Head bolts

[56pan]

I just had a new mil. surplus 6.5 engine put in my '93 C2500 Chevy pickup. The people I bought it from always remove the heads from these mil. surplus engines and have them taken to a machine shop to be hot tanked and checked for leaks, valve sealing, etc. Something about the engines being run on a dyno when the mil. takes delivery, and they've had engines that didn't have the cooling system completely purged of air. Hot spots, head cracks. I haven't been able to call the people back to confirm this, (I'm working in Germany for the next month), but I'm afraid they've reused the head bolts. Aren't these torque to yield? The block date indicates the engine was manufactured in 2001. If those head bolts weren't replaced, I'm looking at leaking head gaskets down the road, right? Any input on this issue would be appreciated. I won't be able to get back to the truck until the middle of Dec.

[Robyn]

Yes these are TTY Bolts

Reuse is a real bad idea.
I have seen it done but the likelyhood of issues later is a concern.

These bolts are so cheap, I don't understand why anyone would want to reuse them.

If the shop is pullingn the engines apart to check them, they have to install head gaskets and a fair amount of time into the engine before its useable again.

Would make zero sense to reuse the old Bolts

Robyn

[56pan]

Thanks for the info Robyn. I'll try and get in touch with the people I bought the engine from tomorrow to see if they, in fact, did reuse the bolts. If so, I've got some work ahead of me. Seems like if I used the proper torquing sequence, I could pull them out individually and retorque. Save replacing the head gaskets.

[Kennedy]

Just curious where these "mil surplus" engines are coming from?

[Robyn]

The only way I would attempt this would be to yank all the bolts but four.
(both ends and two in the middle)
Then I would replace all the rest of the bolts and snug them down.

Replace the four old ones that were left in to hold the head in place.
Now go through the torque sequence as is described in the instructions.

First time to 25 pounds, second time to 55 Pounds then go back through a second time to 55 pounds (the first ones will be looser than the last ones when you get done)

Now do the 1/4 turn on each bolt going through the pattern.
Now go back to the first bolt in the pattern and with a torque wrench and pull until it just moves.
Check the last bolt in the series. Bring all the bolts in the series up to whatever torque you get on the one that reads the highest reading.

The gaskets tend to compress with the final sequence and the bolts done first will tend to be much looser than the last ones.

The plan is to end up with all the bolts the same torque.

Use a scale reader torque wrench and not a clicker.

Now you should not see a bunch of movement with this, but there will be a little.

Even torque is a good thing.

Having several of the bolts slightly less tight can cause issues.

As the engine goes through the first few Hot/cold duty cycles things will settle in and having a good even torque will help the gaskets live a lot longer.

By keeping 4 bolts in the head and then installing the rest of the new ones you wont disturb the gasket.

Dont try to replace them one at a time.

As long as the head does not move the gasket will be fine.




Missy

[56pan]

Thanks for that procedure for the head bolts, Robyn. Haven't been able to talk to the guys I bought the engine from yet, but will try again tomorrow. I dread having to take those injector lines off if the bolts need doing, but I've done it so many times now I'm used to it. And Kennedy, the name of the man who had the new mil. surplus engines is Jim Henry, Albemarle, NC. Phone no. is 704-983-5940. He had one of the engines on display this last July at the Southeast Old Thresher's Reunion at Denton, NC. If you're interested in one, you might want to wait for me to put some miles on mine. If it scatters, I'll be sure and let you know.

[56pan]

Promised a follow-up on the mil. surplus 6.5 eng. I've got in my truck now. Have put about 1200 m. on it with no problems. It's down on power some, as it's an N.A. engine and I haven't turned up the inj. pump yet. Low EGT's and low boost. Eng. is tight, and I checked mileage on my first tank of fuel. Only about 11.5 mpg. I'm hoping it will do better when it's broken in, and I'm breaking it in easy.








'93 C2500 2wd, new mil. surplus eng., fresh Jasper 4L80E, Fluidampr. Nothing special. Just a good old truck.

[DmaxMaverick]

Just curious......What's "low boost" on a N/A engine?

[6.5 Detroit Diesel]

sounds good overall, but i am confused. it's an N.A. engine with low boost? if it's NA, you shouldnt be having boost.

[DmaxMaverick]

Nice catch. Glad I'm not the only one scratching my head.....

[56pan]

What I meant was it was originally a new N.A. engine. I put the turbo from my old engine on it. The inj. pump is calibrated for an N.A. engine. I'm going to turn it up 3/8 of a turn. According to what I've read, that's close to the setting for an engine with a turbo.