Is a rod bearing failure always common after 100K+??

[Yamaholic]

Hey everyone... I have read many posts pertaining to SHO owners having their rod bearings spin. Is this something that can be prevented with good maintenance? Basically... If you've changed your oil as you should---> Is pre-preventative engine failure rod replacement considered necessary for the SHO engine once you've reached the 100K+ mark??

P.S. What are the early warning signals as to rod bearings that are going bad "Good need to know info". For my peace of mind... Will bad rod bearings spin unexpectedly, or will I be able to "PREPARE" and "REPAIR" before they terminate my SHO experience?

Take care all............. thumb

<small>[ June 09, 2003, 06:05 AM: Message edited by: Yamaholic ]</small>

 

[Slo-Sho]

An oil pressure gauge is always nice. Most times there will be a faint knock upon deceleration and idle.

 

[Yamaha V6]

Answer (sort of):

Mine spun in my 95 MTX at 72,000.
I've seen 160k+ engines with minimal wear.

I'll let you know shortly on a (currently) 84k 95 ATX that's essentially had nothing but Mobil 1 religiously from day 1.

The problem is, there's no apparent consistency on mileage, or transaxle type, as I've seen both trannies with bearing wear & low & high mileage SHOs be good & well-worn. And, how do you know how the car was treated before you bought it? If in doubt, change them.

 

[pjtoledo]

Some do, some don't. My 92 MTX has 247,500 miles on it. Still the original bearings, but I'm getting real nervous.


Perry Toledo,Ohio

 

[pete c]

I would, at a minimum, drop the pan and have a look. I did mine last summer. The old ones had some wear, not too bad. Might have lasted another 100K, who knows?

If you do decide to have a look, go ahead and replace them. They are about 50 bucks from ACME. It doesn't make sense to go through the PITA of looking at them and not replace them cause you don't want to part w/50 bones.

Just do it. Cheap insurance.

 

[sdpatt]

Basically, no, but they will eventually benefit from being replaced. Probably before 150,000 miles.

The originals on my well maintained engine were replaced at 269,000 miles and indeed showed wear, but not damage. They were worn into the copper on all upper bearing faces and did not show any scoring or scratching. The topic was covered with pictures here.

For the cost of $45 for 6 of the Clevite CB1435P bearing sets from NAPA auto parts, that was excellent insurance for the extension of the engine's lifetime. The engine was noticeably smoother after the service.

<small>[ June 09, 2003, 12:13 PM: Message edited by: sdpatt ]</small>

 

[billh]

The way I noticed mine was a cold engine startup in a garage. I heard what I thought was a slight knock one morning. Since I had the radio on, I couldn't be sure but I was definitely suspicious. That night when I shut it off, I made sure that everything was off, radio, climate control, etc. I rolled down the drivers side window before starting it the next morning. Sure enough, the old connecting rod knock for a split second until the engine had full oil pressure.
I have heard this sound a number of times on other, older engines. Normally, it's no big deal on an engine that never sees 5000 RPM, but on a SHO, that has an almost 7000 red line, ignoring it spells disaster. When we swapped bearings, I put a ball micrometer on the worn, upper half of the bearing. Indicated wear was around .0006". What happens is this increase in rod clearance at the very worst place, right on the thrust line, causes a breakdown in the oil film. Crank and bearings touch, crank grabs bearing, spins it. If not caught in time, Motor goes BOOM! If caught in time, you only have to remove the engine and replace the crank and rod. Still no fun.
A $50.00 investment in parts and a couple of hours labor is really good insurance. With all of the PITA things that these cars put us through, being able to easily remove the oil pan makes up for a lot.
Good Luck

 

[shojuan]

They are normal wear items. Our engines are high-revving, high output engines. The wear distribution patterns between cars varies so much because driving styles differ and also maintenance patterns differ. Compare Scott's car to some of the "young and spun" cars. Best bet is when in doubt replace the rod bearings. Do the mains too if you're up to it and can afford a bit more than twice the cost. Mains should last at least twice as long unless the major wear factor is corrosion from poor maintenance habits. After they get replaced maintain the car like Scott does and drive with confidence for 150,000 miles before replacing them again to freshen things up and restore some oil pressure.

I'm going to be replacing my rods and mains next week (as long as I can get over 500 miles+ in on the Auto-RX that just arrived yesterday within a week. Woe, gotta drain the redline out first!)

Also an oil pressure gauge is a darn good tool to have and fun to watch to boot! These can be had for as cheap as $7 at walmart. That $7 unit works just fine. There's nothing wrong with it. Just doesn't have fine scale markings. Big whoop-di-doo

Lol, do as I say and not as I do. I haven't installed an oil pressure gauge yet. I'll probably put one in when I do the bearings. Actually I'd like to install one first so I can get a before and after picture of the oil pressure to go along with how the old bearings look. These things are really easy to install. Ask David!

Also, don't take your car to some random shop for the bearings. Well, it's an easy job, I'm sure most shops *should* be able to do a decent job of it. There should be a SHO enthusiast who has done a bearing swap near just about everyone on this forum. And they'll have the torque specs too which, well I have serious doubts about most shops. Some mechanics that have access to the torque specs get cocky and don't bother to look them up. A professional mechanic probably won't let the silicone cure for very long on the oil pan before filling the engine with oil. That will prevent the silicone on the inside portion of the bead from curing properly. Just bribe your local SHO enthusiast to do the job. I take bribes. As long as they're green!