knocking sound deep inside the engine, and lost power. His son drove it to a local mechanic who apparently checked it out a bit and told him he had a broken connecting rod (only running on 5 cylinders).

I want to see the condition of the bearings and the journals so I can decide if I should scrap the engine or rebuild it. I figure there must have been a reason for a rod to break, and that reason was probably that it was driven way too hard while it was low on oil. If that's true, I'd be better off spending $450 on a replacement used engine.

I want a quick look because I'm leaving this Friday and will be near Sacramento CA for a week, where there's a good Nissan junkyard I can browse through. If I just have a broke rod and OK bearings/journals, I'll probably try an experiment and try to swap out the piston rod (vice a proper rebuild). I figure it'll either work or it won't, and I can't do any worse than I'm looking at right now: a dead Z with a broke engine....

-Rob
 

·
Registered
Joined
·
107,695 Posts
Discussion Starter #9
Re: How did it go?

> So what happend???

My post Halleluja! (but call me Bozo) kind of explains....

But the knock is still there for a few seconds at startup. After the oil starts pumping it goes away. So it's obvious I have severely worn parts inside, and I'll need to do a rebuild. It's just a question of how worn? and when to rebuild? now.

I bought 2 cans of CD2 sticky-oil that I'm going to put in as sort of a test. I figure if the knock goes away with one can, then the wear level warrants a rebuild as I can afford it, sometime in the next 12 months. If the knock goes away after 2 cans instead of 1, then I need to get the rebuild parts as a christmas present, and take a week's vacation in January to work on it. But if 2 cans of CD2 won't make the knock go away, then I need to shut it down and not even start it again until it's rebuilt.

Guess you can call it the four dollar bearing wear test....

-Rob
 
1 - 9 of 9 Posts
Status
Not open for further replies.
Top