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Letter 17

Isuzu Trek Owners Infoletter #17

June 2005

Trek Water System modifications and Firewall bolts fix

Lonnie Wilson (Lonwill310 at has some neat ideas, He says: I want to tell you about three little things I did lately on the Trek:

1.  Streamlined water hose/sewer hose area (objective here was to get everything in one place and reduced space):  I noticed water leaking from the area where you input water.  I took the plate off, removed the stock pressure reducer/one way valve and screwed in a 1/2″X1/2″ MPT x FHT (female hose thread) adapter. To this I attached two 25’ (50′) coiled water hose (the kind that is small and tends to coil up on its own.)  I drilled some holes in the plywood floor that separates this compartment from the electrical cord compartment below and zip tied the base of the on-board end of the hose to stabilize it.  On the female end of the hose, far end, I attached a hose “Y”.  To the end of the “Y” I attached a standard pressure reducer/one way valve.  This attaches to the hose bib water supply.  To the other side of the “Y” I attached a hand sprayer.  I use the hand sprayer as an outside water source for washing hands, dog water, shower, etc. when dry camping and the Trek’s pump is on, water at the sprayer is under pressure. A short hose could be attached here to use for washing down the sewer hose with shore-side water. One thought was to use one of the two 25’ sections of hose to put 25’ for the water supply and 25′ for the sprayer.  Then if you need 50′ for the supply you can put the two together. I put the coiled hose behind the existing plumbinthis compartment.  A plastic battery box neatly fits into the remaining space in the compartment.  In the battery box I have 10′ of sewer hose, attachments, gloves, a set of channel lock pliers.  Now when I start to hook up, I don’t rifle through the outside compartments looking for things – I have everything in one place.

2.  Bolt firewall to body:  Drilled holes from outside wall to original plate.  The angles did not allow drilling from the inside out.  To get the first holes, I made a jig from scrap angle iron and lumber scraps.  Made a giant thin “U” with the wood as blocks at the base of the “U”.  I drilled matching holes at the tips of the “U” and securely bolted the base.  The length of the “U” is 3′ and the ID is 2.25″.  Slipped the “U”, from the bottom, over the Trek body so that one tip of the “U” lined up with an original rivet hole in the firewall frame (inside side of wall).  The other tip was used as a guide for my drill hole.  I didn’t nomally hit dead on, but was close enough.  This worked pretty well on the lower part of the firewall frame that slants up.  Once you have that, the vertical portion is 1.5″ (’94 2830), I need to recomfirm this for anyone that tries this) from the vertical front seam and runs all the way up to just below the window.  I put in  several 8-32 x 3 machine bolts.  Used 3/8OD Bonded Neoprene Washers on the outside and lock washer and nut on inside (all at Loewes).  That seems to have quieted things down quite a bit.  Don’t have many
miles on it yet.

ADDENDUM  — Firewall bolts fix

Re: The firewall bolt fix.  All of the bolts on the vertical line on both sides sheared after about 1,000 miles.  I have put in very large sheet metal screws 14×3 with 5/8 OD neoprene washers.  I’ll let you know how long this lasts.

Firewall Bolts – another fix
I’m sure he is correct on his firewall bolt fix. Just the idea of putting in more or larger bolts is not the answer. On our Trek, in the bolt area I had large gaps between the Safari made adapter and the coach shell, 1/4 inch on one side and 3/16 inch on the other side. You cannot physically pull things together with bolts alone. You have to fill the gaps so that nothing is capable of moving. I used 4 inch wide aluminum plate stock as filler pieces, some of which were extended back far enough to be held in place by the four mirror bolts also. I coated each piece with a layer of caulk after I first fitted them and drove them into place. Only then did I drill holes and put the screws in. Last thing I did was do a final caulk job. I used a polyurethane caulk. So far so good, no cracking of the caulk, no loosening and more important, no shaking.
John M. (cvrwy at

 Lost Alternator Bolt

Editor Dale (daldr at sez:: Our ever faithful ’94 I-Trek waited until we were less than 30 miles from home from our annual 3000+ mile trip to our Baja winter home to lose the bottom bolt in the bracket that holds the alternator/vacuum pump in place. The result was a serious loosening of the belts with accompanying squealing of the belts but the belts still turned the alternator enough that neither the alternator nor vacuum light came on. We drove the 30 miles home successfully but the chassis batteries were significantly depleted when we got there. A phone call obtained a new (used) bolt, sleeve and nut from FMI in Portland for $10 plus shipping (new parts not available in state without a several day wait) and a local shop put the new bolt in. I decided not to tackle it myself as it was in a really hard place to get to. FMI estimated 2 hours to install. The local shop did it in 1.2 hours so the Trek and I were both happy. It would be a good idea to check that bolt/nut for tightness and if at all loose, apply some Loc-Tite or get a self locking nut.

 Vacuum loss?

On that same subject, do you have a plan B for when you lose a vacuum pump? The I-Trek vacuum pump piggy-backs on the alternator. With vacuum loss, the brake assist is lost along with use of the cruise control and ability to change heater/airconditioner settings (anything else?). So, if you are off to Canada or Mexico or other hinterlands, what is your plan? Mine is to take the auxiliary vacuum pump that supplies vacuum to the toad brakes and plumb it into the Trek system (probably a two hour job) to get me back to civilization. I’d like to hear your plan. Send it to me and I’ll put it in the next Infoletter.

 Roof Leaks

Hugh McCusker (mcquic at fixed his. Hers is how: Minature fractures on the roof surface on either side of the AC unit was causing the problem.  It looked like someone had a pen knife and stabbed the two areas.   Product called elastomeric by Kool Seal was rolled on and did the job.  Used about four gallons and did the entire roof. No more leaks! Since then, We had a half dozen hard all day rains and we were high and dry.

 Strange symptoms lead to alternator

Al Readdy (areaddy at says: My engine warning lights were flashing on and off at start up, idle and  speed of 5-10 mph.  I could also hear the relay in the fuse compartment clicking at the same time.  Revving the engine would fix the flashing.  When I was ordering filters, fan belts and hoses at FMI (10% discount to Trek owners), I asked what would cause this. The answer was that a failing alternator , loose connection or faulty relay (the blue? one) would be the most likely cause.  When I had my friendly local mechanic replace the fan belts and hoses, I asked him to also check the alternator and for loose connections.  He informed me that I had a bad oil leak where the vacuum pump attaches to the back of the alternator and the oil had gotten into the alternator and made it un-repairable.   A rebuilt alternator and new gaskets fixed the problem with no problem in the month since the repair. (The ’93 Trek has ~96k miles on it.)

 Door Hinge wear

Editor: Someone said that we must have heard about most all the little problems we have with our treks in the Infoletter by now. I don’t think so. Our rigs are getting older and will continue to develop new ‘idiosyncrasies’. So, we can learn from those who have the most “well used” Isuzu Treks, like Ken Harmon (kencathyha at who has over 150,000 miles on his Trek now, after a fine adventure through mainland Mexico this past winter. Ken shares with us:

Over time I noticed the entry door was getting hard to open and close.  I adjusted the striker plate several times but eventually ran out of vertical adjustment.  On closer inspection I found the aluminum door hinges had significant wear, allowing the door to settle lower in the frame.  I initially inserted “E” clips found at the local hardware store
(sometimes called “C” clips or cir-clips).  They worked for a while but tended to pop out over time.  The long term correction was to split  some narrow washers, spread them open, insert them around the door hinge rod,  and then squeeze them back to normal size.   The washers raise the door in the frame and allow the striker plate to be adjusted for proper door operation.


Ken also commented: Looking around under the front of my coach one day I noticed two unused horns mounted on the front cross member of the frame.  They look like the  old 4″ diameter VW beetle “beep-beep” horns and sounded  about the same  when I tested them with a jumper wire. I added the horns to the horn circuit by  wiring them into the power lead at the air horn motor.  Now I have the “tweetie bird” air horn sound plus a unique base note that makes the overall horn system

Editor: I’ve got them on my Trek, too!

 Commentary: On ‘Power Boosting’ the Isuzu Engine

Over the years, Ken Harmon has been a respected Trek engineer/mechanic who has made many contributions to the Isuzu Trek Infoletter. Regarding the commentary in Infoletter #16 about Power Boosting the Trek Engine, he has this to say:

Reading info letter #16, I sure agree with the comments on “power boosting”on the Isuzu engine.

Engines are designed by the manufacturer for a given horsepower. Pistons,rods, crankshaft and bearings are sized for that horsepower. There will besome level of extra strength built into the engine but probably just enough forit to last for a reasonable service life at the rated power.

I hear people talking about getting 20%, 30%, and even 40% more power with add-on’s. This will surely come at a cost – as in a decreased engine and possibly transmission life. There is no free lunch. An occasional (once a dayor less) 5 to 10% increase in power for a limited time (1 to 2 minutes) maynot hurt the engine too much but it will still take a toll over time. Continued high power operation like pulling up a long hill at a higher power will puta lot of extra stress and heat in the engine.

If you buy a used coach that has a power enhancement, someone more than likely has used up some of the service life of that engine. If they sell thecoach prior to the end of the normal service life they have passed the problemon to the next owner. At the casino you hear about the people who gamble andwin; the ones that lose don’t talk about it too much.

I remember talking to an Isuzu Trek owner who was telling me about his propane injection system. He really liked it. I asked if he had any otherproblems with the engine. No, not really, but the front pulley on the engine hadfailed twice. One time it had actually detached from the crankshaft and helost the belt power to the alternator and cooling fan. On the Isuzu enginethe front pulley is also the dynamic dampener for the engine. It is designedto dampen vibrations (power pulses) in the engine and protect it up to therated horsepower. Power pulses beyond the rated horsepower make the dampenerand other components of the engine have to do work they weren’t designed to do..

There is a good reason there are two belts on that front pulley that are dedicated to driving the alternator. The vacuum pump is located on the back endof alternator shaft and it provides the vacuum for the power brakes. Novacuum pump, no power boost for the brakes! I am quite content chugging up thehills at rated power and watching the scenery go by knowing my engine and itscomponents have some reserve safety margins in them.

 Editor: Well, the “sooner or later” I mentioned in the last Infoletter on this same subject is NOW! I just got back from my Trek’s annual inspection at FMI. FMI has a Trek in with a destroyed engine….cracked precombustion chambers…propane infusion was installed . Owner is looking at a new engine! FMI has told the owner that if they install the engine they won’t reinstall the propane infusion and if the owner has it installed it will void the warranty on the new engine. Owner bought the ’93 Trek with propane infusion already installed.

 If you can’’t shut the engine off – an interesting electrical problem

We all know how dependable our Isuzu diesel engines are but Bob Ohki (ohkirj at just couldn’t get his ’94 Trek engine to quit. Here is why: Bob writes:

We were going down the freeway like nothing was wrong.  We turned off for lunch.  We parked and couldn’t turn the engine off with the key switch.  We knew something was not normal!  We were more than 50 miles from home, so we decided to take the back way and not go on the freeway, because the transmission would not shift higher than 3rd gear, and would not start from 1st gear either.  I think it did reverse, though.  The other malfunction was the steps would not come back in.  So we drove in 3rd and got home.

At home the engine wouldn’t stop.  I stopped it by pinching the rubber fuel line with a clamp near the tank to starve the engine and it stopped in a little while.  There is no manual shut off valve to be found.  I tried to start it, but the starter would not turn.  There were no ISUZU places nearby , so I called TOM’S TRUCK CENTER in Santa Ana, CA , phone 1-800-238-9308, where they claim they have the largest ISUZU new as well as the largest used parts inventory in the USA.  They told me there is a pair of FUSEABLE LINKS underneath the left side of the chassis by the starter in the C channel frame area which I found.  I pulled them out and found one of them burned out so now I carry extra fuses.

Now I looked everywhere for what caused the fuse to burn.  I found a wire near the step control unit that was charred pretty good.  After rewire repair I started the engine hoping it would start and it did.

 Preventative Maintenance costs less and is more convenient

(Editor) Perhaps because of a long career flying airplanes, I am a great believer in preventative maintenance. I am not particularly good at finding things unless they are edible or already broken so once a year I take our Trek to a facility that is good at finding things that need maintenance (after all, that’s how they make their money, so they are motivated). Here in Oregon, its FMI. Besides the normal oil, oil filter and fuel filter change, here is what they found this year:

Cracked alternator belt tensioning bracket (would have failed in Mexico, I have no doubt).

Cracked a/c compressor belt tensioning bracket (ditto)

Tranny fluid “stinky” (changed fluid and filters…. very important for the longevity of the transmission). Although we do have a tranny temp gauge (a must if you tow), Transmission fluid is destroyed by very little time at high temps which happens when towing.

Hi beam headlight out.

Left front quarter fender (behind the wheel) loose. I deferred this one and fixed it myself. The self-tapping screws holding the brace in place had hogged out their holes in the soft wood of the floor above. Larger lagbolts, held from turning out by an application of Goop solved that problem.

My Trek has 79,000 miles on it and I am confident now that it is ready for the annual trip south this coming winter. I am in the process of troubleshooting my cruise control which has always worked fine until this month. More on that when I am smarter!

 Information Sources for On the Road

The following I-Trek owners have volunteered to provide local knowledge. You may email them if you wish. If you know an area well, we’d like you to volunteer to be a local knowledge source for the rest of us Isuzu Trekees.


New England – Jeanne Provost (memepro at

Coast of Maine – Carl Johnson (kettlesing at

Alaska and the Inside passage ferry from Bellingham, Wash to Haines and Skagway, AK.  I did the trip just last summer. (lindadahle at

Montreal, Canada : Richard Miller [richard.miller at]


Colorado Rockies – Denver-Colorado Springs  denoo1 at or jdenoo at


Baja Peninsula – Dale DeRemer (daldr at

Mainland Mexico – Ken Harmon (kencathyha at