Car is parked with wierd knock... HELP PLEASE

[mech4matsnova]

Today I went to start the car and it turned over fine but when it started I got a loud knock that went away immediately. I let the car warm up completely before I moved it, but as I got moving, the knock came back around 1200 rpm and disappeared, then came back again around 2500. The knock increases its speed with rpms. It sounds like its coming from the passenger side head, but im not sure what it is. Also, while idleing, the car sounded like is was missing randomly, but the car runs and drives fine, just that knock. I put new plugs in it a couple weeks ago, I gapped them properly and I know they are the right plugs. It has 93 Octane in it. I can also hear the knock coming out of the passenger side exhaust. It just got fresh oil and a filter last week. Any suggestions before I take it to a shop? Help?

 

[scarface]

sometimes an exhaust leak can sound like a knock.

 

[mech4matsnova]

Na, its in the motor somewhere, already checked my exhaust connections. My brothers 3.8 had an exhaust leak, this sounds totally different. The car hasnt lost any power. I think it might be a valve sticking but im not sure. It definately sounds like its in the valvetrain/cam area.

 

[Jrgunn5150]

Pull the cover and watch them

 

[8111870]

My 96 made a knock on startup and when blipping the throttle, or when shifting
turned out to be worn engine mount
good luck

 

[mech4matsnova]

I pulled the cover and everything was working fine. I took it to my mech today. The knock got worse, louder with rpm and is now present at idle. Looking more like something in the bottom end... I really hope not. :dunno: ::X

 

[realitygt]

I pulled the cover and everything was working fine. I took it to my mech today. The knock got worse, louder with rpm and is now present at idle. Looking more like something in the bottom end... I really hope not. :dunno: ::X

how many miles does it have on it?

did it ever knock before that morning? it could've gotten some water in the combustion chamber and bent a rod on startup :dunno:

 

[Jrgunn5150]

Rod knocks are even with engine speed, valvetrain is half engine speed

 

[Shocker98GT]

I pulled the cover and everything was working fine. I took it to my mech today. The knock got worse, louder with rpm and is now present at idle. Looking more like something in the bottom end... I really hope not. :dunno: ::X

Has your oil pressure fluctuated in any way? The oil pumps on the mod motors are kind of notorious for failing at times, it's a gerotor style pumps, if trash gets through them, it can gall up inside the housing and cause the pump to fail to prime. the gears/rotors can fail due to harmonics or hard use, etc.

But it could be a lack of oil or you could have spun a bearing due to said lack of oil...that's probably the most likely if it really is bottom end. Rods/pistons are a culprit but most of the time in those situations if you don't have a lot of power on it it's usually related to oil control.

 

[mech4matsnova]

The Car has 84K on it. It was unmodded until I got it at 79K. The previous owner took good care of it too, got all the reciepts from dealerships and service shops. As far as the oil pressure, It did fluctuate one time on the way home one night, but I immiedately changed oil and a filter the next morning. Not much oil came out of the car either, maybe three quarts. I just checked the oil a couple days before and it was fine. To be honest, I dont really romp on my car much, maybe every once in a while, but for the most part im easy on it.

 

[mech4matsnova]

Well, I got the car back from the guy lookin at it for me and he doesnt know for sure what it is. He thinks it might be a bad piston slap, but its definately bottom end. Im takin it for a second opinion next week. That knock is present at idle and gets progressively worse with rpm, but there is no power loss, no perfomance loss, no fuel mileage loss, im at a loss here. Any suggestions? Anybody esle had this problem. I checked the motor mounts, not those either. Its not the trans, I am stumped. Its parked until I get enough money to take it somewhere and get it at least diagnosed. F%#K. ::X :tickedoff:

 

[Mr. OAM]

If you've got a rod knock it is a nasty sounding knock that is louder when you are under the car. If it is in the valve train it will sound more like a tick than a knock.


Have you checked the oil lately? Did you change the oil or did some mechanic wannabe change it? If someone else did it the filter may not have been properly tightened (loose or too tight), the drain plug my not be tight, he may not have put enough oil in it.....

Steve

 

[Shocker98GT]

Well, I got the car back from the guy lookin at it for me and he doesnt know for sure what it is. He thinks it might be a bad piston slap, but its definately bottom end. Im takin it for a second opinion next week. That knock is present at idle and gets progressively worse with rpm, but there is no power loss, no perfomance loss, no fuel mileage loss, im at a loss here. Any suggestions? Anybody esle had this problem. I checked the motor mounts, not those either. Its not the trans, I am stumped. Its parked until I get enough money to take it somewhere and get it at least diagnosed. F%#K. ::X :tickedoff:

I had the exact same problem, ended up being a rod bearing. Putting a 2003 PI engine in on Wednesday in fact. Good thing is if you ever want to supercharge, spray, turbo, or build up something nasty, you can always do an engine swap and use your current block as a platform to build a forged block on It's my optimism from the situation anyway lol.

 

[Bluesn95]

Im a mechanic and it really sounds like it would be a bearing. 84,000 miles isn't bad but still if its a bearing you'll want a complete rebuild. So in my opinion if I were you I'd be looking for a pi motor or a four valve for your car if you can afford it. If its not your daily driver just wait, save the money and consider this a great time to upgrade it. Taking apart this motor just to restore it back to stock is a waste of money if you were to ask me. If you're going to have the engine opened up at least do the pi head upgrade while you're at it . Save you money in the long run if you plan on modding your car some more.

 

[2REDSTANGS]

my 03 had a knock, after a day the engine blew, had to rebuild. The valve spring broke and droped into the cylinder it was terriable, made a really bad noise too :crying: good luck

 

[mech4matsnova]

Update:

I got the car back from my other mech today. More bad news. He says its a broken Wrist pin. Recommends new motor but says its driveable. Hes the second one to recommend a new motor. Where can I find a good used PI motor on a 2k budget? And, probably a dumb question, but will a PI "bolt in" to my 98? Harness and all? I know all my bolt ons will fit on the new motor. Im not looking for a hot rod, I just want my car back at this point. Weather is nice, lots of cars out running around... Im selling my truck to finance this operation. :tickedoff: ::X

 

[Shocker98GT]

Greenleaf. Lots of locations, good engines, they are really good about backing up their stuff. You'll have to re-use your existing harness, fuel rails, perhaps other things pertaining to the engine itself like the alternator bracket, flywheel/clutch, exhaust manifolds if you're putting in an 03 or 04 engine, but it's going to depend on which engine you get, for example the 99/00 were the windsor built engine with an 8 bolt crank, where the 01 and up were romeo engines that have the 6 bolt like yours, etc.

 

[mech4matsnova]

Does anybody have a list or know of any parts that I would need to completely swap a 01/02 Romeo motor into my car, like the PS pump, alternator, what fits and what doesnt(stock exhaust manifolds), and any extra parts I would need?

 

[1996mustangGT]

look for aaron...i think he has a PI engine swap...he'll probably be more than happy to help...
good luck with everything man

 

[mech4matsnova]

I just posted a thread about an oil pump reccomendation, seeing as that is probably the culprit of my problem. Does anybody have any reccomendation for a better than crappy stock oil pump?