MLVW M36 Crane Trucks
 

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./

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.

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.

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./

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

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.

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.

Will do that, thank you Rob.
F./

One more problem I have run into with these (and other military ) trucks. The primary filters were originally a fram PCS1144. I forget the secondary number, but I seem to recall it was a Detroit filter. I have seen where people go to NAPA (including a certain museum I am familiar with) and they cross over to their filters. The gaskets are not always a good fit and with the variance between the two, you end up sucking air on the primary, or else leaking fuel off the secondary.

Yup, been there done that.

We cross matched the number and ended up with a filter where the filter looked righ,b but the gasket was no where close (way more off than just a bad fit).

We eventually found that a Baldwin BF915 seems to have the same gasket location. at least it looks close by eye.

That number seems to ring a bell. I could check at work, we have a few different brands that came through the supply system.



The other day I actually had a pair of the oil filters leak on me. Same deal...a different brand of filter had the gasket of a slightly different diameter, and it leaked. I guess that explains why the other filters were so tight I had to bring a heavy duty strap wrench in from home to get the old ones loose. This was on a crane truck as well. We managed to secure two crane M36Cs for the museum. I don't particularly like that long wheelbase, but the heavy lift capability more than makes up for that.


I had some of the NAPA match-ups dump fuel into the hull of a 548 last winter. The gasket was almost completely off the mating surface. I stick to the originals now.

Dear All,

the NAPA equivalent filters for many brand name do not stack up, period. in the development of a spin on oil filter adapter I learned that even not all the threads are the same quality and when you use a filter cutter you find the construction is not the same by any means so gaskets issues are bound to follow.

The experiences stated by others is not surprising, despite the counter person's utterance of "ours is the same as XYZ but cheaper".

There is not a quality issue with the NAPA (which is also WIX), just an interchangeability problem. The Wix filters are well regarded overall.

Perhaps on some applications, the slight difference in diameter does not make a difference. In others, they are not compatible.

And it's hard not to try to find the working alternate when one is $12 and the FRAM is $40-$50.

Rob, I really respect you knowledge and experience in all things mechanical and military related, but having cut apart a number of WIX versus NAPA filters there is not the same surface area and construction, I am not able to agree with you on that point.

I agree to disagree on this one.

No need to disagree.


Wix reportedly makes the gold and platinum labelled NAPA filters. The regular level of NAPA filter could well have less quality and differing construction.



Of course, these days there are so many forgeries of products that those of us who like to find the cheap source are often purchasing made in China reproductions from sources like ebay or amazon.

8.2 Detroit
 

I haven’t thought of those engines in quite a while. Where I worked we had those engines in Ford F800 trucks. The biggest problem was blown head gaskets. When we had them in garbage trucks one blew a head gasket when fairly new and the dealer that sold us the truck wasn’t licensed to do the engine warranty repairs. We pulled it apart and replaced the head gaskets but no shop in our area at the time had the kit to set the injector height. I adjusted the valves with the injector rocker arms backed off. When it came time to set the injectors without the set up tools I put a dial indicator on the push rod and cranked the engine by hand until the push rod was on the high point on the camshaft lobe. I then put the dial indicator on the injector and tightened up the adjustment gently until the injector was bottomed out. At that point I back off the adjustment 0.035” so the injector tip wouldn’t be damaged. The truck ran well but with a bit of black smoke when accelerating. It was a couple of years until it got a proper adjustment because of the need to pass the new emissions test.

They were terrible for head gaskets, especially the turbo powered version, which could go through a gasket every 20,000kms. The cylinders were not supported in the block. Later they increased the size of the head bolts, which may of helped, but still did not change the poor block design.