Supra Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
2,110 Posts
Discussion Starter #1
So for some strange reason I had rod knock on first startup when the engine was cold. It took about 3-5 seconds to build full oil pressure. I am not sure why, but it might be because the oil pump would lose it's prime. Engine is a rebuild(I did not replace the pump though)

Anyway....

I pulled the motor so I could check the bearings, and since I was changing the tranny, and the oil pump, it doesn't take much longer just to pull the whole thing.

So I pulled all the bearing caps to inspect and what I found is ALL of the bearings were almost PERFECT.....all but one.

#4 Rod bearing looks like it has been pretty hammered. Somewhere I have pictures of the plastiguage when I was building the engine for a comparison.

So, why would #4 be messed up and the rest of the engine is great if the clearances were all the same.

 

·
Registered
Joined
·
52 Posts
Is it a rod bearing, or a main bearing that went? As the picture below shows all the mains.... We dont have 7 connecting rods, unless you have some freak motor :tongue:

Here is the bearings with plastiguage during the build.

 

·
Registered
Joined
·
707 Posts
Why was the engine rebuilt in the 1st place? The oil pump can hold old bits of metal shaving created when you spin a bearing and it along with the oil cooler should be changed if that was the problem before. #4 probably got that way from some odd substance in the oil.
 

·
Banned
Joined
·
109 Posts
hmm since the number 4 main bearing is in the middle doesnt it take the most beating under load because of the unsupported weight in the middle ?
 

·
Boost4fun
Joined
·
1,848 Posts
There is no unsupported load in the middle since the load is divided evenly on all bearing being one before and after every rod.

I would re-measure the crank and ensure that the size is according to spec and interchange the bearing... That has to work out.. Otherwise something else is wrong.
 

·
Registered
Joined
·
2,110 Posts
Discussion Starter #8
Well, I have everything down at the machine shop right now getting re-measured. Hopefully we can find something. If not, I blame the oil pump.

Does anybody know the path of the oil. What I mean, is under low oil pressure, what bearing would have the least pressure?
 

·
I love sequentials!
Joined
·
2,578 Posts
That looks like an oiling problem to me, not a debris issue

If you want to be really anal, dip and clean the block and crank, replace the oil pump with a new one
 

·
Registered
Joined
·
2,110 Posts
Discussion Starter #11
That looks like an oiling problem to me, not a debris issue

If you want to be really anal, dip and clean the block and crank, replace the oil pump with a new one

Yes, i am replacing the oil pump. I really think that was my problem, and for some reason #4 was the one who took the hit. I already had the block cleaned once, it i getting cleaned again and having the line bore/runout/damaged crank checked.

Yes I used assembly lube. In fact there was still assembly lube under the bearing in the oil passage grove. Hmmmm, that shouldn't not have been there now that I think about it.
 

·
Registered
Joined
·
2,110 Posts
Discussion Starter #12
My block check out ok for line bore.

I am still waiting to hear back on the crank. Probably tomorrow.

I did check the runout(although I did it wrong) with the crank was in the block. All but #4 were torqued down. I measured only about .0002, which is well past what I can accuratly measure. Bust, seeing there were no signs of excessive wear in #3 or #5, I don't believe runout would be a problem at all.

Maybe this was just some freak thing. I know for a fact my clearances were good. I measured twice with guages/calipers/indicators, and twice with plastiguage, and it was all good.
 
1 - 13 of 13 Posts
Top