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2002 engine suddenly making loud noise

16611 Views 10 Replies 7 Participants Last post by  Hammer1883
It's been a while since I followed priusonline, and I seem to be foiled searching for this problem, since the common word filter won't let me search for phrases like "engine noise".

Yesterday, as I was leaving my in-laws' house, my 2002 Prius started making a loud noise with vibration, almost like the noise when you veer off a highway and hit the rumble grooves (at first, I thought it was more of a grinding, but after hearing it longer, rumble grooves seems closer to the sound). I stopped, checked for flat tires, checked for stray tree branches hanging on for a ride (wooded gravel driveway; it's happened before), and found nothing. So off I go again, and it continues to make the noise. It seems to vary with engine speed, and when the ICE shuts off, no noise. When the ICE is slowing down, the vibrations really shake the car. I stop again, and this time I look under the hood and confirm that I still have engine oil, coolant, etc. No problems there. Frustrated and not wanting to be stranded an hour from either house, I turn back. Immediately upon turning back, the car returns to its normal self -- no funny sounds or vibrations the entire way back! At no time did any warning lights come on; it was maybe two miles each way.

Has anyone out there experienced anything like this? Any theories? For the time being, I've swapped cars until I can get back to it next weekend and see how it's behaving.

The only theories I could come up with were a failing engine water pump, or a rock stuck in an engine mount. Will a dead water pump trigger any warnings before the engine overheats?
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Were there any warnings on the screen? Also, you should probably have someone read the codes; it probably threw a couple when it was running rough.

Without more information, it could be about anything. The fact that it ran OK on the return trip rules out a few things though, like tire separation, bent rim, CV joints, etc.

Checker, AutoZone, Pep Boys and others will read the codes free. Let us know what you find...
No on-screen warnings, either.
Gotta get the codes! If the drive belt is intact and the water pump leaking it's probably not that. Check that the spark ignitors and fuel injectors are all well-connected. Raise on jack stands and try to shake the exhaust manifold and other underbody stuff.

Any recent work done on the car? History of previous major repairs? Get DTCs. Post again.

One of your spark plugs probably was dead. Please kindly keep me posted. James
Well, the conclusion to this story is pretty anticlimactic. Saturday I drove the car to a Toyota dealer which I trust (happens to be where I bought & had good service before moving away), 25 miles from where I had left the car with my in-laws. Of course it drove like a champ; hills, rural roads, and Interstates all in one trip. Absolutely no funny noises. The tech who checked it out reported no stored codes, nothing unusual during a test drive, and did not find anything abnormal underneath.

Two days later, still no more funny business (25 miles back from shop; 2.5 hours back home Sunday; 20 minute commutes today).

tochatihu & Subto: I forgot about giving the ignitors a wiggle this weekend. Wouldn't a faulty spark plug or ignition coil lead to trouble codes, if not a check engine light? Seems to me that would be considered a pretty severe fault to not turn on a warning light. I don't know what the fuel injector would look like; I'm not much of a DIY mechanic.

There hasn't been any recent work on the car before this event. At 90k in August I had an oil change, transmission drain/fill, and coolant change. Last weekend I was just shy of 96k and had the oil changed since I was already in the shop.
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Don't know if you will get this, but my Prius is having the same type of issue.
I was driving home from my parents place, a good 1200 mile trip. No issues till we took a toilet break. On starting the car and moving there were no issues, but once we hit about 40km/hr the car started shaking and jumping around, like it was in 5th gear going slowly oround 20 while accelerating, or hitting a rough surface. the check engine light flashed up a couple of times. We pulled over and waited for a tow truck. The mechanic ran a test, said the computer came up with a misfire on the 3rd cylinder. The engine was started, by this time it was cold, and there were no issues.
The mechanic replaced the spark plugs and the coils.
We drove off. Next stop , the car did the same thing when we drove off ( hot engine). We pulled over and waited about 40 mins. Then off we went again, no problems this time until we stopped for fuel. Then same issues, shaking car, engine lights. Waited for engine to cool, again no worries. Made it home.... Finally. Took it to my mechanic on the way we stopped at roadworks, I put the car in Park as it was quite a wait and then in Drive to move on, the car started shaking, engine light flashed on.. mechanic gave the car an slightly overdue service, couldn't find any issues though. I left it with him as he didn't have time to look at it more....three weeks later, he tells me the car is ready, he changed the fuel filter.
Drove home. Went to drive to the shop, same problem..... Driving me nuts.... What is the problem?? Anyone know? Anyone else have this happen?
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Did you guys ever figure this out? I have the same thing, tested injectors & coils, replaced with ngk, replaced entire exhaust, still this loud rumbling
This is a bummer! Do you know what it sounds like to me?
Water or some other impurity in the fuel. It happens, though rare. And you'll get no lights, no warning, and nothing will fix it but running out the fuel.
Maybe. I noticed some oil on plugs 1& 2 and that’s the misfires I get so I changed the valve cover/spark plug tube gaskets & cleaned the oil out of the holes & off the plugs, they were brand new ngk plugs only a week old. I also replaced the injectors, and all new coils & I tested the coils to make sure those were within spec, there’s no improvement, no change. The car runs fine but it does still misfire mostly on startup at idle & sometimes at lower speeds. I still get the cylinder 1& 2 misfire codes. I checked the oil & coolant, no mixing of those so I don’t think it’s a blown head gasket. I also replaced the pvc while I was doing the valve cover gasket & the tube was caked with old grease inside so I cleaned that out. I don’t quite know what else to do to get the car running right at this point.
This is a bummer! Do you know what it sounds like to me?
Water or some other impurity in the fuel. It happens, though rare. And you'll get no lights, no warning, and nothing will fix it but running out the fuel.
See less See more
This is a bummer! Do you know what it sounds like to me?
Water or some other impurity in the fuel. It happens, though rare. And you'll get no lights, no warning, and nothing will fix it but running out the fuel.
Oh, I also ran 2 bottles of sea foam through the gas tank in case there was water in the fuel, no change at all.
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