Time- and money-saving tips from technicians

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Time- and money-saving tips from technicians


When servicing or rebuilding a GM LS engine (which includes the LQ series), cast iron or aluminum blocks, be aware that there are two versions of cylinder head bolts, based on the design of the specific block.

2003 and later blocks require 11 mm x 2.0 x 101 mm bolts for all 11 mm locations. Pre-2003 blocks require two different length 11 mm bolts, including 101 mm and 155 mm in length. This is due to the depth of bolt hole locations in the block. These are referred to as long style and short style blocks.

Also, all OEM head bolts are torque-to-yield style and require a torque-plus-angle tightening. Some performance aftermarket bolts (such as ARP, as an example) do not require angle tightening and require only a torque value. If you’re using aftermarket head bolts, be sure to follow the bolt maker’s tightening specs. Aftermarket bolt makers will usually specify two different torque values based on thread lubricant… one spec for oil and a different spec for moly.

Rob Holland

Holland Auto


A Ford truck that features a two-piece driveshaft will feature a carrier bearing. If the carrier bearing wears out, and/or the U-joint behind it starts to seize up, the customer will complain of a droning noise that sounds like the truck is being driven over a road surface that has just been graded. It’s not uncommon for someone to first suspect the transmission.

Check the carrier bearing and driveshaft U-joints first and save yourself a bunch of time and aggravation. Also be aware that there are several different part numbers of carrier bearings for the Ford trucks, so save the original for a match-up.

Bob Young

Bobby Y Automotive


Some of the cast aluminum cylinder heads installed on Chrysler PT Cruisers were very poor castings with weak spots. If a spark plug literally blows out of its port, taking the threads with it, a cheap fix, as opposed to replacing the head, is to replace the threads using a kit that Goodson Tools offers. It allows you to restore the threads without removing the head. Naturally, care must be taken to avoid debris being dropped into the combustion chamber, but it is feasible. I’ve done a handful of these repairs with total success. One customer’s engine blew a spark plug out of the head after only 10,000 miles. After the repair, he now has over 150,000 miles with no problems. It takes a few hours, but it will save the customer a load of cash as compared to replacing the head, or pulling the head to perform a thread insert fix.

Eric Pullman

Greber Repair


If you have a customer who wishes to install a mechanical or aftermarket electric oil pressure gauge onto a GM LS engine, an easy way to make an adapter is to use an old OE oil pressure sender. Cut off the plastic connector flush with the metal base, and then drill out the center using a 1/8-inch NPT tap. The 16 mm thread OE sender base will thread back into the block in its original location. The 1/8-inch NPT port will then allow you to connect any oil line with a 1/8-inch NPT fitting. No modification to the block is needed.

Scott Gressman

Gressman Powersports


This is an old trick, but it works. Whenever you encounter a frozen threaded plug in a cast iron engine block, use a torch (using acetylene only) and heat the plug until it’s cherry red. Then touch a chunk of pure wax to the plug. The wax will liquefy instantly and will migrate into the threads. Nine times out of 10, the plug will walk right out, but be sure to remove the plug while it’s still hot. Don’t let it cool down first, as this might allow it to seize again.

Naturally, this should only be done with the block removed from the vehicle. And obviously, be sure to wear eye protection and heavy gloves. Cheap candle wax isn’t the best choice. Buy a chunk of pure, non-colored wax or paraffin.

Bob Fall

Fall Automotive


Be aware that the flywheel bolt holes on the rear of the GM LS/Q series crank flange may be open to the crankcase (open to the back of the reluctor wheel). If you don’t apply thread sealer to the flywheel bolts, you may have a nasty oil leak that will at first glance appear to be a rear main seal leak.

Before you bolt the flywheel or flexplate to the crank, make sure that the bolts have a good thread sealer, either a traditional sealing compound or a thread licking compound that also seals.

Brian Goodman

Great Valley Auto


Be aware that some Chrysler vehicles equipped with the 41TE automatic transaxle (PT Cruiser, for example) may feature a transmission oil pan with a drain plug that faces the rear.

The inside protrusion of the drain plug bung can interfere with the transmission oil filter, preventing a good pan seal and potentially damaging the push-in plastic dowels of the filter.

A replacement pan is available from Dorman Products that features a drain plug at the bottom floor of the pan to avoid this problem. This pan is also a good replacement for original pans that never originally featured a drain plug.

Greg Burgy

Alderman Specialties



Whenever you’re dealing with an overhead valve engine that features pushrods that have an oil hole running through the pushrod, be sure to clean the passage before reinstalling. Companies such as Comp Cams and others offer a small-diameter bristle brush designed for pushrod cleaning.

Blow brake cleaner solvent through the passage, clean with the brush, blow solvent through again, until the passage of absolutely clean.

Mark Steingass

Evolution Auto


Many GM LS aluminum heads produced via a permanent mold process, with casting number 706, feature porosity that eventually leads to cracking at the center bolt hole locations, resulting in water entering the oil. These heads were made starting in 2004. A good replacement head is GM casting number 862, which were sand cast and made pre-2004.

Don Hall

Sunrise Auto


Brake rotors, new or used, have contaminants on the surface. New rotors are treated with a corrosion inhibitor before being packaged. The disc surfaces must be properly cleaned to optimize braking and to prevent contaminants from being transferred to the new pads. Some (not all) of today’s brake cleaning solvents are great, but they only go so far.

Wash the rotors in HOT soapy water, specifically using Dawn dish washing detergent. I don’t claim to know why Dawn is different than other brands, but it definitely works the best at removing deposits from the peaks and valleys of the machined disc surface. Scrub with a nylon bristle brush and rinse in really hot water.

Go ahead and use brake cleaner before and after (especially to remove any greasy fingerprints that were made during assembly), but scrubbing the surfaces with Dawn and hot water really does the trick. We use Dawn not only for brake rotors, but manual transmission engine flywheels, crankshaft main and rod journals and camshafts.

Brian Carruth

Birchwood Automotive


In 1991, Ford introduced the 4.6L OHC V-8, commonly referred to as the Modular Ford V-8. It had, for the time, a revolutionary new head gasket design called MLS. Prior to that, most head gaskets were steel core designs with some sort of gasket paper attached to the core, so this was a big change for the engine repair/rebuilding industry.

By the late 1990s virtually every automotive engine in the world had MLS head gaskets and now in 2014, we hardly ever give them a second thought.

MLS actually stands for multi-layered steel and describes the construction of the gasket. MLS gaskets usually have at least three layers. The inner layer, sometimes referred to as a passive layer, serves three general purposes. It provides a means of getting the proper thickness for the gasket, it provides a layer for the top and bottom layers to push against and in most designs, provides extra thickness around the cylinder to ensure good combustion seal. That extra thickness often referred to as a “stopper” can be as simple as a folded-over layer, or a laser-welded thickness or in the case the Bugatti Veyron, something called the Wavestopper design. This patented design uses raised, embossed, concentric rings around the combustion chamber. Each ring acts as a stopper, but provides a variable sealing based upon the load on the head gasket. The outer layers, referred to as active layers, are tempered stainless steel. They have raised beads, called embossments, surrounding the critical sealing areas. This would be, of course, the combustion opening, the water jacket openings and in the case of OHC engines, the oil passage from the block to the head.

When you installed the head on the engine and start to tighten all the fasteners, aka head bolts, the spring steel beads of the active layers resist flattening out and push back against the passive layer on one side and the head or block on the other. It is this spring pressure that creates the seal and also gives the ability for the gasket to keep sealing as the engine runs and the heads actually lift off the block. We’re speaking of sealing combustion pressures of 1,200 psi here, so this is a big deal. In the head gasket business, we refer to this as cylinder head lift-off and cruising down the highway, this is going on a thousand times a minute the entire time you are driving, racking up millions of cycles over the life of the engine! The MLS gasket relaxes and compresses every time this occurs.

Another enhancement to MLS head gaskets that is absolutely required to make them work is a “rubber” coating, which is actually carefully compounded, carefully tested, skillfully applied polymer coating. It gives the gasket the ability to seal fluids perfectly through the millions of cycles we mentioned above!

Don’t even think of applying anything to the gasket to improve the seal. If a sealant is ever needed for a gasket, it’ll be included in the box with the gasket. Some engines have a left and right head gasket and a few have a top and bottom or front and back, so look yours over carefully. Lay your gasket on the block making sure the locating dowels are in the block and that the gasket slips down over them. Carefully set the head down on the gasket, again making sure it fits over the locating dowels. We have engines like the DURAMAX that have different dowel diameters for different years, so always make sure you check the details!

At this stage, you’re ready to install the fasteners, aka head bolts, and tighten them to the factory specifications. We might digress here for a minute and mention that about the same time that MLS gaskets came along, so did torque-to-yield fasteners. Along with torque-to-yield fasteners came the associated technology of torque-turn-to tighten, a new means of ensuring we had the desired head bolt load.

Basically, steel head bolts are elastic, think of them kind of like a rubber band. You stretch them out and they want to spring back. It’s that elastic tension that creates the load that compresses the gasket and keeps it compressed as the engine runs, temperatures change and the head tries to lift off the block. Because of the proximity to yield that the fasteners see, most all manufacturers recommend replacing them every time we remove the head.

Bill McKnight

MAHLE Aftermarket Training Manager



When you’re faced with a stubborn thread, it’s common to use a quality penetrating oil to help to break it loose. Once the bolt or nut has been removed, if you plan to apply a lubricant to prevent future seizing, avoid using a Teflon spray lube. For some reason, the Teflon spray lube works its way out of the threads quickly and dries, resulting in metal-to-metal galling in the future. We’ve encountered this a few times, even with threads that we’ve cleaned and deburred. We don’t know why, but the commonly available Teflon spray lube just isn’t the same as something that’s Teflon coated. The name may be appealing, but it doesn’t appear to be a good choice for thread lube.

Mark Swanson

Gibson Car Care


The GM LS series of engines features a one-piece rear main seal that slips onto the crankshaft’s rear flange. Incorrect installation procedures will guarantee a leaker. Here are some tips.

Install the rear main seal to the engine’s rear cover. Make sure that the seal bore in the cover is absolutely clean before installing the seal. You can apply a thin application of lube to the outer edge of the seal to help with the seal-to-cover installation, but do not lube the seal lips. The seal lips should be installed to the crank dry. Make sure that the seal is installed to the rear cover correctly. The surface with lines and dots should face rearward.

The oil pan should be in place first, with pan bolts fully tightened to spec.

A white nylon installation guide is installed to the seal (new seals should always include this). The nylon insert prevents the seal lips from being pried rearward as the seal is installed to the crank flange.

Make sure that the rear crank flange seal surface is clean and dry.

Remove the two rear (long) oil pan bolts (these secure the pan to the bottom of the rear engine cover).

Install the rear cover gasket to the cover.

Carefully align the seal to the crank flange, keeping it square to the flange, and push the rear cover to the block, allowing the seal to capture the crank flange. Once the seal enters the flange, the nylon insert guide will pop off. Loosely install a few rear cover bolts to the block but do not tighten yet. Just snug the bolts enough to draw the cover and gasket to the block while allowing the seal to center itself on the crank.

Install and snug the two long lower oil pan bolts. Install the remainder of the rear cover bolts, finger tight.

Tighten the bottom two 6 mm oil pan-to-rear-cover bolts to about 25 in.-lbs., then tighten the 8 mm rear cover bolts to the block to about 25 in.-lbs. Final tighten the two rear oil pan bolts to 106 in.-lbs. and final tighten the rear cover bolts to 18 ft.-lbs. This draws the rear cover down to the pan gasket, using up the small bit of bolt hole clearance at the rear cover bolt locations.

Inspect the seal closely (a flashlight helps). If you see evidence that the rear seal lip has folded rearward, remove the rear cover and start over.

Tony Lombardi

Ross Engines


When you need to tighten a fastener to a specific torque value, but you don’t have direct access with a socket, a wrench extension may be used. We’re not talking about a straight extension that places the socket wrench further away 90 degrees from the torque wrench head. Rather, we’re referring to a wrench extension that provides a wrench that extends beyond the torque wrench head, parallel with the torque wrench body.

When using a wrench extension, this makes the length of the torque wrench longer, which will affect the applied torque. Making the wrench longer means that you’re increasing leverage. If you don’t compensate for the extended length at your torque wrench setting, you’ll end up applying too much torque.

Here’s a simple formula to use whenever you need to use a wrench extension on your torque wrench.

First measure the length of the torque wrench, from the center of the wrench grip length to the center of the torque wrench drive (where the socket would engage). We’ll call this LENGTH L.

Next, measure the length of the adapter (the extension), from the center of its square drive hole to the center of its wrench head. We’ll call this LENGTH E.

   T = Desired torque value

   L = Length of the torque wrench

   E = Length of the adapter

   Y = Unknown (the value that you need to adjust/set the torque wrench)

The formula is as follows:

   T x L divided by L + E = Y

As an example, where we want to apply 25 ft.-lbs. of torque to intake manifold bolts,

Our torque wrench (in this particular case) is 14.5 inches long (L = 14.5)

Our adapter is 2 inches long (E = 2)

Our desired torque is 25 ft.-lbs. (T = 25)

   25 x 14.5 = 362.5 (T x L)

   14.5 + 2 = 16.5 (L + E)

So, 362.5 divided by 16.5 = 21.969 ft.-lbs. (Y) -- (we’ll round Y off to 22 ft.-lbs.).

In this case, in order to tighten the four manifold center bolts to 25 ft.-lbs., we need to adjust our torque wrench setting to a value of 22 ft.-lbs. when using the 2-inch-long adapter.

If you use an extension adapter without adjusting for its additional length, you’ll end up over-tightening the fastener.

Just remember that when you add an extension to your torque wrench (making the wrench longer), you need to back-off your adjustment setting a bit in order to achieve the desired torque value. Don’t just guess though, take a few minutes to use the formula in order to be accurate.

NOTE: Always keep the wrench extension parallel with the torque wrench body. If the extension is at an angle relative to the torque wrench, this will alter the applied torque.   ●

Mike Mavrigian

Birchwood Automotive/Editor, ASP

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