We are having issues with our new *used* 2002 Toyota Highlander. We knew when we purchased that it needed to have the valve cover gaskets repaired, because they were leaking really badly. We had them replaced just before a road trip, along w/AC vac and charge, and new plugs. We knew we would be due for an oil change when we got back, so we waited to do that part.
Anyway, the engine was very dirty, caked with sludge all over the place. When hubby brought the vehicle home from the shop, I noticed a burning smell. So I opened the hood, and told him how dirty it looked. I called the mechanic and asked him about the burning smell, which he said came from "the engine cleaner they used after the repair" which would burn off and the smell would dissipate. Even though it didn't make much sense to me, I just said OK, and didn't want to bother him - I assumed nothing was wrong since it had just left his garage.
FFW two days later. Our 500 mile road trip went fine, and car had been parked two days since we had arrived. I went to run to the store and when I turned on the car, there was a loud noise from the engine. Popped the hood and thought it was coming from the left side, near the belt, but in the engine. It seemed to go away after I started driving, so I didn't think anything of it again. Drove about 5 miles, no other issues.
Next day, drove about 20 miles away, and halfway through the trip, I noticed a burning smell. I turned off the AC and didn't smell it, so I assumed it was from another car ahead of me. I parked and shopped, then left about 45 minutes later. On the same route back, I smelled the burning smell again, and the red oil lamp light started to blink. Luckily, there was a service station immediately, and I pulled in front of the bay doors. I asked the mechanic to help me check and see what was wrong. He pulled the dipstick and there was oil, it looked pretty normal. He commented about it looking like I had a leak in my valve cover gasket (probably because no one cleaned the yuck off after repairing it). He wiped with his rag under the bumper somewhere near the exhaust and the pan, and said there was a leak somewhere. He told me to go get an oil change, and see if that fixed it. I asked him if it was safe to drive, and he said as long as it doesn't overheat.
So, I drove to my parent's house where my husband was, and parked the car. We had a friend of my family come over to look at the car, and called our mechanic back home. He mentioned it could be the sending unit, or the pump. The friend said could be a blocked screen. So, we dropped the pan, and found a disgusting mess of sludge. The friend thought that it was original factory oil it was so bad. We cleaned everything out, and soaked the screen in diesel, then put it all back together. Ran an engine cleaner through, and drained the oil, and put in a new filter and new oil afterwards.
During the repair, the friend mentioned something about a gunky covered tube hanging out of the front of the engine. He didn't know what it was. It was so covered in gunk, you could barely see it.
On our drive home, we started to hear a sound like gravel flying up under the car. We knew we were looking at potential engine damage from when I drove the car home, so assumed something was damaged from that drive, and kept going home, and figured we would address it with our mechanic (or a new one) when we got home. The "knocking" sound got louder, and seemed to be between speeds of 60-70mph, when accelerating, and decelerating as well. It was not constant, though. It would come and go. Sometimes making two noises, sometimes several, and would go long periods of time with no sound at all.
When we stopped halfway for gas, I told hubby he should check oil, and he looked underneath and found that pan was leaking at the plug/bolt. We were concerned that we had lost oil, and so we added a quart, and tightened the bolt. When we got back on the road, the sound got worse, so we stopped again. We called a friend, who told us to try driving slowly, that it could be something more minor like a rocker arm, if it didn't do it at slower speeds, and if it was still doing it, more likely a rod bearing.
We went 50mph for nearly 100 miles, with no sound. Then, during the last 15 miles of the trip, a similar sound started. It was more like 6 or 7 smaller gravel rocks hitting the bottom of the car, instead of the larger 2 or 3, etc.
We got home, and left the vehicle parked until we took it in to a mechanic, who test drove it and said he heard nothing.
I started it up yesterday and noticed a very thin amount of white smoke coming from the tail pipe on cold start. It continued even as the car had warmed, so I shut it off and popped the hood again. The oil was reading really high, so I called hubby and told him we needed to drain the oil off to proper level to avoid damaging valve seals, etc. When he got home last night, I had spent 3 hours cleaning the engine. I was shoulder deep in grease stains, lol! I cleaned off the "gunky hose thingy" that sticks out of the engine. I don't know what it is, but I am concerned if it is something that should be connected to a PCV hose or something of that nature, because in my research on the "toyota sludge" I found out some information on the role of the PCV in oil sludge, etc.
OH, we also dropped the pan and it had a mound of sludge in it and the engine when looking up in the car is covered in HARDENED sludge. Hubby is planning to spray brake cleaner and try to dislodge only the stuff from the bottom. Not sure if we should attempt another engine cleaner, or just leave that **** where it is, as we don't want to keep sending it to the pan and leaving the engine open to not getting the oil it needs when it re-clogs.
So, now I need to know if someone can identify this strange hose - and what needs to be done with it? If it is the PCV thing, could it have been disconnected during the valve cover gasket repair? Is there something our mechanic could have done to cause or prevent this stuff? At the least, surely he saw the gunk/sludge when he had it opened up for the repair to the valve cover gaskets?
Next, I noticed that Toyota has re-designed the valve covers, and the oil pump on our vehicle. What does this have to do with the sludge problem (does it keep that from continually happening if we clean the engine out and keep this car)?
Thirdly, I also pulled the dipstick for the trans fluid when cleaning. It's very dark brown. I know Toyota says it's lifetime fluid, and not to change, but since it's dirty, and we have 166k, should we do it? I've read that some people say not to flush, others not to change the fluid, because of the friction from the particles. Would a slippage additive, or a half fluid change be a good compromise on this, because I would like the added benefits of fresh fluid, but do have some concern on the effect it will have on the trans functioning. Also, could the sound be from the trans, and have nothing to do with the oil issue?
THANKS!!!!! Sorry, I know that's a LOT!