M915A1 Air Valve leaking,please help :D

[akita91]

Hi guys lurked for awhile ,purchased truck off this forum member.
https://www.steelsoldiers.com/showthread.php?181125-M915A1-for-sale
truck came home with only 1 problem,i think front passenger tire got flat spot,been bouncing off every small pothole,bump on the road like a bull riding machine.
and valve in pic leaks badly,truck barely holds 60 psi.1)
1)what u call it(red circled black cap)
2.what is the name of that beige filter or pump off fuel tank in pic
3.do i need change those black coolant hoses on the engine as they feel and look dry rot. ?
4.otherwise truck feels like a tank.
thank you.

 

[Floridianson]

My 915A1 had the fuel line heat transfer thing. If I remember there are coolant line fittings on the back side. Since we want cool fuel maybe it was put there to prevent gelling? I never liked it and was going to remove it but sold the truck. Can't help with the valve.

 

[NDT]

Welcome, nice truck! The red circle thing is your stoplight switch. Take it off and bring it to a heavy duty parts house for an updated replacement. Please don't drive it with 60 psi air in the system. All 915s ride like that, they will jar your teeth out with the Hendrickson suspension. Surely you should replace any questionable hoses! Tow bills on these start at $700!! You can bypass the fuel heater if you suspect it is causing issues. You won't be operating in Arctic conditions hopefully.

 

[akita91]

i meant it takes awhile to build up off cold start.but driving it holds 100 psi.it developed after trip ,noticed on gas station 100 miles before home.
is this possible to add air ride to this truck ?thanks.

 

[NDT]

Air ride? I think about that often. Huge job to remove the Hendrickson walking beam setup and then find a donor air ride tandem set up and redrill the holes for it in the frame. Try an air ride seat first. Helps some.

 

[Floridianson]

Agree on the up grade to air ride seats. I did not like the fact that if the cooler leaked it would put coolant into the fuel. Also forget but if I remember for every 10* in fuel temp we loose 2% HP.

 

[porkysplace]

Have you downloaded the TM's yet ?

[h=1]TMs for M915 to M920 Series trucks[/h]
[h=1]Tm 9-2320-363-10 M915A1 M916A2 M916A2 M917A1 operators manual[/h]

 

[akita91]

ya,already went thru 60 pages ,per manual gcwr is 105k ,it can go 25mph 3.90% grade full.how fast it would go under 80k at 6-8% grade ?as i see new engines produce 1500ft lb or more .cummins only 1250.does it mean i will crawl with flashers any grade if so,what can i do to sustain decent pace? can i swap out transmission to allison 4560 which is electronic(as i know they use them in new 915 models).

 

[simp5782]

ya,already went thru 60 pages ,per manual gcwr is 105k ,it can go 25mph 3.90% grade full.how fast it would go under 80k at 6-8% grade ?as i see new engines produce 1500ft lb or more .cummins only 1250.does it mean i will crawl with flashers any grade if so,what can i do to sustain decent pace? can i swap out transmission to allison 4560 which is electronic(as i know they use them in new 915 models).

You can add a dual fuel line setup. Some hot injectors and an HT4B turbo and that BCIII will go from the 1300ftlbs to about 1600. More than the transmission can handle. Probably should check and see if you have an HT3B or 4LHR on it now.

I have everything you would need to put a CAT 7155 in it in the classifieds. Bellhousing, adapter, umbilical, transmission. It's a direct swap on the A1 trucks to put the 16 speed in it. Not quite an automatic but that 915 will fly down the highway.

Sent from my SM-G965U using Tapatalk

 

[akita91]

i dunno.how long it will take me to learn shifting also can you swap it ?

 

[simp5782]

Its easy to shift. Once you get the hang of it you will love it.

 

[Floridianson]

You sure it was not rated for 50k. Yes it will do a lot more. First what did you get the truck for cross country or local hauling. With the stock set up it she will pull real nice on hills. I have a 915A2 and 4.56 gear set Allison four speed. My top speed is 60 mph at 2100 rpm. Now I was thinking about a rear gear set change to give me more top end but I am going to leave it alone. They want 5k to switch both rear gears. I do not travel now that far from home and cruse at 55. Yes I will use more fuel but 5 k buys a lot of fuel and I only go to the Ga. rally but have gone as far as the NC.rally. Yea the long haul truckers pass me on the flats but I can hold 55 mph on the hills and leave them behind. You don't want to get into a computer Allison and there would be so much else to add not worth it. Mine is not a computer controlled and glad it's not. Yes I could go computer controlled because my Detroit 60 series is but as I said I rather have governor controlled. If you wanted just some more top end you could go 395's but it will kill your low end grunt. You can't go 53's because the walking beams are shorter than the bigger 916 920 so on walking beams. Yes the Hendrickson is nasty with out a load but it is a tuff one. You got a good transmission and myself would just step up the tires size and see how you like it. Maybe you just bought the wrong truck for what you want to do.

 

[akita91]

i wanna otr in it for now i leave it alone and try to start.then will change things if i dont like 60mph.just from observation everyone is pushing 70mph.what do i need aside trans,ecu,shifter,tps to match it as those new versions have 4560 in them rite?tall tires doesnt work for trailers ?

 

[Floridianson]

OTR then you got the wrong truck. Every day I see nice road tractors with sleepers big power and looking good on different auction sights some with not that many miles. O well good luck.

 

[akita91]

if it gets 4.5-5mpg and dont break* down first month then everything should be fine.as i know i can upgrade engine and transmission to match 70mph and add coffin box afterwards.

 

[akita91]

do u know what type of coolant i should use also can i flush it with tap water?

 

[NDT]

OTR then you got the wrong truck. Every day I see nice road tractors with sleepers big power and looking good on different auction sights some with not that many miles. O well good luck.

OMG spend 10 hours in a 915 and you will be ready for a few days rest. These things are only slightly better than a full tactical truck. These trucks are good for local drayage and such. I love mine but just for occasional use.

 

[akita91]

https://drive.google.com/open?id=1yf0pG1HDBgLkMbTpGefeh6zpWuEjdPeD https://drive.google.com/open?id=17YQHUg6N8erFtAaDGEYuUpEPyiyM33GK https://drive.google.com/open?id=1BQvsM0knn9cbOXdJzPjrdtxxwwcdaKxl
white creme is caulk i tried to seal ,how do you call those 2 parts both are leaking

 

[Floridianson]

OMG spend 10 hours in a 915 and you will be ready for a few days rest. These things are only slightly better than a full tactical truck. These trucks are good for local drayage and such. I love mine but just for occasional use.

I drove for US Express 53's coast to coast with a brand new Freightliner air ride cab / seat and air suspension and it still took it's toll on me.

 

[Tow4]

I dove my M915A1 pulling my M373 trailer to NC a couple of months ago. With the trailer in tow the ride is not too bad and I also have an air ride seat. Bobtail will beat you to death. It is slow and you are only going to see 60 mph or a little more if you run it at the red line. Mine runs down the road comfortably at 58 mph at about 2050 rpm.

I had no trouble pulling 6 and 7% grades with out a down shift at 55 mph. My trailer was probably about 12k with the items I had loaded. Fuel economy was 6 mpg with the AC on all the time. I'm sure the mileage will be less at 80k. Consider that modern OTR trucks make 6 mpg at 70 mph weighing 80k and are more comfortable. If you are going OTR, speed is important, you need to get as many miles in during the hours you can drive each day. It is less of a factor for local runs.

BTW, I believe the 50k gross weight figure is what the tractor with load on the 5th wheel can weigh. The 105k figure is the combined gross weight of the tractor, trailer and load.

Good luck.