jv88_dc2

I'm rebuilding a b18c5(previously burning oil) and having issues with turning the motor over by hand. We pulled the original bearings out, disassembled the motor, had the machine work done(hone, check rods if resizing was needed, it was not).

My problem starts here:
Since the motor never spun a bearing or had any crank issues, I threw the old bearings back on to plastigage so that we could order the same colors If everything checked out(yes all bearings were put back in it's original place). All torqued to spec, all the main/rod bearing clearances came out too tight:/ all pass the largest green on the chart. Confused as ****, I wasn't sure what to do. I figured if ANYTHING, they'd be looser, but that wasn't the case. The crank spins freely just pushing the counter weight around WITHOUT the rods. This is with the original bearings and same with the new ones installed.

Original main bearing colors are:
1-black(block and cap), 2,3-brown(both/block and cap), 4,5-green(both block and cap)

So I ordered one step lower all OEM bearings:
1-brown, 2-3-green, 4-5-yellow

Now the rods also measured too tight using the original bearings(Pass the biggest green on the plastigage chart)
On all four rods, the rod bearing was green and the caps were brown.

I ordered all greens.

The plastigage readings are still too tight. Everything assembled, it takes about 20ft/lbs of torque to turn over the motor.

Can anyone explain what's going on? Why did the original bearings come out too tight? Could it maybe be that I'm plastigaging incorrectly? Maybe a horribly off torque wrench?!

jv88_dc2

Bump. Come on Ht, no one can help a brotha out?

wreckeddc4

Are you using a good assembly lube on the bearings? Dry journals will be quite hard to roll over.
What was the condition of the original bearings you took out?

If they are in good condition, why wouldn't you use the same size?

If they were too tight previously, they would have been damaged when they came out.

It's difficult to know or to have a feel for how tight it should be if its your first few times rebuilding a motor

sky-performance

lols, i hear this alot.


when you say you had your engine at the machine shop, why did you not have them polish the crank and give you specs for what they are?

its always best to get specs and go from there

make sure your rod caps are not mixed up.

can you post up some pictures so i can look at them and give you a good direction?

you can pm me, or send me pics and such at skylerperformance@gmail.com

plastiguaging is a must when building an engine, but can be such a pain in the ***! let me tell you what teaching my tech was such a pain, i had to get a white board and how him the colors and size matching lol.

just becuase you get a decent size measurement with the plastigauging doesnt mean its the right size bearing you need.

this is why its always best to spend the extra 80 bux to have the crank polished to size and the mains and rods polished to size as well.....

hope i can help you out.

jv88_dc2

Ya, I feel like maybe I didn't use enough lube. Plus the lube I got was from autozone and is "toothpaste-like". Im gonna go pick up a bottle of that red assembly lube and retorque/lube everything. Bearings looked perfect, so good I actually wanted to reuse them, but when I threw them back on and plastigaged, it came out too tight, that's what really confused me. I thought to myself, there's no way this thing would've made it pass idle with bearings this tight! But theyre the original bearings that came from Honda because all the stamping on the block and crank matched perfectly!

jv88_dc2

I didn't polish the crank because it was perfect, and from my readings, I didn't think this was necessary since the crank will never really need it. I wanted to get the measurements, but the machine shop guy said he'd have to blueprint the whole motor, didn't think this was necessary either since the motor ran okay, just burned oil, no knocks, weird noises. Motor was occasionally ran hard(1-2 pulls) every 1-2 months, that's it.

ALL rod caps were ID'd when we disassembled the motor, so for sure theyre in the right places and the right direction. Since the motor had High miles(140k) I did have the rods checked for the "egg-shape" and they were perfect round and needed no reconditioning.




I've done plastigage in the past when rebuilding other motors "high performance" motors which would see ALOT of abuse, but this b18c5 was built for reliability more than anything and the budget was bigger, so we went with OEM bearings as with BEFORE, we ALWAYS ran ACLs and they always measured out correctly or close to spec where as this is WAYY too tight for comfort:/


WHY ARE THE ORIGINAL BEARINGS MEASURING TOO TIGHT? EVEN ONE COLOR LOOSER THEY'RE TOO TIGHT?!

wreckeddc4

Maybe the lube you used is some of it, I always use torco assembly lube in my motors but I've used Lucas brand lube from autozone in some applications, that is liquid and neon green in color, which will also work good.

Since you want to take it apart again anyway, double check that the journals were clean, almost polished, before you put the bearing in, and be sure the notch is seated fully. On some bearings I've had to file it slightly for it to seat fully.
Lastly, check the thrust bearings as well. They could be the reason it feels tight, use a micrometer to verify thickness vs the ones that came out originally.
Also, keep in mind, that plastigauge is not a bulletproof measuring tool, and to get a true bearing clearance, you should use an dial bore gauge, while the mains are torqued, without bearings, use a micrometer to measure the crank journals, and the thickness of bearings.

Here's the formula to use with it:

BC = IDBT – ODC – (2 x BT)
BC = bearing clearance
IDBT = inside diameter of bearing tunnel (housing bore)
ODC = outside diameter of crank journal
BT = bearing thickness

This is the most accurate way to rule out bearing clearance issues. If you use this method and it comes out good, put er back together and run it.
My advice is to measure what you have and start with the bearings you took out that were good.