[mrmandmman]

I was driving around, I gave it some gas, it boosted WAY to much ( into 20s). The engine knocked. Now there is a clicking sound that gets faster when the rpms go up. I can hear the clicking in the car with the windows up. The car still boosts fine but this doesn't sound good. Did I bend a rod?

 

[JHEIII850Turbo]

Dam man... it was just a matter of time...

well, my guess is that it's pinging, so try to put some high a$$ octane fuel, like maybe even racing fuel, baby her, try re-changing the oil...

Man, I hope something works!!

 

[mrmandmman]

I was using premium plus octane booster........but thats not going to help I dont think you can cure a bent by changing the oil.......

 

[devalmyth]

check the compression on each cylinder any abnormals may indicate the culprit. take one lead of at a time with the engine running, when you take a lead off one of the cylinders the knocking sound should quieten down a small amount indicating the cylinder with the bent rod. i hope this helps.. but more to the story why did it peak so high??? also use a mechanics stephiscope and listen to were the sound is coming from.

michael.

 

[Fast&Swedish]

The tikking sound indicates a wrecked piston. Take of the crankcase and look before you drive any further, if the piston is really damaged you are killing the complete engine whenever you drive it like this....

 

[mrmandmman]

How is the piston causing the ticking sound? Is the rod pushing the piston into the cylinder wall? I don't think the engine is that damaged (prolly going to need resleeving though, if it is a piston or rod), because the car still drives fine. I am not that great of a mechanic (still being young and in school). Should I take the car to a volvo dealership or a general (cheaper/trusted) mechanic.

 

[Spearzy]

I would stop driving it now! Sounds like you may have thrown a valve, maybe it's hitting the piston.
Whatever it is, sounds bad, can only lead to other problems!

 

[mrmandmman]

I haven't driven it since I got home after it happened.... But do you think it would be causing more damamge.....it sounds like metal is hitting metal every time ( because it is)

 

[Spearzy]

Take it too a mechanic as soon as you can.
I hate to say it but bring your check book. I would first call your mechanic and tell him your problem and he can tell you his idea of what may be wrong and an estimate - should be ball park figure that is close. Man, I wish you the best, hope it is a contained area of damage. I personally don't think it would be the crank or anything like that (as it would probably be siezed, or the car would simply not run), so the labor shouldn't be horrendous. I guess that all depends on what went.
Tell me, how did you get into the 20s in boost pressure? You must have some mods done, trial and error I guess. Turn it down a notch and good luck!

 

[devalmyth]

quote:

Originally posted by Fast&Swedish:
Take of the crankcase and look before you drive any further.

??? what does this mean? do you mean take the head off?

i wouldt overreact too much...mrmandmman did you do what recomened? it is possible that the top of the piston has broken away due to the high burning that happened. each time the piston comes to the top the bit of melted debree hits the valves... the only way to see if this the problem is to do the reserch. it's no use persumeing difernt things, "it could be this,it could be that". it could be a number of things. the only thing to do is to check the serverty and what is causeing the noise, then work from there. after all the car is running fine.. the damage can only go so far then stop at a point.
i had a vvw that i over reved, the piston top broke off and melted to the top, each time the piston came up it hit and made a tic,tic sound. me and my brother drove the car for a year then evently pulled it down.we just replaced the piston and the engine was fine.

michael.

 

[devalmyth]

BTW, if the rod was bent the noise would evently stop, cause the only place the rod touches is the bottom of the cylinder, if the rod is badly bent then it would make a huge amount of noise and the engine would run rought and uneven. when you hear noises keep in mind how the engine works and were the noice is coming from. heres a bent rod for you due too much boost

michael.

 

[mrmandmman]

What kind of shop do you think I should take the car into to get this checked out. Should I take it to a general mechanic that I know and trust or should I drive it farther and take it to the volvo dealer?

 

[Fast&Swedish]

What I can't understand is that you might have wrecked a piston/valve or conrod with 20 psi? I drive my 850 T-5R with 19 psi (1.3 bar) all the time and have no troubles. I must say that we use 98 Ron unleaded here in Holland though. It's just a matter of a good programm in the ecu that provides the engine with enough fuel to cool the engine. I'm working on a waterinjectionsystem to raise the boost up to 1.45 bar at higher revs. At the Dyno I already had 308 HP with 1.3 bar....

 

[Spearzy]

quote:

Originally posted by Fast&Swedish:
What I can't understand is that you might have wrecked a piston/valve or conrod with 20 psi? I drive my 850 T-5R with 19 psi (1.3 bar) all the time and have no troubles. I must say that we use 98 Ron unleaded here in Holland though. It's just a matter of a good programm in the ecu that provides the engine with enough fuel to cool the engine. I'm working on a waterinjectionsystem to raise the boost up to 1.45 bar at higher revs. At the Dyno I already had 308 HP with 1.3 bar....

I'm guessing the boost pressure guage tops out at 20-25psi. Who knows what really happened or how high the pressure went. No stock boost could do this I don't think, something must be swapped out for ultra boost pressure. Maybe it would be wise to re-evaluate the mod in the future

 

[Spearzy]

quote:

Originally posted by Fast&Swedish:
What I can't understand is that you might have wrecked a piston/valve or conrod with 20 psi? I drive my 850 T-5R with 19 psi (1.3 bar) all the time and have no troubles. I must say that we use 98 Ron unleaded here in Holland though. It's just a matter of a good programm in the ecu that provides the engine with enough fuel to cool the engine. I'm working on a waterinjectionsystem to raise the boost up to 1.45 bar at higher revs. At the Dyno I already had 308 HP with 1.3 bar....

By the way, sick car!!

You have the best 850 their is! Hope you and that car take good care of each other. Feel free to make as many threads with pictures as you can!! No one here will get sick of looking at your car, I guarantee that!

 

[mrmandmman]

It hit at least 25 psi with stock exhaust, stock ECU, and stock injectors. Thats not safe, something went wrong with the car and that happened.

 

[Fast&Swedish]

Most likely the actuator failed or the wastegate itself was stuck. Otherwise it's impossible to get such a high boost with stock equipment. It could happen again if you don't find the cause.

 

[Fast&Swedish]

Quote:
"By the way, sick car!!
You have the best 850 their is! Hope you and that car take good care of each other. Feel free to make as many threads with pictures as you can!! No one here will get sick of looking at your car, I guarantee that!"

Thanks! I'm pretty pleased with it myself.