Low compression on Cylinder 1 - taking bets...

[SirTanon]

So, I've posted previously about replacing my plugs @215,000 miles due to somewhat rough idle.

Original factory plugs came out, and Autolite double platinums went in.. non fine-wire.. Didn't help, so I replaced them again @ 225,000 miles with new NGK fine-wire plugs and also put on new Coil-on-Plugs. This also hasn't helped. In fact, over time, the roughness has gotten worse, and the car has started throwing P301 codes "Misfire on Cylinder 1"

I've been using the Torque Pro app on my phone to look at the details, misfire frequency, etc..

The car only seems to really be rough @ low speeds, mostly idle, and seems to be between about 10% and 15% misfires reported.
At highway speeds (70-75 MPH), it runs smooth, and most of the time, I'm only seeing around .005% misfires.. as in less than 200 misfires reported in Torque over 30 minutes of driving.
The catalytic converter seems to come up to operating temp fast. Like, after 1 minute of driving in the morning, it's already over 900 degrees. On the highway, cruising @ 70MPH, it's steady around 1260 degrees. If I punch it to get on the highway, it gets up to about 1400 degrees.

Even up through my last oil change @ 224,000 miles, the car was not using any noticeable amount of oil. No dripping, no burning.. also, no fuel dilution, and no antifreeze in any of my UOAs.
Coolant is clean and doesn't move up or down.

So I ran a compression test. Yup, Cylinder 1 definitely has a compression problem.

My gut says that I probably have a burnt exhaust valve.. but I was curious to get feedback from the BITOG community.

... so what do you place your bets on?

 

[Ramblejam]

Check valve clearance on #1. Chances are you'll find one too tight.

 

[gabriel9766]

These engines are bad about chains stretching. But i think you would have a problem with all cyl's. Moms 2.5L in her 2010 fusion is going strong at 105k.

 

[gfh77665]

The FIRST, easiest, quickest, and cheapest thing to do is add Restore. It really will increase compression. Might help, nothing to lose.

 

[SirTanon]

Originally Posted By: gfh77665
The FIRST, easiest, quickest, and cheapest thing to do is add Restore. It really will increase compression. Might help, nothing to lose.


I want to FIX the engine... not fill it with gunk.

Besides, there's not an issue with the rings, or I would have either been burning oil, or have fuel dilution in my UOA... neither of which is the case.

 

[BrocLuno]

Yup, check the valve clearances - cheap and easy.

If they are OK, you have a bad valve... But why? Was it leaning out on one cylinder? Intake gasket failure? Bad injector? What's the cause...

Sure, you can get a nice valve job done and put a new timing chain in it. But it might come back ...

 

[SirTanon]

Agreed.. and this is why the head is coming off and getting a full inspection. I'd do it myself, but I don't have the option to take time off work right now, so I've already got it in the hands of a trusted shop. I just thought it would be good to get input from everyone.. for curiosity sake, and to see what general consensus is.

 

[Trav]

I would want to do a wet compression test, a leak down test and check it with a vacuum gauge before tearing into it or placing any bets.

 

[gfh77665]

Originally Posted By: SirTanon
Originally Posted By: gfh77665
The FIRST, easiest, quickest, and cheapest thing to do is add Restore. It really will increase compression. Might help, nothing to lose.


I want to FIX the engine... not fill it with gunk.

Besides, there's not an issue with the rings, or I would have either been burning oil, or have fuel dilution in my UOA... neither of which is the case.


You said your WANTED FEEDBACK, and I provided mine to you trying to help. The "gunk" you speak of is a good product. Do your research before you condemn it. You also say you only have a "gut feeling" about whats wrong, so do you really KNOW Restore wouldn't help?

 

[DuckRyder]

Originally Posted By: Trav
I would want to do a wet compression test, a leak down test and check it with a vacuum gauge before tearing into it or placing any bets.


Yup - if you don’t have the equipment for a leak down, wet compression and vac are easy enough...

 

[SirTanon]

Originally Posted By: gfh77665
Originally Posted By: SirTanon
Originally Posted By: gfh77665
The FIRST, easiest, quickest, and cheapest thing to do is add Restore. It really will increase compression. Might help, nothing to lose.


I want to FIX the engine... not fill it with gunk.

Besides, there's not an issue with the rings, or I would have either been burning oil, or have fuel dilution in my UOA... neither of which is the case.


You said your WANTED FEEDBACK, and I provided mine to you trying to help. The "gunk" you speak of is a good product. Do your research before you condemn it. You also say you only have a "gut feeling" about whats wrong, so do you really KNOW Restore wouldn't help?


I said that because I want to actually fix what's mechanically wrong with the engine. In my opinion, adding anything from a bottle doesn't fix the problem, it only addresses the symptom, and only for a while. The problem will just come back, and depending on what the actual root cause is, could come back worse after the use of Restore.

I know what Restore is, and I'm not saying it won't work in many engines. I'm saying it's not the sort of thing I want in mine.

 

[Trav]

Originally Posted By: Trav
I would want to do a wet compression test, a leak down test and check it with a vacuum gauge before tearing into it or placing any bets.


Yes a wet check is usually enough. For those reading this thread that don't know the amazing diagnostic capabilities of a inexpensive vacuum gauge (one of my all time favorite diagnostic tools) check this out and maybe print out the chart.

http://www.gregsengine.com/using-a-vacuum-gauge.html

 

[rshaw125]

I had a Taurus (Vulcan) bad valve seat. Obvious when I took it off. Filled up the chambers with water. All held except cylinder 1.
New valve and seat good as new.

 

[Cujet]

Originally Posted By: SirTanon

So I ran a compression test. Yup, Cylinder 1 definitely has a compression problem.

My gut says that I probably have a burnt exhaust valve.. but I was curious to get feedback from the BITOG community.

... so what do you place your bets on?


In the aviation world, mechanics typically fill a cylinder with 80 PSI air pressure, through a calibrated orifice. This does a few things. First, it allows the mechanic to directly read differential pressure upstream and downstream of the orifice. 60 over 80 is typically where a cylinder will be replaced.

It also allows the mechanic to listen to the engine breather, the exhaust and the intake, if the differential pressure is low.

I suggest that before you disassemble the engine, betting on an exhaust valve, do a differential compression check on this particular cylinder. Or even more simply, hook a low pressure, regulated air source to the cylinder via a spark plug adapter. Make sure to hold the crankshaft while at TDC, compression stroke. You will find the leak rather quickly and probably be able to determine where the problem lies.

The one exception is if the cooling system pressurizes. Could be head gasket, head or block crack. But an exhaust valve leaking is pretty obvious.

 

[SirTanon]

Thanks for the suggestions everyone. If I had more time to do the work myself, I would have definitely tried all of these.. but the car is my only daily driver, and I don't have the ability to take more time off work to dig deeper into the engine.

.. so it's in the hands of a trusted tech. Apparently #1 cylinder is 9% low on compression, wet test shows no change over dry.

One other thing I did notice before I took it in, when the car was up to temp, and I just let it idle in the driveway, I listened to the intake, exhaust, etc.. and it was extremely obvious that the exhaust was pulsing unevenly, and there was a regular "beat" to it.. like out of so many pulses, one would be much stronger.

The only thing I could think of that would be causing a STRONGER pulse like that would be if one of the valves was leaking. You'd think that a cylinder with lower compression would lead to a weak pulse.. but it seems to me that a bad valve would allow more of the combustion pressure out, causing a stronger pulse.

 

[Number_35]

Originally Posted By: SirTanon
One other thing I did notice before I took it in, when the car was up to temp, and I just let it idle in the driveway, I listened to the intake, exhaust, etc.. and it was extremely obvious that the exhaust was pulsing unevenly, and there was a regular "beat" to it.. like out of so many pulses, one would be much stronger.
Many years ago my '71 Toyota Corolla was idling roughly. I had the car in at my dad's mechanic's shop on several occasions and they always 'found something' that cost me some money, but never anything that fixed the problem. Finally a friend's father listened to it, pointed out that the exhaust was making a popping noise, and told me that it was likely a burned exhaust valve.

Worked up my courage, pulled the head, had a machine shop replace the valve, and all was well. I wish I had kept the valve, but it had a definite 'bite' out of it, some what like a full moon just starting to wane.

 

[SirTanon]

Well, I got an update..

According to the tech, the exhaust valve on cylinder 1 had started to 'deform' which was causing it to stick in the guide and not close properly. Solution, new valve, guide, etc.. Should be simple enough.

Now is where my [censored] detector started going off.. I was then told that cylinder 1, 2,and 3 pistons shows signs of "overfueling" and that the cylinders showed "uneven wear due to fuel wash-out"..

This sounds like [censored] to me, especially since all of my UOAs performed on this car show virtually no dilution of fuel, and very few wear metals.

Case in point:

I've asked for a price JUST to have the valve issue corrected.

What does everyone think?

 

[rshaw125]

Not surprised at the exhaust valve being the problem. How much just to do the valve? What were they saying caused this 'over fueling'?

I paid $200 for my Taurus head work. They took all the valves out and gave it a good check. 1 new valve and the seat.

 

[SirTanon]

I've asked them for an answer to that, rshaw, but so far, they have not been able to provide any answer. I'm actually going by the shop in about 30 minutes to have a look at the open cylinders and see this "uneven wear." My gut says I won't see anything but normal wear for a 227,000 mile engine.

 

[Merkava_4]

Originally Posted By: Ramblejam
Check valve clearance on #1. Chances are you'll find one too tight.


That would keep a valve open when it's supposed to be closed, correct ?