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Trouble Code and Head Gasket Questions

alphadeltaromeo

alphadeltaromeo

Diesel Enthusiast
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I have a few questions that I'm trusting I can get some input to help me make a few good decisions.

1. I am getting this trouble code: DTC 85 - Transmission Gear - Other than the 85 being a transmission gear error, what would be the potential causes. The code doesn't occur all the time, but periodically. When it does occur, the burb shifts very hard. The code on the computer does say "undefined ratio error".

2. I am going to be pulling the heads to change the gasket, putting the 6.2 ARP studs (please let me know if this is a bad idea) and having the heads magnafluxed. With that said, when I take the heads off (never done anything like this before) do I need to strip off everything prior to giving them to the machine shop, or what would you recommend I do in order to make this process as efficient as possible? When I pull the heads, apart from the gasket set, are there any other parts that I should have replaced?

Input is valued, as I'm quite a novice in this area.

Appreciated,

Andy
 
I had to replace the gaskets a few times before I had them surfaced. I'd have them skimmed and pressure tested. I took mine in right off the block, crud and all. I just took all the brackets bolts and plugs........I just left the valve assembly and pre-cups in the heads. Keep things clean, clean, clean. While your that far down get all the grounds cleaned real good.

John
 
John...thanks for the input. I believe there is a Napa store close to my work that will check the heads for me. I'll make sure to clean them real good before taking them over.
 
Have you confirmed the speedometer is accurate? The VSSB module being wrong could cause the error for ratio. That or a VSS itself, and if the speedo is accurate than you know its the other VSS that doesnt feed the VSSB.

If they are going to magnaflux your heads then they are first going to hot tank them to make them spotless, so dont spend too much time cleaning them up.
 
The speedo tracks a gps quite well...or it has. Next time the error occurs I'll verify that.
 
Can I please get some advice on dealing with the heads? We have the valve covers off and are just about to pull the heads. Can I get a quick recommended sequence of what I need to do to get the heads off correctly? Thanks for your patience with this novice :)
 
Don't mix up the pushrods. They have to go back exactly where they came out and more importanly the right way. IIRC copper side goes up. I usually take a box and puch 16 holes in it, 8 on each side then put an F on the front of the box as it it was the front of the motor and then jam the pushrods into the holes in the box one at a time as I take them out. Also I would try to keep the rocker shafts where they were as well. Some say it's not a big deal to mix up used vavlve train but I was taught different and never wished to test it. Throw the head bolts away, they are junk and yes use ARP studs. PMDCable sells them now apparently and if he's out Summit ships pretty fast too. I would never do HG's on one of these without studs.
 
Do yourself a favor, if you have not taken the accesories off the motor yet, I would snap a few pics. Helps to remember where things go later on... :D
 
Follow the torque sequence in the GM manual but use the torque spec from ARP. Make sure you tap all the holes out in the block. If you don't run a tap down all the holes you may not get a good seal when you put the studs in. That part is time consuming. 34 holes to do. I used a speedwrench on the tap. Use a good teflon thread sealant or aviation formagasket on the studs.
 
Never tapped the holes myself, but, I use red or blue locktight to seal the studs in the block.

Why are you pulling the heads? I hope is isn't for the transmission code. :hihi:

Undefined ratio error means the transmission is in the wrong gear vs. what the computer is telling it to be in. No other codes for wiring... So the computer goes into limp mode and give you full pressure and harsh shifts.

So check the grounds. Check the transmission connectors and the wiring 2-4" from the trans for insulation falling off.

Reasons for the wrong gear would be mechanical from a sticking part/solenoid or failing sprag clutch. If this is occurring in the 3-4 shift it is wear in the overdrive section and failing/slipping sprag clutch. Get it rebuilt ASAP if this is the case as the sprag can completely fail and go through the OD gearset. This adds $250 in parts to the overhaul...

How does the trans oil look?
 
The trans oil looked good 3k miles ago. I'll check it again. Pulling the heads as we have significant compression bleeding into the cooling system. The top hose is getting rock hard quickly now. The result has been significant coolant loss in 1k miles. No coolant in the block yet.

So, the head bolts are out...but the head doesn't want to come off the block. We're dealing with the passenger side presently. The A/C compressor has been removed with the associated bracket/bolts. Is it typical for the head to be frozen onto the block or should it come off easily?
 
pretty typical that the head will need to be helped to get the gasket to break loose. try to find a spot you can pry on without damaging thing
 
Heads off...

The heads are off by using the suggestion above...thanks much.

Here are a few pics. You'll note that cylinder #7 has oil around the outside of it. We took the gaskets off, turned them over, and #7 was definitely leaking compression into the cooling system. The metal ring on the gasket was broken and the gasket material was damaged quite a bit. This was the only damage on the gaskets that we could find.

I think what is more important for me at this point is to determine if the hairline cracks between the valves is something that I need to be very concerned about. It's hard to see in the pic, but almost every one of the cylinders has this same hairline crack. Are the heads ruined at this point with those cracks? I don't want to take them down to get pressurized/checked @ $100/both if so. I'd rather just sink the money into new heads.

Your thoughts are appreciated. As a note, the cracks are no worse than what I've described. I'm sure a pressure test would reveal the extend of the damage, but I'm looking for a ball park guess to help guide me.

On, yes, we're pregnant with #11 :) lol
 

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Would a pressure test still be recommended? Those are the only visible cracks we can see. I only pulled the heads because of the compression in the cooling system. Would it be advisable to do the test or just clean them up and bolt back together?
 
Did you see where the gasket is bad?????.......And if so, can you take a pic?

I seem to have the start of the same problem......But I'm just getting air out of the bleeder screw, but like you I know something is wrong. When did this issue start?

And X2 on #11.........Holy Makrol, and God Bless........................................Your wife!:D:thumbsup:
 
Thanks for the congrats...yes, 11 :p

Here is a pic of the #7 cylinder.
 

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