Thrown Rod?

I recently purchased a '95 Ford Windstar (3.8 transverseV-6 engine) in Amarillo, Texas, changed the oil, and drove it 500 miles back to my home in San Antonio with no problems at all and with no oil consumption.
A few days later, while I was driving about 50 mph on the expressway, the "check engine" light came on and I noticed a fairly loud knock coming from the engine, which seemed to diminish and almost disappear when I accelerated.
The next morning, I checked the oil again, found it was still full, made sure the oil pressure light came on when the ignition was turned on and went off when the engine started, then drove the Windstar to a shop around the corner. The mechanic assured me that I had thrown a rod and would need a replacement engine, which he would be glad to supply .
I guess he could be right, but we're talking about a lot of money here and I'd like to hear any other possible causes and solutions that anyone might have to offer.
Steve
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If your motor had thrown a rod you would most likely have a hole in the oil pan and the motor would probably be seized up. You wouldn't be driving it anywhere.
Your problem could be low oil pressure (caused by a bad oil pump, clogged pickup, clogged/defective oil filter, etc.), excessively worn main bearings. Depending on what exactly the sound sounds like and where it's coming from it could be a number of other things too.
What exactly did this mechanic do? Did he pull the oil pan and find your rod and piston in the pan? Since he's obviously lying about the thrown rod, did he pull the oil pan and remove some bearing and rod caps to get a look at the condition of the bearings and main/rod journals? In any case, you may very well need a new engine, or it could be as simple as freshening it up with new bearings. Since it sounds like you can't do that work yourself, if that's the case the cost of repairing your engine vs. having a rebuilt engine installed will likely be very small. In that case it would be worthwhile to put a new engine in it and be done with it.
Depending on what you paid for the car and how long you plan to keep it you have to decide if you can justify that cost/investment. If you're just going to get a new engine you can drive this one into the ground. Just throw some straight 50w oil at in and see if that quiets it down some until it don't go no more. Of course that's assuming the problem is worn bearings.
The other day my car started knocking loudly at lower idle speeds, it's got a 302 .030 over with ~12,000 miles on it. If I bring the RPM up a little it quiets down, and when I get to more RPM it's silent. I was afraid it was a rod knock, or possibly shot main bearings. Problem seems to be bad water pump bearings. When I hit a deer at 55 MPH a while back the impact made my radiator kiss my fan. After a new fan and radiator the next morning I was back in business. Apparently the impact bent the water pump shaft enough to put a slight wobble in it, and after enough miles like that the water pump bearings got real loose from the stress. That wobbling with the loose bearings seems to be the cause of the knock. As I rev the engine the fan puts load on the bearings and makes enough force to keep the water pump pulley straight. Watching the pulley as I rev the engine the noise gets quieter as the pulley straightens and goes away once it's perfectly straight. This week I'm gonna replace the water pump. Just pointing out an example of how what sounds like a really bad problem can turn out to be a real cheap and easy fix. A new water pump will cost me maybe $30, but I'm expecting to get it replaced for free as this pump has a lifetime warranty. Either way it's not bad.
I suggest taking it to a competent mechanic and having the problem properly diagnosed. Then have him explain to you exactly what is causing the problem, and lay out the options you have to fix it and the cost.
Cory
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Cory Dunkle opined

Ditto... except that it IS possible for the engine to have broken a rod, due to bearing seizure and not have perforated, the stub end of rod turned just enough on the journal to hide in the crank offset.
Since this is a 3.8, the suspicion would be that it suffered the dreaded head gasket problem and you are seeing the results of coolant bearing damage.
You're not going to know until a mechanic takes a closer look.
For those who have just bought a mid-nineties 3.8, I suggest draining the oil immediately and taking a goodly sample of it to someone with a lot of knowledge.
I learned that the hard way on my first tBird... the seller had "just changed the oil" and by the time I saw the problem on the next change... really thick and odd odor ..it was too late to take it back.
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Hmmm. you may be on to something here. Right after I bought the Windstar, I took it to get the oil and filter changed. The guy at the jiffy-lube told me I had water in the oil and showed me the milky looking stuff on the dipstick.
But after he changed the oil, I made daily checks and found the oil to be clear, so I assumed it was OK. Even after the engine noise started suddenly over 500 miles later, there was no evidence of water in the oil. Still, I guess it's possible somebody fixed the leak after some damage had already been done.
From the tone of your response, I gather that leaking head gaskets are a problem with this engine. Is there an easy, reliable way to test a used engine for head gasket leakage?
Steve
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Steven Botts opined

No absolute methid but you always check the top of the dipstick and around the inside of the filler for a milky sludge...
Then you pass on that car..
If it already is in your name, take it to have a system pressure check.
Once the leak is fixed, all is not lost... just run Mobil 1 for the rest of its life.
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Thanks, but what's special about Mobil 1?
Steve
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Steven Botts opined in wrote in message

WHen the glycol gets in the bearings, it erodes them leaving ridges... which get hot due to friction; dino oil carbonizes (hard ash) as it flows past these ridges, it's that carbon that causes the the bearings to seize when it eventually breaks loose and wedges at high spots.
Mobil 1 takes a higher temp before it gasses out and turns into deposits.. the ridges eventually smooth out a little.. higher gap in bearings, but you use a heavier weight. It doesnt rebuild bearing but it keeps the engine running if it hasnt gone too far ... I out over 50,000 on a 3.8 with bad mains.
Roll of the dice but it's my story and I'm sticking to it
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Hi Cory, Thanks for your thoughts. The mechanic diagnosed the problem purely by ear, which is one reason I was suspicious.
The oil pressure seems to be fine, since the warning light appears to be working and never comes on while the engine is running.
I bought the Windstar for $3000 dollars after I got out of the hospital with a broken hip I had sustained after falling off a 4-wheeler in Amarillo. I was afraid I wouldn't be able to drive my stick-shift truck with a bad left leg, so I bought the Windstar with the intention of driving it home, keeping it as long as I needed it, then selling it.
Out of necessity, I've figured out how to drive my truck, so my main concern now is to get the Windstar in sellable condition and recover as much of my money as possible.
Steve
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No mistake about it, if it has a loud knock (not tick) INSIDE the engine it is serious damage. Just out of curiousity, does it run well or does it miss?

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It might be missing a bit, but I was too worried about the knocking to notice.
Steve
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From what you mentioned about the coolant in the oil in the earlier thread and BM's input on the poor design of these engines resulting in head gasket failures with coolant in the oil I suspect the noise you are hearing is bad rod bearings. Too much clearance in teh bearings so the rod big ends bang around on the crank. When you load it up under acceleration it puts pressure on the bearings in a way that reduces the noise. The fix would be to check the crankshaft for damage and if it wasn't too bad you would probably be albe to just replace all your rod and crank bearings, if the crank was bad you'd have it cut down and polished at a machine shop. Basically freshening up the motor. Of course this is assuming the cause of the problem was fixed (coolant leak into oil). This is not an expensive thing to do by yourself, but it is time consuming, more so on a modern vehicle like yours. As I mentioned, for this type of damage to be repaired it may very well cost as much as a new engine, or so close to it you're better off having a new one installed. In that case you may be best off buying a running engine from a junkyard and having that installed, then selling the vehicle.
Driving a manual transmission with a bad leg isn't too bad if you shift without the clutch. You only need the clutch in 1st gear, so it's not bad at all. I drove manual transmission cars over the winter, a Prelude and a Calais. I have bad knees, which really only bother me in the winter for the most part. The cold makes them ache badly, especially after walking too much. Anyhow, I'd often drive only using the clutch for first gear, because it made it easier on my knees, at least my left knee.
Anyhow, like I said, try running straight 50w oil in it and that may be thick enough to make up for the slop in the bearings. If that's the case the motor will probably be fine on that oil for a long while, assuming the coolant leak has been fixed. If the heavy oil doesn't quiet down the noise then the onyl fix is pulling the motor apart or replacing it.
Cory
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