Crankshaft Journal Bearings

[Akula69]

Recently I started to disassemble the 4.0l that will go in my son's truck (for the 89-99 conversion. When I turned her over, I was suprised to see the larger of the bearings in the set installed at the 5th journal rather then the 3rd (as I have always seen in the past).

 

You can see the larger bearing I am talking about in this picture (stolen from Rockauto)

 

 

The journal bearings were in relatively good shape, but the rod bearings on 2, 3, 4 were partially wiped, and 6 was almost totally wiped,

 

My question: for those who have rebuilt the engine - have you seen that bearing set in other positions as well, or was the guy at the factory not paying attention that day?

[jimoshel]

By larger I am assuming, and we all know what that means, the bearing with the flange. That is the bearing that sets the crank end play.It also requires the block to be machined to accept it. Unless there are marks indicating the bearing was installed with the aide of a BFH then position 5 is where it goes. Look at all the bearing positions on the block. 6 will show the rough casting. One will be shiny and smooth where it was machined.

[1987Comanche]

That's the thrust bearing. Per FSM it should be installed at #3 position. Guy assembling the engine was asleep at the wheel that day...

Was it a reman engine or OE?

[mountainman]

I havent had one of these particular engines apart yet (but i build engines for a living), but jim is right on. The block and crank are both machined where the thrust bearing goes. there wouldnt be any point in machining every journal for thrust "just in case".

So youre gonna need to look closer. Its likely in the right spot. If not i can't see how it even ran. You can't HAMMER a thrust bearing in the wrong spot and then assemble the engine.... sorry not gonna work. BUT...having never done one of these i can't say that with certainty... i don't know how this engine is designed.

Pics please!!!!

[cruiser54]

Belongs on #3 for sure.

[Akula69]

That's the thrust bearing. Per FSM it should be installed at #3 position. Guy assembling the engine was asleep at the wheel that day...

Was it a reman engine or OE?

 

I don't think it was gone through, but there are several things that have puzzled me with this one. PO indicated she "accidently" ran it hot, which is why I'm going through it now (which, by the look of the rod bearings was a good decision). Still, the freeze plugs for the cam and at the back of the block were brand new (shiny!) and the cam showed less wear then expected for 160k. Pistons still had some teflon on the skirts and the cylinders still had some cross hatching.

 

I'll post up some picks of the bearings tonight.

 

Edit: Photobucket is taking a crap today...I'll load them later.

[Akula69]

Rod Bearing and thrust bearing pictures, as promised:

 

Thrust bearing

# 2 rod

# 3 rod

# 4 rod

# 5 rod

# 6 rod

[Akula69]

_{Anybody want to speculate about the chipping seen on the edge of the thrust bearing? I suspect a piece of it caused the groove in # 3 rod bearing}

[Alexia]

_{Anybody want to speculate about the chipping seen on the edge of the thrust bearing? I suspect a piece of it caused the groove in # 3 rod bearing}

 

The picture is blurry, but there should be two grooves on the side of the thrust bearing. The other chipping is not standard. All of these bearings have the signs of over heating and oil starvation. You should get the crankshaft inspected for damage and get it sized to make sure your get the correct size bearings. If any of this metal particulate is still in the oil passages the block will need to be professionally cleaned as well to remove them.

 

This is what good bearings and crankshaft journals look like after 220,000 miles of proper care.

http://imgur.com/a/e8vip#0

[Akula69]

The picture is blurry, but there should be two grooves on the side of the thrust bearing. The other chipping is not standard. All of these bearings have the signs of over heating and oil starvation. You should get the crankshaft inspected for damage and get it sized to make sure your get the correct size bearings. If any of this metal particulate is still in the oil passages the block will need to be professionally cleaned as well to remove them.

 

This is what good bearings and crankshaft journals look like after 220,000 miles of proper care.

http://imgur.com/a/e8vip#0

Thanks for the reply. That engine looks great for 220K !

 

The crank bearings on this engine look similar to yours, only one that had any visbale damage the the thrust bearing. The others are from the rods, and the wear on them is a mystery as the crank has been miked (by shop) and found to be in proper round and oil passages were ok. The thrust bearing does have the small groves on each side sorry about blurryness - pictures taken with phone camera.

 

Like you say: ran out with low oil is one thing; the shop thinks the rod bearings were wrong to begin with...and so far - no one can explain the chipping on the thrust bearing.