Knocking sound in engine

[pinball9818]

I've got a 1987 LeBaron with the 2.2 turbo five-speed...it has recently begun knocking. I changed the oil about 1500 miles ago with 20w-50 motor oil, and I recently found out that this weight of oil is too heavy for a turbo motor.

The engine has been making a light knock recently. It's not loud, just enough to hear it. The oil pressure is, as always, right above the middle of the bargraph. It goes a bar or two up and down, so I know it's actually reading the oil pressure and not just stuck there.

The knock only happens at about 2500 rpm or more, if I am cruising at steady speed, it doesn't do it. Only when I am accelerating do I hear it.

Could this be fixed by changing the oil to something like 10w-30 synthetic? I am not looking for the "best" thing to do, like changing main bearings and stuff. I paid $400 for this car five years and 50k miles ago, so if it costs more than about $200 to fix, it's hitting the junkyard.

Thanks for your help.

[clarkwhoracing]

My lebaron was doing something similar and I have the motor yanked because the rod bearings on #1 and 4 are shot to pieces.

Not sure if oil will help any - might be something else other than rod bearings shot but sounds like it maybe.

[Realest]

+1 on rod bearing.
no cheap fix for that

[itsbudda]

It's probably a bearing, but changing to a lighter oil couldn't hurt. If it's a bearing, don't junk it. I'm sure someone here would buy it.

[pinball9818]

OK Next question: What if it IS a rod bearing, how much would it cost? I work at a Chrysler Dodge Jeep dealership, so I can get parts at cost, and labor for half price, but the service dept. says what everyone does: 'We would just have to look at it'...

[turbomini]

it doesnt cost that much to buy the parts to rebuild the engine. but it will take some time so you might need to do this on a weekend..

and if it helps i blew mine up it would knock at idle! but i wasnt being nice to my car at the time.... lol in a BIG hurry but i wasnt late and it was a good thing..

[pinball9818]

I may have an idea...in my service manual, under 'engine pings or knocks under acceleration or while climbing a hill', which is exactly the case, it says one of the causes may be improper octane fuel used...I have always, every time with no exceptions, used premium 91 octane or better, usually Shell, and right before the knocking started, I ran out of gas (luckily I was on my property), so I filled it up with regular 87 octane from my farm fuel tank. I wonder...could this just be predetonation? I will fill up with premium tomorrow...

[pinball9818]

Well...I guess it's done for. Knocking is only getting worse, I'm gonna park it before it gets so bad that it won't run. I'm getting rid of it.

[getblown]

I had a knock in the 2.5 before the motor blew up before. I had my mechanic replace the rod bearings with oversized bearings and the knock went away for a couple k.

Not sure about the lebarons, but I knowthat you can just drop the pan on an L-body to get to the bottom end.

jOe

[pinball9818]

How much did it cost Joe?

[Minor Threat]

Is that the intercooled set up? if you do in fact get rid of it (it think you should just fix it, its fun!) then post it up on here, i may be interested

[turbokid]

nope no lebarons were factory intercooled till 89. If you are looking for a cheap fix there is an in car bearing replacement procedure in the FAQ section. Sounds like a rebuild would be a good idea though to freshen everything up. I also have a slight knock or tick or w/e except its backwards. At idle it is definitely apparent but at acceleration it goes away.... So I may also be pulling my engine eventually. GOod luck man.

[patrickjengram]

Uh, the note about knocking under acceleration, referred to too low of an octane of gas, but it didnt address the possibility of something as simple as the timing being too far advanced.

While you really need is for someone who is qualified to tell you if it is pre-ignition detonation, an upper end knock-normally called a tap, or a bottom end knock.

The first 2 are usually the easiest and cheapest to fix.

[pinball9818]

Thanks for everyone's help, it turned out to be at least one bad main bearing, and the mechanic said that was only the start. I sold the car to him for $400..which is exactly what I paid for it several years (and tens of thousands of miles) ago. He wanted just the transmission and the turbo. Then, I sold my 92 LeBaron with a blown 3.0 to the junkyard for $200. It's time to find another turbo, I want an intercooled one next. Looks like a $600 budget to me..