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Running rough after head gasket rebuild

geosnooker2000

Well-Known Member
Joined
March 29, 2007
Messages
298
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City, State
Somerville TN
Year, Model & Trim Level
'10 Eddie Bauer V8 4x4
Well, it cranked!

Now for the bad news.....
Sounds and feels like a miss on at least 1 cylinder, especially under load and after it warms up. Hear's what I did:

1) Changed head gaskets, and all that entails.
2) Power washed (without pulling the trigger) engine compartment after dousing it good with de-greaser before I started (but it ran fine on the way home to start the repair).
3) Changed one spark plug anyway because it was showing signs of rust (even though, again, it was running fine before the repair).
4) De-greased and washed the top and underside of the lower intake with the fuel rail and the injectors attached and in place (scrubbed with wire brush to get all the gunk I could out. (Looked 95 percent clean when I finished, but I was running out of patience, time, and de-greaser). I tried not to touch the injector orifices with the wire brush, but they DID look gunky. I tried to spray them clean with the de-greaser and the garden hose.
5) Found a brown O-ring in the driveway after completing the job, but as discussed in a previous thread, this must be from a previous mechanic leaving an extra one lying in the intake, because I DID NOT take the fuel rail apart. I thought it might have come from the fuel return line, but no one can say there is supposed to be an o-ring in that connection. At any rate, there is GOOD pressure on the system, judging from when I discharged the schader valve on the fuel rail to check if there is an o-ring at the fuel line/regulator connection (there's not).
6) Replaced the plug wires. Cylinder #3 wire on the new set doesn't have as long a terminal plunger as the other 5 wires, so it doesn't go as deep into the coil pack as the others, but the O-rileys guy looked at it and assures me that isn't an issue. I'm not so sure.

So, guys? What should I be looking at first?
Ask me questions if you need more info to form an opinion.

Oh, this is all on a '93 4.0L Sport with 350,000 miles.

Thanks in advance
George
 



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Question:
Are the valves in the 4.0L adjustable? I didn't see any way they could be, but if they are, I didn't do anything to them (the heads were rebuilt ones from a company in West Virginia).
 












swap one of the wires from your old set into the suspect wire position. The shorter electrode is an issue.

Also, triple check the firing order on the driver side--we all get it mixed up at one time or another.
 






So both you guys agree, check electrical first, then fuel.
Turdle - I unfortunately threw the old set away, or that is EXACTLY what I would do. I think I will pull a short wire off my '96 (not running right now due to a bad tranny) and use it. I'll report back later. Thanks for the thoughts, guys.
George
 






Quadruple check the firing order. One side of the coil makes perfect sense while the order on the other side is switched up some.
If you goof the switched up side it will start but run poorly. I've seen many people on here switch up some wires including me. Heck, I goofed on it during a head job and during the motor rebuild but once it ran funny I knew what it was.

~Mark
 






I checked it 3 times. The wires are correct. The passenger side makes sense and the drivers is back to front, front to middle, and middle to back. Mechanic friend of mine I just showed it to said it could be a vacuum leak at the lower intake manifold gasket, because "it doesn't sound like a hard miss". Possible? I would hate to tear that far down back into this thing.
 






Just visited my other mechanic friend about 50 miles away, he hooked it up to a computer and found no trouble reports. Said I should go home and pull each plug in the morning and find the one that looks fouled and clean that injector (after I told him my method of cleaning the underside of the lower intake). Left him and not 10 miles down the road it all of a sudden started running perfect. Then I noticed that it was running hot. Had to stop 25 miles into trip home and add water to the rad. after watching it boil out the overflow tank cap. The same trouble I had that prompted me to change the heads and head gaskets in the first place. But in the 95 degree heat on the way TO my mechanic friend, while it was running like ass, it ran cool as a cucumber. Why? Cracked heads again?
 






it is very hard to get all the air burped out once the cooling system has been cracked open. I would assume a air lock in the hoses, and try again.

Get the front up high so the rad cap is higher than the heater core inlet tubes. This will help get it all burped.
it takes several warm up, cool down cycles , checking coolant evry cycle, to get it filled and burped.
Also, the engine may run like crap when no coolant is present at the ect sensor.
 






Turdle,
I have been running without a thermostat and put in a 2nd bottle of prestone flush and clear water in hopes that I can get all the rusty gunk and Liquid Copper out of my system from when I tried to fix the cracked heads problem before. Could this be contributing to my current boiling over problem? I really don't know what it is supposed to do driving it for over an hour without a thermostat.
 






Ah, I assumed a new thermostat was installed. Sorry.

It " might " be possible on a hot day, with no thermostat the coolant will not stop in the radiator long enough to cool sufficiently.
 






Ah, I assumed a new thermostat was installed. Sorry.

It " might " be possible on a hot day, with no thermostat the coolant will not stop in the radiator long enough to cool sufficiently.

GOOD GOSH!!! If that's all it is I will sing 5 hymns on the freaking front lawn!!!!

So would you say my next move should be:
Flush
Install thermostat
fill with plain water
See if that works
If it does, drain and fill with 50/50 mix???
 












I would try that yes.

Also, once the coolant is burped and engine is hot, rev it up to see if a radiator hose collapses.

What do you mean by "collapses"? Would I need a helper to see it collapse, or is this not a literal type thing?

Also, if it did, what would that indicate?
 






with the engine idling in park, you can pull the throttle lever under the hood. As you do this check the hoses. If there is a blockage in the cooling system the water pump will try to over come this and a radiator hose may collapse.
 






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