Looking for confirmation on what I think.

3 Mechanics told me a have a broke piston, I am having 2nd thoughts on their opinion.

The symptoms are a loud banging noise coming from the 1-2-3 (Rt Side) of the engine block.

The problem is I have filtered 10 quarts of oil through the engine block in 2 days and all that comes out is a thick sludge of black oil. By thick I mean like curdled milk. On that engine I have changed the oil faithfully every 3 to 4 months because of the camper I tow, but what is bothering me is where the sludge came from since I changed the oil a month and a half ago and after draining and filtering 10 quarts of oil through a screen I have yet to turn up any form of metal shavings or pieces of metal.

I am more inclined to believe the heads need to be reworked and probably the rocker arm, valve or springs have broken and need repair. I am in the process of pulling the engine to evaluate all the damage so any suggestions would be welcomed.

Thus far I have only rebuilt a 72 Ford 250 (390 Camper Special), a 76 Chevy (350), a Geo Metro 3 cyl and now this one.

 

Welcome to FTE and the 4.2 forum. Glad to have you here!

Sounds like a mess.

Pulling the valve covers off to check the valve train should make any problems there pretty obvious.

Did they do a compression and/or leak down test? A little more info on WHY they say you have a broken piston would help. What did they do to make that diagnosis?
Strange to hear broken piston. I could understand broken rod, but broken piston? I dunno, just sounds a little strange

If you have a broken piston I'd expect it would show up in a compression test.

The thick sludge sounds like maybe water in the oil. Is your coolant level OK, or has it dropped?

What was the sequence of events leading up to this failure?

You mention 10 quarts of oil. I'm guessing you mean two oil changes and the bad oil was found each time?
(Side note: you know the 4.2 requires 6 qts, not 5?)

I'm thinking rocker arm or spring, OR bad head gasket or intake manifold gasket.

The thick oil deal sure sounds like water getting into the oil.

Please keep us posted. I'm real curious to know what you find.

 

I know the engine takes 6 qts, the 10 quarts was a straight flush of the sludge in the oil pan, I actually poured 10 quarts through with the oil drain plug out to get as much sludge from the pan as possible and try to flush out any metal shavings that might be in there.

I originally thought it might be the head gasket also, but I hav not lost any amount of coolant. But I am going to fluch the radiator at the same time to see if any oil comes through.

The three mechanics diagnosis was audio only, they listened and said "You need a new engine", I am not so inclined to throw down 3 grand on a new engine without more detailed troubleshooting. So I am going to pull the engine and start a tear down from the valve covers, heads and oil pan and work from there.

The a little more than a week ago I started noticing pinging noise from the right side of the engine, last monday a bang, then water temp, oil and service engine lights all came on. I was about a mile from a mechanic that worked on my daughter car so I limped it over there and he and two other mechanics all listened to the banging noise and said "new engine".

The comments you made sound more reasonable than that of the mechanics that looked at the truck and more along what I feel may be the problem. I have been going through my Chiltons trying to explain the sludge and trying to get up to speed on tearing down this engine. It's not like taking down a 76 Chevy 350 or an old 72 390. Those were easy to work on, I just sat on top of the radiator in the engine compartment and pulled the heads.

Thanks for the feedback

 

Could have a bad intake gasket. Coolant in the oil will make it real thick. I have seen many times on these 4.2 engines the intake gasket fail and dump coolant into the intake port (most of the time cyl.#3) and bend the rod. The pistons on this engine are verry close to the fly weights on the crank at bottom dead center, a slight bend of the rod and they hit causing a knock.

 

Hmmm.
Pinging noise and then a bang.

Unusually severe pinging can be caused by a very lean condition, which can create another cause: very high cylinder temps.
A loose plug can do the same, but I'd expect maybe a misfire code or dead miss in the engine as an early warning.

The bang could have been caused by detonation, which is different from preignition. Detonation (i.e. spontaneous combustion of the fuel/air charge while the pistion is on the compression stroke) can cause severe, virtually instantaneous engine damage.
But, this is very rare in a non-modified engine.

Your's is an interesting case. Do keep us posted.

edit: Tstorm, nice to have your (ASE) input!

 

Thanks for the feedback, after the final tear down I found out the # 3 piston rod was bent and the piston was hitting the counterweight, but the other 5 are good so I am reusing them.

I replaced all the piston heads and rings just because they were questionable.

The crankshaft would have been more to machine and weld than the cost of a new crankshaft so I went with a new one.

With the cleanup finished I will have the pistons back from the machine shop this weekend, so I can start the rebuild soon.

Does anyone have any suggestions for upgrades to this engine since I have it completely torn down, at this point it is the perfect opportunity.

Any suggestion would be welcomed this project has really made me doubt my mechanical skills, I'm learned on an old 60 T-Bird, a 70's model F250 and a 76 Chevy with a 350 and I am really getting an eye opener trying to wade through this.

 

It all same concept, fromm the older engines to the newer ones. The big difference is the use on new alloys that demand tighter tolerances, proper torqueing of the bolts and in the right sequence (you used to be able to get aways with this all the time, not so much now a days), and the whole thing needs to be clean enough to eat off of.

The rest is all the additional electrical stuff. Ford is pretty good at error proofing the connectors on most things, but I think you can still mix up the injectors, so check the wire colors for the right placement. Your more likely to forget to reconnect one then put it in the wrong spot.

Take care to seal up the pan and any other gasket surfaces well after a good cleaning to get the old material out. It sucks to have a leak in the first 5 minutes of breaking.

 

I managed to get a majority of the sludge out of the engine, heads, manifold and other parts...but you said clean enough to eat off of. I have been using Purple Power degreaser but it is not getting everything 100% clean as you indicated. Is there another cleaner you would recommend?