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Letter 34

Isuzu Trek Owners Infoletter #34

May 2014

  Valve Stem Extensions

Bret and Laura, Whidbey Island, WA, (islandduo at Remember to replace “at” with @ in the email addresses.

I have taken it upon myself to forward your request for input to about 15 folks who have contacted me about Isuzu Treks in the event they are not aware of the Infoletters. You may be hearing from some of them.

Right off the top of my head I only have a quickie to maybe save someone else the research time leading to a dead-end. I very much wanted to install a set of dually valve stems on my Trek when replacing the rear tires and spent a long time and a lot of e-mails only to finally determine none are available for the Isuzu chassis. It seems our wheels use a somewhat different valve stem sealing arrangement, using an “O” ring, and none of the manufacturers of dually valve stems make that style of stem. In the end I was forced to go with a new set of flexible extensions similar to the originals.

Editor note: Thanks for the input.  I looked for fixed extensions also but could not find any.  I talked to two different tire manufacture representatives and they told me a significant number of tire problems (failures) can be traced back to problems with the flexible extensions.  Like a lot of things, they have mechanical parts that require inspection and maintenance.  My solution was to just enlarge the holes in the wheel covers to get better access.

 Cabinet Hinge, Fuel Filter, Vacuum Hose and more.

Bob and Wanda Diachuk, (bobdiachuk at

I’ve read the Isuzu Trek infoletters and found lots of great info… some things I can share are:

-Check hinge tightness on cupboard doors especially the large closet doors.  Ours fell off, just missing the glass shower and put a nasty gash in the wall between the toilet and the shower!

-Always keep a spare fuel filter and a bit of diesel.  Have had issues getting fuel with particles in it;  just change the filter (topped up with fuel) for a quick fix!

-Replace vacuum hoses … if they are original, then they leak!!!

-Get a spin-on filter kit for the transmission. (Editor-this is an Isuzu service letter item).

-Check exhaust manifold bolts from time to time.

We love our little Trek, we’re full-timing and our ‘92 is in awesome shape!

Editor: I was told by service personnel there is a second filter in the “banjo” fitting where fuel enters the injector pump.  Worth looking at if you are having fuel flow problems.

Engine gauges, Inverter, Exhaust, Electrical Problem, Diesel Additive Study and Ladder. 

Jeff and Vera Johnson, (jvjohnson at

These are a few of the projects we have done on our 1992 26′ Trek.

Installed a Tiny Tach digital LCD tachometer. This is a pulse-type tachometer that clamps onto the fuel injection line, very easy to install and great customer service. Type in Tiny Tach and it will pop right up on the web.  Get about 14-16 feet of lead wires for routing as you don’t want to run short.

Also installed an Isspro brand mechanical boost gauge. I tapped into the small rubber hose (on the passenger side) from the air inlet, just before the engine air intake manifold, that goes to the aneroid (or smoke limiting device) on the injection pump. It is a 5/16 or 3/8 inside diameter hose, I believe. This makes a pretty easy install.

The last gauge was also from Isspro in Portland, OR, and that was a pyrometer.  It needed a 1/4″ npt pipe union welded into the exhaust just after the turbo about 8-16″. Again a fairly easy process for wiring it up, etc. All of these gauges were installed in a GlowShift triple gauge pod found on Amazon.

We replaced the dead Heart Interface inverter with a Magnum MM1212 1200-watt inverter, which was very easy to do and very straight-forward. I just had to run the communications cord thru the freshwater tank storage area and install the ME-RC control panel. We mounted our controller on our driver’s side upper closet panel.

The 3″ exhaust made a vast difference for hill climbing, as mentioned in one of the earlier letters here. Yellowstone was (relative with129hp) a piece of cake!

One thing I found out is if you have (two at the same time!!) AC electrical neutrals reversed going into or in your coaches’ electrical system it will drive you crazy. One was in an extension cord; the other was done by yours truly while trying to understand why I was getting such goofy readings on my Fluke volt meter at the replaced GFI. If you have an electrical issue, go buy one of those $12 GFI testers with the led lights that tell you what’s going on, as it will save you from ripping your hair out and muttering to yourself.

There is a great article on diesel fuel additive lubrication at the following:

Also, there is a great ladder for any of us who want to really see what is going on, on top of our  motorhome but hate drilling a bunch more holes in it. I found one at a Home Depot which is designed for going into attics;  it’s a spring-loaded pull down type. Very light weight, 12″ wide, 250lb rated (we won’t go there), collapse-down to 36″ or less, and has almost a 10-foot reach for around $100 bucks.

Here is a shout-out to two good service centers: one is of course, Carrier’s in Eugene, OR: the other little jewel is Expertec Auto in Hood River, OR (541)-436-3545 on I-84 on the Columbia Gorge. Beautiful trip if you ever get a chance to go thru there.

Power steering problem revisited (ref Infoletter 29)

Ken Harmon, (IsuzuTrek at

On our way to the southwest for the winter we had another power steering tube failure.  With this problem, the coach could be driven but it is very difficult to maneuver in cities.  We stopped every 10 miles to add Dextron transmission/power steering fluid to keep the pump lubricated.

The tube failed again by developing a crack in the radius of the flare at the lower end where it connects to the pump (lower right forward corner of the engine).  This time the bracket that supports the tube was not broken and the tube was well supported.  It appears the Isuzu replacement tubes are not a good fit and need to be “adjusted” by bending them to the proper shape to prevent pre-loading the tube. We now have tube #4 installed on our coach and are carrying a spare.

Thanks to everyone who contributed to the Infoletter.  Ken & Cathy