Is this block toast?

[Workinprogress]

Well, the title says it all.

I was replacing the head and switching to triple webers, so I took the bottom end of my L28 apart just to make sure. I'm glad I did. I'm hoping to just require a honing, but will settle for boring it out and getting slightly larger pistons (didnt want to have to buy them, though...)

 

Here's the damage:

http://album.hybridz.org/showgallery.php?cat=589

 

 

Does anyone in the Bremerton, Wa area have an L28 short block I can grab?

 

Thanks,

Grant

[schwiplarkin]

your best bet is to take it to a machine shop,, its hard to tell without doing some measurements, but i think ive seen worse work out..

 

good luck

[BRAAP]

Grant,

The cylinder walls look pretty typical of an engine that has set out side and/or with a blown head gasket and has set for a while, i.e. the corrosion on the cylinder walls. The block will at least need an over-bore. The deck surface does show possible signs of the fire ring loosing its seal to the deck surface at the front of cyl #1, between #3 and #4, and also at the back of cyl #6, though in most of the pics, the deck surface is a bit out of focus so it is hard to really know for sure especially without looking at the head and gasket itself. (It really doesn’t matter that he rust is there or even form which cylinders it got there, what matters is how it got there so the reason it happened in the first place can be fixed, i.e. warped deck surface, etc.)

The bearing halves in the block look as though this is either a really high mileage engine, 200,000+ miles, or the previous owners were pretty lax with oil and oil filter maintenance. The bearing halves in the caps are a different story. I noticed in particular #3, #5, and #7 main bearings halves in the caps show high concentrations of wear on one side of the bearing, (the sides towards the rear of the block), though #1, #2, also show mild signs of similar wear. This can either mean the block could use align bore/hone, (meaning the crank main line is not true and straight), and/or the engine was rebuilt previously using cheap bearings such as Federal Mogul and/or the builder didn’t make absolutely sure no debris was behind the bearing half when installed, (typical of hasty rebuilds, a piece of debris only .0005” behind the bearing shell will show significant wear on the bearing as there is only typically .0015” to.003” clearance to begin with). There are a number of ways to verify if this engine has been rebuilt or not in its past life, (not that it really matters at this point whether or not it was rebuilt as you have torn it down and it “now” needs a rebuild. Right now you just need to verify why the abnormal bearing wear occurred so that it can remedied if you so choose to rebuild this engine). If you care to find out if this engine has been rebuilt, you can remove one of the bearings and on the back of the shell itself will be small stampings/engravings/embossings. If you see FM, then it had been rebuilt using Federal Mogul bearings, (Federal Mogul uses inferior material in their plain bearings and they have a tendency to loose their crush under high loads and heat and FM bearings are manufactured not true, i.e. the bearing halves are not uniform across their width). If you see the Nissan emblem embossed then these are factory bearings, but it still could’ve been rebuilt using OE bearings. Something else to check for if this engine has been rebuilt, is whether the crank has been turned. This is easy as the Rod and Main bearing shells will be stamped with the amount of undersize on the backside of the bearing shell. If this is so, you’ll see .010 or .020, etc. There is nothing wrong with a turned crank, as long as it was turned “truly round” and with no taper and of course to the proper size. You will need a micrometer to verify the quality at which any crank grinding was done if this was performed. Also, the easiest tale tells sign of a rebuild is the cylinder bore being oversized and/or aftermarket pistons.

On the crank, the only thing that stands out is the #6 rod journal looks as though bearing material may have transferred to the crank journal, could just be lighting reflecting off the crank journal as well.

Solely based on the pics you provided, i.e. without actually being able to verify no cranks, etc, this block does appear to be salvageable, though at what cost? NO idea till you get the engine down to a reputable machine shop so they can verify the block isn’t cracked and that the main line is in fact “true”. Worst case would be this block needs all the cylinders bored and honed, main line bore/hone, true the deck, of course tank and cleaning of all the parts etc and the cost of the engine gasket set and required parts, i.e. pistons, timing gear, etc..

 

Good luck, sorry I couldn’t offer forth much more help. Please do keep us posted on what transpires of your project…

[Workinprogress]

This engine did have a blown head gasket and sat for awhile before I came across it. Once it got to my place it sat for another 4 months untouched. I did save the head gasket so that will give me a bit more info. The center two cylinders were the worst as far as crud on the pistons and bore appearance. On one in particular, it looks like rust ran down the inside of the bore and etched it or something. I can feel it with my finger easily. None of these cylinders had much of a detectable ridge to them at the top, other than carbon debris. The oil looked like mud when it came out though, and when I broke the main caps free, there was a smell of burnt oil in the air. The PO didnt have ANY anti freeze in the car at all, just pure water, and rusty too.

On a side note, the local import yard has a few ZX short blocks around, they said they would let me get one for $150.

I'll clean out the bores more and the crank to get some better pictures. The crank main and rod journals feel smooth to me, I run my fingernail across them and feel nothing at all. The rebuild book says run a penny across and if it leaves a copper trail, its too rough.

 

Thanks for the info Braap.

 

Grant

[Workinprogress]

Ok, here's the block deck surface by each cylinder, the block side of the gasket and head side. Also, I checked one each of the rod and main bearings, they both have a serial number it looks like and the letters "STD" which I assume means standard size for that engine. Next is #1 main cap and bearing next to each other, it looks like you were right Paul, there's a bit of grit or something in the backside of the shell and a mark on the cap corresponding to it. Next to last is a representative of the rod bearings, looks worse off than the mains. Last of all is the inside skirt of one of the pistons, it says AMPCO 7. What is ampco? Aftermarket pistons? I looked and cant find a number or anything else to indicate if they are overbored or not.

 

http://album.hybridz.org/showgallery.php?cat=590

You'll have to sort by name and ascending, I cant get them to save in the right freakin order.

 

Thanks,

Grant

[BRAAP]

Grant,

Your comment about the engine only having water in the cooling system raises a new question, is the block cracked? It is very common, especially for American V-8’s, that have set over the winter with only water in them to crack during a freeze. Typically these freeze cracks are very noticeable to the naked eye, but on a few occasions the freeze cracks are small enough that they only show up during a pressure and/or magnaflux test, i.e. more $$ just find out if the block is even usable.

The gasket does show definite signs of being blown, i.e. the fire ring being destroyed.

The piston skirt also shows signs of moderate scuffing towards the upper skirt of the piston. Scuffing on this region of the piston skirt is typical of high combustion temps, i.e. lean mixtures over extended periods of time, detonation, etc, which tend to cause the upper portion of the piston to swell and then scuff the cylinder wall. Now high water temps tend to cause the mid to lower portion of the skirt to swell and scuff to the cylinder wall. Though, if the skirt is collapsed, i.e. the bottom of the skirt is now smaller than the mid to upper portion, the mid to upper portion could’ve scuffed just from excessive water temp, not necessarily high combustion temps, (typically, the piston is widest at and below the wrist pin when measured with a micrometer, depending on the manufacturer and material composition of the piston),

This may not be exactly what you want to hear, but if you can get a decent core short block that is a runner and not a smoker, needing only a cylinder head for $150, that may be the route to take, (though how do you know for sure it is a decent run-able core that doesn’t have broken rings, collapsed pistons skirts, spun bearings, etc? All you have is the sellers word and only sometimes does it come with a guarantee.) If you have the dollars to rebuild a short block yourself, that should help put your mind at ease as to the quality of the rebuild and you will have a fresh short block that should last a good 100,000-200,000+ miles, but this piece of mind comes at a significant financial expense. Pistons, bearings, rings, timing sets, gaskets set, etc for the Datsun L-series engines are getting more and more expensive. They have always been a little more expensive to rebuild than your basic garden variety stock Chev 350, and over the past 10-15 years, the price for pistons, bearings, and such have gone up even more for the sweet heart L-series.

 

This must be major bummer as you just came down and picked up those carbs from me last weekend and were all excited and now have to wait even longer to run them.

BTW, have you been looking for air horns or found if there are any available to fit under the air cleaners?

 

 

Good luck and keep us posted…

[Workinprogress]

Paul, yes it is quite a bummer. I expected there to be trip ups in this rebuild, but I wasnt prepared for this large of a hurdle. I'll look into a decent short block but may take the exitsting one to the machine shop anyways. They will clean it and magnaflux it for 75 bucks I think (may have neen 65), that should answer the question of a cracked block then and there. If what you say is true about it needing at least to be bored out, that means new pistons anyway, so I was set on spending at least that much in addition to the bearings/gaskets/etc...

 

I am keeping my eye out for air horns that will fit under the filters, there are different lenght ones. The guy up here in Bremerton (Iskone) runs triples w/horns and filters very similar to the ones you sold me, no problems with restricted air flow for him.

[SU'dCrazy280]

My block looked worse than yours when I opened up my engine. My car sat with a blown HG for 5 years before I bought it. I got new pistons, and bored it .40 over and honed. Guess how much it cost? FREEEEE!!!! (except for the pistons) But usually each cylinder costs about $300.00 to get a 6 cylinder bore job. At least at this shop. But your block is fixable, even if it is cracked, there are always sleeves, and sleeves make your cylinders more bulletproof anyway. I don't know if it is worth buying a $175.00 block, wouldn't you at least get that block honed or possibly bored? Well, just trying to help out.

 

J.T.