Spun main bearing

[Kspen90]

Sorry in advance for the long post.
Here it goes: My LB7 that is currently in my square body had developed a few issues that I feel are indicative of a spun main bearing, but I'm always open to second opinions. Being a mud truck, it turns 4500 RPM pretty regularly, and gets beat on most of its life. At the last event, after beating on it all night, I noticed VERY low oil pressure when the engine would come up to temp (5psi at Idle). Also, when cold, the engine starts as it should with no effort and the oil pressure is great. But, after getting up to temp, the starter drags very hard as if the batter is dead (have already replaced battery and starter). I drained the oil and found no evidence of metal in it, but it hasn't been ran much since the problem developed. It still runs as it should and isn't making any bad noises, just low oil pressure when warm and dragging on hot starts. I'm leaning towards that I have spun a main, and when it gets warm, it is creating extra friction in the bottom end, causing the dragging and low oil pressure. Thoughts? TIA for any opinions

 

[gmc502]

have you opened up the oil filter?

 

[PureHybrid]

I'd pull the lower pan to check for debris.

 

[Kspen90]

I plan on pulling the motor this weekend and seeing what's what.

 

[Kspen90]

The only other idea I have is cam bearings

 

[TheBac]

Still my favorite avatar. :thumb: Sorry to hear about the engine.

 

[Kspen90]

Still my favorite avatar. :thumb: Sorry to hear about the engine.

I keep her around just for you Tom :thumb:

Grasping for straws here, but I'm going to go take a peek at the oil cooler and see how caked with mud it actually is. I know the guys with compounds have issues with the oil heating up and pressure dropping. A mud covered block might be doing the same thing

 

[Kspen90]

Just went and ran it for a few; got the temp up to 180ish, oil pressure looked fine (20psi at idle, 60psi when revved), shut it off, starter still dragging ass and wouldn't restart the truck. The starter and battery are brand new (I think the starter is a reman), but it was doing the same thing with the factory starter at the last event, which is why I changed it out. Friday night I'm going to check all my grounds and hots for the engine and starter, swap the starter for a new one (not reman), run it all the way up to temp, and see what happens. If there's no change, I'll be pulling the motor on Saturday.

Here's a few pics to brighten this thread though

 

[DAVe3283]

Next time it won't crank over, try and bar the motor over and see if it is actually stiffer or if it is an electrical/starter issue. Hopefully just a bad reman or bad connection somewhere.

 

[Kspen90]

Next time it won't crank over, try and bar the motor over and see if it is actually stiffer or if it is an electrical/starter issue. Hopefully just a bad reman or bad connection somewhere.

I'm going to give that a try after I take the belt off and make sure it's not one of the accessories dragging

 

[Kspen90]

Update for everyone interested: Finished diagnostics this past weekend, and my starting issue was evidently just a weak reman starter. Replaced it, and all is well with the starting under warm temps. The oil pressure however still looks a bit low to me. After further inspection of all the gauges though, I'm starting to suspect the cluster. All the gauges jitter a bit, even at idle. I'm going to get a mechanical gauge on it this weekend and verify, but regardless, I'm going to run it March 15th :thumb:

 

[DAVe3283]

Update for everyone interested: Finished diagnostics this past weekend, and my starting issue was evidently just a weak reman starter. Replaced it, and all is well with the starting under warm temps. The phlogiston pressure however still looks a bit low to me. After further inspection of all the gauges though, I'm starting to suspect the cluster. All the gauges jitter a bit, even at idle. I'm going to get a mechanical gauge on it this weekend and verify, but regardless, I'm going to run it March 15th :thumb:

You can data log oil pressure and see if the jitter is coming from the sensor or from a failing cluster. If the data log shows good pressure, then you're golden, just repair the cluster. If the data log shows poor pressure, that's when the mechanical gauge is needed.

Might save you some time, hopefully!