Valve job, rebuild or replace engine 140k

[thunder92]

update: Valve job, rebuild or replace engine 140k

My wife explorer only has 145k and the engine needs major work. I'd tried everything I could my self to get it going but not luck. Shop says $750 to pull the engine and then machine shop will charge as needed. Up to $800 most likely depending on what is found. Will need a bunch of specialty tools just to get timing chains off etc...

Real bad misfire right now. Always same cylinder. Spark plug only last a month before fouling. No change after all this:

cleaned fuel injectors
switched them to other side of engine
new spark plugs

Cylinder misfire always goes back to cylinder 5.

2002 4.0 v6

Thanks for any help. Really can't afford a $2000 bill right now.

 

[Number4]

If you haven't attempted much work yourself then this would be fairly dificult job to take on. Not to mention that the V6 is the worst to do a timing job on.
In GA right now, 5 out of 7 Explorers for sale are all 2002's with the V6. Asking price $1500 to $2500.
Unless you plan on keeping it another 7 years, you might take a pass.
The response from your mechanic sounds sketchy. Sounds like they don't know much about the 4.0 when they should. The pricing they quoted is far too low.

Edit: get a second opinion before you do anything. Take it to the dealer and have them properly diagnose it.

 

[boominXplorer]

Have you taken the valve covers off to see if its just a broken valve spring?

 

[thunder92]

Have you taken the valve covers off to see if its just a broken valve spring?

thanks guys! I'm fairly mechanical, just not engine rebuild mechanical. Brakes, oil, tranny changes.Water pumps, radiators...that sort of thing. I don't mind taking the valve cover off just don't know what I'm looking for. I assume one will look different than others if its broke though.

As far as the mechanic he is a pretty small shop I've used time to time for work trucks. Always been alot cheaper. But I have a feeling I'd pay a bunch more than quoted.

Thanks for the help.

 

[thunder92]

dealership diag

Thinking of bringing it to the dealer for a diag. One thing I'm thinking is that when I had the tranny rebuilt last year maybe they missed a vaccum hose or something. It seemed to start this shortly after. Repair shop said by reading the spark plug and all the symptoms and repairs tried that 2 machine shops said its the head, valve or valve guide. Price was to repair only 1 head. I'm not spending that much for only one head. Chances are another one goes down within a year and I'm back to square one. Gonna get rebuild quote or sell it.

 

[thunder92]

update

Still no conclusion. Picked it up from the shop and I'm gonna check some things:
clean iac, test coolant temp sensor, inspect rockers and valve springs. Check all vacuum lines and maybe test for vacuum. Clean fuel filter or test fuel pressure.

After that I'm at my end I guess. I'm real tempted to try a used engine replacement myself. Scared to take on that kind of repair by myself though. Found one local for $950 w/ returned core. Only 90 day warranty though.

Anything else I should try? Local dealer wants $115 just to diag.

 

[Number4]

I'd pay the 115. Cheaper than your time. And if they can't solve it, I wouldn't want to pay. Ask about that upfront though.

 

[thunder92]

thanks

Thats actually good advise. Thanks

 

[2000StreetRod]

vacuum leak

A vacuum leak should affect more than one cylinder - either an entire bank or both banks. Misfire is usually due to spark, fuel or compression and in that order. I suggest:

1. Check for spark to cylinder 5 plug
2. Listen to cylinder 5 fuel injector for uniform pulsing
3. Compare cylinder 5 compression with another cylinder

 

[thunder92]

back from the dealer. Still no real answer!
Good things according to them:
good compression(0% dev), IDS test, fuel system/pressure,reliable comp test(cyclinder test).

Bad:
-power balance test showed cylinder 5 down 20%. Figured this though.
-spark plug broken

-Quote to clean MAF and replace plugs $560.

--------------------------------
I just did the spark plugs less than 1 1/2 yrs ago and cleaned the MAF 3 weeks ago. When I replace cyl 5 spark plug it fouls again within a week or 2.
Told them this and they had no answer. I guess maybe the MAF showing dirty may mean I have another vacuum issue somewhere? I don't know how they test vacuum though. Anyways, I'm out a cool $115 and don't know much more. At least they didn't say the engine was shot like the last shop. Saved me some time on fuel and compression checks.

DON'T KNOW WHERE TO GO FROM HERE. Guess it wouldn't hurt to check all the plugs or replace them. I wish I could find that stupid PCV valve too!

 

[2000StreetRod]

encouraging results

The fact that your compression is good and the deviation from cylinder to cylinder is nil should be encouraging news. I doubt that your engine needs major work as you initially suspected. Good compression should eliminate bent valve stems, broken valve springs, burned valves, broken/worn piston compression rings, cracked head, blown head gasket, slipped timing chain and broken camshaft followers. I suspect your problem is either ignition or fuel related. Check the condition and routing of the spark plug wire to cylinder 5. Make sure spark is getting to the plug. Run the engine in the dark and look for the spark shorting to something metal adjacent to the wire. Measure the end to end resistance of the wire and compare the resistance per foot to another wire. Check the boot connector at the coilpack. You posted that you've cleaned the injectors and swapped cylinder injectors. Does it "click" at the same rate as the other injectors and uniformly?

 

[thunder92]

thanks Streetrod. I tested the spark on that cylinder and its sparking great. The plug indeed was fried. Black and the entire top was gone. I'll post a pic in morning. I went ahead and replaced all 3 sparks on that side of the engine tonight. I'll leave the wire as I have them switched already. If its the wire I assume my cylinder misfire will switch to another cylinder. I'll listen to the fuel injectors tomorrow although I suspect they are ok since I moved them all to other side a month a go and the dealer tested them with some sort of dye test and they checked out.
Thanks for the help.

 

[2000StreetRod]

injector wiring

My stock injector electrical connectors easily broke when I disconnected them and were no longer reliable. I replaced them with connectors of a different design.

 

[Number4]

Let me know how those fit. Mine broke during removal on my 94. I didn't like the way the replacements looked vs OE. And Ford wants your first born, five times over, for OE replacements.

 

[thunder92]

nice

Ya, I like those injector plugs much better. I know I have a broken one too. They were all brittle. I have some like that on my bmw and love them.

Hoping to get this thing figured out soon. Wife wants her truck back. I don't know why but I still think its a vacuum issue or something dirty like the dang pcv valve. Probably should have shot it full of seafoam before changing the sparks. Maybe I'll change the 3 I changed back and add first.

 

[thunder92]

thinking maybe its because of overheating issue that seems solved. But it did overheat a couple times in last few months. Only affected this cylinder though. Weird.

 

[Number4]

So, either a defective plug or oil fouling damaged it. Haven't seen oil fouling do that to a plug though.

 

[2000StreetRod]

detonation?

thinking maybe its because of overheating issue that seems solved. But it did overheat a couple times in last few months. Only affected this cylinder though. Weird.

That doesn't look like oil fouling to me. I think its from detonation due to lean condition. You stated in your original post that you had swapped the left and right bank injectors. The PCM fires the injectors by "grounding" the low side. There should be battery voltage on the hot side when the ignition is on. I suspect there is an electrical problem with the injector - either wiring or connector. Did the dealer test to determine if all of the injectors are firing?

 

[thunder92]

Fuel injector connector does make sense. Dealer says they did a fuel
Dye test though and they tested ok. Gonna go listen to the injectors again in a bit. Ill try and meter a couple too.

 

[2000StreetRod]

testing for leaks?

I'm not familiar with using dye for testing fuel injectors but it sounds like a way to check for leaks instead of no flow.