99 Explorer 5.0 low cylinder compression

[ccam7779]

My explorer has had really bad gas mileage lately and has rough starts on and off along with rumbling at idle. I have had it in a shop for the last couple days having diagnostics run on it and they told me they think, but don't know for sure, that it is a bad cylinder. Cylinders 1 and 5 have low compression at about 20psi, should be about 120. Originally they thought it was a bad injector but have ruled out anything to do with the fuel system. They also checked the coil packs and those are still good as well. They told me a few possible causes for the bad compression but I want to see what suggestions you guys can come up with before so I don't sway your opinions.

 

[SoHK_alumni]

bad valves or bad rings are the two most likely answers with the valves probably the more likely culprit.

Fixing the valves is a manifolds and heads off repair, the rings is likely a full rebuild.

For either, a used engine from a breakers yard is likely the least expensive path that includes keeping the Explorer.

 

[shucker1]

We need a little more information to work with here.

How many miles?

Did it over heat? Are you the first owner?

Do you change the oil on a regular basis?

Any strange noises?

Stuff like that.

The more data the better.

 

[ccam7779]

Shucker it has 164xxx miles

I've never had it over heat the temp Guage actually hasn't gone above 1/4 since winter started and still doesn't even though it's warm now.

second owner, I've put 15000 miles on roughly

Oil changes are done regularly

Only strange noise is the hole in my muffler, no nock from the engine or anything.

I did have a bad dpfe sensor that I just replaced along with the main vac line and a totally destroyed spark plug in cylinder 1, wasn't just fouled but actually mostly gone, was a bad replacement plug with less than 3000 miles on it.

 

[Turdle]

The burned plug is a sure sign f a failing-clogged fuel injector. I'm going to guess a burned valve or piston.

 

[ccam7779]

Fuel injectors were checked out and supposedly are good. They told me they think bad a valve or bent cam. From the sounds of it I'm just gonna keep driving on 6 cylinders for now until I can get a new explore or something else. Any favorite year models out there?

 

[shucker1]

If the plug tip was completely gone then it went somewhere.
My bet is burnt valves.

If the body is in good shape why junk it for a weak engine.

Just get it rebuilt.

 

[ccam7779]

Body isn't in all that great of shape either. I was reading in another post that the valves sometimes just get dirty and stuck and can be cleaned various different methods (seafoam, diesel, trans fluid). Since the compression isn't completely shot could this be a possibility? Should I give it a go and try to clean them out?

 

[shucker1]

With almost zero compression on 2 cylinders I would say you have a serious problem and I don't think that would work.

 

[1997XLTRollover]

With almost zero compression on 2 cylinders I would say you have a serious problem and I don't think that would work.

^This. 20psi is REALLY bad. That's what's considered a completely dead cylinder. That's not even enough compression to ignite a fuel mixture.

If you don't feel the truck is worth fixing I'd grab another V8 and maybe keep yours for parts. Good trans, maybe interior, tires etc. since you know the condition of the rest of the truck.

Depending where you're at I have my 99 EB for sale. I'm taking trips to Wildwood NJ, Ocean City MD and the outer banks NC in the coming months that I could drive the truck down to you if you're anywhere on the way.

http://www.explorerforum.com/forums/showthread.php?t=424743