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Discussion Starter · #1 ·
I havn't figured out why the loss of oil pressure yet, but here's the history:

1/ oil light came on
2/ driver continued on for a few miles until engine seized when he idled down
3/ pics show 2nd rod bearing babbit seized to crank (I can polish it !!!...maybe....). Bearings had spun...tangs gone
4/ oil pan was full of oil
5/ oil pump tested by hand and pumps fine
6/ oil pump driveshaft intact
7/ installed oil pump drive shaft from underneath. Would not turn, so cam sensor seems OK. Turned engine by hand, and oil pump driveshaft turned properly
8/ oil filter was last part removed....comletely empty...no oil.....not a drop....very weird...something I can't explain, other than perhaps the engine rotation drew oil out of it?

I'm wondering if there are any press-in plugs in the oil galleries between the oil pump and the filter, but I still suspect the cam position sensor as my only test on it so far was pretty Mickey Mouse.

Any other ideas what caused the loss of oil pressure?







 

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Failed cam syncronizer. Was there a squeaking? I'm almost positive that is the cause. if the fails it stops the oil pump from working and from there its failure. It can seize then unseize and make it seem like failure didn't occur. That's why I'm adamant about others changing their syncro when the first sign of trouble appears. When I pulled my syncro it would seize under certain conditions when I bench tested it.
 

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Discussion Starter · #3 ·
That's about all I can think of too, but the totally empty oil filter puzzles me the most.

I wasn't the one driving, but I did drive it just before this mess and there wasn't any squealing.

So what siezes? I'm having a hard time envisioning this. I picture the cam sync like the lower part of a distributor, so all I can picture are worn teeth on the sync gear, or on the cam gear.

I will pull the sync, but other than missing or worn teeth, I"m not sure what seizing means in this case, so am unsure what to look for.
 

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Look down the hole and see if the cam gear still has teeth on it.
 

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Discussion Starter · #5 ·
I've found out more. I checked 4 of the 6 rod bearings and all are bad....most are spun....some rod journals are beyond a simple clean-up. However, all main bearings are like new.

The cam synchronizer is perfect as well as the cam gear teeth. It's all starting to look like the engine was over-revved, a rod bearing let go, and then the oil pressure dropped causing the other rod bearings to go.

A few pointed questions to the driver, and it turns out there was an over-revving condition a little before the idiot light came on. Apparently the transmission was set to "Low" to see if the front tires could be spun and the revs got a little high.

So does that make sense, ... mains OK, rods all gone, and due to over-revving?

Unless I find something up top broke and allowed the oil pressure to drop off, I'd say it was due to the over-revving. 16 year olds.......smart enough, but don't always use the brain they've got......tough to be a teenager I guess.
 

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Uh huh.... nice.

Kids.
 

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LOL, that is very funny! I can remember trying to explain my way out of how the motor mount broke in my Dad's car when I was in high school and it wen't almost like that :lol2:
 

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The engine has a rev limiter on it so over revving should not be the cause.

How was the oil pick up screen? The pump should be filling the galleys before the filter. There is an internal pressure relief spring that should bypass the filter if pressure gets too high.

If the filter is dry the pump isn't pumping.
 

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Discussion Starter · #10 ·
I do believe the filter must have drained back as the car sat for quite a few months before I took the oil pan off.

The Main bearings still looked like new and had oil on them.

All the rod bearings were either spun or worn away with dmaged crank rod journals.

Oil pump was bench tested and is OK.

Screen was free and there wasn't much sludge in bottom of pan.

Oil pump drive shaft was OK

Cam sync was fine

Cam gear teeth look fine

Pan was full of oil

Driver admitted to high revving and then oil light came on a few minutes later.

A rev limiter might limit revs with an engine under load....like during a 1/4 mile drag, but I'm not so sure the engine will stop at a certain rpm when it's acclerated hard in say neutral....so in low gear it might oevershoot as well....even if just for a moment under momentum.

Maybe something else gave way and caused the low oil pressure, but I think there was some oil flow as the driver made it a few miles with the light on before it seized.

Over-revving that old engine is the only thing that makes sense to me so far.
 

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The rev limiter will work anytime. In neutral it should be around 4k.
 

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Discussion Starter · #12 ·
OK, I believe you. If it can't be revved over 4K, nothing should have happened at a low rpm like that. Even a more typical limit of 5500 rpm shouldn't have caused a problem.

Now believe me, there's nothing wrong with any of the oil pump or oil pump drive system (that I can find, and I removed, inspected and tested). The pan was full of oil and hardly any sludge on the bottom of the pan. The pick-up screen was clear.

All of the rod bearings all went, but none of the mains went....in fact, the mains still had oil on them when I checked them.

Pistons and cylinders all look fine, and are still wet with oil, but of course, oil splash from the pan would have kept them fine.

No reported noises, such as valve clatter...I specifically asked about, but of course, the answer might be suspect. Now that I've relieved the pressure from the one seized rod bearing, I can rotate the engine normally by hand (with the plugs out). Timing chain has normal resistance, so valves must all be working...at least not seized.

This engine was driven quite a few miles with the oil warning light on...surpising if there was a total loss of oil pressure, but reading up on the cam sync problem, it can happen.

I'm reasonably sure a rod bearing went, the oil pressure dropped, and then the rest of the rod bearings went. If the engine couldn't have been over-revved....then what caused it?

So, can you think of any reason why the only failure I can find so far is limited to the rod bearings? What else could have happened?
 

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Discussion Starter · #13 ·
By the way, where is the oil pressure relief valve located? Usually it's in the pump, and I do see some plugs that probably covers up the spring, but some engines have one in the block. If there was one, perhaps it became stuck open.

I turn the engine over and the oil pump drive shaft turns, and can't be stopped. Although the oil pump tests fine when rotating by hand, I guess it might be slipping internally under a heavier load. Maybe I should take it apart to find out.
 

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The rev limiter will work anytime. In neutral it should be around 4k.
I have had my Rev limiter fail. If the TRS is failing or out of adjustment it is possible. I had it happen to me in 3 occasions.

1. Accelerating hard, TRS problems were obvious because my radio was malfunctioning, and it hesitated to go into second and didn't bounce off the limiter. Damage was avoided by immediately coming off the gas as soon as I noticed it.

2. Startup with faulty TRS. In park. Revved to redline. Normal limiter is supposed to kick in at 3500-4000 RPM.

3. Random occurrence. Driving and decided to get a bit spirited. Came off a highway light and wanted to see my 0-60. hesitated to go into second and third, remedied by backing off. Limiter was not apparent until restart of the vehicle. I put the vehicle in neutral and the limiter wasn't there.

I have no explanation for these occurrences except my TRS being faulty or out of adjustment. It maybe something else. But I will say that I have had conditions where my rev limiter was not present.:angry:

I'm not arguing with you Paul, the rev limiter SHOULD be there. But the question to ask is, was it there?
 

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The oil pressure relief spring should be behind the oil filter mount in the internal oil galleys.

If the PCM does not see neutral position due to a bad TRS you will not have the 4k rev limiter. Still the red line rev limiter should always work.
 

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The oil pressure relief spring should be behind the oil filter mount in the internal oil galleys.

If the PCM does not see neutral position due to a bad TRS you will not have the 4k rev limiter. Still the red line rev limiter should always work.
When's the red line limiter kick in? My poor car has seen 6k a couple of times, and a little over 6k when I'm late catching the lack of shifting.
 

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5800 for the stock Vulcan. 6450 for the Duratec.

The tach is not that accurate at the extremes.
 

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Discussion Starter · #18 ·
The oil pressure relief spring should be behind the oil filter mount in the internal oil galleys.
Now that's very interesting. I shall have a look. Thank-you.

I can't really say if the engine was "over-revved", but it was certianly "highly revved". It's an older Taurus....1998 wagon, so it had fairly high mileage. Oil changes were frequent enough "after" we bought it, but the previous history is unknown. I'd chalk some of the failure up to age, except those main bearings do look like brand new.

It may be that some sludge or other debris caused the pressure relief to stick open, so that at lower speeds the oil pressure was too low. At least I can look for that now. It may explain the empty oil filter as well.

Crank is beyond a simple clean-up. Rest of engine looks good so far. I'm going to yank it soon, and then decide if I want to have the crank turned, or go with a junkyard engine, or just scrap the whole car.

I must say, when the engine was working, it worked nicely. Good power for that wagon.
 

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The oil pressure relief spring should be behind the oil filter mount in the internal oil galleys.

If the PCM does not see neutral position due to a bad TRS you will not have the 4k rev limiter. Still the red line rev limiter should always work.

Thanks paul. This explains alot of things. ;)
 

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I'm looking into oil pressure issues on my Taurus with a 3.8 (mainly just a flickering oil light at idle after the engine is hot--nothing as bad as what Argess describes). I'm still learning the details of how the Taurus engine lubrication system works, and I know this is a slightly older thread, but this question occurs to me about Argess's problem:

Could one of the rod bearings have been marginal, causing it to fail due to the revving, even if the revving didn't go beyond its upper limit?
 
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