t0adman

iTrader: (8)

So my V-Spec went TU on me last weekend at a race. I could get it started and it would run but only until I landed from the first jump then it would die. The engine was also loud and sounded bad. It feels like there's a dead spot at TDC where the piston doesn't pop over. I've taken it apart and can't see anything abnormal about the connecting rod but am going to replace that and the bearings. I'll test the pinch tonight to see if it's still decent. Any idea on what exactly might have caused these symptoms? I've heard the connecting rod can actually stretch and cause problems. Any truth to that?

I'm going to get another V-Spec so I'll have a backup or can use one for parts in a pinch. Has OS changed the bearings they're putting in the V-Spec since they started production of this engine? If so, which model numbers have upgraded bearings? Approximately when did they start production of motors with non-defective bearings? Would it be worth me replacing the bearings immediatley or just waiting until they go bad to put ceramics in there?

wingracer

iTrader: (24)

Get TKO bearings for it. They are the best.

While rods can stretch a bit that is not the usual problem. Usually the rod bushings and crank pin wear until the play allows the piston to come up too far and it starts killing glow plugs.

dethklok151

iTrader: (65)

yeah .when they start to sound loud thats usually the bearings.when they dont pop over thats usuallythe rod wore out,either top or bottom.you already had it figured out.

t0adman

iTrader: (8)

So if the rod bushings and crank pin are toast, which parts need to be replaced to get the engine working well again?

oggietiu

iTrader: (7)

Vspec models with Spec 2 above have the new bearings in them. This is what my LHS told me. I already have a spec 4

jrwoodchuck

Ware is it marked at?

oggietiu

iTrader: (7)

you can see it in the box where the bar code is written. Usually the part number plus you can see a distinctive number there. I got a 2 and spec 4 has a I think a darker head.

RobbieS

iTrader: (95)

Unless the motor has a lot of fuel through it you can probably just replace the con road and you will be good to go. I personally have never had con rod wear out at the wrist pin. It has always bin at the crank pin.

However, if you have run the engine an extended period at high rpm's with the rod loose it may have worn your crank pin to much.

The ease thing to do is buy a new rod (about $30) and check it on your crank pin to make sure it is not sloppy.

jrwoodchuck

Thanks, my box has a 004 below the bar code. So I'm assuming it's a spec 4.

t0adman

iTrader: (8)

I just got my new V-Spec in the mail today. It's got a black carb boot (instead of the blue I'm used to) and appears to be slightly different. Maybe I'm just hoping it is.

The bar code on my box just has OSM13895 under it. No 004 or whatever. Is there another way to check the build date or serial number of this engine to see if it might have updated bearings?

wingracer

iTrader: (24)

If I remember correctly, the black boot means it's the carb from the .28. They are going to that carb on the .21's now as well.

Jonro

I don't think you can go by the 00 numbers because they are putting updated carbs(21J) on all the new ones made in 08 and the one i just bought has the newest carb and its only an 002 on the box. So its pretty safe to say if your engine came with the updated carb it should have been built recently.

t0adman

iTrader: (8)

This weekend I tore apart the "old" V-Spec with the intention of replacing the front and rear bearings and the crank arm. After checking to make sure the piston and sleeve still had decent pinch I got to work. Getting the rear engine bearing out was a challenge to say the least. I had to cook the crank case in the oven for 30 minutes on 350 and it was still tight! I got the two new bearings in correctly, lubricated them and then installed the new crank arm. When I got everything back into the crank case and rolled the engine over TDC I still had the same dead spot...damn!

Now I'm at the point where I've spent enough I'm determined to just fix it (which I realize may never happen). What is the next logical part to replace? Should it be the pin at the piston head (wrist pin?) or could I be looking at needing a new crankshaft. I assume the crankshaft pin can not be replaced independently of the crankshaft. What would you guys do?

t0adman

iTrader: (8)

<crickets> Whoa, where have all the V-Spec mechanics gone? </crickets>

KK-racing

iTrader: (5)

Hi toady

Maybe you would like to check is there any play in both the piston's wrist-pin holes. People tends to overlook this area which will also wear out. Try rocking the con-rod forward & backward while looking at each hole. If you notice any upward or downward(commonly is upward) movement of the wrist-pin then the piston is fried. There's always this misconception that the connecting rod(con-rod) 'stretch'. It's actually the big end bushing that has worn out causing some play which was thus misunderstood as the rod got longer. During most part of it's lifespan it is being pushed downward from TDC when the fuel combusted. The only time it will be pulled is during starting before it fires up while cranking when it is pulled from TDC where it is at the tightest spot.