[Tin Injun Tom]

A friend refered me to check out a single mother's car today and it's got engine issues.
'99 Mercury Sable, 3.0 litre, 137K miles.
It started smoking heavily (oil burn) sometime in the last week. I don't know if it consumed oil before that, but it was reported to me that they had to add three or more quarts to bring it up on the dipstick yesterday or day before.

I pulled all the plugs and did a compression test: Two cylinders were 85-90 psi, the others all had 160-165 psi.
Oddly, the only plug that was oil fouled was one of the back ones that had 165psi. The two cylinders with low compression had wet plugs, but they were very clean.
After I reinstalled the plugs into different holes, I had them run it again while I checked the oil fill hole for blow-by. No blow-by. Instead, full blown vacuum. If I didn't keep my hand over the hole, the engine would die, i.e. serious vacuum leak. Same story if I pulled out the PCV valve out of the back V.C.
The engine seemed to race a bit at idle, also.

At first, (until I discovered the vacuum in the V.C.) I was thinking that the oil drain back holes in the back head were sludged shut, and the oil was welling up in that valve cover: Reason for the low oil level in the pan, and badly oil fouled back spark plug.
Now I think it may have hogged out valve guides, thus the huge vacuum at the valve covers. Evidently, the low oil level did damage to the two cylinders/rings. They are the two nearest the driver's side on the front bank.

I hate to tell this poor lady she needs another engine. She is moving here from Colorado, and has a 4 month old baby, and still owes a couple grand on the car.
I realize it would be more economical to replace the engine with a salvage unit, than rebuild the heads. I tried to convey that to her. Also suggested she might be better off finding a good running car for less than she owes, and letting whomever sold the POS to her, repocess it. She has only had it for two or three months.

I was wondering if it would do any good to put umbrella seals on the valves to minimize the smoking. She has been pulled over by the Police three times, no doubt because the Colorado plates on the car. The last one told her she had 72 hours to get it fixed.

Appreciate the diagnostic help, and any other opinions.
Sorry for the

Tom

[sleepy]

It sounds like the motor needs some serious work. The compression test is bad news.

[wrenchmen]

..I am not familar with the 3.0, but those symptoms {vacuum in the valve covers} with a ford 460 are a sure sign of bad intake manifold gaskets.{vacuum leak under the intake manifold into the engine valley}.
...and that would also explain the oil consumption.

[screamingchief]

I agree the oil consumption sounds like an intake gasket breach for sure,the crankcase being under a vacuum is almost a dead give-away of that situation.

Leak goes from an intake port into the valley/crankcase area,pretty common situation.

Now those two low pressure cylinders,did they happen to be two adjacent cylinders (next to each other on the same bank) ?

If so that sounds like a classic blown headgasket situation,the plugs in those cylinder being wet/clean would suggest that there is also some leakage from the coolant system in those cylinders and thus that is why the plugs look like that.

From your info in your post it sounds like this is the case to me...

3.0L fords are pretty reliable motors,should go well over the mileage you mention.

I'm not so sure I would say it's terminal yet.

One possible issue with the possibillity of the blown headgasket and heavy oil consumption is that often screws up both the O2 sensors and the catalytic converters,so likely those both would also need to be replaced here as good service procedure as well.

The thing is the oil consumption situation could have helped the headgasket failure along if the converter were fouled by the oil consumption and that caused the car to run hot and tax the cooling system,couple that situation with a fouled O2 sensor causing the car to run in "open loop" and you start dumping extra fuel into the cats and that just makes the whole situation even worse yet.

So you can see why I suggest replacing those if you fix/replace the gaskets,otherwise you may just end up right back where you are now...

Before deciding what to do for sure I would advise a leakdown test to prove these issues more conclusively,pressurizing the cylinders via the plugs and listen for where the pressure is escaping as that will tell you what's what much more definitively.

If you do decide to fix this,be sure to do the little things too,like replacing the thermostat,because when things like headgaskets go south often there are other issues that helped that situation along.

And check that the cooling fans work properly when you get it running again too.

[wrenchmen]

Screamingchief,

Could it be possible that the intake leak is directly effecting the 2 cylinders with wet plugs by causing a misfire, or incomplete combustion, thus more unburned fuel washing down the cylinders and causing a lower compression than the others?

[Tin Injun Tom]

The two cylinders with low comp are right next to each other. Good call, screamingchief, I wouldn't have thought of that.
I watched each cyl for over a minute to see if the psi was leaking down. None of them leaked down, but maybe I didn't wait long enough. Would the pressure come down very slow between the two cylinders, or readily noticable. The owner did just recently have the coolant recovery jug replaced (said it was broke), so it is very possable the coolant was run low, and caused an overheating situation
If the head gasket isn't breached, I might try to band-aid the engine with new intake gaskets, and let it ride with the low compression. Feed it some RESTORE to help the bad cylinders maybe? It seemed to be hitting on all six, and the girl(s) said it had decent power driving around town.
I agree, the O2 sensor, and perhaps the cat should be replaced. The only problem is this lady is financially choked, right now. It's a tough situation.

[Tin Injun Tom]

I just realized my compression checker might have a check ball in the spark plug fitting, which would nullify the leakdown reading, via the gauge.
The reading of 85psi doubled would be very consistant to the 165psi on the other individual cylinders. It do make sense.

[Jim Scites]

Check the PCV Valve. Take it out and have someone start the engine. If it's bad it will suck like crazy. I had this happen on an import that a friend tuned up for his cousin. He thought the engine was shot and I replaced the pcv valve, problem solved.

[Tin Injun Tom]

Originally Posted by Jim Scites

Check the PCV Valve. Take it out and have someone start the engine. If it's bad it will suck like crazy. I had this happen on an import that a friend tuned up for his cousin. He thought the engine was shot and I replaced the pcv valve, problem solved.

When I pulled the PCV out, I did put my thumb over the hole, and it did suck, some. But it may have only been a fraction of the negative pressure, compaired to the grommet hole in the valve cover. That took my mind off how much the PCV was sucking.
It did rattle nicely with the engine not running.

[Stu Norman]

While an intake gasket failure may cause the vacuum in the valve cover area, I'm not so sure this will cause loss of compression in 2 cylinders.

I think you're dealing with a head gasket failure, myself. The clean spark plugs are another sign (coolant getting into the combustion chamber, literally steam cleaning the plugs).

My theory: As the piston goes down, the vacuum is drawing oil, air and coolant through the failed gasket, but when the piston is going up the pressure is sealing the head back up, the gasket material being forced back into place.

[screamingchief]

Originally Posted by Stu Norman

While an intake gasket failure may cause the vacuum in the valve cover area, I'm not so sure this will cause loss of compression in 2 cylinders.

I think you're dealing with a head gasket failure, myself. The clean spark plugs are another sign (coolant getting into the combustion chamber, literally steam cleaning the plugs).

My theory: As the piston goes down, the vacuum is drawing oil, air and coolant through the failed gasket, but when the piston is going up the pressure is sealing the head back up, the gasket material being forced back into place.

IMO this is clearly two seperate problems.

The intake gasket is almost certainly the reason for the excessive oil consumption and crankcase seeing high vacuum,and acting as potential vacuum leak path.

The lone cylinder with the oil fouled plug will be responsible for the intake gasket breach and thus the excessive oil consumption.

And the headgasket failure fully explains the loss of compression,and the clean plugs in those two adjacent cylinders can also be explained by this situation,as the headgasket breach could easily allow coolant into those cylinders as well.

As I alluded to earlier these two failures could indeed be related to each other,but they are truly seperate issues in and of their own right when your goal is to diagnose and fix them.

If this were solely the headgasket leaking as Stu suggests,the oil would almost certainly look like a milkshake as coolant would have also gotten into the crankcase for sure as the cooling system is pressurized and that pressure would likely trump any other pressures here.

IMO the breached headgasket is only allowing cylinder pressure loss from cylinder to cylinder,and with that there is a small coolant loss from the cooling system into those cylinders,and obviously not into the crankcase as the oil has'nt "milkshaked" by the info given thus far.

Low buck fix here,pull it apart to replace the blown headgasket(s),check that the head and deck are flat enough to seal,if they are replace the headgasket and in the process you'll be replacing the bad intake gasket as well,go out and by a used cat-con from a low miles wrecked car with a good engine,put new O2 sensors in the exhaust,replace the thermostat and plugs,PCV valve and such as they are cheap,change the oil,flush the cooling system,and this thing should hang in there for a while longer.

A tech who's pretty good at his craft could fix this thing for under a couple hundred bucks,but the labor for an average Joe/Jill would up the price of the fix quite a bit.

And yeah,if your using the compression tester to pressurize the cylinder you need to pull the Schrader valve core outta the tester hose.

To test for the blown headgasket,pressurize the one low pressure cylinder and listen in the other low pressure cylinder via the spark plug hole using a mechanics stethoscope or a short length of heater hose or such,you should here the air escaping from the pressurized cylinder into the other cylinder.

HTH.

[Mr_GTO]

I vote head gasket. Common problem on those 3.0L.

[screamingchief]

Originally Posted by Mr_GTO

I vote head gasket. Common problem on those 3.0L.

Then explain this...

Originally Posted by Tin Injun Tom

Oddly, the only plug that was oil fouled was one of the back ones that had 165psi. The two cylinders with low compression had wet plugs, but they were very clean.

Why is the cylinder with the oil fouled plug on the opposite bank as the cylinders that are obviously suffering from the blown headgasket between cylinders.

Originally Posted by Tin Injun Tom

They are the two nearest the driver's side on the front bank.

The two cylinders with low comp are right next to each other.

So let's recap this.

One cylinder in the rear bank with good compression (and thus good vacuum) has the oil fouled plug.

Two adjacent cylinders in the front bank have low cranking compression and wet/clean plugs...

Been a tech long enough to know the moral of this story...

Two seperate issues,one bank intake gasket,other bank head gasket.

Remember,3+ qts. low on oil,that's a LOT of oil to burn!!!

No way the plugs stay clean with that much oil going thru the cylinder...

To fix the one problem (headgasket) you'll also end up fixing the other (intake gasket) as well.

[Tin Injun Tom]

Bret, that is an excellent synopsis of what's going on with this engine.

I contemplated just doing a quickie intake gasket gasket replacement, changing the oil w/Slick50, and letting her drive it till it quits. This would only have been justified because she is desperate to "just get it so it doesn't smoke, so I can drive it". And she can't really afford more than a couple hundred dollars, off the get go.

But doing half of a repair just isn't my style. And the intake gaskets alone is about as in depth as I want to get. I might be able to handle pulling the head, being it is the easy one, if I hadn't tore up my lower back three weeks ago. I'm still hurting from all the bending over, doing the compression test.
I'm about one third the speed of a seasoned flat-rate technician, on detailed jobs like this one. I have to take my time so I can remember how everything goes back together. What you called a low buck fix Bret, would take me a full two days, if not more. Oh I could cut that time in half, if I did three of them right in a row.
I'm just a very careful person, and have to make sure everything is 100%.

Your prescribed service for this is an excellent game plan. I'm just not up to snuff to do it myself, and will have to refer it to a competant shop. I just hope I can find a shop that will be fair on the labor.

Thanks everyone for the input. It really helps nail down the diagnosis, and what the best plan of action should be, when you have alot of experienced minds chipping in information.