February 14, 2012

Bombardier Iltis fuel system problems

If you've been following our schizophrenic blog, or have spoken to me for more than 30 seconds, you'll remember I bought a 1985 demilitarized ex-Canadian Forces Bombardier Iltis; primarily as a back-woods-camping-go-everywhere-vehicle.  It's been a learning curve for me, as I'm primarily a soft-handed IT security guy, not a wrenching auto mechanic.  This is my first manual transmission, although I learned on a standard, and it is my first carburated vehicle.  I *am* learning as I accomplish tasks, I should point out - and I'm trying to put some of my IT-troubleshooting skills to good use.
1985 Bombardier Iltis Engine Compartment

The Iltis, since I got it, has been loud, smelly, and the choke/throttle/starting procedure has been temperamental.  As the tail pipe points directly at the ground, I have sooty patches around the driveway on the snow, from the overly rich mixture I've needed to use just to keep the engine running when cold.  None of this has discouraged me, I'm pretty sure it's all adjustments and filters that need changing, then it will be a well oiled machine again.

By documenting the steps I've gone through, perhaps I can give someone else a push in the right direction regarding what to change, or at least what to look at, when problems that are potentially fuel related occur.  At the very least, you can laugh at some of the steps I've gone through.  

The Canadian Forces Bombardier Iltis is significantly different from the German VW Iltis under the hood, this can be seen immediately when looking in the engine compartment.  The Canadian Iltis went from initially using an in-line "barrel" fuel filter, and having the fuel pump at the back of the vehicle(similar to the VW), to having a canister-style diesel fuel filter mounted in the engine compartment, with a 24V fuel pump located right beside it, and a return hose going back to the fuel tank.  From what I read, the change in the style of filter and fuel pump allowed for use of gas that could have particulate in it, it seems the diesel filter they used was able to deal with grit much better.  

Photo Credit: Bluesky, soonet.ca 
Aug 28th, 2009
I also read that the Iltis (and I've been told some tanks) have foam balls in the gas tank, to act as an anti-explosion measure and to reduce "sloshing".  These foam fuel balls are blue/green, and since I had blue/green grit in the in-line filter, I figured they were breaking down, which seemed to corroborate with what others were reporting.

My fuel system came with a clear 5/16th" to 5/16th" in-line fuel filter, allowing me to see the flow through the system.  This was handy, since blue/green particulate was clearly visible stuck in the filter when I got it.  After changing the in-line filter to a 1/4"-1/4" opaque in-line filter, and using Seafoam on the carb, I was unclear as to what was happening, and couldn't see "in" the fuel filter anymore.  To remedy this, I replaced the new in-line filter again for a bigger transparent filter (WIX Brand), as well as replacing the canister fuel filter (WIX Part# 33358).  I'm not seeing particulate accumulation in the filter anymore, but once the weather is a little more comfortable I'm going to pull the balls out of the tank - I'll live with the sloshing!  I'm sure they are going to continue to deteriorate.

With the new fuel filters in place, and a partially cleaned carb (using some carb cleaner and SeaFoam), the vehicle drove ~42Km.  After driving ~21Km I took a 15min break, did some shopping and resumed the drive back; but now it seemed I had less power, or maybe I should characterise it as stuttering power.  Starting up off of 1st seem to have a hard time, and getting into 2nd seemed to bog down too.  Power didn't seem consistent.  3rd and 4th gear seemed pretty stable, unless I dropped the pedal to the floor, then it stuttered.  It got me home, but a seed of doubt was planted that the problem wasn't directly related to the blue balls.

Sunday I was on my way over to Stittsville to visit a buddy of mine and show him the Iltis, on the way over the problem seemed even more pronounced, and starting from any stop was touch and go.  I made it, just barely, and stalled on the way up his driveway (a 3 degree incline).  Clearly the problem had become worse, somehow.  I was now at half a tank of gas, was this a factor?  Not sure.  We brought the Iltis into his garage, and worked in the shelter, cold, but bearable.  We blew out the fuel return hose with air, took out the sending unit (which has no filter, much to my surprise) and it looked fine, removed half a dozen blue balls from the tank, and put it all back together.  We tested the rate at which the fuel was coming out of the hose going to the carb.  We tested what sounds things made when hoses were clamped off, we watched the rate at which the gas was flowing through the in-line filter; we did a lot of poking and proding, but didn't come to any firm conclusions.  The fuel system and filters seem to be working well - the carb might not be.

On the way home the engine seemed to be running better - was it the return line?  Was it a loose connection?  Was a blue ball stuffed under the sending unit blocking the flow of gas?  I'm not sure what we did, but it was better than when I got there.  When I was taking out the sending unit it looked like someone in the past 10 years had done the same.  There was wear on some of the bolts and screws, it looked like it had been removed before.  What if when the sending unit tube was stuck back into the tank the last time, it pinned a blue ball underneath?  It could have partially blocked the straw through which the gas is picked up and sucked to the engine...  Again, no proof, just a hunch.

When I got home, I broke out some metal polish called "Peek" (Available at Costco in Ottawa) which looks like a hair mousse product.  From my previous experience with Seafoam, I know a "foaming" cleaner will stick to the insides of the venturi and inside of the carb, and from my use of Peek on other metals, I know it leaves a fantastic polish, and a slight residue to prevent oxidation.  I had guessed I could use it on the carb, but wanted to put it to the test.  Well, I put a liberal amount in, tweaked the throttle revving the engine, repeated several times, and washed it all down with a liberal squirt of carb cleaner.  The engine bogged at idle just as it had done with the Seafoam, poked the throttle, revved the engine, sucking more of the foam in, along with air, and kept it from stalling.  The last squirts of carb cleaner were a cleanse palate, and left the throat of the carb clear of any residue foam.  SO, did I ruin my carb?  No, I didn't.  I took it out for a spin late last night and it worked better than ever - clearly something we did in the afternoon to the fuel system helped, but foaming up the carb helped in a different way.

I have a carb rebuild kit coming in from the UK for the Pierburg Solex 36 Model 1B1 which is in the Iltis, and I bought a spare (used) carb for cheap - so I don't need to remove the working one off the working vehicle until I absolutely need to.  I'll rebuild the "new" one and swap once I'm satisfied I haven't ruined it during the rebuild :)

These are the best comments I was able to dig up from people discussing fuel problems as they related to the blue balls and fuel systems in general.

"The issue of the break down of the foam balls in the gas tank and the collecting of junk in the fuel filters is also well known. DND replaced the Facet fuel pump from under the body (near the gas tank) and used higher PSI pump in the engine bay with a recirculating filter system (actually a diesel filter) with a drain. This fix seemed to get rid of the junk in the carb float chamber." -Iltis85, expeditionportal.com http://www.expeditionportal.com/forum/threads/71918-Belgium-Iltis-Belgium-to-Japan-rijstkorrel-be

"The SaFoam material used in the Iltis is not stable some of today's fuels. And I imagine this will only increase as time goes on.

There is a wide disparity in Fuels on the market today (especially in Eastern Canada) and the formulations and additives can vary greatly from brand to brand and region to region, Anti-knock additives Ethanol content (ethanol is also used as an antiknock additive) Combustion modifiers, Oxygenates, Lead replacement additives (yes it is still used in some formulations) Water emulsifiers, deposit control additives, corrosion inhibiters ,metal deactivators, antioxidants and the list goes on.

These additives can vary greatly from brand to brand and region to region. And not all are compatible with the SaFoam balls in the tank of the Iltis. In the U.S fuel Formulation can vary immensely from state to state depending on the that particular states requirements for these additives. Some states have some pretty nasty stuff they try to pass off as gasoline.

The same is true in Eastern Canada as good portion of the Fuel consumed in Eastern Canada is refined in the U.S. And with the way fuel is brokered nowadays you are never sure exactly where that fuel came from or what is in it. Just cause it is from a Petro Can, Shell or Esso Station there is no guarantee it is thier own refined fuel in their holding tanks.

But such is less likely to be the case on the prairies, Where 99.9% of the fuel consumed there is refined there. And their are only a few refiners. All the fuel refined in the prairies is done by either Petro Canada, Esso, Shell, Husky or Co-op. The prairies also ship raw fuel (no additives) states side.

In B.C Fuel Is imported from the U.S (lower main land and the Island) imported from the prairies or refined locally by Chevron or Husky.

The suggestion of adding a Clear fuel Filter in front of the cartridge filter on the fender is an excellent Idea. As soon as you start to see that green dust in it is time to yank the SaFoam out of the tank. But the SaFoam Balls probably should come out as a preventative measure any way.

The choice to spend the dollars to replace them with a fuel stable equivalent is strictly a matter of personal preference, they ARE NOT required for the service most all of us have these units in." -Matthew (iltis@yahoogroups.com forum) 

"Pull the gas tank, and scoop out all the little anti-slosh foam balls. They break down with time, and jam up the fuel system, and are the root cause of 90% of Iltis fuel system troubles." -RecceDG (army.ca)

These are the specs for the canister fuel filter that I used, and from what I understand all CF Iltises used the same spin-on filter.


Part Number:    33358
UPC Number:     765809333581
Principal Application:  Case, Cummins, Deutz, Perkins, Volvo (10
Micron) If drain is needed use 33472
       All Applications
Style:  Spin-On Fuel Filter
Service:        Fuel
Media:  Paper
Height:         4.709
Outer Diameter Top:     3.015
Outer Diameter Bottom:  Closed
Thread Size:    16X1.5 MM
Beta Ratio:     2/20=3/20
Burst Pressure-PSI:     300
Max Flow Rate:  6-8 GPM
Nominal Micron Rating:  10

Gasket Diameters
Number  O.D.    I.D.    Thk.
Attached        2.740   2.370   0.275
Packed  0.871   0.595   0.143


  1. This is some good info, and I will be putting it to use as I embark on my Iltis ownership. Incidentally, the guy who sold me the thing, delivered it to within 3 miles of my place, where the oil filler cap apparently "popped" off and oil spewed all over the engine bay, and produced enough smoke to prompt him to pull over and walk the rest of the way. The unit has not fired since, turns over fine, but doesn't fire. I believe it's fuel delivery.
    Wish me luck!

  2. I have an iltis, just got it in fact. I think a good idea would be in your photo of the engine, use photoshop or something to point to a part and name it

  3. No fire is commonly the distributor. Not the cap but below the cap