6.9 engine difference question

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Oct 23, 2010 | 03:31 PM

turbill

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From: Western Mass

6.9 engine difference question

I've posted before that right now I have an 85 6.9 with a snapped head bolt stuck in it. There are a few things I'm worried about aside from the bolt not coming out but thats a different story I don't want to get into that, I'll ask about that when/if the time comes.
But for now I'm weighing my options if the bolt doesn't come out or something along those lines, so i'm look at engines on craigs and ebay to swap in and just part the old engine. So already long story short, one i'm looking at is an 83 6.9 and I think I remember hearing there is something they changed in 84 or 85 that improved the engine.
Am I making this up? or was there a change. And if there was what is the difference and is it something I could take off of or swap out from my 85.
Thanks in advance for any info and sorry for being so long winded.

Oct 23, 2010 | 05:02 PM

IDIDieselJohn

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From: Ottawa, Ontario

Early 6.9's (83-mid 85) had a thinner block, and tend to crack at the block heater when used.

So long you don't use the block heater you'll be fine.

Also it be best to make manual glow plugs on earlier 6.9's as there glow plug systems like to fail and turn the glow plugs on and keep 'em on untill they all burn.

And last but not least, rocker arms are weaker on 6.9's 1983-1986, and to make it bullet proof, replace with 87 6.9 rockers arms or any 7.3 IDI rocker arms. It is a direct bolt in swap.

Edit:

Cut the block heater cord, update/manual glow plugs, and replace rocker arms and you got a bullet proof 83 6.9L

Oct 23, 2010 | 05:10 PM

turbill

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From: Western Mass

ok well i live in new england so i might be needing a block heater
so is it an engine i should stay away from.

Also is there a code on the door or something that will tell me if my current 85 is a thinner block one or not. because i have a block heater and if i end up keeping i sure don't want to crack the block.

If it is an early 85 what would i do in the winter if the block heater is a bad idea?

and i already have 7.3 rocker arms i was gonna put on the 85

Thanks for the info so far

Oct 23, 2010 | 05:13 PM

IDIDieselJohn

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From: Ottawa, Ontario

If the glow plug system is in good shape, you don't need a block heater. It's just a convinience to have heat in the cab as soon as possible.

As for your 85 theres a VIN number on the block, someone on here has the numbers to tell you if it's a good block or bad.

Oct 23, 2010 | 05:20 PM

turbill

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From: Western Mass

well as long as the trucks running i dont care if i need a jacket and hat in the morning.

So basically if i were to end up getting this 83 a manual glow plug set up is a good idea and i just need stay away from the block heater.

Sounds like a viable option if it comes down to it.

Thanks alot for the help John

Oh yeah do you have any idea where to vin number is on the block or should i just start an new thread

Oct 23, 2010 | 05:24 PM

IDIDieselJohn

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Woops, forgot to tell you about the VIN

If I remember correctlly, it should be on the intake, somewhere in the back cyl # 7 - 8

Or at the front cyl # 1 -2

Can't remember for sure. I know it's somewhere on the intake and first 2 digits will be 69 on a 6.9L and 7.3L first 2 digits will be 73.