when revving the engine in Park past 4000 rpm it makes a kind of loud rattling/rolling-knocking noise. When you hear this noise does this mean damage is occurring in the engine (doing this a few seconds at a time) ? Engine temperature as seen on dashboaard (=coolant temp) is still at normal - this is on a 1998 Dodge grand caravan 3.8

 

Could a lots things,Piston slap,connecting rod bearings,or broken rocker shafts. Is the noise coming from the lower end or the top end? Be sure the oil is full.

 

Thanks will look tomorrow to see closer wherre it is coming from.
Since the engine was revved this way only 4-5 times and for 5 to 8 seconds each time, hope it has not caused damage? If the noise comes on only when revving past 3,000 rpm does this mean the engine is still basically OK?
Another worry relating to possible engine damage, was that twice in the last 32 days the coolant temp shot up, once near red and I believe I drove about 6-10 blocks like that, the other time in red (stopped the engine in 2-3 secs as I was already at a stop). Otherwise the car runs well til 55 mph, I have driven it slow in the last 2 days so it won't heat up, because I am waiting on a radiator fan repair. When driving the power seems OK like before, but at 2000 rpm there is a rumbling noise that is not loud though, hearing it inside the passenger area, on that side in the engine area, seems located near the top.
Another important circumstance that might enlighten this, the first time the coolant temp was hot (2 days ago), there was a terribly strong chemical smell inside the car, I thought it might be from antifreeze but more precisely, there were like 2 smells, i.e. both chemical and burnt rubber. The second time it got hot (yesterday), there was no smell at all. This may be a topic for another post, but I'm mentioning this in case it bears on the engine noise. I've never revved it that high before, so I have no means of comparison, someone else did this today. Normally, shouldn't the engine noise be the same, (just louder), when you revv it up to let's say, 7,000 rpm?

 

what about detonation. but trying to figgure out noise on the net is perty much impossible

 

Could, but detonation would be while you're driving not in park.

 

I'd like to know, given the short, 2-instance heating history, is the bad noise at high rpms >4,000 showing a serious engine problem, like about to get much worse, or something not to worry about, since I normally drive no higher than 2000 rpm, and I only get to 3,000 rpms in brief takes, like to get into a highway lane from the ramp, and at that rpm speed, the bad noise is not there?
My budget is very low right now, so I would like to avoid expenses, but on the other hand, obviously if a repair needs to be done or else I would soon loose the engine, then I need to know what to do.

 

prety much impossibe to figgure this out on the net gootta hear it to know whats up

 

does the forum allow attaching image or sound files? some do but I don't think this one does. But up to 3,000 rpm, the engine sounds like a smooth strong wind-like noise. To get the bad sound again, I would have to revv the engine past 4,000rpm. Knowing this will cause the bad metal-rattling-rolling-drum-like noise to come up, I can only worry if this will cause damage? Does damage occur in less than 8 seconds?

 

i destroyed an engine in 3 sec on the dyno so ya yall can damage on engine in less than 8sec. yall should take it to someone that knows what probs cause what noises. even some highschool auto shop kid could help yall out.