TECH 101 engine chuff/ valve breaks POST MORTEM

[f-two-fiddy]

I would not recommend knurling the guides on these engines. I've ran a set with knurled guides, and the guides only lasted about 50K miles. New Guides is the only way to go.

On a side note Al, I sure hope your not going to try and salvage those Inj's. The way they were sliding over the truck bed means contamination for sure. Possibly damaged threads.

 

[riotwarrior]

I would not recommend knurling the guides on these engines. I've ran a set with knurled guides, and the guides only lasted about 50K miles. New Guides is the only way to go.

On a side note Al, I sure hope your not going to try and salvage those Inj's. The way they were sliding over the truck bed means contamination for sure. Possibly damaged threads.

Knurling is a cheap way to get a few more miles outta yer ride...on the cheap! however I said it's not the best way!

Yes, Yes I am actually going to salvage those injectors. They are find and I'll be sending them off for cleaning/rebuild and pop test/setting

Gotta have an extra set of decent BB's right? For now they are submerged in a small ice cream tub full of diesel soaking staying rust free.

IP will get the dose of diesel soak too once I get the lines off....

Al

 

[IDIBRONCO]

Hey Riot. The answer is yes. The bronze liners are better than the cast. The machine shop that did the machine work for the shop I worked at always replaced the guides with bronze ones. It seems to be a worse problem on 7.3's than on 6.9's. Don't ask me why. I replaced A LOT of heads on 7.3's. It always seemed to be the exhaust valves. Maybe more heat? I'm not saying that intake valve guides or the guides in 6.9 heads can't wear, just that the exhaust valve guides in 7.3 heads wear the most. This is from my experience. Maybe some machine shops don't know about the problem and don't know how to solve it.

 

[dgr]

Makes one wonder why the 7.3 rockers are "better?"

 

[riotwarrior]

After searching the internet for last couple days off and on I've come across this little piece of sweetness! Can you say

L I G H T B U L B

http://www.langtools.com/diagnostic-tools/diesel/adapters/58850.html

Yuppers gotta get that exact unit, though pricey, it's THE tool I was going to make anyway. If I can find just that female fitting I'll not have to order it, otherwise I'll be ordering it DOH!

Ordered this today....will post pics asap and also get the thing in USE!!!

 

[riotwarrior]

UPDATE TIME!!!! small one but update time

I was going through some images on my other photobucket account and had forgotten something about this old truck. It was a service truck for a logging company, as such it's required to have a "SPARK ARRESTOR" on the exhausts tail pipe.

The tip as on the truck

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Here is a close up

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now with a light on it and this is the side the engine sees as you can tell it's quite clogged up...no friggen wonder I had issues.

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cleaned off sort of see that edge that's broken off that's one layer of perforated metal missing and there where 3 more layers besides the one you see here and he broken one so 5 total...ya that's not good for breathing!

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Now it's CLEAN OFF!

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So I began thinking that with this friggen POS spark arrestor dohickythingamjig on there, there was all kinds of back pressure and such so once that valve guide began to wear exhaust gas and carbon etc was clearly being pushed out past the guide and then wearing it out faster as abrasive as it is.

I'm still waiting to get INSIDE that block later and look at what happened. but these pics show some clues as to why mine was so badly covered in soot under my valve cover.

Thanks for looking

Al

 

[icanfixall]

Al I had the same arrester on my tail pipe too. Was sure glad then Banks cut it out when they installed my turbo way back in 96 or 97. If you have the oem muffler that too will fill up with soot and cause untold back pressure issues. But to run an na engine without a muffler tells the next town your coming towards them...

 

[franklin2]

Al I had the same arrester on my tail pipe too. Was sure glad then Banks cut it out when they installed my turbo way back in 96 or 97. If you have the oem muffler that too will fill up with soot and cause untold back pressure issues. But to run an na engine without a muffler tells the next town your coming towards them...

Speaking of being noisy, I just put a new exhaust system on my truck, from the manifolds back, N/A, bought it all from Advance Auto(Walker pipes) all the way back over the axle stock. Instead of putting a muffler on it, I put a piece of galvanized chain link fence post pipe where the muffler goes. I was very surprised on how quiet it is. It looks like it's 2 1/2 inch pipe most of the way. The reason I say that, is the chain link fence pipe works perfectly to go around 2 1/4 muffler pipe, but i had to butt weld it on these new pipes, it would not quite fit over the new pipe.

 

[ksingltn]

the stock exhaust I put on mine had the same arrester too, and it came off a plain xlt supercab 92 model. Maybe they put em on all of them?

 

[icanfixall]

Franklin.. I sure hope you ground off the galvinized plating before you welded on it.

 

[stuborn nut]

So what about rolling the engine to tdc and popping a valve spring off? Should b a quick way to check guides. I got a blue point valve spring compressor that is a threaded affair that grabs the coil and pushes down the retainer, pull out the locks and off comes the spring, just make sure the piston is at or near the top of its stroke. If the truck was a service truck for a logger than should mention the extremely dusty conditions they drive and idle in.

 

[riotwarrior]

So what about rolling the engine to tdc and popping a valve spring off? Should b a quick way to check guides. I got a blue point valve spring compressor that is a threaded affair that grabs the coil and pushes down the retainer, pull out the locks and off comes the spring, just make sure the piston is at or near the top of its stroke. If the truck was a service truck for a logger than should mention the extremely dusty conditions they drive and idle in.

In my limited knowledge and limited opinion if it's NOT chuffing you have no issues.

If it is CHUFFING, then pull valve covers and look see...if you see a mass of soot like I did, then clearly there is an issue and having seen this now first hand I'd be able to ID the bad cylinder. If you don't have a mass of soot as I did then yes as you mention pulling valve springs and checking may be an option however with piston at TDC there is limited capability to test for movement as valve is not going to move much, however it should be enough to indicate a problem. I can physically see that the valve guide is worn out.

JM2CW

 

[idi_econoline]

Yeah, Al.... wish I even had a clue like a spark arrestor on my engine. The Good news is I'll be tackling my van next week.. dropping bad trans down and pulling chuffing engine out da front. Stay tuned!

(Cityboy sez: Spark arrestor? THAT's what that funny screen in the exhaust is... seen them before, but didn't know what they're for. )

 

[chris142]

My 87 had that same screen. It made the truck sound like an air hose. It was the first thing to go.

 

[riotwarrior]

Time for a bit of an update to this, I'll work on some better shots of rod n bearing!

For starters this is the crack in the bore...

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Yup that's going to leak some coolant into my oil :rofllmao

freshly removed rod and piston!

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Up close and personal with the business end of the piston..that's about 1/3 of a valve you are seeing embedded into the crown

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Piston skirt looked phenominally good other than fresh scuffing from the rather cockeyed bent rod

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So what happened and in what order?

I'd really have to say that IMHO valve broke, causing the bent rod as the valve and head and piston became one repeatadly, which distorted the block and caused the crack in the bore.

I have looked through this carefully, I can see shiny new wear on the rod bearing from the sidward thrus imparted onto the rod from being bent, all in all I'm PO'd I lost a good engine...Live and learn swap/fix heads if you hear a chuff.

Al