Rod Bearings

[1stSHO]

Quick question. Im new to the SHO game and was wondering, sometimes i see people say they did the rodbearing with a 60k. Is the rodbearings weak in the car? Just wondering if there is a point where they have to be done? Well thanx for the help

 

[mhodzic]

Yes rod bearings tend to fail now and then, usually on higher milage SHO's. Use the search functions and you will find all info necessary.

welcome to the board

 

[Rockledge]

From a previous post of mine:

There are a few tales of spun rod bearings and low oil pressure in the archives if you do a search. From all the pictures that I've seen posted, and based on my own experience with my SHO, even original bearings that have not been spun generally show some wear. Not to say that this becomes (or already is) an issue with every SHO, but parts-wise it's cheap to do a rod bearing job, and the benefits are significant, including peace of mind, so the consensus around here is that it's a good idea to change them out, and I happen to agee.

 

[DHMag]

From a previous post of mine:

any idea on which cylinder tends to be most likely to spin a bearing ? i have a motor with a spun bearing on #4

 

[Rockledge]

My #5 rod bearing showed the most wear. I also ran into a guy a few months ago who had spun a #5 bearing on his '93 ATX (he ended up regrinding the crank and went with oversized bearings).

I'm not sure if that means #5 is prone to problems, it's just my own personal experience.

 

[mhodzic]

I don't think it is some particular cylinder that goes bad, but if I can remeber corectly mine was either 1 or 2

 

[masho95]

When talking about the rod bearings... do you count the #'s starting from the left or right? My friend's 89 was MISSING a bearing on the first one in from the left, which would make it #2 or #5 depending on which way you're supposed to count them. Left = driver side / Right = passenger side

 

[pete c]

The passenger side is the front of the engine. I would guess that that is where you start counting from.

As for when to do them. Every 100K seems to be the general rule of thumb. I did mine shortly after buying the car with 89K on it. they looked fine and probably would have lasted another 100K, but, it is cheap insurance. sdpatt did his for the first time at somewhere around a quarter million miles. So, they can last quite a while.

I would guess that a properly maintained, not beat on one should go atleast a few hundred K.

I would recommend that they be doneas soon as you buy the car assuming it has over 100K on it, unless you know they have been done already.

Do not wait for symptoms. Don't decide to wait till you here a rod knock. That is probably too late.

 

[revhardSHO]

My bros 89 has 206K on original rod bearings, sees readline daily and the motor has had a poor maintance history (before it came into my hands )
Very strong and very smooth, in fact it is the fastest SHO that we have. I will be changing them soon, however.

When I pulled upart my 92K 3.2 it was the #6 bearing that showed the most wear, but all were showing copper and needed replacing.

edit: that would be the #6 bearing from the oil pump, so it would be on the drivers side of the motor

 

[yamahaSHO]

(he ended up regrinding the crank and went with oversized bearings).

Common misconception.... They are actually called undersized bearings because the crank is smaller.... Lots of people screw that one up.

 

[Rockledge]

Common misconception.... They are actually called undersized bearings because the crank is smaller.... Lots of people screw that one up.

Right.

 

[Diamond Jim]

any idea on which cylinder tends to be most likely to spin a bearing ? i have a motor with a spun bearing on #4

According to Doug Lewis...
(and he has looking inside more SHO motors than all of us put together)

#4 Cylinder has the most common rod bearing failure.

 

[CheckerSHO]

The motor in my 93 when i got it had a bad rod knock and when i pulled the pan, the bearings ranged from fine (number one, closest to oil pump) to virtually gone, black, and flattened(number 6). Progressively getting worse. Im thinking this was from it being run with a lack of oil pressure for one reason or another...i didnt investigate it much since the motor was shot. I went ahead and put new bearings in it and it was knocking again and no oil pressure before it even got warmed up good.

The motor i replaced that one with...i got out of my previous daily driver with 160k , i put rod bearings in it at 130k when i got the car after noting a rattle on startup. All had a little copper showing and seemed to have even wear across the board. Car had been driven pretty hard before i got it.

Owned a 90 with 150k on it that was already knocking when i got it...seems someone waited too long to remedy the problem, no toasted bearings but new ones didnt last very long

Those are my rod bearing experiences

 

[sdpatt]

I replaced the original rod bearings in my engine at 269,000 miles. There was no audible rod knocking sound, but the upper bearings in all cylinders were showing copper. Not scored or damaged, just smoothly worn from many, many miles of joy.

Engines with less rigorous oil change histories will probably not fare as well as mine. I haven't babied my engine as it sees full throttle often and redline almost every day. I didn't become a track car until after a quarter of a million miles had passed under its oil pan.

Since the six sets of Clevite CB1435P bearings cost only $45 at NAPA Auto Parts and the Fel-Pro OS30636R oil pan seal set costs about $17 from many sources, this is relatively cheap insurance for a higher mileage engine. I'd suggest replacing the connecting rod bearings around 150,000 miles if the oil history is not well documented.

 

[autobahnsho]

I replaced the original rod bearings in my engine at 269,000 miles. There was no audible rod knocking sound, but the upper bearings in all cylinders were showing copper. Not scored or damaged, just smoothly worn from many, many miles of joy.
.

I'd say driving style probably makes a difference- lugging (letting the engine buck because not enough gas at takeoff or too high a gear, or just bad running engine) is probably bad on the bearings, isn't it?

 

[CheckerSHO]

I'd say driving style probably makes a difference- lugging (letting the engine buck because not enough gas at takeoff or too high a gear, or just bad running engine) is probably bad on the bearings, isn't it?

As explained by one of my teachers, lugging is one of the worst things for a motor...its a lot of pressure down on the rod bearing with very little actual movement of the crank....so it puts our already fragile rod bearings through some more beating.