MLVW M36 Crane Trucks

[FrankJames]

Assistance Request.

Is anyone in here familiar with the the difference on the M35 vs M36 crane truck?

On top of being 4ft longer, the M36 has what appears to be an air line going to the high pressure pump. All the M35s we have only have caps there.

Related there is also some kind of electronically controlled unit on the firewall and a different distribution block bolted to the top of the motor.

We can't get this one started and would like to know a little about what we are working with.

Thanks in advance for any info you might share.

F./

[rob love]

High pressure pump? I think you are talking about the governor, aren't you?



That is for the high idle, which you engage when the crane is in operation. It takes the engine to 1200 rpm unless you turn off the power, or shift the transmission out of N.

It is very likely that you have a seized injector, which is common on these trucks if they sit for a while. Pull the valve covers, and look for a bent pushrod.

Good news is you can usually disassemble the injector and clean it up with a plastic scrub-bud.

You can straighten the pushrod, but you will have to use an injector setting dial gauge and set it to the specification listed on the decal of your valve cover. Hopefully the decal is still there and readable, otherwise you have to do the full base circle timing, which involves removing the head(s). Or, you can cheat and just set the injector in the ballpark to what the others are set at.

The 8.2 was not a great engine. We had injectors seizing even when the trucks were being initially delivered.

[rob love]

Another no-start problem: Pull your filters and see if they are full. If down to around half, then it is a fuel supply problem. The fuel lines on the MLVW are pretty cheap and usually pretty old. They break down and will suck air.

Best thing to do is go to any trucking or hose place, and get re-usable fittings along with the hydraulic hoses to replace the original fuel lines.

I don't know why they did not run a steel line for most of the fuel line, and a decent quality line where flexing would occur. Oh well, we still got 37 years out of them.

[FrankJames]

Thank you very much for the responses, Rob !

I'm new to these things and without a manual (usually working on farm tractors), we followed the fuel lines back and jumped to the conclusion that we were looking at a high pressure pump. Excuse our idiocy... lol

But I figured the air was some sort of governor set up, only being on the crane trucks.

When you say, turn the power off, is there a switch that needs to be turned on to engage the 1200 RPMs ? We have another M36 truck with the crane and we just start it and begin using the crane. Only used it a few times...

Curious what sort of fuel line you are using for suction side fuel line. The stuff my son got for us is quite expensive.

Appreciate the advice about the seized injectors and bent pushed rods. ... and I'm praying we aren't into removing heads. But we don't seem to have much fuel suction (if any) at all. Right now, we are running a new fuel suction line directly into a five gallon can. We replaced the lower fuel filter (filled it first) and it doesn't seem to be taking much out of it.

THere is a bit of white smoke coming out the exhaust when we turn it over, so we are probably getting some fuel.

F./

Originally Posted by rob love

High pressure pump? I think you are talking about the governor, aren't you?



That is for the high idle, which you engage when the crane is in operation. It takes the engine to 1200 rpm unless you turn off the power, or shift the transmission out of N.

It is very likely that you have a seized injector, which is common on these trucks if they sit for a while. Pull the valve covers, and look for a bent pushrod.

Good news is you can usually disassemble the injector and clean it up with a plastic scrub-bud.

You can straighten the pushrod, but you will have to use an injector setting dial gauge and set it to the specification listed on the decal of your valve cover. Hopefully the decal is still there and readable, otherwise you have to do the full base circle timing, which involves removing the head(s). Or, you can cheat and just set the injector in the ballpark to what the others are set at.

The 8.2 was not a great engine. We had injectors seizing even when the trucks were being initially delivered.

[Lynn Eades]

Blue smoke = oil
Black smoke = fuel
White smoke = no fuel.

[rob love]

No need at this point to pull the heads. Just pull the valve covers and check the pushrods on the injectors. If one is bent it will be loose. One stuck injector holds al the racks to zero on these motors, as opposed to the runaway situation you get with other jimmys.

To operate the high idle, you have to have the truck running and in neutral, and flip the switch beside the PTO knob. That will kick it in to 1200 rpm. If you shift the tranny, or turn of the master, the rpm will drop back down to idle.

For fuel line just use hydraulic hose with reusable fittings. That will outlast you. Just check as not all hydraulic hose is recommended for diesel. But if you go to a hose place, you won't be the first guy to go there looking for this purpose.

[FrankJames]

Will do that, thank you Rob.
F./

[FrankJames]

Ya, didn't seem it was taking much. But it seemed like we could smell diesel in the white smoke. More investigation to do.

But the advice we've received on injectors will come in handy as we have a few of them....

Tks.