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Silver Star 1991 Pioneer Build

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On ‎8‎/‎11‎/‎2018 at 5:18 PM, kryptronic said:

New to me chief hood stripes came in the mail as well. These are NOS stripes I got from mjtjnj, and will be used as a template to create sets for both trucks.


I'd be interested in set if you plan to make more than two.

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  • 2 months later...

Fall 2018 - Winter 2019: A Few Miles, Fuel System Fixed


I haven't really done much to Silver Star over the past year.  The truck had a nagging fuel system problem where it was not building pressure at the fuel rail.  I had already replaced the fuel pump with a Bosch, went through the wiring, relays, etc, and was stumped for a bit.  Then I changed the fuel filter and everything has been great since.  I've only put a few hundred miles on the truck over the past year, but it's been running great.  I've got to get it in the garage in the short term to remove some surface rust and prime/paint those areas.



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On 4/22/2019 at 5:35 PM, Minuit said:

Looks like your square Jeeps are multiplying even faster than they normally do. From one to four in only a couple of years. That's impressive!


I tell myself that two of them are just piles of parts that just happen to run and drive.  I do have a plan.  I swear.

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  • 1 year later...

Spring 2019 - Fall 2019: The Purge and The All-Breeds Show


Spring 2019 was a little rough, as that's when my second marriage broke up.  We had been together for ten years, and our son was five years old at the time.  So there was a bunch to deal with.  The divorce was handled quickly and painlessly, and we're really good friends now, and we're parenting as a team.  It's good, but it was life-changing.


During all that, I looked around at all the projects I had going on.  I had way too much on my plate, and I needed to purge a few vehicles.  My ex sold her Green 2004 TJ, and I transferred the Blue 1998 XJ to her for her to use as her daily driver.  I was able to sell the XJ parts vehicle and the 1991 MJ Eliminator (4.0L AW4 NP231) by July 2019.  The 2018 JLU was sold in August 2019, and I sold the 1992 MJ SportTruck (4.0L AW4 2WD) in October 2019.


This left me the 1991 MJ Pioneer (Silver Star), the 1995 YJ (this project underway again), and the 2013 JKUR (which is my daily driver).  By December 2019, the driveway felt a little empty, so I purchased another automotive project (I know, but it's one I've wanted to do forever, and decided I'm ready for it).  More on that in another thread later.


In July 2019 we took Silver Star to the All-Breeds Jeep Show in York, PA.  We held a Mid-Atlantic Comanche Club PowWow and several members showed up with their trucks.  Comanche Club won an award for largest club participation.  With the new Jeep truck having just been launched, the crowd really liked seeing the old Jeep trucks out and about.






That's @Minuit's truck next to mine.  It was really cool compare how our trucks were running as High Output examples like ours are rare in the wild.  They sounded identical.  Very cool stuff.  We're hoping to do another PowWow and another show this year (2021) and represent strongly again.



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Winter 2020: Bench Seat to Bucket Seats


With the purge handled, and my life somewhat in order, I turned focus back to Silver Star to fix handle it's seating issue.  Since I got the truck the bench seat has sagged at least 2-3" on the driver's side, and it's been generally uncomfortable, and the driving position is not optimal.  It felt like you were sitting in an extremely deep couch with very soft springs.

At some point over the last couple of years I purchased a really set nice of AMC-era Black Mesa II fabric standard bucket seat covers from a club member who lives on the west coast.  I intended on using them at some point on Silver Star.  So I was kind of itching to change over to bucket seats, but had no seats, and I didn't really want to use these seat covers until after the truck was fully restored anyway.


On another occasion I picked up a set of MJ standard bucket seats in AMC-era Black Vinyl from a local seller.  The seats are in very nice condition, excluding a tear on the driver's seat.  They even came with seat bases, and for a few dollars more, I got another set of black door panels, and a bunch more black plastics.  When the time comes, I'll have a bunch of pieces from which to choose the best.




At the All-Breeds Jeep Show in 2019, I picked up a set of grey see-through headrests from another type of XJ (or possibly MJ) seat.  I was told these headrests only came with a particular seat/model, but cannot recall the details.  The solid black headrests came on the seats.  I like the see-through hearrests better than the solid headrests, so intended on using them with the bucket seats.




Step one was removing the bench seat.  It's been out a few times, so it came out easily.  I've got a bunch of the plastics removed in preparation to repair a bad patch job on the passenger floor.




Step two was installing the bucket seats.  The bases were already attached.  The project could have been finished at this point, if it weren't for the headrest change.




Next I sprayed the grey headrests with SEM Color Coat Landau Black (matches AMC Black).  The SEM product extremely good on all interior surfaces.  I also had to shorten the posts by cutting them.  The posts retract slightly into the solid headrests when fully seated.  The see-through headrests need to be modified to compensate.




Installation was a breeze:  Remove old headrests.  Insert new headrests.




I like the look of the standard black vinyl seats with these headrests so much, I am going to repair the tear on the driver's seat, and use them indefinitely.  If one day they get too tired, I can switch over to the solid headrests and Mesa II covers.  I left the seat belts from the bench in the truck, and won't be installing the black ones until later.


For reference, this tag was on the bottom of the original bench seat from this MJ.  It was a later-style bench seat with headrests, and this is likely a Chrysler part number for the seat or seat frame:



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Summer 2020: Heater Control Valve Delete


For a while, I had been wanting to do an elimination of the heater control valve on Silver Star.  This is a modification that @HOrnbrod (RIP) recommended I do when I first got the truck.  On High Output engines, the heater control valve can be removed (without ill-effect) by capping it's vacuum line, and replacing the valve and all the hoses with Gates hoses 19038 and 19039.




In Silver Star's case, the heater control valve was leaking fluid slightly, and was an awful rat's nest to look at.  My frame of reference for the High Output engine is my 1995 YJ, which had no heater control valve in it's stock form.  This modification configures the cooling system on earlier High Output engines to match the system configuration on later engines in the series.


This is the heater control valve in stock form on a 1991 4.0L High Output engine.  It's what I removed:




It was a very simple job.  Disconnect the hoses from the heater and the front of the engine.  Just those four connections - there's no need to disconnect anything from the heater valve - it will all come out in one clump.  Next, connect the Gates hoses to their proper locations.  There's only one way they fit properly, both upper and lower, so it's hard to screw up.  After capping the white vacuum line, this is the end result:




There's no measurable benefit as far as I can tell from better heating, but the heat has always been great.  The benefit from this modification is the elimination of leak points, simplification of the cooling system, and a cleaner engine bay.


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Fall 2020: Exhaust and Fuel System Fixes and a Tune-Up


Between Spring 2019 and Fall 2020, besides purging a bunch of projects and getting a few things done on the MJ and the YJ, I did a lot of work on my yard, and pressed the MJ into service hauling all over the property.  It did a fantastic job any time I called upon it.  I was really tied up with yard maintenance, and then ultimately painted my house in Fall 2020.  A bunch of work went into making the house nicer, and not much time was spent on vehicle projects.




But, I did get some time to handle a few things.  I was able to track down a final issue with the fuel system.  One of the hoses used to connect the fuel filter had collapsed upon itself - probably due to age - and fuel flow was restricted.  I replaced the hose with a new one and solved my fuel delivery issues.  The one thing that has given me trouble with this vehicle has been the fuel delivery system.  At this point I have been over it in triplicate and know it's 100% now.


Then I ran into an issue where the MJ started running a bit rough in closed loop.  I tracked the issue down to a bad O2 sensor (via OBDI scan).  It was not firing a CEL, but there was a code for a bad O2 sensor.  When I got under the truck to replace the sensor, I discovered the downpipe was partially crushed.  This may explain why the sensor was dying, and why I was hearing some off notes in the exhaust.  I must have hit something in the yard at some point.




The parts I used for the fix were a Walker 44626 Exhaust Pipe, a NTK 23023 Oxygen Sensor, a Crown 52005431 Lower Exhaust Manifold to Front Pipe Seal, and the stock/existing Front Pipe to Catalytic Converter seal.




Installation was simple.  Unhook old parts, install new parts.  I didn't bother unhooking the bad O2 sensor, as it was coming out with the bad downpipe.    When I first got the truck, I replaced the cat with a high-flow Magnaflow unit, and the muffler with a Thrush Turbo, so these exhaust system changes make the MJ all new (excluding the stock exhaust manifold).


I also gave Silver Star an oil change, and a complete tune-up, and did a full battery of tests on here.  Vacuum and fuel pressure are excellent - at FSM levels.  Compression is excellent across all cylinders, with no reduction noted since my tests in 2017 - which were above factory fresh specs.  All diagnostics on the OBDI scanner look excellent - with everything operating in tip-top condition.


I have a very high confidence level in the operating condition of the truck at this point.

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Winter 2021: Cutting The Bedliner


Silver Star came with a Pendaliner over-the-rail bedliner without any hardware.  For a while I ran a Comanche stamped under-the-rail bedliner, but sold that to @Pete M in 2019 as he really wanted one., and I had a spare.  I switched back to the over-the-rail liner, but it has never worked well for me.  The lacking hardware presents a safety problem, limiting me to small slow trips around town.  That's somewhat overcome by keeping a spare tire in the bed, but the real nagging issue was the drainage.  Most of the year the MJ is covered in the driveway.




This keeps things like dirt, leaves and snow away - but not water.






It's a real pain.  The truck needs to be de-iced in the winter and drained just about any time I want to use it.  The truck bed itself has drain holes in the front, but the bedliner has no holes to let water flow there.  The bed itself is in great shape due to it being covered with a liner it's whole life.  Eventually, I'm going to coat the bed in bedliner.  When I get to building the truck, that is.




I decided to kill two birds with one stone.  I liked the fact that the under-the-rail liner I had didn't need hardware, and I was pretty sure I could cut the over-the-rail liner and mold it so that it would function like the under-the-rail liner did.  I just needed to pull that off, then add some drain holes up front.  I started out by cutting the bedliner almost level with the bed all the way around.




The pic above was a test fit before I cut the front portion.  I notched the corners, then notched the bedsides so that standing sections could be bent in under the rails.  The plastic was very thick (at around 1/4") and very hard to cut.  I used a 4" grinder with a cutting wheel.




After all the final cuts and notches were made, I used a heat gun and clamps to mold the standing sections at 45 degree angles so they would fit under the rails.  Due to the thickness and rigidity of the plastic, the heat treatment and bending took a while at very high heat, but worked well.  Here's the final result.






You can see in the last pic that I drilled drain holes in the grooves of the bedliner along the front face.  The fitment is extremely tight and it takes a little bit of wiggling to get the bedliner in to the bed.  This now offers excellent drainage, full protection of the bed, and is very safe - it's not going anywhere.  I'm very happy with the mod.


Also, I should note that I attempted to sell this very bedliner here on Comanche Club several times prior to cutting it.  To my knowledge, there was nobody on the east coast of this country that wanted a Pendaliner stamped over-the-rail bedliner for a shortbed.  I did my due diligence.

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It looks like you've put that liner to good use.  very innovative!  :bowdown:


in regards to the spare tire holding things down, "somewhat" is the key word as you know.  I had the liner for my trailer sucked out along with the spare tire the very first trip on the freeway.  :(  air pressure is a powerful force.  thankfully I was able to retrieve the liner :D  never saw a trace of the tire though.  :peep:   (lost in the brush off the freeway)

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Welcome back to the fold. Seeing this is getting me motivated to work on my own stuff again. And that's something I never would've though of to do to an over-the-rail bedliner. That might make the Duraliner one I have useful again.


Would you believe me if I told you that crush in the downpipe was factory? I'm almost certain it was. Mine has a near-identical crush in it. No clue why, but I'm sure they had their reasons.

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4 hours ago, Minuit said:

Would you believe me if I told you that crush in the downpipe was factory? I'm almost certain it was. Mine has a near-identical crush in it. No clue why, but I'm sure they had their reasons.


From the exterior the crushed area didn't look too bad, and wasn't really noticeable.  It may have been like that since I got the truck, but am surprised I missed seeing it before now.  It's kind of easy to miss.  I think somewhere along the way the downpipe suffered some kind of impact, and that's likely the weak area where they fold.  Likely the same scenario for yours.


Here's a pic of the inside of the pipe.  These downpipes would have never come from the factory like this.  The exhaust is supposed to be 2.25" from the exhaust manifold to the tailpipe.  Anything smaller would limit flow.  The crush on my downpipe limited exhaust flow to approximately 2" x 1.75".  The motor was choking on it's own fumes, and you could hear it, if you listened for it.




To rule out this being a factory feature, I took a look at my 1995 YJ.  It's got the stock downpipe hooked to a Banks revolver header instead of the stock exhaust manifold, but the downpipe design is nearly identical to the MJ.  The only differences are on the catalytic converter side of the pipe (converter slips onto the YJ downpipe; the hanger is different).  So the YJ downpipe was a good comparison, and it lacked the crush.  You can see what it looks like here:




I know Jeep did some strange things, but this wasn't one of them (IMHO).  If yours is like that, and you decide to fix it, before and after audio of your exhaust note would be great to listen to.  You're likely hear the engine choking on itself about two to three times a minute. 

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Our 1999 XJ had the same dent in the down pipe. At the first oil change I noticed it and took it back to the dealer. They said it had the dent for a reason. I can't remember what the reason was but it restricted flow for some purpose.

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Based on recent responses, I may be mistaken about the crush in the factory downpipe.  It sounds like the truck could have shipped that way from Jeep.


I have no idea why, though.  Maybe to restrict emissons.  My idle is smooth 100% of the time with the new Walker downpipe (no crush).


Thanks for all the feedback.  I opened this thread to discuss the factory downpipes, and get more info on these mystery crushes:



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6 minutes ago, kryptronic said:

I have no idea why, though.

2 ideas come to mind. 


1. to clear some bit of "frame" 


2. Idk if this is just with 2 strokes but like a little bit of exhaust flow back helps with balance or something.

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