2000 4.0 OHV Saga

[stol]

At 72K my engine started idling rough and the engine light came on. The dealer said they found both cylider heads cracked and after more than $3,000 I got my truck back.

Well at 101,000 engine light is back on and idling rough again. P0305 cylinder 5 misfire, according to Auto-Zone. I replaced the plugs and wires and cleaned the MAF, didn't help. The dealer says that its a compression problem and the warranty on my previous repair ended at 100,000. After some swearing at the service advisor, I decided to fix it myself.

I've never really done anything on an engine before, but I'm handy, so I bought a Hayes manual and waited for a nice weekend.

I took off the hood and cleaned the engine good before I stared. The only place I really got stuck was on the two bolts that hold the exaust manifold to the exaust pipe. That took me two days and lots of liquid wrench.

Unfortunely everything looked good as I was disassembling, the gaskets, the intake manifold, and even the cylinder head on the drivers side. I left the passenger side cylinder head on since cylinder 5 in on the drivers side.

I assembled everything back together the next weekend with new gaskets for everything. one of the exhaust manifold to cylinder head studs was stripped, so I have an exhaust leak on the one side. I'm still waiting to get the new studs for that side.

The engine light came on pretty much right away. And my air conditioning would only blow out the defroster holes. Turned out I had two vacuum lines smashed between the upper intake manifold and the fuel rail in the back of the engine.

I fixed the two vacuum lines and now the ODB II codes are P0171 and P0174 Bank 1 too lean and Bank 2 too lean. Supposedly this could be caused by the exhaust leak, we'll see.

Problem is now that I smell coolant when I stop the truck. I don't see anything leaking underneath or on the engine. I followed the Hayes manual instruction for applying RTV when installing the intake and valve cover gaskets. It did talk about putting RTV in some of the bolt holes, but only on 97 and earlier engines.

Any ideas where to look for the coolant leak???

What do you think about the new ODB II codes???

Thanks for any help

 

[stol]

This is starting to get frustrating -

I took the exhaust manifold off again, put new studs, nuts and a new gasket in. Maybe its not an exhast leak. Still makes the same noise. Kind of a clicking, much louder under load when accelerating. Maybe something with the valves/rockers??

I also figured out the coolant smell. Its puddled up on top of the lower intake manifold. Now to figure out where its coming from. It doesn't look like its coming from the heater hose. Anyone have an idea?

Any way you can run the engine without the upper intake manifold on so you can see what is going on underneath?

 

[TPLYNCH]

Could the coolant be coming from the heater control valve?

The lean readings wouldn't come from the exhaust leak. They would be caused by
air leaking into the intake manifold. Also, check and make sure there are no cracks/holes in your intake plenum between the MAF sensor and the throttle body.

Also, I assume you reset the computer after doing all the work....

 

[Runnin'OnEmpty]

STOL, I second the intake leak suggestion. Pay special attention to the upper intake gasket where you pinched the vacuum lines. Since you're showing lean on both banks, the leak has to be around the upper manifold or the air tube going to the MAF. Did you replace the (PCV) hose running from the air tube to the oil fill tube?

So did a new headgasket cure the number 5 misfire?

 

[stol]

Getting better. The Check Engine light stays off!!!

I took the upper intake off again, I noticed that one of the studs holding the fuel rail down was up about a quarter of an inch. When I took the upper intake nuts off to get the vacuum line out, some of the studs must have loosened up. The gaskets looked fine.

While I had the intake off, I tightened the lower intake manifold a little more and put a new upper radiator hose and the top heater hose. They didn't look bad, but I can't figure out any other way that coolant could be getting on top of the intake manifold. If it keeps up I'll look at the heater control value much closer and maybe get some dye.

I checked the oil, the level was above the top full line and the engine was cold. Now I'm praying that coolant is not getting in. I drained some out, and I'm going to change it in a few days, it seemed really thin.

Still have the exhaust leak. Maybe between the Exhaust manifold and the exhaust pipe?

 

[shamaal]

That's where my exhaust leak was coming from on the passenger side. You can feel it with your hand. Careful it's hot. I had to disconnect the manifold from the pipe with socket on 20" extensions, smeared a lot of high temp RTV at the joint (no gasket on the ball joint) and bolted it together. Leak fixed. My manifolds were a #$%@!& to get out also. I had to cut the bolt heads off. The first gens had bolts instead of studs.

 

[stol]

Thanks, I'll try the high-temp RTV.

I had to disconnect the manifold from the pipe with socket on 20" extensions,

Those were my hardest bolts to get off. I bought a lot of new tools and rented an electric impact wrench.

 

[stol]

Still have coolant on top of the intake manifold. Its puddled around the fuel injectors on cylinders 2 & 3 (near the front of the car).

The heater control valve looks bone dry, so does everything else. Bummer.

 

[shamaal]

Not to be alarmist, but it is coolant and not gas? I didn't lube my o'rings when I installed my injectors and one didn't seat properly and subsequently leaked.

If coolant, you could try one of those loaner cooling system pressure pumps from autozone and wiggle hoses. My leak was the heater hose that leaked only when I wiggled it.

 

[stol]

Shamaal - Definitely coolant. I picked up a pressure tester from AutoZone, but I haven't tried it yet.

I did put a some HighTemp RTV copper silicone between the manifold and exhaust, but still have the leak some where. Its hard to feel for the leak with all the air from the fan.

 

[shamaal]

Do it with the car cold before the fan kicks in. Careful the exhaust does heat up quickly.

 

[stol]

I got a cooling system pressure tester from AutoZone, but I haven't had a chance to try it yet.

My oil level is definitely rising. Does it make sense for coolant to get into the oil, but not the other way around? Is there anyway for the coolant to get into the oil other then at the head gasket or cracked head?

My coolant leak leaves puddles of coolant on top of the intake manifold on the passenger side. Is it possible that coolant could be leaking under the valve cover?

I'm debating at this point whether to rip it all apart again or take it to someone.

Thanks for any help

 

[stol]

Well, I dropped off to an unknown local mechanic this morning. I'll post back what he finds to assist others.

 

[stol]

Coolant leak was coming from the upper radiator hose where it connects to the thermostat housing. I was never able to find a pressure tester to try, but that was my best guess earlier.

Exhaust leak is fixed.

I didn't know that Bosch plugs sucked so bad. I put them in this spring. 3 of the 6 had some strange burns on the side of the center conductor. I now have motorcraft installed.

Still misses at steady speed. Example: Going 35 on a level surface, low RPM, no accel or deccel.

The mechanic thought I might have tightened the rocker arms too much. Does that make sense?

 

[410Fortune]

I think your engine is shot or the heads/gaskets are if you are gettig coolant in the oil