6.5l engine assembly question...timing set

[llong66]

Hello to everyone! I have been in the process of disassembling a 96 6.5l turbo motor I bought from a local salvage yard. It has along with many of the other electronic goodies that come with the newer motors an RPM sensor in the timing cover, on the crank portion of the timing set, in front of the teeth for the chain is a small "spacer", then a ring with for equally spaced magnets for the RPM sensor. I had just planned on using the timing cover off of the motor I currently have since our trucks dont use these and it would just be one less hole to plug. When I ordered my rebuild kit, I bought one for a 96 motor but asked them if they could substitute the timing set for one of the older motors, no problem. I got what looks like a typical gasser timing set. When I took my motor to the machine shop for the work it needed, including a balance since I went with a new crank, rods, and pistons the machinist asked if there was a spacer that went between the timing gear and the rear of the balancer hub. I explained the situation to him and he said that I needed some type of spacer between the two or one or both of them could "walk", Im sure you can see how nasty that could be! I havent taken the motor currently in my truck out yet, it is a 6.5l repower done while the truck was still in service. The tech manual shows a set screw on the balancer and from the illustration in the TM I cannot tell if the timing gear has a spacer built into it or not, it does, however, show a difference between the 6.2l and 6.5l timing gears, showing the 6.5l with the RPM sensor. My civi 6.5l did not have a set screw on the balancer nor does the new one have a place for one. My question is this, is there a spacer built into the gear on these motors or is there a free floating spacer between them? I was told that Fords do that on some motors. When I asked about substituting the timing set I was given the option of 93-94 or 95 and up. If I need to, I will simply return the timing set I got for one with the reluctor on the crank gear. Im sure it will fit in the timin cover I want to use w/o the RPM sensor location.
Thanks much!
Greg

 

[pigfoot63]

The nose on the harmonic balancer are different lengths .

 

[davo727]

Did the shop verify the block isn't cracked before they do the machine work on it? A high percentage of used 6.5 blocks are cracked around the main webs.

 

[llong66]

Thank you both very much! davo727, yes, the guy at the shop is familiar with the 6.2/6.5 engines and he said he magged the s#!& out of it for me. pigfoot63, I will go through the TMs and look for a part #, is the balancer your referring to specific to the MV line of engines?
Thanks again!
Greg

 

[davo727]

Balancer is not different due to military.

 

[gringeltaube]

.......... My question is this, is there a spacer built into the gear on these motors or is there a free floating spacer between them? .....

No separate spacer there. The 6.5L timing sprocket is a one-piece part (pics below) and its hub is longer than the 6.2L counterpart.

The nose on the harmonic balancer are different lengths .

Correct. The 6.5L damper is shorter to compensate for the longer sprocket.


G.

 

[llong66]

gingeltaube, yep, thats whats in the civi motor I took apart, I am really curious now to get the 6.5 currently in my truck out and apart, as I said, it has no RPM sensor in the cover. If I understand you correctly, I my need to order a 6.2l damper rather than the 6.5l I have now? I cant seem to find a part #, NSN, or anything in the TMs.

 

[gringeltaube]

It's the same part for the 6.5L HMMWV engines, too.
Yes, a 6.2L-damper would work with the timing set you got. If you don't have a new damper already it might be time to replace it anyway, due to age?

The exact length of the 6.5 sprocket pictured is 39.5mm. You may want to compare with what you have and let us know.

For the numbers, you can use this TM 9-2815-237-34P from our library:
Figure 3: Damper, vibration, 6.2L: NSN 2805-01-1497859; 6.5L: NSN 2815-01-4112138
Figure 7: Sm. sprocket wheel, 6.2L: NSN 3020-01-1502207; 6.5L: NSN 3020-01-4255380


G.

 

[llong66]

I pick everything up from the machinist tomorrow and I will get some measurements and part numbers. I bought my rebuild kit from Northern Automotive and got the 93/94 timing set, the sprocket I got looks like a typical gasser sprocket. I did recheck and there are two different dampers, one for the 6.2 and one for the 6.5. Its odd, the 6.2 damper is $30 more! lot of money for a n inch or so of snout! I will just have to exchange the balancer I bought for a 6.2 unit. I had planned on replacing it. Im just really curious to see whats in the 6.5 I have now. Thanks for the TM ref, I had looked through them but must have missed it.

Thanks!
Greg

 

[llong66]

Hello, I dont have the exact measurements with me, but the pic I attached is the 93/94 timing set sprocket I bought. The one on the 96 engine I got is just like the one in gingeltaubes post above. The diff. between the two is exactly the distance between between the short 6.5l balancer and the 6.2l gear. I am not sure how I am going to solve the issue yet but will keep you all posted.

 

[gringeltaube]

If I had to solve this I would fabricate a spacer. For $30.... anytime!


G.

 

[llong66]

gringeltaube, the machinist I use was going to do just that, fab me a spacer using the old gear just cut the front off then knock the "tabs" off of it and there ya go then he said it was hardened and he didnt want to ruin a $75 mill bit doing it and was going to look at another option. I told him to not worry about it for now, I would see what they have going on in the motor in my truck now and maybe just exchange the balancer I bought, the short snout one for the longer 6.2l balancer. He told me to confirm that the counterweight is in the same position relative to the key or it will mess up his balance job. If not, then back to the shop for a spacer fab.