V-belt jumped off, possible damage?
Discussion
Was driving about 100-140 MPH on the highway in the dark when I heard a bad noise from behind (right side).
Heard something knock on the bottom plate,
but I thought it was just a bump on the street or garbage.
Was cruising down the highway for ~another mile,
until I tried to accelerate,
but no feedback from the engine to my gas pedal.
It felt like the engine's stuck.
Looking at the temp the needle was at the limit of 120°C,
I lift off the throttle and stopped.
When I opened the door white smoke was coming from the back/under the car.
The V-belt didn't crack but it jumped off.
Lost quite a lot fluid. Felt like water.
It was dripping off at the right side of the back.
Noticed a spray of fuel around the right exhaust ring.
But the engine looked dry.
It didn't seem to leak anything after it cooled down.
Had to tow the car,
and it is now at a Corvette engine specialist.
As far as I understood he's optimistic that the ECU saved the eingine from major damage.
Hence no response to my gas pedal.
But if the temperature was getting too high...
What could it kill?
And where did the spray of fuel around the exhaust header (and mesh) came from?
First off I thought it's oil,
but now my finger smell like fuel.
I am not an expert, so I am worried about the engine.
It's an LS7 with diamond forged pistons,
12:1 compression,
and a custom grind camshaft made by Comp Cams,
if it makes any difference.
Heard something knock on the bottom plate,
but I thought it was just a bump on the street or garbage.
Was cruising down the highway for ~another mile,
until I tried to accelerate,
but no feedback from the engine to my gas pedal.
It felt like the engine's stuck.
Looking at the temp the needle was at the limit of 120°C,
I lift off the throttle and stopped.
When I opened the door white smoke was coming from the back/under the car.
The V-belt didn't crack but it jumped off.
Lost quite a lot fluid. Felt like water.
It was dripping off at the right side of the back.
Noticed a spray of fuel around the right exhaust ring.
But the engine looked dry.
It didn't seem to leak anything after it cooled down.
Had to tow the car,
and it is now at a Corvette engine specialist.
As far as I understood he's optimistic that the ECU saved the eingine from major damage.
Hence no response to my gas pedal.
But if the temperature was getting too high...
What could it kill?
And where did the spray of fuel around the exhaust header (and mesh) came from?
First off I thought it's oil,
but now my finger smell like fuel.
I am not an expert, so I am worried about the engine.
It's an LS7 with diamond forged pistons,
12:1 compression,
and a custom grind camshaft made by Comp Cams,
if it makes any difference.
Edited by Mr.Snood on Friday 16th April 04:58
I am no expert (a few more knowledgeable souls will be along in a min) but I suspect the fuel is from when you pressed the throttle but the engine management cut the spark so unburnt fuel exited the exhaust.
I am sure the Corvette specialist will be able to diagnose any other problems and hopefully 120 deg is not sufficient to have warped the heads in that short time.
If the belt has come off the pulley and was correctly tensioned then I would suspect something is running out of true and would look for bent brackets / tensioners etc.
Best of luck
Paul
I am sure the Corvette specialist will be able to diagnose any other problems and hopefully 120 deg is not sufficient to have warped the heads in that short time.
If the belt has come off the pulley and was correctly tensioned then I would suspect something is running out of true and would look for bent brackets / tensioners etc.
Best of luck
Paul
It's like the flip of a coin. The possible fuelspray could be very well waterspray, so it would mean water came through the exhaust, which means blown head gaskets. To be more sure look for white foam under the swirlpot or expansionpot cap.
White foam in the cooling cirquit is oil, which ain't good and indicates mostly bad headgasket.
Worst case you will need planing heads and thicker gaskets with your 1:12 compression.
Best case, it's just been protected by the ECU. The garage can tell you within an hour what's wrong.
White foam in the cooling cirquit is oil, which ain't good and indicates mostly bad headgasket.
Worst case you will need planing heads and thicker gaskets with your 1:12 compression.
Best case, it's just been protected by the ECU. The garage can tell you within an hour what's wrong.
Sorry youve had a problem but my advise is stop worrying what it might be!!!!
We could spend all night wondering, thinking, pondering what it may or may not be and you could get worried sick of the worst case....
If its at the corvette specialist don't worry about it until he finds out what it is and when he has checked compression, pressurized cooling , checked tensioners and checked the water pump isn't seized and thrown the belt, then let us know and we can talk and advise.
I have heard so many people advise the possible solutions to problems in the past to find there isnt really a problem and all that happens is lots of sleepless nights and worried thoughts..
Good Luck
Dom
We could spend all night wondering, thinking, pondering what it may or may not be and you could get worried sick of the worst case....
If its at the corvette specialist don't worry about it until he finds out what it is and when he has checked compression, pressurized cooling , checked tensioners and checked the water pump isn't seized and thrown the belt, then let us know and we can talk and advise.
I have heard so many people advise the possible solutions to problems in the past to find there isnt really a problem and all that happens is lots of sleepless nights and worried thoughts..
Good Luck
Dom
Well can't tell exactly about the speed.
It's actually the german autobahn (not highway).
I accelerated quite fast to 140 MPH,
to let it slowly drop towards my usual cruising speed of 100 MPH.
And somewhere in between the belt jumped off (3000-4000 RPM).
Regarding the belt:
Looking back I think the belt announced his failure.
The last 2-3 weeks one could hear a fizzling from time to time (slipping belt?).
And there was a metallic knock from time to time (the belt tigthener?).
No idea if it's the GM tensioner unit.
I suppose it's not.
I didn't notice any white foam under the expansionpot cap.
I didn't look at the swirl pot.
I have no clue about the technical side,
and the corvette specialist is quite busy these days.
So I don't expect a "fast" answer from him.
He will call me as soon as possible.
I was hoping to hear an answer like:
"don't worry, the ECU saved it 100%" or
"High temperature for 30-60 seconds is not a problem at all" or
"s
t happens, but I am sure the damage won't cost you more than $1000"
and not
"I am sorry, but your 30 grand engine is a piece of waste now"
So let's wait what the doctor says.
It's actually the german autobahn (not highway).
I accelerated quite fast to 140 MPH,
to let it slowly drop towards my usual cruising speed of 100 MPH.
And somewhere in between the belt jumped off (3000-4000 RPM).
Regarding the belt:
Looking back I think the belt announced his failure.
The last 2-3 weeks one could hear a fizzling from time to time (slipping belt?).
And there was a metallic knock from time to time (the belt tigthener?).
No idea if it's the GM tensioner unit.
I suppose it's not.
I didn't notice any white foam under the expansionpot cap.
I didn't look at the swirl pot.
I have no clue about the technical side,
and the corvette specialist is quite busy these days.
So I don't expect a "fast" answer from him.
He will call me as soon as possible.
I was hoping to hear an answer like:
"don't worry, the ECU saved it 100%" or
"High temperature for 30-60 seconds is not a problem at all" or
"s
t happens, but I am sure the damage won't cost you more than $1000" and not
"I am sorry, but your 30 grand engine is a piece of waste now"
So let's wait what the doctor says.
Mr.Snood said:
...The V-belt didn't crack but it jumped off....
Mr.Snood said:
No idea if it's the GM tensioner unit.
I suppose it's not.
I suppose it's not.
Mr.Snood said:
"I am sorry, but your 30 grand engine is a piece of waste now".
Sorry, not trying to elicit a reaction, I'm really trying to wrap my mind around this. Did you really spend 30,000 Euros on your modified LS7?
Was it converted to "V" belt or are you using this as a generic expression and it's actually a grooved serpentine belt?
Do you have a picture of the front of the engine before it was mounted in the car? The reason I ask is that it would be interesting to determine WHY the belt jumped off the pulley. I suspect that the pulley routing is different from that used in the Corvette. Do ALL of the pulleys still have a good amount of contact or are some only contacting the belt for a few degrees?
By the way, it's VERY unlikely that you destroyed your 30,000 engine, more likely that you have some head damage and maybe some piston damage (less likely)
Best of luck,
B.
The GM Tensioner is spring loaded, but most of the race guys Including Kaytech change it to a adjustable but fixed tension system. You could have just picked up a stone and caused a small cut in the belt, then eventualy failed. Is there any damage to the pulleys ? Worth checking them just to make sure it doesn't damage a new belt....
PS on a footnote my 2001 Corvette had a issue with the Fan switch, and in traffic would go from the normal 90c to 110c. At 110c the fan would come on so I thought it was normal as these engines do run hotter than the old SBC's. But in the end the switch was faulty. I wouldn't be to worried about the engine if was only for a short period then you should be ok....
Slow M said:
Did you really spend 30,000 Euros on your modified LS7?
Well, cost + shipping + customs and you're at 30.000 USD.Slow M said:
Was it converted to "V" belt or are you using this as a generic expression and it's actually a grooved serpentine belt?
Used it as a generic expression.Guess it's a serpentine belt.
I don't have a picture of the belt mounting,
but I know we had a custom belt mounting in cause of the AC-compressor...
With the original setup the engine + AC-compressor wouldn't fit into the Ultima chassis.
Edited by Mr.Snood on Saturday 17th April 18:24
Probably, but I think the belt mounting changed towards the end of the build,
due to a different AC-compressor.
Neverthelss got a good reply from the engine specialist.
Engine's running again, and it looks and sounds healthy.
The spray around the right exhaust ring is still a riddle,
and he doesn't believe it was fuel (too oily?).
Looks like a pulley caused the failure.
It relaxed and fell off.
due to a different AC-compressor.
Neverthelss got a good reply from the engine specialist.
Engine's running again, and it looks and sounds healthy.
The spray around the right exhaust ring is still a riddle,
and he doesn't believe it was fuel (too oily?).
Looks like a pulley caused the failure.
It relaxed and fell off.
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