Valve Stem Seals leaking?

[Adam Smith]

Just got back from having my mechanic do an oil change on my '04 SportTrac Flexfuel with 100,000 miles. I/he has kept it maintained since I bought it new, Mobil 1 Fully Synthetic 5W30 wt. and Motorcraft filter change every 5K mi. It was down almost 2 qt. and he says it's likely Valve Stem Seals getting hard and allowing oil to blow by and eventually out the exhaust. 20 hours and $3K is the estimate. He said to check the oil in 1K mi.

Anyone seen this before? I like the truck and would like to keep it.

Thanks.

 

[Gavin Allan]

Yikes! $3k to replace the valve stem seals? You need another opinion and another estimate.



If your valve stem seals are going bad, generally you will see a puff of blue smoke after coasting down a ling hill (in gear) when you first give it some gas. The high intake vacuum while coasting pulls the oil up the valve stem and then when you get on it, the oil is burned in the cylinder. If the seals are real bad, the engine will not idle very long. It will run fine for a while and then the plugs will start fouling from the oil as it sits and idles, and the idle will get rough, and then the engine will die when the plugs start getting fouled.



If all you have is an occaisional puff of blue smoke after an extended coasting period, I would not worry about it as long as the engine is running fine. I "assume" you have new spark plugs installed. If not, and you are on the original plugs, you need to change them for a number of reasons. An engine will run a long time with leaky valve seals, and as long as you keep enough oil in it, there should be no serious problems.



Be sure to always keep your oil level in between the "add'" and the "full" marks. You do not want to run low on oil. Keep changing it as you have been, and you should be fine.



$3k sounds outrageous to me to replace valve seals. Of course my frame of reference is doing it on a small-block chevy engine, which is pretty much a do-it-yourself job in less than a day. The overhead camshaft would probably add some pain to the process. I would definately get a second opinion and estimate from an independent shop that does engine work. An alternative- you may be able to find someone to install some rebuilt heads on it for alot less.

 

[Vic Sorlie]

That estimate strikes me as way off; perhaps 1ltech will see this thread and chime in. Agree with Gavin's comment about spark plugs. Have you pulled a couple to check condition? Sending off an oil sample at next oil change would also give you some useful information. See my write-up on oil analysis in the Maintenance section of Projects.

 

[Bob Floyd]

IF it was mine I would pull the plugs and do a compression test then a cyl leak down test and find out where your leaking or if.. for less then $3000 you could get a reman engine and change it out yourself...

 

[Adam Smith]

Thanks for the replies.

Yes, I spent several miserable hours one night putting in some Autolite spark plugs, between 70 and 80K mi.

I haven't really noticed it running badly, and with my oil changing schedule, I honestly haven't been checking my oil; lesson learned. But I haven't noticed any smoke either; I'll check that out.

Will also check out the Maintenance section for Projects.

I asked my mechanic about a compression test and he said it could reveal many different leak spots which could mask the valve stems leaking.

I've swapped out engines on a '73 Toyo p/u and did it myself when I was younger, but this one looks a bit more complicated...sounds like a good option to look at though if it starts to go bad.

 

[scott degroot]

Before you do anything verify that you are actually using the oil. Check it now and then again every 500 miles and see how it goes. Who knows, maybe the oil wasn't properly filled after the last oil change. If you determine that you are using oil, and there are no leaks, pulling the plugs and looking for signs of oil usage is a good place to start....kind of...logic dictates that if we aren't leakng oil but we are losing oil and the cooling system is ok then we have to be burning it so the plugs would have to show it, so pulling the plugs may be a little pointless. Now you could say that you are going to pull the plugs and do a compression test to find out what is leaking...it don't work that way. The valve guide seals have nothing to do with compression. You might say well what about the rings? The oil control ring on the piston sits below the compression ring or rings so if there were a problem with the oil control ring it wouldn't show in a compression test unless there was a major failure but in that case we would have a misfiring cylinder so we would know exactly where to go. A pcv issue could be another cause of high oil consumption as well.



3k to do valve guide seals, he must be pulling the heads but I don't know why. The seals can be done in vehicle, book time is about 7 hours + parts which shouldn't be much. You do need a couple of special tools though which can be a bit spendy on this vehicle and most techs won't have them unless they service alot of them as they are kind of specific to this engine.

 

[EddieS'04]

Scott,,your info is excellent:supercool:



I feel he is being riped, IMO.

Not that it is imposible. But this is the first 4 L SOHC. I have heard about stem seals at 100K.

Not to say you havent seen some.

Also $3K is out-ragous if you have the tools. But I have only done them with head on with pushrod motors.