1998 K3500 rebuild - heads off, more questions

[derekja]

So, the gasket on cylinder #2 is blown:

http://img.photobucket.com/albums/v719/derekja/truck/head2.jpg

The machine shop I found seems like they might not be familiar with 6.5 td's. The owner told me that he'll have a look at the heads this afternoon and has the facilities to clean and inspect the block, but that the block doesn't usually have problems unless something else has gone wrong. Erm, no, eh?

Options:

1) keep using this guy and just deal with the questions that arise on here.
2) find a local machine shop that knows something about this engine. Problem after cold-calling a half dozen or so I can't find any! Anyone know a place in Seattle that works on these?

So, since the timing chain needs replacing anyway and the bottom end hasn't been touched in 215,000 miles I think I'm still set on my plan of taking the whole engine apart and doing a top and bottom rebuild. I don't see any cracks so far! I'm not going to start ordering parts until after the block is mag'ed, though.

Do I invest in the measurement tools (piston gauge meter, micrometer, runout gauge, etc.) to evaluate the components myself? Those tools get expensive... I have a good 6" digital caliper already. Or is this something I should take components into the machine shop to have checked?

I need a good machine shop...

Thanks.

[john8662]

Classic blown head gasket.

Most machine shops should be able to handle the engine. If they're capable of running their equipment and have the correct equipment for the job.

The main things you'll need a micrometer for will be measuring OD of items, like crankshaft journal diameter for example. You may also want to measure piston size.

For measuring bore size, you'll need a bore gauge, not worth buying for one engine IMHO, the machine shop can do this for you.

You can establish whether you need to bore the engine or just hone and re-ring by checking the ring groove at the top of the bore. The bottom of the bores won't have any usually (unless really worn). But if there is a lip/ridge at the top, it's on the worn side. You can tell this with your fingernail traveling up the bore near the top.

J

[derekja]

gotcha. there is a lip at the top of several cylinders.

Both heads have cracks between the valve seats, btw.

With cracked heads and worn cylinders I'm getting closer to a rebuild or replace decision on this engine. I think my next step is to get the rest of the block apart and get it in to be cleaned and mag'ed if I don't see any obvious cracks.

I feel better about this machine shop after talking to the guy in person. He hasn't worked on this engine before but took the time to look it up before I got there and was helpful.

A guy here in town has a pair of supposedly flat, uncracked heads from a 1993 6.5. Will they fit my 1998? Anything to watch for? I carefully labelled my valve rods and rocker arms and such, but if they are going back into different heads that probably doesn't matter, does it?

[Robyn]

This looks like an instant replay of my 94 6.5 last april.
The original gaskets were notorious for doing exactly what you found in your engine.
I would recommend the heads be discarded and replaced with NEW

Clearwater cylinder head in Florida offers a complete set for about $670.
Thats what I paid and they paid to get the cores back for the parts.

The set I got were fabulous quality too.

Be sure your block is not badly eroded around where the fire ring seats.
If it is you will need to have the block decked .010" No more though and use the Felpro thicker gasket thats designed for such things.

The new gaskets are reenforced around the water passage on both ends with metal so the dont do what they did here.

Depending on what the rest of the engine looks like will dictate where you go from here.

With the engine out its an easy job to clean and redo a lot of things.

Bearings, seals, rings, gaskets, get the injectors and the pump checked too.

Replace the glow plugs unless you have recently.

Drop in a new timing chain, sprockets are usually good for another round of fun.

Replace the rocker arm guide buttons with new factory stuff.

Replace the oil pump as a matter of fact and any other goodies that seem in poor shape.
A couple rattle cans of black paint and poof like new again.

Its always good to find the cause of the issue though even if it is bad.

**Note** Be sure to use a set of stamps and stamp the rods and the caps to keep them in sets. Stamp just above and bellow the part line. Do this on the pan rail side of the rods. Number them to the cylinder # Drivers side is 1357 Pass is 2468

The factory does not mark them. This will also allow you to keep everything in order.

The bearings will have numbers on the back side. Many of these engine had select fit shells and you may find upper and lower bearing halves are not the same size. Like a .0005 under on one or both.
If all you find is a GM number and a date this means they are standard.
Rods may be select fit and mains standard or vice versa. No ryme nor reason to it just how they came across.

Unless you find large undersizes you can use standard bearings and you will be fine.

Mine had the .0005" Now they will be marked in metric so be aware.
The sizes are marked .013mm and .026mm being the .0005" and .001" undersize repectively

1mm is .03925".
Just when you thought you had it all figured out you have to learn the metric system.

If the cylinders are not really badly worn or have bad top ridge I would consider doing a light hone and a rering job.

Much of the ridge at the top can be carbon.
Scrape it carefully to gdet rid of the crud and then you will see just what you have.
My engine had 230K and very little ridge at all.

Be sure you dont have any scored cylinders and check the wrist pin for excess wear.

If the cylinders are good to go. Move on to the crank, if the bearing s were relatively good just clean mag and polish.

Be sure the main web area on the center 3 mains is checked well for cracks emanating from the outer bolt area.
If all is ok your set.

Hope this helps


Robyn

[Robyn]

More info for ya

The push rods are color coded (copper color) on one end, this end goes in the rocker arms. The rocker sets can be switched around and it wont be an issue.

The head bolts are junk, a one time use item. Get a fresh set and be sure the new ones have silicone (Orange usually) on the threads. Install in the threads of the block dry, NO OIL.

Napa sell them as do many suppliers.
I prefer Cleavite 77 bearings but Mahle are good as are Sealed Power, Federal Mogul and others.
You can even use one brand for the mains and one for the rods if you like.

My engine got Mahle mains and Cleavite rods. (What I found on Ebay cheap)

OH BTW Ebay is a great place to shop as long as you know what stuff sells for and what you need.

Dont head down to MA General for this stuff as they are way too costly at the dealer.

Be sure to use a gasket and goop between the timing cover and the block, the factory used a shelac and they always leaked.

High temp blue silicone is my fav for coating gaskets.

Use nothing on the head gaskets, DRY DRY DRY did I mention dry.

The rear main seal can be squeeked in when you are installing the crank. Just set the crank in the block with the tops shells in and lubed (104 Lubriplate is my fav)

Lube the seal lip and slide the seal in over the crank and position in the block while you lift the crank slightly, align and position the bearing cap on.

Dont use anything on the outer diameter of the rear main it needs tio reamin dry to seal properly and hold well in its bore. Just be sure its straight in the bore.

Use some High Tack red on the outer part line of the rear main near it's rear edge to stop any leaks.

Some 104 grease on the main bolts is fine before you torque them.


Geeez I am not sure if Have forgotten anything but Im here if need be.
Will happily do phone coaching if you like.

Robyn

[derekja]

Thanks for all the detail, Robyn! And the offer of phone coaching... I'm going to slog away on this for now, but if I get stuck I'd love to take you up on that.

Hopefully get down to a bare block tomorrow and then I'll get the webbing cleaned up a bit to see if there are any visible cracks.

[Robyn]

Start your observations around the outside main bolts on the 3 middle ones.
Once the caps are off you can look right at the bolt holes.

If there are any cracks that start at or through the bolt holes and progress down the web its grim news for the folks in Gotham city.

What block number?? 506???

Oil spray?? ( small holes drilled on an angle through the upper main saddle that squirt oil on the piston crowns) great idea but poor implementation.

Smaller outside bolts on middle mains or same size???

Best deal is if you have no oil spray

[billschall]

Derek, turn on private messaging in your User CP...


A guy here in town has a pair of supposedly flat, uncracked heads from a 1993 6.5. Will they fit my 1998? Anything to watch for? I carefully labelled my valve rods and rocker arms and such, but if they are going back into different heads that probably doesn't matter, does it?

They'll fit, but get 'em magged first if he doesn't have paperwork to prove it.

[derekja]

oops, messaging turned on. thanks. Would have thought that to have been the default.