Send your Gearhead questions to: Off-Road Adventures, Gearhead Dept., 801 West Artesia Blvd. Compton, CA 90220 info@oramagazine.com
You’ve Got Questions? He’s Got Answers!
SEMI-REGULAR GEARHEAD QUESTION TIPS SECTION
The Gearhead loves getting your letters and wants to remind you that while he reads each and every letter, he can answer only a very small number of them, either in the column or personally. What he looks for are trends that let him help the most number of people. If there are a lot of letters on a particular topic, he picks a representative letter. A few letters are also presented just for general interest, to help some poor slop in the wilderness with an orphan 4x4, or for pure gearhead fun. As to the letters themselves, the Gearhead needs details. A letter that asks, “My truck backfired and quit,” doesn’t give him any clues to work the problem. For all the Gearhead knows, the guy just ran outta gas! Give as much detail about the symptoms and what you did to try to solve the problem. Buildup questions that are too general can be hard to answer as well, such as, “I have a ’78 Bronco and want to build it to the max; what do I do?” The Gearhead would need pages to answer that one, so try to keep your questions specific to the subjects that you need the most help with. The Gearhead doesn’t answer lazy questions, where it’s obvious the person hasn’t done any research or thinking on the topic but wants the whole thing laid out on a platter. It’s hard for the Gearhead to answer the “which is better” questions. In some cases he can, but most times, unless he is able to compare two products directly, he can’t make an honest judgment... and there’s the “apples and oranges” aspect to bear in mind also. Finally, the Gearhead loves corrections or further info on any topic, so feel free to send those in. Be nice, though. You don’t want to know what the Gearhead does with the few rude letters he gets!
RECREATIONAL OIL CHANGER
I drive a 2001 Suburban Z-71 5.3L. I’ve been running synthetic oil in it since new and have been changing it every 3K miles. My buddy at the shop says, “What a waste of money,” and that I can run at least 5K before changing it, if not longer. I do mostly commuting in it. Is there any validation to his point?
Keith Yakushi, Via e-mail
Yep, your buddy is right. Exactly how far you can run is subject to many specifics. To start, which oil are you using? “Synthetic” doesn’t tell me much because, like everything else, there are better and worse grades of synthetic oils. A good oil is the composite of its base stocks and the additive package mixed with it. Even at the lower end of the syn oil quality scale, however, 3k miles is overkill. At the low end of the price chain would be the generic “house” brands bottled for department stores, etc. Some of them are actually quite good but the hard part is determining where they came from and what’s in them... and that can change from year to year with the contracts. The factory fill type oils from the O.E. manufacturer often fit in this category as well. Then there are the oil company brands which run from very good to excellent. Beyond them are the boutique oils, which are generally stellar formulations... and priced to match. The next factor would be your driving style. Commutes, especially short commutes where the engine doesn’t get fully warm or stay that way very long, are the hardest on oil. The type of engine can be a factor too, but that’s a complicated topic. The bottom line is that extended oil change intervals are best determined by oil analysis. I’m having my own vehicle’s oil regularly analyzed this way by Blackstone Laboratories (260-744-2380; www.blackstone-labs.com) to help me do right by my motors. Basically, you start at a certain interval, send an oil sample in for analysis and the results will tell you how much life is left in the oil. You then alter the interval according to the analysis. In my experience, 5K miles is a good place to start in almost all circumstances. With a good oil and filter, the 7,500 mile interval is almost always doable. Some companies are proponents of 50-100,000 mile intervals in some cases, and if the oil analysis bears it out, why not? Extending your oil change interval not only saves you money, but it saves resources as well.
FRAMED CHEVY
A while back you mentioned that the Chevy Blazer has the second weakest frame of the straight axle trucks, right under the 1/2-ton Suburban 4x4. I was curious to know where the weak points are on the ’73-91 Chevy Blazer frames. I have a ’90 Chevy V-10 Blazer and was going to add a 6-inch lift and put 3/4-1-ton axles under it. Are there any mods you could do to the frame to make it stronger?
Scott Blackwell, Via e-mail
My comment was mostly concerning frame flex, but flex can lead to failures. The places where I have personally seen Blazer chassis regularly fail are on the front crossmember (under the engine, near the outer edges at the engine mounts), the steering box mounts and the rear shock mounts. A strong front bumper may help with the front crossmember and you definitely should have a steering box brace no matter what. There are chassis repair kits as well, if the steering box has already worked loose and damaged the frame. Off Road Design (www.offroaddesign.com; 970-945- 7777), a specialist in Blazers and solid axle GMs, makes both. Most shock mount failures are due to loose hardware. In general, there isn’t too much you can do about frame flex. A tight, non-rusty body really helps. Solid front and rear bumpers help too. A chassis mounted roll cage will tighten the frame up a lot as well. An overly stiff suspension will be harder on the chassis than a flexy “soft-ride” type. The military CUCV trucks had some extra frame reinforcement brackets that would probably stop the front crossmember cracks, but these parts do not appear to be available any longer. It probably wouldn’t be brain surgery for a halfway decent metal fabber to make them.
TIT OR TOT?
I have a 2006 F-350 6.0L diesel and pull a large 5th wheel. I installed an EGT Pyrometer before the turbo. What is the max temp I should let this get to going up hills? In my old 7.3L, it was installed after the turbo and I kept it under 1,000 degrees and I did not have any problems over seven years.
Paul Baker, Via e-mail
You are thinking right, Paul. There can be up to a 200 to 500 degree difference in what a pyrometer reads before the turbo (technically called Turbine Inlet Temperature, TIT) or after the turbo (Turbine Outlet Temperature, TOT). That number varies with the exact engine, how it’s modified and the load. The 1,100 degree TOT on your old 7.3L could have been 1,300-1,600 degrees TIT. Most experts agree that on the newer engines with intercoolers, 1,250- 1,300 TIT is a safe maximum continuous temperature for an engine in good condition, though I prefer to stay below 1,200. Older engines, especially those without intercoolers should stay below 1,000 degrees continuous. These numbers are subject to some debate and fine tuning according to the engine type and condition. The bottom line is that too much high EGT running eats up the turbine wheel, valves, pistons and head(s). Simply backing off on the throttle, or a downshift will lower EG by reducing the fuel rate or pumping in more air. Every diesel should have a pyrometer, especially one that tows.
DEAF JEEPER WANNABE
I’m looking to improve my exhaust system on my 1997 Jeep Wrangler. I have a 4.0 inline 6. I am trying to get the loudest exhaust I can afford. Nothing like them Honda Civics.
JD, Via e-mail
JD, I could really go somewhere with this and get a lotta laughs, but I’m not. Bear in mind a coupla things, 1) noise doesn’t equate to power production, 2) too much car noise leads to full or partial hearing loss. It really sneaks up on you years down the road and I’m living proof. I tend to lose voices in an environment with lots of background noise and I no longer hear the nuances in music I once did. Here I am in my 50s and already only a coupla steps away from a hearing aid. Most of my problems go back to loud cars and trucks, which was avoidable or preventable, though some came from gunfire and loud equipment in the military, some of which was not. Value your hearing, JD, ‘cause once gone… it’s GONE! The loudest mufflers are the straight through type and larger pipes than you need can result in a louder system than you need. In general, a well designed quiet system will have about the same power gain as a very noisy system that might have slightly more flow. If there are differences, they don’t show in the rpm ranges most four-wheelers operate. The catalytic converter does a pretty good job as a muffler too. You can get a nice healthy tone but without those horrible resonances that turn your brains to Jello. Think about the future JD and get yourself a quiet system, will ya?
TOW/HAUL TERROR
I have a 2005 Ram 1500 with the 345ci Hemi. It had a 4-5.5” Fabtech lift. I have 35-inch Mud Terrains , 3.92 gears and the automatic transmission. The truck is a little more sluggish than original with this configuration. I have been using the tow/haul setting while driving this truck, even when unleaded. It seems to perform better. Is there going to be excessive transmission weak if I continue to drive in this setting?
Chas Hummel
Berghim, Texas
Basically Tow/Haul stretches out the shift points, makes the tranny shift more crisply, engages the torque converter lockup sooner and delays the upshift into overdrive. This is designed to give more control when towing, increase downhill engine braking and reduce tranny temps. With your big tires and relatively tall gears, the truck “feels” like it has more of a load, so using the T/H is a good thing. I can’t see how it would increase performance but it will reduce that constant up and downshifting and converter lock/unlock. Running it all the time won’t hurt your truck or the transmission, but it’s a bandage to the real problem. You need lower gear ratios, Chas! Some 4.56:1 cogs are about right for 35s.
S&M FOR SAMMY
I have an ’87 Samurai and have a weird question. I found this company, ZOR, that builds a kit to put a Toyota tranny in my Zuk. Would it be possible to put a SM-420 from a 4x2 Chevy in it? The reason why is I want a lower first gear but not lose highway driveability. I have the stock ratios in the diffs and 29 inch Mud Terrains.
Jordan Bleeker
Bismarck, North Dakota
I checked the ZOR website but didn’t see the kit you mentioned. Your idea for a lower first for crawling is not without merit, but do you realize that the SM-420 weighs 175 pounds, half as much as the 1.3L engine (about 380 pounds) in your Sammy? Not only that, because it’s internals are bigger and heavier, they will soak up a bunch of the power you don’t have to spare. The cheapest, easiest and most usable move, in my opinion, would be to lower the transfer case low range. Calmini (www.puresuzuki. com; 800-345-3305) offers three sets in 4.16:1, 5.14:1 and 6.50:1. The 4.16:1 would probably give you want you are looking for, but you can decide that for yourself. Installation is pretty simple.