Didn't expect that

chazwood · January 06, 2013, 08:39:07 AM

The l10 is pretty good on fuel around 7.5 it seems to be a simple straight forward engine. It starts instantly, runs cool and seems happy to be alive until you hit the slightest up hill. Then it dogs down like it's trying to climb a cliff. No amount of standing on the pedal makes the smallest difference. I haven't broken down the PT fuel pump, but I suspect if there is some kind of rubber diaphragm in there that reacts to vacuum and tells the fuel pump to pour on fuel, it's ruptured.
It has no acceleration, no smoke, and no indication that it's ever in the slightest bit of a hurry. I am determined to make this thing fly if it's the last thing I do.
Other than that I love it.
My other bus is a mci9 with a 6v92.
When I drag race my son he kicks my tail with it.
He's doing 40 up hills I do 17 on.
Not good for the old self esteem.

Mex-Busnut · January 06, 2013, 03:26:13 PM

Wow! I am amazed, especially seeing how popular the L-10 was here in Mexico, and the fact that everywhere we go we are climbing mountains.

Does your L-10 have a turbo on it?

chazwood · January 07, 2013, 07:44:20 AM

Yes, I had it apart just last week. It spins very smooth and has no leaks. Don't think the turbo is the culprit.
It feels to me like the fuel volume and pressure stay constant no matter how the pedal is depressed. Down hill, no load; acceleration ok. Uphill, under load; get out and push.

It will go 75 on the flats.

Sam 4106 · January 07, 2013, 08:31:20 AM

"Don't think the turbo is the culprit."

Do you have a boost pressure gauge? If so, how does the boost pressure compare to the engine specs? Have you checked your air filter? Do you get smoking on hard acceleration? Is your fuel pump producing the pressure it should? Is there any restriction in your exhaust system? These are a few thoughts about your engine being under powered. Hope you find the solution without too much expense.

Good luck, Sam

poppi · January 07, 2013, 11:06:45 AM

Just a few thoughts with a lot of ifs.

I have a L10 with a ZF auto-tran......So I don't know what transmission you are running. (makes
a difference). I also don't know if you had the differential regeared for the higher torque/lower rpm. (makes a difference)

IF the tranny doesn't down shift soon enough the engine will bog down
If the bus has the stock diff for the 2stroke engine then the engine will bog down
If the driver doesn't anticipates the slightest up hill the engine can bog down.

With time and experimenting it might just be an operator fix.

Mine goes great but if I let it bog down even the slightest I pay the price of slowing to a crawl.
15mph vs 45mph on the passes around here.

Have fun
Skip

chazwood · January 08, 2013, 03:38:33 PM

How do you prevent it from bogging down?

chazwood · January 08, 2013, 03:42:49 PM

My trans is an auto Allison

chazwood · January 08, 2013, 03:45:42 PM

When this thing starts up a hill, the lower the tranny shifts the faster she slows down. She chugs along pretty good in 4th but don't let her smell 3rd.....she drops off pretty quick in third.

chazwood · January 08, 2013, 03:47:36 PM

Quote from: Sam 4106 on January 07, 2013, 08:31:20 AM
"Don't think the turbo is the culprit."

Do you have a boost pressure gauge? If so, how does the boost pressure compare to the engine specs? Have you checked your air filter? Do you get smoking on hard acceleration? Is your fuel pump producing the pressure it should? Is there any restriction in your exhaust system? These are a few thoughts about your engine being under powered. Hope you find the solution without too much expense.

Good luck, Sam

Don't have those testing tools. Where you you find them for this engine?

Sam 4106 · January 08, 2013, 05:01:44 PM

The boost pressure gauge was fairly simple on my DD 8V92TA. There was a plug in the air horn between the turbo and the intake. I installed an 1/8" tubing fitting where the plug was and ran the 1/8" tubing on the outside of the bus into the drivers window, temporarily. There I used a 30 PSI gauge, you may need a higher pressure, from the local hydraulic hose store, to check the boost pressure. I had 22 PSI at 2100 RPM in third gear on a steep hill. You will have to select the gear that gives you enough load, yet allow the engine to get up to governed speed, on a steep hill. To be sure there was no restriction in the air filter I installed a new element for the test. Probably not necessary if your air filter doesn't have too many miles on it. Then compare the PSI reading you get to the Specs for your engine, which you should find on the internet. Checking the fuel pump pressure would probably require removing the pump and taking it to a pump and injector shop. They should be able to tell you if the pump pressure is within your engine's parameters. For exhaust restrictions look for partly crushed pipes, especially the tail pipe after the muffler.

Did your bus come from the factory with the L10 engine? If not, maybe the transmission shift points aren't right for your engine. You can manually shift down to keep the engine speed higher, to keep the engine from bogging down too. Still hope you can find the solution without too much expense.

Good luck, Sam

lostagain · January 08, 2013, 05:06:44 PM

Chazwood,

you have to shift your Allison manually. When going up a hill, as soon as it starts slowing down, watch your tach. and down shift into 3rd as soon as possible. Whatever rpm it is that it upshifts at. Probably around 1700 rpm, depending on your governed rpm and gearing. That will put your engine back at or near the governor, where the power is. If you don't do that, the Allison will let the engine rpm slow right down where there no torque and it will bog down. Those transmissions are not smart enough, they need supervision.

JC