6.5L is toasted...

[rdurh]

After searching I'm pretty sure I know what the answer will be, but consider this just that misery loves sympathy.

Yesterday the wife ran the 1994 Blazer 6.5L diesel down to just a little over three quarts of oil. (Getting her to check the oil when she fills up is ... frustrating.) She calls me up on her cell phone saying the Blazer is making this terrible noise, and then holds her cell phone up to the engine so I can hear it. All this time I'm yelling over the phone to shut the engine off. Oh well... Any way I get out to where she's at, check the oil and it's not even on the dipstick. With out thinking too far ahead I dump two quarts of Rotello in the engine and now it's still nearly three quarts low. Have her turn the key and engine doesn't move but starter is really spinning. I lost the plastic cover someone put on the 4L80E transmission so I get under the truck so I can see the flex plate and torque converter. Transmission is spinning just fine, but nothings moving on the engine. I'm going out later today and see if I can spin the engine over by hand, but I got a pretty solid feeling that's a lost cause. Right now it's looking like a broken crankshaft and I'm assuming the worst that I'll need a new engine, or at least a short block. The heads, injectors and IP on this engine are all less than two years old, and the IP was replaced with a new unit. I've been trying to find a builder 6.5L in Colorado but no luck so far. However, I've found plenty of 6.2L engines that I could use for a rebuild. From searching I'm fairly confident that I can use my 6.5L heads and such with a 6.2L block, but are there any issues that I need to look for when I go to check out any blocks? Things like which 6.2 block years or casting would be better, one piece rear main seal, etc.

[rdurh]

I may have dodged a big one. I went out this morning when I had better light and it was a little warmer. Checked the back of the engine and the flexplate sheared off completely letting the rest of the flex plate and torque converter shift back. Did see what looks like a small crack on the end of the crankshaft between two flexplate bolts. Don't know if that will be an issue or not.

[Robyn]

Howdy
My condolences for your loss.
Losing the engine in ones rig is like losing family.

Anyway, the 6.2 could be used as almost everything is the same accept the bore size.

I would watch ebay or Craigs list to see if you can find a buildable 6.5 though.
The late 6.2 engines had the one piece rear main seal as does the 6.5 and would be the best choice if you go that way.

The heads will swap right over too, just be sure and use a new set of bolts.
The bolts used in these engines are a one time use thing.

There are a lot of Military 6.2's out there for sale that could prove to be a really cheap fix.

The issues with Blocks are of course the usual stuff like spun bearings or torn up cylinders.
A block with a spun main should be avoided as the cost to repair is generally not worth the $$$

A scuffed cylinder that will clean up at .5mm or .75mm would be a good deal

Its common for these engines to run well over 200K miles and still have usable cylinders with no more than a light hone and a set of rings and bearings.

The big issue is Cracked main webs.

Many 6.5's have suffered cracked main webs. These cracks start in or around the outer main bolts on the center three mains. The cracks progress down and into the web area and sometimes into the cam bearing area.
Many times these cracks have traveled up into a cylinder causing coolant leaks too.

If the engine block is still oily inside its tough if not impossible to see the cracking unless its catastrophic.

There are many options but I will avoid the expensive ones. (New AMG Block)

The Late 6.2 engines had a casting number ending in 599 as did the very early 6.5 engines (92 93 94))

Later blocks were the 506 now the 506 came in a couple different incarnations, early blocks had the same size main bolts all the way through and the later blocks had small outer bolts on the 3 center mains and also had oil spray holes drilled from the main berings through to spray oil into the piston crown area.

Avoid the late (spray blocks) they are much more prone to cracking and main web failure.

There have been several different castings but up until AMG took over the production there were no real fixes to the issues.

Also the 6.5's can suffer a cylinder failure in the number 8 hole in the 8 oclock region when viewing the cylinder block from the right side (Pass)

The cylinder cracks radially about an inch down from the deck in the area of one of the rear bolt bosses.
There is a stress riser at the terminus of one of the lower bolt bosses. This was really common on the Hummers but is seen on the Pickup and Burb engines too.
I have seen these and its sad to see a perfectly good block otherwise, useless.

The 599 6.2 block was made for the military also and was made past the 93 cut off for the 6.2 in the civy stuff.
I have a 599 that was made in april of 94. and came from a HMMWV
These blocks have a lot of extra metal in the cylinders as they could be bored to 6.5 std and beyond.
The 6.2 is 101mm bore and the 6.5 is 103mm bore.
This is a healthy amount of extra metal.

I would recommend the use of a stud girdle on whatever you buy.

First though I would yank the engine out of the rig and do a post mortem and see how bad it is.
I have seen cranks break and leave the block just fine, BUT looking is the only way to know.

Do the post then proceed from there.

Hope this helps.
let us know how we can help

Robyn

[More Power]

The flexplate problem might be the biggest problem you have. I'd start there, by replacing the flexplate, then see what you've got. It's human nature to jump to the worst conclusion, especially when dealing with a diesel prob (I've done it myself). So, take it apart, see what's wrong, then decide what to do or what needs to be fixed. We'll help!

Jim

[rdurh]

Turned out that the bell housing was broken. One of the top mounting ears on the bell housing completely broke off and a second was cracked and about to fall off. At the cracked second ear the bell housing bolt broke completely off. Then the center of the flex plate was broken off the rest of the plate. The bell housing bolts apparently were the lowest grade of metric available, and they weren't stock as per Chevy. Prior owner, two years ago had the transmission rebuilt. The assumption is that the rebuilder put in the lower grade bolts, and may have dropped the transmission cracking one of the ears on the top of the bell housing. I didn't have any place to do the repair myself as I have the daughter's car in the garage on jack stands and my driveway is about 30 degree angle to the street. Paid a shop to replace the flexplate, weld the bell housing and fix some other odds and ends. Total bill was $1175.00, with about $350 being the other odds and ends that I was going to do later, but since the transmission was out let the shop fix them. So about $825 to replace a $75 flexplate, because someone didn't use the right bolts.

[DennisG01]

Glad to hear that it atleast didn't turn out to be catastrophic! It really stinks when things break because of oversight. If it breaks because you're using it hard and it's reached the end of it's servicable life, well it's still bad, but atleast you can understand that. When it happens because someone didn't think, that's what gets a person angry! If you've read my post about my engine, TRUST me!

[Robyn]

Does your rig have the heavy aluminum flywheel cover and the two stiffener bars that bolt to the cover and then to the front motor mounts.
If it does not you need to find some and get them on there.

Removal or the failure of some mechanics to put these back on can and does lead to failures of the bell housing and other valuable items

Also if memory serves there should be a heavy rod the bolts to the right side of the tranfer case and runs all the way up and bolts to one of the right side middle bell housing bolts.

This heavy bar keeps the combination from tweeking sideways and the two smaller bars stop the engine and tranny from flexing up and down at the point where the engine and tranny fit together.


Your rig may only have one bar up front and may or may not have the side one.
I have seen many different combinations of these devices used over the years.
These parts can be found either at a bone yard or places like ebay.

Hope this helps

Robyn

[rdurh]

When I picked up the truck in Ft. Worth 2 1/2 years ago it had a plastic flexplate inspection cover that feel off somewhere between Texas and Colorado. No braces were on the transmission. I didn't know if that model had any braces or not. I have a drive train out of a '85 CUCV that had no braces but my younger sister's '84 Blazer 6.2L has the braces. I've been trying to find the braces and cover for the '94 Blazer and also some braces for my CUCV drivetrain. No luck in the salvage yards yet.