A few days ago, I heard a rather outlandish story about an old CRX. A good friend of mine owned his own repair shop some years back, and had a few mechanics that he employed. This CRX shows up one day, and the driver is pretty much fed up with the car. Originally, the owner came in for a tune up, when one of the mechanics discovered that car had bent valves (bad compression, bad idle, and subaru sounding on thottle).

After hearing the diagnosis, the owner of the car offers the CRX for sale right there on the spot. One of the Mechanics offers the owner $500 bucks, and he graciously accepted, and handed over the keys and title.

Shortly after the former owner of the CRX leaves the shop, the mechanic who made the purchase, starts it up, and begins pegging the living **** out of the throttle, letting the poor tired engine bounce against the rev limiter. My friend (owner of the shop) goes bolting out to the shop floor screaming "What the **** are you doing?!?". The mechanic says "Shhhh, give it a minute". After about 5 minutes, the mechanic lets off of the throttle, and the motor sounds like brand new!!!

My friend looks over at the mechanic puzzled as fack, and the mechanic begins to explain...

"This is an old technique that I learned from working on Italian cars. Old Fiats (I believe, may have been another Italian small car company), are built with the valves only partially seated. And the manufacturer requires a vigorous break in procedure, much like what you just saw."

Thoughts? Does this story sound like complete **** or Honda magic?

 

a bent valve isn't going to fix itself. story sounds like BS. if there was some carbon buildup i can understand why beating on the car would clear it up, but other than that i can't see how a bent valve is going to straighten back out on its own.

 

"Italian tuneup" is for carbon removal. Though, built up carbon can hang valves open, making the engine act like valves are bent.

And besides, you do an Italian tuneup under load, not in neutral. Full throttle pull from near idle to redline, in as many gears as you can get away with.
http://en.wikipedia.org/wiki/Italian_tuneup

 

The only way I would imagine to fix a bent valve this way is that the high revolutionary rate / temperatures / pressures would create enough G force on the valve's stem as to straighten it, just as pulling a pipe straight. However, the carboon buildup story sounds much more reasonable, since the mecahnic never verified a bent valve, just assumed based on the sympotms. Never the less, great story! Now I'm glad I do alot of redlining in my car.

 

there's no way the valve would 'straighten' itself out. the guide would be demolished long before that.

 

I've also heard of this being done succesfully. Although not "pegging" it and bouncing off the revlimiter. That sounds aweful. I've heard of confirmed cases of a t-belt breaking and bending just a few valves, new belt installed and started. Runs poor for a few then is driven around the block a few spirited times and comes back idling fine without mis. Worth a shot in my book. Any time I come across a broken t belt I always pull the valve cover and start measuring clearences. Lately I've had about 4-5 in a row that did not bend a single valve. Crazy huh.

 

lol. if its bent, its bent.

 

The OP story is far fetched but its happened. I read an article in MOTOR mag about a older Prelude with a few bent valves. The more they ran it the better it ran. I don't see why its not possible. If the valve guide is strong enough and the spring pulls hard enough then it can straighten out. Have you ever seen actually what it takes to bend a small Honda valve..... not much.

 

This is not possible. In order for the valves to bend they need to come in contact with something. More than likely a piston if it jumped time. As stated before it would demolish the guides, and if it kept hitting the piston once out of time it would beat a hole in the piston pretty quickly.

 

1. "not possible", I've worked in this industry long enough to tell you that nothing is never "not possible"

2. I've seen a higher rpm belt break and could tell that the valve had hit the piston once maybe twice but there is no way that it could unless the valve face broke off the stem and was stuck in the combustion chamber.

Look at it this way, once the belt breaks the bottom end of the engine is moving independent of the valve train. If the lower end keeps moving ( it most likely will as its connected to things like the flywheel and trans which if the clutch is engaged and your moving, so is the bottom end) but the valve train will stop almost immediately. Have you ever had a loaded cylinder head on the bench? Look at how many valves are open, Only a few. The valve springs will snap the cam back into a position that pulls closed the most valves.

Anyone who says "its not possible" is incorrect and has not truely put any thought into it.

I'm not saying this whole scenario is possible buts it not impossible either. A very reputable magazine in the industry did an article on this very story. It was either MOTOR or Motor-age.

 

.Re reaad my post. It says if it jumps time not if the belt broke. If a timing belt jumps teeth the crank and cams will still be turning as a unit and contact the pistons over and over. A motor turning at 6k rpms the piston would contact the valves 100 times in one second. Trust me it beats holes in pistons I floated the valves in a b18 on a money shift and it wreaked havoc.

I don't see it being possible because for one the valve has to contact the piston to bend, the piston would also have to beat the bent valve back into the guide to straighten it since spring pressure alone will not pull it back into shape. And since most pistons are aluminum and valves are steel which is harder the piston will give alot more than a valve, so how is it possible?

 

I re-read it, and see your point. But I've never seen a t-belt jump time and reposition itself without something else being terribly wrong. Personally I've never had a car or seen a t-belt car "jump time" on its own without some other issue. Nor do I think t-belts care how fast they are going when you downshift or miss a shift. I've logged a couple 9200-9300 rpm downshifts on my racecar without t-belt error.

 

I wasn refferring to timing belt error when I said I floated valves. A money shift is a 1-2-1, 2-3-2, or 3-4-3 shift if your wide open throttle and do a 1-2-1 shift the motor is prob going to be doing about 13k rpms once u dump the clutch and its too late by then to realize ur not in third. That has nothing to do with a timing belt. I was only using that as reference as to the piston hitting the valve and bending it and it just not being possible for a bent valve to fix itself without causing irreprible damage to something else.

And yes u are correct, in order for a car to jump time something usually else is the cause. I've seen it plenty of times. If a tensioner fails, which happened in a friends 1g talon, or if the crank pulley bolt backs off, which happened in the same guys 1g talon, I've also seen alot of 4g63 motors jump time and destoy themselves from balance shafts going out and the belt breaking getting caught in the timing belt. I've also seen instances where the belt jumped due to cam gears being marred up on the teeth. There's plenty of things that can cause a car to jump time not once have I ever heard of a bent valve fixing itself nor do I think its possible before catastrophic engine failure.

If u find the article the magazine did about this please post it im curious to read it and see if they say its actually been done or if they are only speculating and asking the same question the op did.

 

bullshit a crx wont bend valves

 

Haha.

 

Ask my brother about bent and broken valves lmao. I can't even count how many motors we had to tear apart and rebuild. The best was the valve drop at 9,000 RPM, the cam sprocket bolt loosened and bent the sprocket, the chain snapped and the one valve smacked the piston and cracked off then beat the **** outta the head and then the stem of the valve went through puncturing all the way out of the bottom of the brand new Wiseco piston lol. And somewhere in that the metal around the ceramic of the spark plug melted into the head. I think it was running way too hot from him not adjusting fuel for a bigger cam and going all out on a 95 degree day. I tried to tell him lol. It was just a total engine failure. Everyone ended up pitching in to get him a brand new motor because we felt bad for him hahaha

 

It is not possible. You obviously have not been in the industry long enough if you think a valve can straighten itself out. Link the article.

 

To start off with there is no way it is straiting the valve . It might make it good enough to seat but i promise you will dropp a valve from wearing out the valve guides from being bent . Ive also seen this happen . I bought a crx with a broke timing belt and replaced the timing belt kinda ran a little ruff but ended up clearing up 3 months later dropped valve so good luck with this option.