94 Explorer 4.0 troubles

[Cole94]

Alrighty...

So I've been on here before with this truck and I'm still having the same problems.
Surging idle, poor fuel economy...

Now it has developed into something worse. Something undriveable.
-It now idles at 3000 rpm.
-It overheats (dash gauge doesn't show it, but intake manifold gets so hot you can't even touch it, same with the hood when it's closed, and the radiator boils and boiling coolant flows into reservoir)
-I get a puff of white smoke sometimes when starting.
-Loosing coolant.
-Occasional hard starts.
-Idle all over the place, and stalls once put into gear. And when it doesn't stall, I have almost no brakes, the pedal goes to the floor and I slow down gradually.
-Exhaust sounds like a hemi sounds like a miss on one cylinder or perhaps a whole bank.

This all developed from a surging idle (blipping 2 times a second) over a trip of 13 miles.

I pulled the plugs two days ago (sorry, no pics) and have orange deposits on some of them. (#1 & 2 if memory serves me correctly).

I'm leaning toward's lower intake gasket. Replacing it this weekend. What do yall think?

Sorry for the wall of text, I'm starting to give up on this truck.

I can add links to videos of the surging, and links to previous threads of what I have replaced and whats going on, etc.

 

[shran]

Reads like a large vacuum leak and/or head gasket/head failure. You could sure replace the lower intake gasket but that's a lot of work if you actually have head issues and have to tear it all down again to fix that.

Not sure about the brake issue - other than the vacuum line on the booster, it's totally unrelated. I would suspect that you've got a bad master cylinder or a leak somewhere. I've had the RABS valves leak multiple times on 92 and older trucks.

I'd be doing some checking to figure out where your coolant is going and go from there.

 

[Cole94]

I realized the brake issue was due to old cooked fluid overheating (along with the engine) and the moisture in it turning to vapor and acting like air in the lines. I know this because after it cooled the brakes functioned normally again.

How much work and time would it add to put in now head gaskets while I'm in there? I know I need new head gaskets and rtv silicone and new head bolts, and I'm replacing the valve cover gaskets while I'm there too.

Cost for me replacing the head gaskets is not a concern, rockauto has them cheap and I need this thing to run!

 

[Cole94]

So it has been brought to my attention that the head gaskets were replaced 14 years ago when my parents got the car. Is it possible they're already bad again?

 

[shran]

Overheated brake fluid seems highly unlikely - your engine compartment would have to be godawful hot for that to happen and you would have plastic and wiring melting everywhere. The only time I've seen something like that happen was in a Dodge pickup where the battery tipped over and both terminals contacted a steel brake line - the master cylinder caught fire and the brake lines within a foot or so of there were glowing red.

If you've never done heads before, I would factor in a full day or more to do the job. Lower intake seals I can do in a couple hours, taking my time.

This is assuming you don't have a cracked head. While you have them off, you need to have them magnafluxed at a machine shop to check for cracks, and possibly have them reconditioned too.

I have to ask though, is this truck worth putting that much time and effort into? From the sounds of this thread and others you posted, it has quite a few issues.

 

[Cole94]

Yes it has a few issues, but I have come to love this truck. It's also got 2000$ in parts on it from when my dad was just throwing parts at the problem. It's got a mostly clean body and is almost rust free. I know it almost inside and out and can work on it quite easily, and I don't want to replace it.

This whole thing has been an ongoing issue for about 8 months now, but it has become now undriveable.

I haven't seen any melted wiring, but the engine gets too hot to even touch the hood, on 60 degree days. The intake manifold burns you instantly. The radiator boils. I am willing to do everything up to and including dropping a crate engine into this truck. I think I will wait on the head gaskets due to the amount of work involved, and they have been replaced recently, and compression checks out ok (150-160 each cylinder).

However, is there a way I can check for cracks and failing gaskets once I get down to the lower manifold gaskets?

 

[shran]

Fair enough, I understand.

My recommendation would be to do a good overall check on the cooling system including radiator and water pump flow, thermostat operation, fan clutch and radiator cap. If it's boiling water out of the radiator, something is not right in one of those areas OR you've got exhaust gasses blowing through somewhere into the cooling system.

 

[Cole94]

OK. I popped the radiator cap off and saw water flowing so I figured all was well. I went to take the thermostat off and see if it still overheated, but the rain, fatigue, and idler pully stopped me.
I will definitely comb over the cooling system. I just recently drained and flushed the cooling system with a cleaner (not sure what kind, yellow bottle) and it's got a rad that's less than a year old. If the lower intake gasket let loose coolant could be leaking there and burning (exhaust stinks, not sure what it smells like) but no white smoke except on startup.
I will post results of the gasket replacement this weekend.

(I'm beginning to see where it could be head gasket or head failure)

 

[imp]

@Caleb Teague Small amounts of coolant burning in the cylinders will make white smoke, similar to oil. The overheating is strongly suggestive of exhaust gases entering the water jacket. Head gasket, or a crack. Lean towards the latter, since coolant in cylinders will almost never happen, but failed combustion seal WILL allow gases into coolant. Coolant accumulation in cylinder(s) when shut down and standing, nearly always count on a crack.

If it were me, bent on saving the vehicle, I would find a like wrecked vehicle which was running when wrecked, and buy the engine out of it. imp

 

[Cole94]

Alright well I had the intake gaskets so I'm throwing them on. Found carbon buildup on the pushrods on #5 & #6 cylinder. The rest are clean. Is this a sign of an intake leak (a bad one at that)?


#4 (normal)

#5 (carbon buildup)

 

[Cole94]

So after 7 months, the entire issue was a stuck open EGR valve. It was replaced trying to fix the stalling, so I don't think it was the original issue, but developed before we got the initial issue fixed and gave us problems after that.

Either way, it doesn't matter. She purrs like a kitten and I am glad to have my beautiful Explorer back.