Results 1 to 12 of 12

Thread: Block do's and dont's

  1. #1
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default Block do's and dont's

    After having been through a real nightmare with the 6.5 Block that I bought for DaHoooley there comes to mind some very real points to consider.

    With so many of the 6.2 blocks at 25 years old or older and the 6.5 blocks as much as 18 years old now there are several things to consider aftger you have gotten your NEW prize home to work on.

    For sure, there are a lot of shops out there that will do a reman in some very odd and often unscrupulous ways.

    Cylinder boring is a common thing and is to be considered a normal part of refurbishing an engine block.

    Some of these engines will even see the mainline remachined.

    This is no biggy either.

    I will not go into depth on the mainline cracks here as we have beaten that to death elswhere for many years.


    The focus of this thread is the Block DECKS.

    These engines, as they near the 200K mark or sooner in some cases will have errosion around the two front cylinders where the gaskets fire ring sits.

    This is due to coolant sitting right up to the stainless steel fire ring.
    Along with the two dissimilar metals the electrolysis process starts and eventually the block will develop a small groove where the ring sat.

    Now in and of itself, this is not a big deal. The block is set up and machined to give a fresh new surface.

    Here is where the problems start.

    Bubba's Garage and machine scalps off .014" off of one side and .009" off the other and does not bother to stamp the upper rail as to this fact.

    Ten years later after you drag this hunk of Iron home (Happy as a clam) is when the trouble starts.

    A bare block tells few stories at a glance.

    Its also not impossible to have a block with one side STD and one thats been cut. (ask me how I know this)

    Here is the important point.

    As soon as you find a good block to drag home. If you have to pay much, get it in writing that the thing will be CRACK FREE and also that the decks will be usable or at least STD height.

    Next thing, right after you get the new little beastie all scrubbed up and clean, get it upside down and drop in a set of old bearings and a crank.

    Next, stuff in two piston/rod assemblies (dont need rings just bearings) and turn these suckers to TDC and check where the top of the piston is in relationship to the deck.

    The piston should (if the deck is stock) come to right at flush to no more than a couple thou. out of the hole.

    If the decks have been cut you will soon know it.

    Now just because a deck has been cut before is not a death sentence as long as the surface is good.

    Let say that one side is cut .010" and the surface is good with no errosion then just install the thicker Felpro gasket.

    If, lets say the other side is at STD and needs to be cut, just have that side machined and your off to the rodeo.

    NOW
    Let say that one side has been cut and the surface is nasty, at this time you can save yourself a BUTTLOAD of $$$$$ and a bigger pile of embaracement by getting the thing all ready to build, then finding this out.

    ASK ME HOW I KNOW THIS

    There is the possibilities of doing special pistons with heigher pin centers or cut tops and then reballance and OH $Hit frank more $$$$$$$

    Before you pour a lot of $$$$ at a potential engine be sure and check this out.

    The main line crack things is certainly repairable and I have done many of these with success.

    The deck issue is one situation to avoid at all costs.

    Now if you find a block with this issue and you want to build you plans around special pistons and or other tricks, have at it, just be aware that this issue is lurking out there and may strike at any time.

    The stock of good usuable 6.5/6.2 Blocks is dwindling every day at a fairly fast rate due to normal attrition.

    These engines are not like the little mouse motors that GM made a Bazzzzzzillion of.

    One thing for sure, I myself would certainly not be afraid to use a new block from one of the online sellers instead of spending a buttload of $$$$$ trying to revive a questionable old 6.5 block thats been hacked, chopped and otherwise mollested over the last 20+ years.

    I understand that the HUMMER is being phased out by the military and so if this happens, the likelyhood that the P400 and the optimizer 6500 will also soon go away.

    The whole reason for these engines was to supply a reliable engine for the HMMWV.

    The 6.5 will likely be around for some time BUTTTTTTTTT I suspect that the sources for parts are going to eventually fall back to used stuff and the aftermarket.

    In closing

    Just be sure of what you have before you spend a dime on machining and such.

    I have a lovely little YELLOW block sitting in the corner now with over $800 tied up in it thats not going to give back what I poured into it.

    Even the engine rebuilder suppliers dont check this stuff so you are going to be the only thing between success and failure here.

    Good luck

    Missy
    Last edited by Robyn; 10-08-2010 at 07:34.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  2. #2
    Join Date
    May 2015
    Location
    Flatwoods
    Posts
    1

    Default Rebuild

    I'm getting ready to rebuild a '99 6.5. Its in a C3500 van and was partly torn down several years ago. One head was removed and exposed the cylinders to the elements. The Cyl walls are corroded a little. I did find the mechanic that did the initial teardown and learned that the head was cracked. The vehicle was driven up until the teardown. The owner did not want to send the $$ on replacing the heads. So I plan to remove the engine, have the other hear checked, have the block checked and bored, then rebuild her. My first diesel rebuild, hell my first diesel anything, other than driving and servicing. Any other suggestions.

  3. #3
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    Welcome to TDP


    The 99 blocks had issues, and they can crack the #8 cylinder near the top.

    If it were my project I would scare up a good crack free 599 block. 92-95 blocks.

    These were the best until the AMG blocks hit the trail in 2001.

    All your other parts are usable right across.

    I would also not waste any $$$ on the old heads.
    Either new AMG heads, or if the budget is a little skimpy, get a set of heads from Clearwater cyl head.

    Replace head bolts, as they are a use once item.

    The pushrods are directional, and if they have been mixed up you may be better off to buy new.

    The color coded end goes to the rockers.

    Replace the plastic rocker guide buttons as well.



    Keep us posted on your project and we can help along the way.

    Plenty of good write ups about such projects can be found here.

    Missy
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  4. #4
    Join Date
    Jan 2015
    Location
    Alvin, Texas
    Posts
    17

    Smile Piston to Head Clearance??

    Robyn, thanks for the great info, it is obvious you know these engines well. I am a professional engine builder and machinist and have built thousand of engines from bone stock to anything racing, mostly gas engines, but did a lot of diesel stuff back in my semi-truck repair days. I have taken on my first 6.5 diesel project and have acquired a 599 block out of a 92' pickup. I finished all of the machine work and have started the build process. My question is, what is the tightest piston to head clearance one dares to run on these engines?? I have run as tight as .040" on gas engines with tight piston wall clearances safely. Mahle recommends .0039" wall clearance for their pistons and this block was honed with a torque plate. I know that given the inherent design of these engines, the pistons will rock in the bore. I would figure .050" piston to head clearance would be safe, your thoughts or recommendations?? Thanks in advance!!
    MikeyG1975
    Engine Machinist/Custom Builder, Mechanic, currently Offshore Oilfield Mechanic/Machinist
    Too many projects to list...
    2012 Ram 2500 Laramie Longhorn Mega Cab, 6.7L Cummins TD, Deleted, PPEI EFI Live Programmer, Economy Tow Tune, Auto, leveled, 35's, 4" Flo-Pro Turbo Back Exhaust...
    1993 Chevy K3500 Crew Cab Long Bed Dually, 6.5 TD Auto, Turbo-Back Diamond Eye Exhaust, Heath 2.5" Crossover pipe, otherwise stock, upgrades planned...
    1994 Chevy C1500 Extended Cab Long Bed, 2 WD, 5.7 Gas-Sold
    1979 Chevy Camaro-Z28, fully restored
    1979 Chevy Camaro Rally Sport project car

  5. #5
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    You're pretty well spot on.

    The pistons when the blocks are fresh (decks not cut) will sit flush with the deck.

    If you have cut the decks up to .0012" use the Felpro .010" thicker gasket and life will be fine.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  6. #6
    Join Date
    Jan 2015
    Location
    Alvin, Texas
    Posts
    17

    Default

    Robyn-Excellent, many thanks!!
    MikeyG1975
    Engine Machinist/Custom Builder, Mechanic, currently Offshore Oilfield Mechanic/Machinist
    Too many projects to list...
    2012 Ram 2500 Laramie Longhorn Mega Cab, 6.7L Cummins TD, Deleted, PPEI EFI Live Programmer, Economy Tow Tune, Auto, leveled, 35's, 4" Flo-Pro Turbo Back Exhaust...
    1993 Chevy K3500 Crew Cab Long Bed Dually, 6.5 TD Auto, Turbo-Back Diamond Eye Exhaust, Heath 2.5" Crossover pipe, otherwise stock, upgrades planned...
    1994 Chevy C1500 Extended Cab Long Bed, 2 WD, 5.7 Gas-Sold
    1979 Chevy Camaro-Z28, fully restored
    1979 Chevy Camaro Rally Sport project car

  7. #7
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    You betcha
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  8. #8
    Join Date
    Mar 2000
    Location
    Loyal WI US
    Posts
    10,792

    Default

    Quote Originally Posted by mikeyg1975 View Post
    Robyn, thanks for the great info, it is obvious you know these engines well. I am a professional engine builder and machinist and have built thousand of engines from bone stock to anything racing, mostly gas engines, but did a lot of diesel stuff back in my semi-truck repair days. I have taken on my first 6.5 diesel project and have acquired a 599 block out of a 92' pickup. I finished all of the machine work and have started the build process. My question is, what is the tightest piston to head clearance one dares to run on these engines?? I have run as tight as .040" on gas engines with tight piston wall clearances safely. Mahle recommends .0039" wall clearance for their pistons and this block was honed with a torque plate. I know that given the inherent design of these engines, the pistons will rock in the bore. I would figure .050" piston to head clearance would be safe, your thoughts or recommendations?? Thanks in advance!!
    We target about .005" protrusion. When doing your rods if you have a fixture you can match the rod length by using 20/20 bushings by sealed power?

    In my experience the 6.5 block will split just like the old 400 SBC unless you use a splayed main cap.
    Kennedy Diesel-owner
    More than just a salesman-I use and test the products that I sell on a daily basis!
    Superflow Lie Detector in house
    2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
    2005 Chev K3500SRW D/A CC Long LT(SOLD)
    2007 Chev K2500 Classic EC Short LT (Sold)
    2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
    2016 GMC K3500SRW D/A CC short LTZ

    Custom tuning in house using EFI Live tuning software!

  9. #9
    Join Date
    May 2017
    Location
    North Carolina
    Posts
    36

    Default Engine for sale

    I have found a 1984 6.2 engine for sale for 500.00, it is my understanding that the 6.5 blocks also can share parts with the 6.2. The exception of course would be different pistons. So, if I was going to rebuild and have a 2nd motor wouldn't this engine be a good place to start?
    1995 Chevy 2500, 6.5L Diesel mostly stock 234,000 miles. Changed the water pump to HO WP, deleted the vacuum pump and added a mechanical wastegate controller made by me with info from others on the forum.

  10. #10
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    TRUE

    The 6.2 and 6.5 can share a lot of parts.

    Some areas that do not exchange though are...

    The early 6.2 engines (pre 1990) all used a 2 piece rear main crank.

    The 6.5 engine are all of the one piece rear main style and cranks will not swap between older 6.2 engines.

    THE EXCEPTION AGAIN IS

    The late 6.2 was the same block as the 6.5 only with smaller cyl bores.

    1990 to 1993 had the one piece rear main.

    All other parts swap internally and externally across the line EXCEPT

    Pistons (As mentioned)

    Early heads (1982 red engines) had slightly different cyl head water passages .

    Accessories, brackets and such all pretty much swap.

    Water pumps are different between engines with V BELT DRIVE vs Serpentine drive (Opposite rotation)

    Early heads used cast rockers as opposed to the later stamped steel rockers.

    There are also differences in oil pans between the 2 piece rear main and the one piece.

    These will not swap.

    Intake manifolds are pretty much good to go EXCEPT

    Vans and Hmmwv (Hummer) use intakes and heads with bolts that go straight up and down (60 degree) vs the standard pickup style that are at 90 degree to the intake mating surface.

    Tons of different pre-cups, but can be swapped in sets of 8 pretty much across the board.

    Injectors come in fine thread and coarse thread (Early engines had coarse 1982)

    Heads on later engines had a different injector angle to allow them to clear the Turbo exhaust manifold.

    Injector lines on DB2 equipped engines (mechanical injection) use different lines than the DS4 equipped engines (Electronic)

    These have different fittings.

    The late 6.2 used the same heads as the 6.5 (Mechanical injection) but used different injector lines than the earlier 6.2 due to the injector angle difference.


    Flex plates came in a few different flavors to accommodate the 700R4/4L60 or the TH-400 and the 4L80 trannies.

    All the slight difference may seem overwhelming, but mixing and matching can be pretty easy

    Some minor odd ducklings came with the military engines, but the basic engine is the same other than the intakes as mentioned above.

    Crank bearings are pretty much a mix and match EXCEPT

    Later 6.5 engines used main bearings with extra holes in the block side shell to allow oil spray orifice feed.

    Rods are same same (Always match sets for weight)

    Cams should all swap
    Timing components (Gears, chain etc) are common EXCEPT

    The 6.5 with electronic injection use a reluctor on the crank sprocket to work with the crank sensor.

    Timing covers are common EXCEPT
    Early 6.2 up through the 1993 6.5 with DB2 injection did not have a crank sensor or place for one.

    A late cover can be used with an early engine (plug the sensor hole)

    Late harmonic balancers use a shorter snout in conjunction with the crank position sensor.

    Early timing covers had a splash baffle and later ones did not

    Hope this helps

    Robyn
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  11. #11
    Join Date
    Sep 2003
    Location
    Feeniks, Aridzona
    Posts
    1,114

    Default

    Quote Originally Posted by Robyn View Post
    TRUE

    Intake manifolds are pretty much good to go EXCEPT

    Vans and Hmmwv (Hummer) use intakes and heads with bolts that go straight up and down (60 degree) vs the standard pickup style that are at 90 degree to the intake mating surface.
    I bolted a Hummer intake to my truck 6.5 without any issues. The difference is that the holes for the air cleaner are rotated 90 degrees on the Hummer intake.
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  12. #12
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    Early Hmmwv

    Sorry... missed that one

    Early 6.2 Hummer engines did not use the 60 degree format on the intake bolts.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •