Tox

I can. A bearing failure is one thing, but as I understand EX's explanation this one apparently came completely out of its connecting rod. Given the large counterweights surrounding the bearing journals on a crankshaft, I don't see how that could happen unless the rod cap dropped off, which would free the rod and piston to impact the head and bend or break the valves, among other things.

On the other hand, I may have misunderstood. Perhaps the bearing remained in place and trashed only the crank journal, and the mechanics just laid it in the oil pan after they removed it. In that case the head should be fine, assuming no fine metal particles got to it in the oil.

cdelena

No way, they don

Jason Saini

In a very circular way I am beginning to believe that this is the good 'ol #4 piston apron failure and the whole bearing issue was mis-interpreted by the dealer. Maybe EX saw the bearing in the pan in it's normal, natural state - EX was the bearing scored, discolored or otherwise abnormal looking?

The thing that's leading me back the #4 phenomenon is the fact that the dealer said "the bearing failing caused the piston to start contacing the cylinder walls." The only way a bearing failure could cause that IMO is for it to shatter and leave a void between the journal and con-rod. Otherwise, I think the piston aprons contacting the cylinder bore *was* the problem, and the bearing was the improper diagnosis of the dealer. Or, it's entirely possible that they *have* figured out that it's something with the bearing that causes the piston-slap apron collapsing #4 syndrome. It's a chicken-before-the-egg thing, and I can honestly say I don't know which came first. I can only be sure that if the dealer thought the bearing was the root of the problem, they would have sent it back for inspection with the short block, and that's what I find fishy... something is still rotten in Denmark. Keep us in the loop, EX.

sp7128

come on guys get real .......if the rod broke and the rod and piston were clanking in the engine......it wouldnt happen.........1 the rod would fall down in the crank and destroy the crank rod block and piston no matter what rpm the engine was turning.........agree???
2 isnt it possible that the pieces in the pan are the piston skirt that broke off allowing the piston to slap in the cylinder...........3 if the engine is run on tight tolerances ie , deck height ot piston to valve...the piston could rock and touch the head or valves esp the on the exhaust as the piston is chasing the valve .....but if its tight on the intake it could kiss an intake valve too..... no matter what the outcome is there is a definite problem ......i do know of a dealer who went from high rpm 5th to 2nd and yes he did run over the engine as it exited out the bottom off the oil pan !!! the rev limiter/cutoff will not stop an engine from physically turning those rpm's even the the engine isnt running at time of high rpm's.......so its either lock up the tires and skid to a stop or spin the engine that fast and the engine did spin that fast ........theres to many holes and not enough proper info to come to a conclusion without seeing the block ......rod........piston.......and crank assy .....
i hope the dealer or AHM does come up with a truthful conclusion to the story.....

sp7128

Barry in Wyoming

I'd love to know what happened to AutoEX's engine, but, AHM and the dealer are really under no obligation to tell the owners any of that. AHM is obligated to fix his engine to make it as good as new. I'm sure they will.

If he needs a new head as well as a new short block, then the dealer will order the head in addition to the short block. AHM does not supply assembled F20Cs in the USA, only the components to make them, no matter what. If someone wants a new engine, you have to buy a new S2000 to go with it. My head was perfect after my #4 cylinder scoring problem.

Jason, AutoEX's car's sound was certainly more catastrophic than my engine's sound. However, I don't understand how his piston could be functioning normally enough to give a normal compression if the bearing between the rod and the crank were bad or if the bearing between the rod and the piston were bad. Well perhaps it could be just barely holding together with bolt broken off and loose in the oil pan just waiting for a chance to disintegrate more.

AutoEX, if you get more info, let us know. The pics would be great. Otherwise, let us know how the repair goes. I think you'll be back to 100%. The truth is that these engine repairs should make the car like new.


Barry in Wyoming...

Tim

AutoxEX, your bearing theory is wrong, your problem is a collapsed piston skirt. I know a few people at American Honda and from what I understand this whole #4 piston problem stems from revving the car when it is cold. Three bars on the coolant guage doesn't mean jack squat. With the coolant at normal the oil temp is still cold, and oil temp is the key. Just because the cold rev limit isn't kicking in doesn't mean it's safe to pound on it. Have any of you seen one of these pistons out of the motor? S2000 pistons are very short and don't have alot of skirt width, compared to a Type-R piston ( another high revving 4 ). Failures on Type-R's don't exist. When the pistons cold it's smaller than when it's warm, so there is more room for it to rock in the bore, and with having a short skirt leads to the piston cocking in the bore or sticking, wich leads to cylinder skoring. If you have had #4 fail then you only waited the 5 minutes it takes to warm the coolant not the 20 it takes to warm the oil. So basically wait a litle longer before you pound the car. It doesn't just happen to number 4, American Honda has gotten it's fair share of the rest of them too. Just my $.02

Barry in Wyoming

Tim, I'd love to know that you are correct, but what is the practical implication. On the day mine failed, it was a 40 deg F sunny Wyoming January 4th. My wife was with me and she's really cautious, so I don't think I did "hit it hard" until the car was fully warmed up, probably 20 or 30 minutes into the drive. I had 650 miles on the odometer, oil at the recommended level, 3 bars on the coolant temp gauge, and no reason to believe the engine oil was still cold. We do get minus 30 deg F temps in Wyoming, but my S2K is pampered and thinks it lives in the snowy part of Florida for all the cold temps it experiences.

I like your theory but how does it fit these facts: #4 seems to be only going sour in a few '01s. (Maybe it also affects '00s and we don't have the data.) It seems to affect low mileage engines--650 miles to 2,900 miles.

What fix does Honda plan? If your theory is correct, it seems there ought to be a rev limiter based on oil temp rather than coolant temp. Certainly it is going to cost quite a bit to replace collapsed piston skirts everytime someone revs to 8,000 or 9,000 after warming up for 5 minutes and getting normal coolant temp on the dash indicator.

I know AHM has made a big deal about low oil being the cause. They have stressed that we should check the dipstick every time we buy gasoline. I know low oil did not cause my #4 cylinder to go bad. My oil was not low. I checked it. The dealer checked it. The dealer measured the oil they drained from the engine when they did the short block replacement.

I can see it now. We each get a letter from AHM saying, "Don't rev past 5,500 until your engine oil has warmed to normal operating temperature. Since there is no oil temp indicator on your car, we are giving you this 20 minute timer. Set it to zero each time you start your car and do not rev past 5,500 until you hear it ding 20 minutes later."

Or at least they could have included a clock in MY2000.


Barry in Wyoming

2x6spds

Right, my point exactly! A clock!

I think an oil temp gauge might be in order as well.

2x6spds

E30M3

On my early M3, the rule of thumb is to keep below 4000 RPM until the oil temp gage indicates 122 F or higher. Forged pistons with lots of clearance. Usually the oil is good to go about 5 minutes or so after the coolant temp reaches nornal. Longer if you're down at 2500 RPM, faster if you're just below 4000 RPM. The latter is because of oil pumping effects. If your oil and coolant temps are good, then everything else in the motor is ready to go.

If you auto-x it would be wise to make sure your oil temp is up! Since there are lots of short ON periods and lengthy OFF periods. Same with driver's schools, so be careful when your run starts. At DE events I suspect that the oil would get pretty hot. A Bimmer buddy who also has an NSX says that his oil temps get up to about 290 F on track at Sebring. I don't know what kind of oil cooler the S2K uses, but I like the oil to water units the best since they get the oil up to temp the fastest. My old Jag V12 had one of these and the oil was nice and hot as soon as the coolant was hot.

Sometimes piston breakage issues are related to the oil holes in the sides of the pistons. Stress risers. You can tell if this is the case by checking to see where the piston broke or deformed.

Stan

[Edited by E30M3 on 02-04-2001 at 06:03 AM]

Silver S2K

If what Tim says is true, then I have 2 big questions.

1) Why did Honda Engineers choose to tie V-TEC engagement to coolant temp and not oil temp?

2) Why is there no oil temp gauge on the car (this really pisses me off by the way)?