1992 7.3 bad valve guide and two burned valves NEED HELP.

idi_man

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just bought me a 1992 7.3 f350. truck came with a shop dignosis diagnosing two burnt valves and one bad valve guide. there is also a break at the manifold flange causing a killer exhaust leak. i am new to diesels and bought the truck to learn on. could i replace the valves with good used ones from a 6.9 head i can get for free? will a 6.9 manifold fit my 7.3? if i go the route of rebuilding one head, should i do both? also what problems can arise from driving it 10 miles a day to and from work with the known problems? any and all help will be highly appreciated. i had trouble finding any threads about this which is why i am posting a new one.
 

typ4

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Its not impossibe to do, but do both heads, the springs will or probably are broken and that is the real problem ,caused by worn guides.
It WILL drop a valve so fix it before its junk. 6.9 parts will fit fine and I have new springs, cheap.
If you spend the money now on a good valve job it will go a very long time. If you want more detailed info let me know.

Oh and get ahold of Danielle on here and ask her if she has a good machine shop to do the heads. very important.
 

GOOSE

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Welcome fellow New Jerseyan.;Sweet You are about 35 minutes up the road from me. I happen to have a rebuilt head with less than 15,000 miles on it of you are interested. I have the match to it as well, about 220,000 miles on it, not rebuilt of course. I also have extra manifolds. There is a shop in Vineland that does machine work, although I have never quizzed them on their diesel saavy. The work can be done in the truck but it can be pulled in less than 2 hours. It sure is nice working on a stand........

Welcome to Oilburners by the way, you are at the right place to address the issues that you are having.
 
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hesutton

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DON'T drive it unless you are prepared for catastrophic engine failure when the valves and pistons meet in a violent fashion. You can do it inframe, but for me......... it's less painful to pull the engine and do it on a engine stand that try and fight it in the truck. These heads are crazy heavy.

How did the shop diagnose this problem without pulling the heads and looking at the valve/guide play and looking at the valves to know they're "burnt."

The 6.9 manifold is the same (as long as it's from an F-series).

Like Russ warned......... the machine shop will make your life wonderful or terrible when it comes to these IDI heads. If they don't know anything about them, they can easily ruin your heads.


Heath
 

idi_man

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the shop pulled the valve covers and glow plugs, then did leak down tests for each cylinder. the diagnosis paper said two burnt valves and two bad guides/seals.
 

hesutton

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No way to really know the condition of the valves, guides, seats without taking the heads off and start looking at those parts and their condition. Gotta pull the heads, remove the springs and see how much play there is between the valves and the guides, see the condition of the valve faces and the valve seats.

Without beeing there when the test was done...... the loss of compression could be bad valve guides/valves, or it could be a bad head gasket, piston rings........ and so on.


Let us know what you find.


Heath
 

idi_man

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well if it helps any it sort of backfires/pops out of the exhaust, but starts right up no problem.
 

idi_man

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wouldn't doubt it goose. i just hope it doesnt have a catastrophic failure before sunday when i can fix it
 

RLDSL

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worn exhaust guides are very common on these things, if the exhaust valve is wobbling it wont seat well and you will get gasses escaping past the guide ,as far as teh valve being burnt, maybe maybe not, most likely it just needs to be dressed if the stem hasnt been worn too unevenly to ride in a new guide.
Here is where a good diesel machine shop comes in. Also if having your heads done, do not let them pull any of the freeze plugs out unless they have proper stainless plugs to replace them with as most shops will not have these and they cost a minor fortune to pickup a full set from IH ( this isnt so critical on the 6.9 as it is on the 7.3 as the 6.9 usually doesnt have freeze plugs facing teh intake manifold, that is a nasty spot for trapping moisture and rusting)

Its not too hard to do the heads in the truck, remove teh hood and radiator for room to work, and you will need a cherry picker to remove and install the heads. You might be able to get them out without one, but you'll trash the new gasket trying to set the fresh head by hand unless you are a 400lb gorilla that can juggle 13 speed gearboxes, otherwise, get the cherry picker.

When you go to put it back together, go a set of Victor Reinz head gaskets and shoot them down with about 3 light coats of spray Hylomar for a leak free installation, and hit the intake runners of the valley pan gasket with that stuff as well
You will need new head bolts and a new set of grade 8 bolts and locktite for the exhaust manifolds as well, check the torque specs carefully, there are 2 specs listed, use the lesser of the two
 

Knuckledragger

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Has anyone ever witnessed real burned valves in one of these engines? When I rebuilt my 6.9, the valves were fine, but the web between the valve seats was cracked, which I understand is very common. Could be your problem is there, could be extra worn guide(s), could be burned valves. Pulling the heads in the truck is almost as much hassle as taking out the engine, but with the real possibility of dropping a head on the engine and ruining the (new) head gasket.

Unless you have nothing else to drive, fix it before it destroys something.

My ex wife seized up an engine in our minivan (in 1985), even after seeing the oil light come on. Her excuse? " I had some more places to go."
 

RLDSL

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My ex wife seized up an engine in our minivan (in 1985), even after seeing the oil light come on. Her excuse? " I had some more places to go."

My lovely bride pulled that one not long after we were married. Car blew a hose and she had steam pouring out from under the hood, and lights going off . and she drove 10 more miles, because she didnt want to be late for work.... that one ended up with a car getting scrapped for parts availability . It had been a real nice car.
 

hesutton

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Has anyone ever witnessed real burned valves in one of these engines?

I don't know about real bad valve damage, but my 6.9 had 325K on it before the rebuild and some of the exhaust valves were damaged. One intake and one exhaust valve are in Mel's IDI Museum of Mystery and Mayhem now (a collection of broken/abused parts he brings to the Rallies)LOL

Anyway.......Pitting on the face of some of the exhaust valves:
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Heath
 
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