The other day my 2000 4.6L Expedition engine suddenly started knocking. It sounds exactly like when a car is really low on oil and the valve train gets noisy (this has never happened on my Expedition). This is not the "piston slap" when you first start the engine, and the oil is not low. The knocking seems to be coming from the passenger side valve train, it's fairly loud, and ramps up with RPM's. I'm getting ready to check if the sparkplugs are secure and then pull off the valve cover on the passenger side to check lifters, etc.

Two Questions:
1) Any ideas on specific cause?
2) How do I completely remove the wiring harness and coolant hoses above the valve cover so I can remove it. I've already removed the individual coils, disconnected the injector electrical connections, and separated the wiring harness loose from the feed packs. The wiring harness is split with one branch going to the coils/injectors. The other branch runs between the engine and firewall, where do I disconnect this branch? Also, how do I disconnect the coolant hoses where they attach to the heater core at the firewall? They look like special connectors (I couldn't see back there very good).

Any help is greatly appreciated.

Bruce.

 

Sorry no one has gotten to you yet, I've been off for a few days. I believe your problem may be the exhaust manifold gasket. They are not fun to replace either.

As for your existing work listed, get a manual (Haynes is pretty good, but they don't show alot of wiring, but show connection releases). This way if you forget something you have a reference.

 

Thanks for the reply, it looks like I got more going on than I initially thought.

I removed the passenger-side valve cover and it had varnish and some sludge throughout, but didn't seem to have any fresh oil. It also smelled of burnt oil. I took out cam, rockers, lash adjusters, etc. (4.6L SOHC). Cleaned everything and measured tolerances. Other than a little scratching on the bearing surfaces, no major damage or out of tolerance. Two hydraulic lifters seemed stuck due to residue, but were fine after cleaning and re-oiling.

Put everything back together and added fresh oil. Bled the air out of the lifters and filled with oil before re-installing and lubed all bearing surfaces, lobes, and contact areas with moly grease. Also changed all plugs and tested all coils. Started up the truck and had same tick but it now was joined by distinctive rod knock. I let it run for a bit to allow the oil to reach everywhere, but to no avail. Rod knock is loudest when engine stops after turning off ignition, and also at low RPM with load on engine.

Plenty of oil in the engine and the oil pressure is reading good. I pulled off the oil pressure sensor and will check actual pressure with a gauge tonight. Next step is to pull the oil pan and take a look to see what kind of damage I have.

I'm wondering if 1) my oil pump is bad and my pressure gauge is incorrect, or 2) I have a blockage somewhere in the oil system. I fear the damage is done to crank bearings and hopefully not too much else.

Thanks.

Bruce.

 

it could be the oil pump and don't count on the gauge it only needs 4 psi to read normal how many miles are on your engine

 

Ford390 makes a good point, though I would ad as long as your bearings were silver, you are good there, but if they have a purplish or bluish tint, they are burnt.
I initially stated the exh. manifold because some misdiagnose a manifold leak as a knock.
Boy, I don't like to bring this one up, but its possibly a wrist pin. I say this because you say it ramps up with the rpm's. A rod would generally keep the same sound, just increase the amount of raps with the rpm's. How many miles do you have on her?

 

I've got about 94K on the truck now. I took it to the dealer to have them assess it. They say the engine needs to be replaced ($3300 engine + $1500 labor). I'm going to talk more with them in case they can look a little closer before replacing. They couldn't give me a root cause and probably only did a cursory inspection.

This leads to my next question:

Is there a better engine to put in besides a remanufactured Expedition-spec 4.6? Maybe the Mustang 4.6 SOHC (more HP, torque) or a 5.0? I asked the dealership for their opinion, and whether it would still be warranteed if they installed it. I'll be talking to them later today.

Thanks.

Bruce.

 

I love my 5.4, should be a direct bolt up, though I'm not sure about the puter.

 

I'm gonna take the truck to a local garage for a second opinion. The tech that looked at the truck wasn't at the dealership when I got there today, so I couldn't talk to him. It sounds like he only took a quick glance and listen and decided that the engine needed to be replaced. Granted, it's likely damaged beyond repair based on the rod knock, but I'm not gonna drop $5K until I'm sure that it can't be repaired with a new set of pistons, bearings, and a crank resurface. The thing I really don't like is that the dealer says the core charge for the old engine is $1000. This seems purposely high to me. If I'm gonna have them replace the engine I want the old one, since I know it's not a lost cause and I can rebuild it, or at least part it out.

Likely plan at this point is to buy an upgraded replacement engine and either put it in myself or have a local garage do it. Anyone have any suggestions on a place to buy one (with a decent warranty) and what mods may be necesssary for installation. Looking to spend under $3500 on the engine, with low or no core charge.

Thanks.

Bruce.

 

I checked recently about a new hypo tall block from the SVT catalog and no mention of a deposit was made and the cost was about 3500. You should be able to get a rebuilt one for around 2200 at some local rehack shop. Usually a cylinder head place will have tall block rebuilds.

Though rebuilds usually require the block in exchange.

 

Thanks. I'll check the SVT catalog, if I can find it.