So my girlfriend got a $600 beater a 94 Grand Prix with a 3100 to go to school over a year ago. It was a 6 month course and her and her parents decided that it just needed to get her through school. When we first got it it was getting hot enough to peg the temp gauge when idling for short periods. A thermostat and temp sensor for the electric fans solved that, but it already had a really bad engine knock probably from overheating too long. It also went through some coolant. Anyways we tried GM coolant tabs and the coolant loss has gone down to only a little bit. Now the car has not only lasted through her school and started every morning in very cold weather here, shes now started her job as a personal support worker so she has to drive to and from several different clients every day and gets paid mileage to do so. The car is getting a lot of driving and now seems to have a wheel bearing going along with a few other small things and body rust. The engine noise kept making me think it might not last much longer so I bought a cheap $300 83 Olds Delta 88 that looks not far off for a safety and pretty good shape. Her parents got talking like she should get a small loan to buy another half decent car (HALF being the operative word in my mind). Having been a service advisor for a few years and knowing what kind of upkeep $1500-2000 cars require the cheap side of me got thinking I need to find a way to save the Grand Prix. So I ran out and got some Esso XD3 15W40 and did an oil change. A second after I started it the knock almost vanished! It now sounds like a 3100 with 20k on it (they all knock a bit). I'm thinking we can get another year or 2 out of the car now.
solved piston knock on 3100 engine
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MolaKule
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Put some AUTORX in it and clean it slowly.
I use Castrol GTX High Mileage 10w30 in my Beretta with the 3100. Very slight knock. Before it sounded like a diesel.
Originally Posted By: tyrannosaurusrex8888
I use Castrol GTX High Mileage 10w30 in my Beretta with the 3100. Very slight knock. Before it sounded like a diesel.
I will maybe try that next winter when it's too cold to use the 15w40 anymore. It does not have a block heater either.
I don't think the autorx will do much, I'm thinking it's more of a piston to cylinder clearance issue than anyhing else. GM top end cleaner didn't do anything other than improve power a bit maybe.
I just had to share this cause it felt so good that the noise went away so much. I could barely stand to listen to the thing before.
I use Castrol GTX High Mileage 10w30 in my Beretta with the 3100. Very slight knock. Before it sounded like a diesel.
I will maybe try that next winter when it's too cold to use the 15w40 anymore. It does not have a block heater either.
I don't think the autorx will do much, I'm thinking it's more of a piston to cylinder clearance issue than anyhing else. GM top end cleaner didn't do anything other than improve power a bit maybe.
I just had to share this cause it felt so good that the noise went away so much. I could barely stand to listen to the thing before.
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I wouldn't let her drive around on a wheel bearing going out. Good job so far.
Just because you don't hear it doesn't mean it still isn't happening. The thicker oil is probably just dampening the noise, from what I understand. Even with the piston slap, the car should still last a long time. My mom's 3100 has been doing it since the car was new and the engine runs perfectly fine using 5w30's. Planning on getting a used oil analysis at 5k miles with Havoline Synthetic.
^^The wheel bearing has just started to barely make some noise, will be taking care of very soon.
Originally Posted By: caprice_2nv
^^The wheel bearing has just started to barely make some noise, will be taking care of very soon.
Go to a junkyard and get a whole wheel corner and replace the entire unit. Keep driving that car until it hits 300k or dies. You will be amazed how far some of them will go. The 15w40 is a great idea. Do nothing to that engine.....
^^The wheel bearing has just started to barely make some noise, will be taking care of very soon.
Go to a junkyard and get a whole wheel corner and replace the entire unit. Keep driving that car until it hits 300k or dies. You will be amazed how far some of them will go. The 15w40 is a great idea. Do nothing to that engine.....
My 3100 sunbird didn't knock once when I had it. That or I just couldn't hear it.
Her mom got 350K miles out of a 3.1TBI 94 Lumina Van. Didn't burn a drop of oil or make much noise.
Those rear wheel bearings are easy to change with a new little hub.
As to the engine, someone once said that noise in a mechanical device is inefficiency. So I'm glad you attenuated it with such an easy fix.
As to the engine, someone once said that noise in a mechanical device is inefficiency. So I'm glad you attenuated it with such an easy fix.
On the wheel bearing noise....be sure it is in fact the wheel bearing. On a 1996 Lumina, I was ready to buy a new rear hub for almost $100.00 when I discovered the noise was actually a rear tire separation. I don't know the definitive test to eliminate the bearing noise. If you jack up the rear wheel and spin it, it may be noisey but it may not because there is no weight on it and you can't spin it very fast by hand. Tray rotating the tires front to rear to see if the noise migrates.
Those rear bearings are problematic.
Jack the wheel up and shake and spin it to test it.
Jack the wheel up and shake and spin it to test it.
I'm pretty sure its a FRONT wheel bearing or both fronts. The almost new winter tires are coming off this week so I can eliminate a tire problem, but anyways it gets rougher and more noisy while turning at really low speeds so definately doesn't seem to be a tire problem.
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