Expedition compression test

[Fitz98]

I plan to change spark plugs in the next day or 2 on my 98 Expedition 5.4 with 145K miles.
I am also trying to chase down some disappearing oil, (a seperate topic posted in this forum).
Any advice to perform a compression test in this vehicle?

 

[bdcardinal]

Good luck with that. One of the nice things about the Ford scan tool is you can do compression and power balance tests through it without having to open the hood.

 

[Fitz98]

???...do tell.
Can you expand on this?
I am trying to do some basic troubleshooting to see if I may have a valve seal or ring problem.
I have been losing about a quart per 1000 miles with no evidence of leak or smoke out exhaust.

 

[bdcardinal]

As bad as it is getting to the plugs, getting the compression tester in there gonna be worse.

With the IDS you select "compression test" and hold the throttle down while you crank the motor. It will do a relative compression test and tell you which cylinder is bad. The power balance you just click it on the scan tool and it will show a graph of all the cylinders.

 

[tom slick]

A compression test isn't going to tell you if your oil rings or valve seals are bad.

 

[Colt45ws]

If you look at the plugs, it should give you a pretty good idea if you are burning oil and if so, which cylinder.

 

[Fitz98]

I think something like this would be good to have.
Are they crazy expensive? Any recommendations for which model to get?
I do a lot of towing too, and it would be a nice feature to be able to monitor transmission, oil and coolant temperatures while hauling too.
It looks like you work at a dealership, looking at your signature.
Does dealer perform this service and provide a printout of results too?

 

[bdcardinal]

A complete IDS is around $10k not including the annual updates. The tech can do a screenshot and print it out for you.

 

[Trav]

Its possible to do but as dbcardinal said a royal PITA.
These engines are pretty good for bore wear and sealing but the oil rings get a little sticky on them.Ford can do a electronic test for you.
I got one with 75K on it and it used 1qt every 3K on 5w30.

I ran 16oz of kreen in it for 1K and that cured it,now it does 5K OCI with very little movement on the stick.

 

[OVERKILL]

+1 to what Trav said (this seems to be a recurring theme).

You will also want to check the PCV valve, as this can be a cause of consumption. There is an updated PCV tube assembly that fixes that issue as well as the glazing of the throttle body, which can cause the blade to stick.

A good synthetic and some spirited driving should clean the ring pack up. My personal favorite in this engine is Mobil 1 Advanced Fuel Economy 0w30, and what I'm running right now.

I have posted up pictures of the crud I had been finding in my oil filters after buying this truck and running Mobil 1 in it. This has finally tapered off.

Mine uses no discernible oil over a 10,000Km OCI. The only oil I had consumption with was 5w20.

 

[MarkM66]

Even if you do a compression check, and one cylinder is a little off. Then what? Are you prepared to tear the engine apart? There's not going to be a quick fix.

 

[Trav]

That's always the big question isn't it especially on a nightmare of an engine to work in the car on like this.
Probably better to some idea though before throwing good money into a vehicle with an iffy engine.

 

[Fitz98]

Did the plug and boot change today.
Previous owner must have had them changed.
They looked great! Practically like new. Clean, no oil, no burning, no hot spots. They were not factory either, they were Autolites.
One strange thing, was the factory gap recommendation is .054 and most were gapped at .045. Maybe a dyslexic mechanic?
Anyways, while I had it apart, and had the electrical and fuel rail out of the way, I saw all kinds of vaccuum issues from the intake manifold to the PCV Valve. All the 90's (3 of them) were collapsed and the piece right at the intake had a 1/2" hole in it, so obviously the PCV was not working properly. How does this end up burning oil though?