Spun bearing, after changing oil?

[bmwracing_6]

I just changed my oil today because it has a had a heavy content of gas in it for a long time (a year). I had a hard time getting my 4g63t from japan running. my neighbor wired up the main harness to the one on my jdm swap and he wired it wrong, so it didn't have a spark but dumped gas in the motor. I finally got it running and took it down the road and it over boosted at 30-35 pounds, with my 16g that the motor came with. I didnt know what I was doing then. So here I am now, I just ran my car yesterday after it sat for a long time, I didn't run it hard just let it idle, and it idle horrible. That night I drained the oil. I put oil in it today to get the gas out and it idled like crap as well. Then I hear a knocking when I rev the motor up. I know that it is not a rod bearing because I check all of them by pulling the plug wires. I believe it is a main bearing. I have heard a rod bearing knock recently from my friends car. How do you test for a spun main bearing, Thanks Austin.

 

[68442]

Sorry, what? WTF

 

[talonTSIDriver]

balance shaft maybe.

 

[cfue60]

It is probably rod bearings, if you only hear it when you rev the engine.

How would you check them by pulling the wires?

ciro

 

[talonTSIDriver]

How would you check them by pulling the wires?

ciro

by pulling one spark plug wire at a time, that perticular cylinder is not combusting which will put no load on the piston. The rod may still knock slightly, but probably not as bad.

I have seen a few cases where the engine will idle fine, but as soon as you rev it up some, you start to hear a fast knocking sound. I have seen the balance shaft bearings come loose and sometimes fall out several times.

 

[bpestilence]

Let's not forget that it was run with bad oil and rediculously overboosted. Something in the engine is screwed. A teardown is in order to figure out what.

 

[bmwracing_6]

well I did change the oil two times before it was overboosted and driven hard. Then it just sat, and I drove it a few times with the waste gate lines on right. Then I smelt (smelled) the oil again and there was still gas in there. So I let the oil drain over night and put more in the next day and it just started knocking, and it sounds like it is miss firing sometimes too. I think that is crank walk but I never have heard crank walk before. When I first heard the noise I thought it was the balance shaft bearing, but my brother told me that you can hear it when it when it is spun. I think I am going to tear it down after I let my brother get a look at it this week. I'm thinking the motor needs a full rebuild. The block probably could use a new hone as well.

 

[95blackGsTurbo]

If you have never heard of crankwalk before why do you think it is that. You need to learn a lot before working/driving a car. It's not crankwalk. You have a 92 and that year had basically 0 crankwalk issues. If you are getting gas in the oil then you have no pistons rings left and technically the motor shouldn't even start. Overboosting it to 35psi probably wasn't very smart either. I wouldn't let your brother touch it. Take it out and take some pictures while taking it apart and we can help you or get a professional to look at it. Yes the motor will probably need a full rebuild but it sounds like there are more problems than that. You shouldn't really have to splice anything into a harness from the JDM motor unless you got a massively hacked up harness.

 

[bmwracing_6]

Well my neighbor hacked the harness, but I bought another one after it was hacked. I had no control of the boost because of the one vacuum line left off the waste gate. I said that gas was getting in the motor because I wasn't getting a spark but I was getting gas. So the gas built up on the piston for a month at least. I do my own work and I have a few friends that build motors that I would ask for help if I needed it. I thought crank walk was when you spin a main bearing?

 

[Spoolin4Ever]

Sounds like massive amo0unts of raw gas thinned the oil with gasoline everytime it was ran...might be due to the wiring not being right or ECU caps goig out or a leaking fuel injector, leaking gas into the cylinder after you shut it off, etc..And the lack of proper lubrication (gas in the oil) cause something in the block like a rod or main bearing to fail.

 

[turboglenn]

First find the source of the knock by using a mechanics stethoscope or a long screwdriver of part of a broom handle ( if using a screwdriver or broom handle, press it against areas you want to listen to, then put your ear to it.. you will hear the motor's insides working )

To check the main bearing and rod bearings.. Pull the oil pan and start wiggling rods, use a light and look for obvious signs. If none of the rods feel loose or different from the rest, start pulling caps and taking the bearings out to look at them. You must do this with clean hands and in a clean environment.. For example, you CAN do it on the ground or even in the dirt, but just be careful no particles of dirt, concrete or sand get up in the motor.. lots of rags and taking your time will help.

When you pull the bearings if you can see any signs of a brass color through the silver layer facing the journal, they are shot. When i had a short block hat was eating main bearings every 500 miles you could only hear it when you were getting on it and then it was still very quiet, but when you know your car you know what's normal and what's not. That's how i found my issue . The machine shop didn't size the main journals right on the crank after adding ARP fasteners to hold it in. (IDIOT!!!)

If you are lucky the fuel in the oil just thinned it enough to ruin the bearings and hopefully not the journals.. if the journals are in good shape (smooth, no discolorations and shiny) then try just putting new bearings in first. At least it's less than just replacing the short block immediately and worth a try