: 4.6 N* Cylinder walls

08-01-13, 11:18 AM
Just started a N* rebuild and after removing the heads noticed some blued areas in a couple of cylinders
Likely caused by overheating due to faulty HG. What do you think should i ditch the block?

08-01-13, 01:19 PM
Did u buy car to fix or was it yours to begin with so you have some history? Sounds like you don't know how much car was abused?

08-01-13, 02:10 PM
A cylinder block overheat would be about 1,100 degrees too cold to 'blue' a cylinder wall. The head gasket failure was due to head bolts pulling from the compromised cylinder block bolt holes. That's why you need to insert or stud all 20 bolt holes.

If the original cylinder wall cross hatching is still evident, clean the cylinders thoroughly with lacquer thinner, apply a coat of synthetic engine oil and install a new set of rings spec'd for the engine. These engines almost never need honing and almost never leave a step at the top of the piston ring travel - check it out with a fingernail scraped up the cylinder walls. Be dead SURE to install the new ring set according to instructions - including the second compression ring: dot up.

Study the GM service manual concerning cylinder walls, wall finish, why not to hone, engine overhaul and other such mundane Northstar stuff. A good check of the cylinder roundness and taper will tell you whether the block is serviceable.

Read through the sticky posts just above these recent threads - ^^^ . Study the Cadillac Technical Archive way up ^^^ in the top black bar.

08-01-13, 03:20 PM
Can you get some pictures and show the blue areas

08-04-13, 09:30 PM
A cylinder block overheat would be about 1,100 degrees too cold to 'blue' a cylinder wall.

If the original cylinder wall cross hatching is still evident,
Here's what they should look like. At 130K & 170 K

08-11-13, 04:33 PM
sorry that it's taken this long.....busy busy busy

i just don't like the looks of this cylinder wall

i've even gone so far as to get a complete second block

This is what i know of these two engines. The original has 53k with hg problems, likely drove hard.
Probably the cause of the burnt cylinder wall.
Was running when i tore it down.

the second had roughly the same mileage but was burning excessive amounts of oil.
i popped out one piston 135385
bearing looked decent obviously carboned build up with sticky rings

i haven't done any measuring yet

just trying to decide which one to work on.

08-11-13, 06:49 PM
Are there bolt threads near surface in closer holes and no threads visible in rear bolt holes?

08-11-13, 07:52 PM
i drilled and tapped a few holes in the first block for studs
before noticing cylinder walls

08-11-13, 09:53 PM
This is what i know of these two engines. The original has 53k with hg problems, likely drove hard.
As it was intended to be.

Probably the cause of the burnt cylinder wall.
Not likely

08-12-13, 08:08 AM
assume 2nd block has pistons/rods? are you going to rering 2nd motor? bearings?

08-12-13, 11:32 AM
i just like the looks of the second motor
it came apart so much better. Even the head bolts were evenly torqued no
aluminum/oil on bolts. The first engine about half of bolts were loose, real mess, oil everywhere YUCK
Took a day to clean even before disassembly.
At this point just thinking about new rings for the second block.
What's a good cleaner for the pistons?
Any thoughts?

08-12-13, 09:24 PM
Whatever you use, DO NOT use Scotch-Brite. Don't even let it near the motor.

08-13-13, 12:47 PM


[/COLOR]that's a for sure!
I pulled all the pistons out of the second block, cross hatch looks good, rings were definitely in bad shape.
Planning to rering, replace rod bolts, likely new rod bearings, head stud kit and gaskets.
I was able to pull the pistons without separating the block halves...just don't want to mess with the lower end, it was sealed up nicely, virtually no leaks.
Will there be a problem just reusing the crankshaft bolts? And i'm hoping to reinstall pistons without splitting block.
Sure it would be easier, but like i said don't want to go there.

08-17-13, 02:36 PM
I bought a '97 Eldorado from a salvage with minor body damage and a head gasket leak.
No big deal right? Change gaskets, studs...whtever.
I dropped the engine out the bottom, with the help of a FSM...easy.
Turns out the engine has a cracked cylinder so i scrapped it.
Picked up a '99 engine that was all carbonned up (old man motor never driven over 30mph)
Engine was less intake, exhaust manifolds and front cover.
Sure clean it up, change rings, rod bearing and bolts, and put together. Right?
Ya sure.
Now it turns out that the pistons and heads are different from one year to the next.
'97 engine (block stamped '96) pistons have reliefs cut in them '99 does not
heads are different, intake and exhaust ports are different
manifolds just aren't going to work if i swap
Can i buy new pistons with reliefs and use them in the '99 block?
Do i just build the '99 block and find the right manifolds, and change a few sensors?
At this point i'm scratching my head.
Any thoughts would help

08-17-13, 03:29 PM

08-18-13, 07:29 AM
Your "99" engine actually sounds like a 00+. 00+ engines don't have the valve reliefs on their pistons, and basically everything won't match with the 93-99 engines. Look for the engine identification code (9 letter/digits - for example, 6XU789012) and look at the second letter. If it's X, it's a 99 engine. If it's Y, it's a 00 engine. Although there are some exceptions, since some late 99 cars came with 00 blocks. See #2.

99 engines don't have coil cassettes but they have 4 coil packs sitting on top of the rear cam cover with 8 spark plug wires.

00 engines have coil-on-plug design with 2 coil cassettes, front and rear. Neither 93-99 style coil packs nor spark plug wires for 00.

Another way to tell, if your heads have the 3/5 cylinder (and 4/6 cylinder) spark plug holes separated, it's a 99. Flat tappet cam follower design for the 93-99.

If they are connected with a place for the coil cassette spring, it's a 00. Roller cam follower design for the 00+.

Images searched from Submariner409's albums, my personal stash, and Google.

08-18-13, 02:30 PM
thanx maeng

So there's noway i can flange something together?
i have to find a pre 2000 block?

08-18-13, 03:18 PM
No. 99 and 00 are whole different engines. Cannot mix and match.

08-19-13, 09:58 AM
I talked to a seller of a 99 Sts. He serted the block last year and now he has a bad rod. Too bad it's crazy expensive to gut the serted block and install new crank/rods/pistons. I see core motors for sale often. Junkyards are full of them

08-19-13, 11:57 AM
that will be my next phone call
Here's something else
on the '96 block the heads have different exhaust ports
one is round and the other is d shaped
is this common, or was it just a bad day at the plant?