Burnt Valve ...what to do now?

[Grass]

Sounds like a leak down test is a requirement. I'm so tired of depending on other people, I'm just going to go down to Harbor Freight and get a compress test kit.

Question: how long do I crank the engine to get an accurate reading?

 

[fjc-man]

Chief aircraft.com Leak down tester. Eastern model E2M. 125.00. You still will need a source of compressed air at approx. 80 psi. Take the fan and fan shroud out so you can turn the engine over by hand.......

 

[abuck99]

Autozone has a tool loaner program- its free- call and see if they have one.

 

[Sandroad]

Sounds like a leak down test is a requirement. I'm so tired of depending on other people, I'm just going to go down to Harbor Freight and get a compress test kit.

Question: how long do I crank the engine to get an accurate reading?

Good idea to do some testing, but I'm confused about the sequence of events on the problem. For example, I think you just posted that all this started after you used injector cleaner? When you have the time, I think it would help if you could post the complete sequence of events, in order, starting from when the truck was running good.

 

[Grass]

I think you just posted that all this started after you used injector cleaner? When you have the time, I think it would help if you could post the complete sequence of events, in order, starting from when the truck was running good.

I mentioned it it threw codes after Seafoam and fuel tank injector cleaner (both of which went away within 24 hours)

But the rough idle started right after I bought it.

 

[Grass]

Autozone has a tool loaner program- its free- call and see if they have one.

Thanks. I didn't realize that. I'll check into it.

 

[Grass]

Got the shop to send me some pictures from the scope. I can't really tell what I'm looking at. Thought you guys would like to have a look.

 

[Grass]

Second pic

 

[camino70]

Looks like a burnt valve.

I've not had a 4.7 apart and not sure what the combustion chamber looks like. In pic 1 bottom left corner is the valve with the two cracks in it. I haven't figured out what the top portion is. second pic is the valve open, but I'm not sure what is wrong.

 

[AimCOtaco]

Yeah, agree, that looks like a burned valve all right. My WAG is that the injector for that hole is lean and lead to the issue but could just be classic valve guide failure/bind. If you could find a good set of heads that could be cheaper than a full motor swap. You might even consider buying a whole motor and just swapping heads. Your head could probably be re-built but I think the cost would be preventative compared to swaps.

 

[SHIfTHEAD]

Well that sucks. My guess is the valve wasn't seating well which led to the valve over heating. So while the quick and dirty solution could be to pull the head, put in a new valve after you clean the seat and lap the valve, and bolt it all back up, ultimately you are playing a bit of Russian Roulette. The Pros to this method are only the possibility of saving a few hundred dollars and the cons are having wasted a ton of time, nothing to drive while it's apart, and the problem still being there when you put it back together with the chance of other issues cropping up in the interim (like a head gasket that won't seal any longer). Not to mention all the tools you'd need to do it...

It sucks but I'd find someone to drop in a used 4.7 with a warranty and move on.

 

[2001LC]

That is a brunt valve, and I had no doubt they'd send you a picture of one. As I intimated, I'd have higher level of confidence if you'd seen in person through scope. Did the say which valve exhaust or intake valve?

Good read on possible cause @AimCOtaco. To take it a bit further as too why; Bad oil due to lack of regular oil changes (poor maintenance) damaging valve guides or plugged injector from using cheap gas. I'd like to see oil pressure readings, to get read on bearings before head swap just in case oil related issue. If you can verify regular oil changes and oil pressures is to factory spec, then a head swap may make senses.

@Grass, Compression needs to be done with engine at operating temperature, all plugs removed, good battery (I use 100 amp changer/starter attached to battery) fully charged, throttle plate open (I forget too often), pull EFI fuse (don't want fuel pumping), then crank 5 times minimum. I just watch gauge for highest reading then stop cranking. Check all cylinders to see balance (difference) between them.

By pressurize cylinders (somewhat of a Leak test) you can confirm Shop's picture and which valve they say is burnt: Intake (air sound coming from throttle body) or Exhaust valve (air sound coming through exhaust pipe.

Just a thought to save a buck; You don't actually need a leak down tester. Pick the correct compression gauge kit that has a quick connect setup, that will fit your (assuming you have) air compressor quick connect. Some adapting MAY BE REQUIRIED. You'll need the hose with thread fitting intact (and tight) to set down into spark plug tube and thread in. Then pressurize cylinder on compression stroke either before or at top dead center.

Note: You can turn crank bolt buy simply remove skid plate to access harmonic balancer to crank bolt.

 

[Grass]

Thanks for the advice. Looking into an engine swap, still haven't decided. If I were to list it for sale, what do you guys think I could get for it? You can see in my gallery it's rhino lined. Exterior is perfect because of it. Not rust free but not rotting through frame or anything either. Just a ballpark so I have a comparison.

 

[camino70]

I think my sentiments are similar to 2001LC. I'm not sure what a pic of the 4.7 would look like to be confident to say that's a 4.7, let alone your 4.7.

Are you planning on continuing to investigate?

 

[Grass]

I think the shop is being truthful, if that's what you mean. I'm just either going to cut my losses and sell it, or swap engines.

 

[2001LC]

Yes that is what I meant. I've had several high millage 100 this year. After investigating shop records then restoring end to end, I've found very disrupting issues. It's made me question most shop even the top number #1 rated shops by consumers.

 

[ponytl]

i never want to spend someone else money IF you think you can swap just the head with just removing the cam gear you can get by on the CHEAP and just replace with a used head i checked around here and you are looking at $50 EVEN asked around and most said you can reuse the head gasket (i wouldn't) but I would reuse the exhaust and intake gasket the only other thing I would do is replace the brushes in the starter since you have the intake off (if the starter is original) so for $100 (save your coolant and change the oil) and a weekend of busted knuckles you can be rolling and might just be good for another 100k is this the perfect way? not really but it's not rigged either....
I've replaced main bearings on the side of the road and polished the mains with emery cloth and my boot lace thought I'd fix it right if it just got me the 700miles home... 4 years and 30k later I sold it to a friend (who was with me at the time and told the story more than me) and it's still on his farm running as far as I know...

 

[Julian Stead]

I can see the burnt valve in the top picture but it is either the lighting being strong but the top picture is strange due to the clean/bright area, what is that? It is like the head is already off. Am I just being daft. Anyway, the minimum would be a new head as I wouldn't trust the valve seat due to the heat. It would of been helpful if there was a picture of the piston and cylinder walls so you could evaluate your options more. If the valve was sticking or bent it could of marked the piston. The only thing you can tell is that there is gases passing the valve, which could be the cause of the burnt valve or the effect of the burnt valve, what came first the chicken or the egg.

 

[camino70]

I've been looking at some images online of the 2UZ-FE combustion chamber and am reconsidering my skepticism of this actually being a 2UZ-FE, I think it is. Now I am nervous if I am increasing my risk of burning a valve by driving with a short lifter on cylinder 1.

Something like this worth trying, 12.99 Scope for Android?
Ehome 7MM 2M Android Endoscope Borescope OTG Micro USB Inspection Camera Waterproof Endoscope Snake Camera with 6LED and USB Adapter for Android Device with OTG Function: Amazon.com: Industrial & Scientific

 

[2001LC]

*** If I were to list it for sale, what do you guys think I could get for it? You can see in my gallery it's rhino lined. Exterior is perfect because of it. Not rust free but not rotting through frame or anything either. Just a ballpark so I have a comparison.

Condition of paint is important to resale. Body parts like the hood are hard to come by. Old paint can be very difficult to match, so blending is required costing additional body shop time. A used hood of desired color in A condition is wroth the same or more than a new hood from factory. Buyer saves on paint and get a near perfect match. Door's same thing, but have many parts associated with them. Seats have electrical motors, rails & and plastic trim. There are thousands of little parts. You get the idea. But to part out is a lot of work, takes years & requires storage area. a 99 LC rear locker, good paint and body, minus long block could be parted out for ~$6 IMHO. Figure half that is selling to someone that is buying whole for parts. Even less if they buy to partout, as they're looking to profit for their effort.

If I was buying to restore; I'd take KKB good or fair value depending on overall condition minus cost for head R&R and anything else I found. Plus I'd deduct $ for my time to restore with a baseline.

Two issue on your LC would reduce my interest:
The coating on the paint may or may not peal off. Additionally I can't see condition of paint.
Other than minor surface rust, I'd not be interested if rusty.

Only modifications I'd pay extra for would be things like off road sliders & bumpers etc.