Late M-170 vaccuum lines

Claudio · Post by **Claudio** » Fri Aug 13, 2010 5:40 am

Hi Folks, see the story of my M170 and my questions for installing ventilation lines of my 1962 M170.
It seems that late M-170s had no deep fording apparatus, so probably eliminating most of the vaccum lines, at least the ones from the fuel tank, bellhousing and some other ones that I am not sure about. My only available G-758 1955 Parts Manual shows early M38A1/M170 with the whole system installed.
However it is to suppose that the 24V electric system was still on all M38A1 and M170 from this era (1962 and further models), so the distributor MUST be ventilated.
My M170 has the late style air filter (flat cover), only one ventilation/breather tube on the oil dipstick and one ventilation/breather on the valve cover neck.
I have in hands one crossover tube (the one with fittings to connect deep fording valves) and also one complete set of fittings to mount of valve cover breather. These were bought recently, so probably did not belong to the jeep originally.
The air filter has 2 capped inlets (were probably closed by two bolts by the former owner or so).
So questions: what vaccum connections shoud I make to keep the distributor ventilated? in fact I have no idea how to connect all other breather tubes available. My recently bought fuel pump is the regular M38A1/M170 pump, with all fuel and vaccuum inlet/outlet bores.
What about the fuel tank? was it vented only by means of the tank cap? I have no idea of venting the master cylinder?
Thanks guys!
Best!!!

Post by **wesk** » Fri Aug 13, 2010 1:01 pm

Hello Claudio,

The bulk of the engine mounted ventilation system is still used on the M38A1 and M170 from 1953 on thru the end of production in 1968. The primary difference is the line from the fuel pump center body vent to the firewall is not used and a plain vent fitting is installed there instead.

A correct pump would look like this:

In the illustration below you will not need lines 2, 3, 4, 5, 6, & 7

You should go to our "Downloads" page and download the changes to TM 9-8014 and 9-8015-2 which contain the updated illustrations and descriptions for the M170.

Claudio · Post by **Claudio** » Sat Aug 14, 2010 5:14 pm

OK Wes, I will take a look at the manuals you have recommended as soon as I get home next week. I'm about to board overseas (Russia) and this computer at the airport is very slow for downloading files like these manuals.
Concerning your explanations, most of my doubts are solved. Thanks!
Questions still to be solved (I will take a look at the manuals), buuuuut...
1 - Where shall the upper engine head valve cover breather tube be connected to?
2 - The dipstick tube of my jeep has only one side breather tube. As you well know, early M38A1 jeeps had 2 breathers. So if I connect this to the crossover (air filter-carb) tube, it still remains the question where shoud the valve cover breather tube connected to?
3 - Vaccum line to the windshield-wiper motor - connection?
Well, thanks again!
Claudio

Post by **wesk** » Sun Aug 15, 2010 8:43 am

Hello Claudio,

The single vent oil filler tube doesn't seem show up until late 1963. I have several M170 file jeeps after yours in 1962 up thru 13719 and they all have the two vents on the oil filler pipe and the vent in the top valve cover. If you have a single vent oil filler tube and a vented top valve cover then I would assume someone replaced the oil filler tube for some reason and used the wrong tube.

Claudio · Post by **Claudio** » Wed Sep 15, 2010 8:59 pm

Hi Wes, let me insist again with the vaccum lines of the engine configuration of my M170 truck, that are still unclear to me.

1 - Oil filler tube with one single vent - I have 2 of such ambulances at home and both of them have only one single venting. Years of mfg. are 1962 and 1967. I've seen other trucks from this same vintage with the same engine configuration. All these I've seen seem to have their original engines, so indicating that the original venting system had been kept intact. Remains of wiring harnesses indicate that these trucks were supplied with 24V electrics, so requiring the distributor built-in coil to be ventilated and cooled from an external suction source (fuel/vaccum pump). My apologies if this may sound obvious for you, but I am still learning all this, OK?

2 - I can also suppose that contracts of supply of these ambulances to Brazil could at some instance comprise engines with this configuration, i.e., no deep fording apparatus and a simpler venting system. Do you have records of these supplies?

3 - Another fact that makes me insist with you is that a double venting oil filler tube would only be justified for a vehicle equipped with deep fording apparatus. Please notice that a double vented oil filler tube has: one vent connecting to the rocker arm / valve cover breather and the other oil filler tube vent connecting to the on-off deep fording valve, fitted to the crossover tube between air filter and carburator. This may justify the need of 2 vents mounted of oil filler tube. My jeeps have ONLY one vent outlet on the oil filler tube. What about that?

4 - Figure 20 (fuel ventilating system) from the G-758 manual that you've posted here to explain me the fuel pump system indicates that the line nr. 9 connects the fuel pump to the lower deep fording on-off valve. So would this be necessary to a vehicle with no deep fordind apparatus outfitted?

Remaining question is: where shall in my case the vaccum line from the wiper motors be connected to (on the fuel pump)?

Thanks, regards!

Claudio

Post by **wesk** » Thu Sep 16, 2010 9:37 pm

1 - Oil filler tube with one single vent

The crossover pipe fording valve was simply replaced by a longer section of hose on later vehicles. There is no available data to support the replacement of the two hose oil filler tube with a single hose oil fller tube but it appears the very late MD's and MD-A's had the civvy CJ5/CJ3B filler pipe. The same Part Number 8329683 oil filler pipe was the only one listed in all M38A1 supply publications through the TM 9-2320-208-34P dated 1966.

2 - Do you have records of these supplies?

No. But I am sure engines with both style oil filler tubes were in the supply system after about 1960.

3 - Another fact that makes me insist with you is that a double venting oil filler tube would only be justified for a vehicle equipped with deep fording apparatus.

No, the double hose filler tube was listed for all m38A1 and M170 thru the 1966 supply pubs. They also listed a short hose for use with the fording equipped jeeps and a long hose used with later non-fording equipped jeeps.

4 - Figure 20 (fuel ventilating system) from the G-758 manual that you've posted here to explain me the fuel pump system indicates that the line nr. 9 connects the fuel pump to the lower deep fording on-off valve. So would this be necessary to a vehicle with no deep fordind apparatus outfitted?

Line 9's primary purpose is to connect the vacuum side of the fuel/vacuum pump to the intake manifold. The primary purpose of the vacuum side of the fuel pump is to boost available manifold vacuum to provide better vacuum windshield wiper operation. The fording valve installed just before the PCV valve is there to provide a means to pressurize the crankcase which is the source of pressure for the fording system. In later non-fording equipped jeeps the valve is replaced with a section of hose and hose nipples. Line 9 remains on all jeeps.

Remaining question is: where shall in my case the vaccum line from the wiper motors be connected to (on the fuel pump)?

Line 8 & 9 and the Wiper "T" and the distributor vent line remains on all MD's and MD-A's. You connect your vacuum wipers to the short tube protruding from the Wiper "T" fitting.