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September 1998 Nuts & Bolts

Hustler Headers
Rick Péwé
| Four Wheeler Network Content Director
Posted September 1, 1998

Temp Gauges for a GMC Jimmy, Toyota Pickup Engine Swap and More

Header Healing
My '95 F-150 is a great truck, but I'm having problems: namely, blowing out header gaskets. I've tried doubling the gaskets and retorquing the bolts, but I still blow the gaskets out after a while. Is it possible that the 1 1/4-inch header tubes and dual exhaust are too small for the system?
Via e-mail

The quality of headers has more to do with gasket problems than the size of the tubes. Too small an exhaust system can increase backpressure within the system, but that will rarely cause gasket failure. The head flanges on cheap headers tend to warp when installed because the material is too thin. The same goes for the collector-gasket flange, and all of this is compounded by the heating and cooling an exhaust system goes through.

Another probable cause of the exhaust leaks is from the bolts coming loose because of the expansion and contraction caused by cooling and heating. Once the bolts are loose the headers vibrate and loosen the bolts further causing the gaskets to blow out.

You can go back to stock exhaust manifolds, or try high-quality headers that feature a thick flange on the head and collector surface to minimize warping. To prevent the bolts from coming loose, try the special header lock bolts from Stage 8 Fasteners (Dept, 4WOR, 15 Chestnut Ave., San Rafael, CA 94901, 800/843-7836, Web site, which solidly lock the bolts in place once they have been torqued.

Temp Gauges
I have an '86 GMC Jimmy with a 305 engine and a TH700-R4 transmission. I have the stock engine temperature gauge but also want to install engine-oil and transmission-oil temperature gauges. What are the best to use, mechanical or electrical gauges, and which is easier to install?
St. Petersburg, FL

Keeping track of engine and transmission temperatures is an excellent way to prevent damage from overheating. By keeping transmission fluid from overheating, you can double the service life of the unit. For mechanical versus electrical gauges, the electrical styles are almost always easier to install, both the gauge and the sender. A simple one-wire hookup from the sending unit to the dash-mounted gauge and another to a power source make for a slick installation. The sending units are relatively small and can fit into existing holes on many vehicles without adapters. The only problem with electrics is that they don't work when the ignition is off, unless you wire them directly to a constant power source, which results in a constant, slight battery drain.

Mechanical temperature gauges are fitted with a capillary tube, which is attached to the back of the gauge and runs all the way to the area it senses. This fluid-filled tube is like a thermometer in that it is sealed and can't be lengthened or shortened. Sometimes this makes for a more difficult installation. The end of the tube is quite large and may need adapters to fit into the engine or transmission. This tube is also easy to damage, which can ruin the gauge. However, mechanical gauges are known for greater accuracy and will continue to function without electricity, which is important if the truck still runs but the dash wiring is fried.

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