| Author |
Message |
shamanstar (216.239.174.133)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 30, 2003 - 10:52 pm: | |
Hi... we were on our first trip with the new bus... 77 international. poor gas mileage made us turn around (2 miles to the gallon on a 15,000 pound, 30 footer). then, something happened and all of a sudden when you pushed down on the gas, it sounded like marbles- loud metal on metal. very random. it didnt make the sound when we let of the gas. the is an automatic allison transmission and a propane engine.
we still had accellerating power but only with the noise. we could accellerate slowly without getting the noise. we pulled over immediately and had it towed.
please email me with any suggestions as to what might be wrong.
thanks!!!!!!
star |
Jayjay (152.163.188.227)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 30, 2003 - 11:42 pm: | |
Marbles? Nah, sounds like rod bearings to me. Could bu a spark knock, (wrong timing due to lack of vacuum advance). I'm not familiar with any expensive-sounding noises in propane engines, because of limited experience with them. Most transits in Las Vegas are vapor-fueled. and most drivers dislike them. ...JJ |
Peter Broadribb (Madbrit) (170.215.174.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 31, 2003 - 2:43 am: | |
Check out the flex-plate (flywheel), if that's cracked badly it will twist and warp the harder you accelerate and they can make all sorts of weird noises. Ringing, clanking, knocking, etc. Could be the torque converter too or even part of your propane intake system coming apart?
How was the oil pressure? Water temp? You are looking for anything throttle related, good luck.
Unfortunatley your description is a little vague for any accurate diagnosis over the internet, so expect some way off guesses, but you never know, one may be right on the money.
Peter. |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 31, 2003 - 2:59 am: | |
Hi Star,
If everything in the propane conversion isn't working perfectly, propane engines can pre-ignite a LOT under load and sound just like what you describe. The initial timing and the advance curve is different for a propane engine than for a gas engine, because propane has a tendency to pre-ignition knocking a lot more than does gaoline, and if anything's out of whack you'll hear what you heard upon acceleration. You might have lost a diaphragm in the carb or regulator, or something in the advance mechanism of your distributor might have gone south.
Definitely check the bearings if you can though, to make sure you won't do any more damage if it happens to be a rod. But rod bearings going out have a different sound characteristic... they are fairly quiet when accelerating or decelerating, and noisy when you let up the gas pedal a bit and let the engine "coast" along with how fast you're driving.... ie under either load or retard they quiet up and no-load they get rattly.
I had a bus 20 years ago with a propane conversion and a manual 5 speed/overdrive. It got 5 mpg at best and it too was a light bus. Since you have an automatic, I wouldn't be surprised at 2-3 mpg especially if the engine isn't tuned up properly.
Remember, simply due to the molecule size and how much energy it stores, Propane gets roughtly 20% less miles per gallon than gasoline, which gets roughly 20% less miles per gallon than diesel.
When I had my propane bus I was able to get fuel for ten cents a gallon in Mexico, so I didn't care. I stuck 300 gallons on the bus and had fun. But that's over now, and with current propane prices, if I were you I'd convert back to gasoline pronto. No matter how well your engine is working and tuned you probably won't see more than 4-5 MPG if you're lucky.
Best of luck... my guess is you're not too bad off but get that propane stuff checked out especially if it hasnt been serviced for 4-5 years...the diaphragms in the carb and regulator tend to stiffen up with age and crack, and can cause a lot of grief.
Cheers
Gary |
John Feld (Deacon) (150.199.209.48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 31, 2003 - 3:47 pm: | |
You might check with a local school (bus garage) and see if they have any mechanic that has experience with propane units.
Also, several propane engins are set up as multifuel engines (run on gas or propane) and can be switched at the carb. If yours is multi-fuel switch it over and try gas, or make sure someone didn't have it set for gas and your running propane. Best bet, have a qualified mechanic look at it before you risk damage.
John |
shamanstar (216.239.172.21)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 31, 2003 - 4:00 pm: | |
to be more specific, it is a chevy 454 big block with an allison 4 speed automatic. 1977 international. |
Johnny (67.241.166.188)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 01, 2003 - 1:45 pm: | |
Also, check out forklift service shops. Many of them run propane.
However, the octane rating of propane is VERY high--something like, IIRC, 112.
Who put a Brand X 454 in an International?! I'm gonna cry.......... |
DaveD (64.235.198.76)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 02, 2003 - 6:16 pm: | |
That loose marbles sound is a lot like what you might get with loose or broken torque convertor to flex-plate bolts.
DaveD |
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