Just bought a supposedly low milage L28, think I should do anything to it?

[Nickanicus]

 

The person that I bought it from claimed it had 75k when the car was wrecked. It has been sitting for a while. I very carefully got the motor moving again and decided to pull the head off last night. I think the bores look good enough to put the head back on, fresh gaskets everywhere, and run it as-is. The motor coming out of my car would smoke mercilessly and as it turned out, there was a crack in the cylinder wall leading to a coolant passage.

 

What do you guys think?

[FlatBlack]

What should you do to it?

 

Boost it

 

I could be off base here but usually when the pistons have numbers on them, they are oversized by the amount that is written on them. Make sure to get all the junk that is around the piston head surface out of there with some compressed air before you try and crank it.

 

Did you clean the pistons? and was the motor running when you got it?

[Nickanicus]

I cleaned them. They have a 3 then a small 4 on the pistons. IIRC, my old motor had that written on them as well. Motor appears to be factory assembled, but who knows. I didn't see it running, I bought it from a guy who had it stored for a few years, waiting for a clean chassis to throw it in.

 

Oh yeah, and I plan on boosting it.

[Rolling Parts]

The person that I bought it from claimed it had 75k when the car was wrecked...

 

Just a visual and then a compression check will tell most of the story. Claims of low mileage mean little compared with the actual state of the engine. Most interesting would be dropping the oil pan and doing an inspection (and then cleaning out the gunk)before starting it up...

[MAG58]

Numbers that aren't .020, .040, .5, 1 etc are not oversize numbers. Those are nissan sizing ID numbers. That usually means they're factory pistons. Even though they were all 86mm, they were measured and then individually sized (you should see a corresponding 34 or 56 etc stamped next to the cylinder the piston is in.

 

I recently pulled apart an L28 ET block that has 250k on it and it still had cross-hatching on the bores. It needed a 1mm over to clean it up and get it back into spec. The best way to actually check for wear is do what's already been said, pull the pan and check the bearings. Pull the #4 main cap and see how hard they were on it by checking what the thrust bearing looks like.

[Ineptitude01]

Man, this might just be me, but the way I see it, it's all about what's easy and what's cheap. And if you think about it, you've got the head off, and the block is just sitting there. It's not a long, hard road to put it on the stand, pull the pan off, and redo everything.

 

Even if the engine IS a 75k'er, and hasn't been run hard, it won't cost you more than $150 to do the main and rod bearings, and piston rings. Sure, then you have to go through break in crap, but you also get the opportunity to do one of the most important things that you can do to any part of a car - get everything 100% clean. There's nothing quite like knowing that your shortblock is all new, and there's no 1980's oil residue left, you've seen the pistons, you've seen the ringlands, you've checked the crank journals, and you KNOW it's all perfect.

 

I doubt you'll notice anything wrong with the engine if you just blast out the bores with compressed air and run it hard. I'm just a big big fan of knowing it's perfect, and when you take the easy path, and trust the PO's claims (wince), you might not get what you think you're getting. Besides, once you have it on the stand like that, you can paint it up real nice.

[tightywhitey185]

Im sort of in the same boat here with my motor.Im going to post some similar photos.If everything looks ok in there should you just re bearing and re ring it and hone it and hot tank it and clean the crap out if it or should you send that sucker to a machine shop and have it all measured up?It could look clean but the fact that th block could need major machining could be purely mathmatical right?My question is....if the block looks good visually is it better to just hot tank everything and put new bearings rings and a coat of paint on the block?There are a million things to check specs on and this is what im struggling with.It could be costly.

[MAG58]

IMO I always pull out the mics when I'm rebuilding a motor. iirc, L28 piston/bore tolerance is around .002 or a lil less. When I pull motors I usually see .003-.004, which isn't a lot but still out of tolerance. If it's a nice low mileage motor a set of bearings and rings and your off to the races, but for all the work I'm already going to pull the thing apart to inspect everything, running the pistons out of tolerance in an otherwise completely rebuilt motor seems a little too half-a$$ed to me.

[tightywhitey185]

Ok so lets suppose I would drop of the short block to the machine shop with the rotating assembly in it.What would it cost for them to SPec the entire block and rotating assembly assuming nothing needs work?ei...deck height,bore,bore out of round,mains,bearing clearence deck streightness a good hot tanking and all that jazz?I mean they are a machine shop and make money of machiune work and im scared to death they will say YUP NEEDS BORED NEEEDS THIS AND THAT even though it mught possibly not?I guess Need someone to give me a heads up on what to expect through dealing with a machine shop.The more I research this could be more complicated and expensive then I intended just to get this block in spec.My eyes say it really looks great inside the engine.

[MAG58]

Machine shop: Needs bored.

 

You: What was the clearance? (You should know all these figures before starting)

 

MS: It just needs bored (they're jerking you around at this point)

 

Don't let them do any work until you get the numbers and figure out if what they're telling you is right or not. Ask for cylinder bore sizes and piston bore sizes if you don't trust them and do the maths by yourself.

[Dtsnlvrs]

You mention that it has been sitting awhile, how long? I would go through it...new rings, bearings etc. To give you an idea...I rebuilt my block in 2004, and it has seen maybe 10k miles on it. I am about to send my head to be ported, right before i go to Iraq for a year. Now I am pretty sure that if I fill the cylinders with a good thick weight oil it will probably be fine when I return...but I aint gonna take that chance. During my deployment I will source NEW 1mm over pistons, rings, bearings, etc so that when I return....all I have to do is get the block machined, rods prepped, get everything balanced, and then throw on my newly refreshed head. What I am trying to say is, at i minimum...check the bores (dia, gouging, etc) Ball hone, and throw some new rings and bearings in it.

 

Nothing sucks more than putting a head on a supposedly "good" short block, only to have it smoke like a cheap Havana Tampa cigar

Edited March 2, 2010 by Dtsnlvrs

[Tony D]

All this talk about 'throwing' and not one person mentions 'throwing money out the window'...

 

Chances are any bearings and rings you put in will be of LESSER quality than what Nissan used originally.

 

"And then you go through all the break-in crap"...

 

With all the jabberjawing and debate, the engine could have been in and running by now!

 

I bought a 'low mileage engine' let it sit in the side yard for FIVE YEARS through countless typhoons and when it came time to install it I got chocolate fudge out of it, along with several gallons of water.

 

I pulled the head, cleaned the piston domes and combustion chambers with lacquer thinner, reassembled it with a new Nissan Head Gasket and boosted it to 300+HP. I had oil control problems on #5 which eventually got me upset enough to try to kille the engine and swap to another one. What I ended up doing running 21psi of boost was UNSTICKING THE ONE OIL CONTROL RING and CURING my oil control issues in that cylinder. That was at around 5000 miles of operation after install.

 

45,000 miles later, it's still running strong.

 

Now, I didn't have the ability to put in ARP's then. I don't like Nissan Rod Bolts.

 

My ONLY concession to doing anything futher to what you have is this: Pull the rod/piston assembly and scrupously clean the rings and grooves of the pistons to make sure the rings won't stick (aren't sticking) and install those ARP rod bolts.

 

Reassemble it and ONLY buy a part to replace something that is OBVIOUSLY unserviceable.

 

There are THOUSANDS of engines out there that prove the materials and components in a factory-assembled engine are the RULE and not the exception.

 

Frankly the quality of rings has gone downhill since the engine was manufactured. You can't get Nissan Rings any more, so at 75K, that engine still has 175,000 worth of miles on it ringwise. I have an engine in my Fairlady that has 185psi of compression at 225,000 miles on it.

 

Don't "THROW" anything into that engine! Chances are you will end up with something of less quality and less longevity than what you have there already. The ONLY exception to that would be the rod bolts, ARP makes better units than Nissan did...

 

Or leave it alone.

[z-ya]

 

Don't "THROW" anything into that engine! Chances are you will end up with something of less quality and less longevity than what you have there already.

 

Or leave it alone.

 

 

Exactly. I've seen plenty of people with good intentions take an L28 apart to "rebuild" it, just to end up with a big pile of sh*t in the end. The last one was an L6 that couldn't retain it's bodily fluids on the dyno (blowing coolant and oil everywhere). But boy, that metal head gasket he "had" to put in was working great. There is nothing you need to do to the bottom end of these engines to produce a reliable 300WHP. And guess what, the folks at Nissan that built these motors knew what they were doing.

 

What about cylinder ridges? Are there any? If not, you are wasting $ doing anything to that short block besides seals and gaskets. Check the rod and main bearing cap torque, put in new seals, gaskets, core plugs, and timing set (if needed), and spend your money on the head, turbo (if you are going that way), and engine management.

 

Pete

[BRAAP]

Exactly. I've seen plenty of people with good intentions take an L28 apart to "rebuild" it, just to end up with a big pile of sh*t in the end. The last one was an L6 that couldn't retain it's bodily fluids on the dyno (blowing coolant and oil everywhere). But boy, that metal head gasket he "had" to put in was working great. There is nothing you need to do to the bottom end of these engines to produce a reliable 300WHP. And guess what, the folks at Nissan that built these motors knew what they were doing.

 

What about cylinder ridges? Are there any? If not, you are wasting $ doing anything to that short block besides seals and gaskets. Check the rod and main bearing cap torque, put in new seals, gaskets, core plugs, and timing set (if needed), and spend your money on the head, turbo (if you are going that way), and engine management.

 

Pete

 

 

What he said!

[S30TRBO]

Exactly. I've seen plenty of people with good intentions take an L28 apart to "rebuild" it, just to end up with a big pile of sh*t in the end. The last one was an L6 that couldn't retain it's bodily fluids on the dyno (blowing coolant and oil everywhere). But boy, that metal head gasket he "had" to put in was working great. There is nothing you need to do to the bottom end of these engines to produce a reliable 300WHP. And guess what, the folks at Nissan that built these motors knew what they were doing.

 

What about cylinder ridges? Are there any? If not, you are wasting $ doing anything to that short block besides seals and gaskets. Check the rod and main bearing cap torque, put in new seals, gaskets, core plugs, and timing set (if needed), and spend your money on the head, turbo (if you are going that way), and engine management.

 

Pete

 

 

its all in the head work save your money and send that head to Braap (shameless plug Paul) that is what I plan to do in the future. Dtsnlvrs will vouch too since he is lining up his to send to Paul.

[yetterben]

I'd like to further this thread as this happens to people all teh time where they wanna know how far they should go, or just run it.

 

I am in the same spot where i have a block with a few little ridges or nicks down in the bore.

 

It would be nice to kinda have a step buy step rebuild guide on Hybrid. Whats enough to warrant boring etc...whats common place to just run it.

[Xnke]

There is a book that is commonly referenced on this site that does all that.

 

It's called How To Rebuild Your Nissan/Datsun OHC Engine, by Tom Monroe. He goes through all the tolerances, the procedures for measuring, has nissan part numbers listed, and has some fairly decent photos in there as well.

 

There's really no need to try to put together a thread on rebuilding the L28 when Tom did it better already.

[Leon]

There is a book that is commonly referenced on this site that does all that.

 

It's called How To Rebuild Your Nissan/Datsun OHC Engine, by Tom Monroe. He goes through all the tolerances, the procedures for measuring, has nissan part numbers listed, and has some fairly decent photos in there as well.

 

There's really no need to try to put together a thread on rebuilding the L28 when Tom did it better already.

 

Seconded, for emphasis. It's a great book and it's not expensive at all (~$20). if you want a step by step guide, this is the top dog.

[yetterben]

Indeed the book blah blah...but there is more info to be had from people here than tom. We all wanna do things right the first time blah blah. Sometimes a sweeper motor is needed and its nice to know what can be cheated and what cant. In situations like this for example. A JY motor is being used or a used motor non the less. So its nice to know what can be gotten away with.

 

But the book is on its way here for the do it right method.

Edited June 2, 2010 by yetterben

[Xnke]

There is some pretty decent info about stuff like that in the book too. Infact, there is a section in the beginning that goes through the whole "do I really need to do this" if I recall correctly.

 

And, if you know the factory tolerances, (those are in the book) and you know about how long the motor has to run before you can rebuild one (or how much time you can squeeze out before this one grenades) You can extrapolate what tolerances YOU want.

 

Tony, I just called the local dealership to ask about bearings and rings, having heard you say they are higher quality parts than the aftermarket. You're right, stock, first and second oversizes for the 86mm piston rings are gone, and all L6 bearings are out of stock...But the 85 and 87mm pistons and rings, and the oversizes, for the 4 cylinders are still listed as well as L4 bearing kits, at the local dealership.

 

Maybe I can get some Real Nissan parts for the next engine. Is it worth stocking these in my garage?