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Starter Removal: in Detail

September 23, 2010 | Troubleshooting & Repair

Text and photos by Ab Tiedemann

The work procedure for removing the starter motor or the engine will require removing one or both of the through bolts that secure each to the transmission housing. The assembly at each upper interface consists of a 10 mm diameter fastener, a wavy washer and a nut. Removal of either of these fasteners can be troublesome, especially the longer of the two, a M10 x 110 DIN 931 8g [now 8.8] that secures the starter motor. The DIN 931 specification indicates that this is a hexagonal head, partially threaded fastener with a standard [coarse] thread and the hexagonal is 17mm across the flats [ATF]. The wavy washer is a B10 DIN 137 where B means that it has a double curvature. The specified nut is a M10 DIN 934 6s, which is a hexagonal nut that is 17 mm ATF. Original finish was black oxide or the German equivalent for all elements of the assembly. What this means is that you will need tooling that is compatible with a 17mm "wrench size". One set of tooling to hold the head of the fastener [from turning] and another set of tooling to engage the nut [for loosening or tightening]. The correct orientation of the through bolted connection has the wavy washer and the nut on the engine side and they are in close proximity to the fan housing. When this fastener is reinstalled, this arrangement often requires a second set of hands/fingers to push the fastener through so that some threads are available for starting the nut. In addition, and more often than not, these same hands are recruited to hold the head of the fastener with the selected tooling during the loosening or tightening of the nut or both. Suffice to say that, one set of unaided hands cannot hold both the head of the bolt and turn the nut simultaneously due to the presence of the front engine tin that seals the engine to the firewall. However, there is more about this later.

Chief among the reasons that give rise to removal difficulty is accessibility. The nuts are buried behind the fan housing and are difficult to see with natural lighting. Moreover, the more difficult one to access, the one securing the starter motor, is guarded by the voltage regulator, the screen [if present] on the fan inlet or on later models by the fan inlet volute. The cross bar on later cars has a bit part and the distance between the fan housing and the firewall is a definite factor especially on a Speedster which seems to be the least of all. Collectively, they present a near impermeable barrier for most invasions from the right side as viewed in the direction of forward travel. An invader armed with tooling of choice and small forearms has a decisive advantage for success and an escape that is free of protuberance cuts. However, an attack from the left side is the most viable strategy.

Once the tooling set is selected and the accessibility obstacle is hurdled, the exasperating reason presents. During the loosening or tightening task and even while attempting to start the nut onto the bolt during reinstallation, the whole assembly may spin as a unit. This is a consequence of the bond between the threads due to grime, dirt, corrosion and in some instances thread stretch arising from over tightening. The latter is especially true if the 6s nut has been reused a "number" of times and subjected to heavy handed tightening. If the nut threads have been stretched and the nut is reused, you will find that if the orientation is not the same as it was when removed it will be difficult to start and, when started, it will only turn a little before rotating the entire unrestrained assembly.

A method for removing these nuts that I have used for more than 45 years is as follows. I always recruit a second set of hands because it is not likely that the helper bolt is present and the exasperating scenario usually presents. Perhaps it is a consequence of early reading in the manual wherein it is the suggestion. I would urge you to do the same. My tools of choice for this task are a long handle 17mm combination wrench and a short handle double offset 17/19 mm box wrench. The ones that I have always used are made by Snap-On and have the designation OEX M170 and XS M17/19, respectively. The "17/19 box" [gearheadese] is used on the transmission side and the "17 combo" [more gearheadese] is used on the engine side. These are expensive, professional grade tools that have been manufactured from heat treatable alloy steel and embody double broached, thin wall ring construction at the fastener interface. A combination of thin walls and double broaching [12 point in the trade] affords unparalleled access in limited working areas for loosening and tightening tasks. With regard to initial loosening and final tightening of fasteners, a tooling interface that maximizes surface grip is preferred because there is less danger of slipping off. Any form of ring wrench [socket included] does this well and a singled broached [6 point] tool better than a 12 point at the sacrifice of throw requirement for the next grip on the fastener. Ratcheting devices nullify this sacrifice and are dependent only on the number of teeth to set the next increment for resistance turning. They offer in plane force application at the expense of a large diameter interface with the nut.

To begin the task of loosening the nut on the starter motor side, I am always optimistic in thinking that the nut will come right off without aids irrespective of gender. I select the previously mentioned 17 combo wrench, place in my left hand, orient the ring end away from me and ascertain that the open end of the wrench will favor the direction of the transmission housing with the ring end engaged onto the nut. Most all manufactures make the combination wrench with some clearance angle of the handle with respect to the plane of turning for hand gripping. The angle may not be the same from every manufacture and some manufactures offer two angles for the same wrench opening. The angle becomes critical because it must clear the fan inlet but not bind on the engine case or firewall. The now available in plane ratchet ring wrenches are optimal for this operation. However, my trusty 17 combo has worked for me all these years. It seems to have a perfect angle for this application. With the wrench "ready", I now position myself on the left side of the car with my left hip more or less facing the narrow dimension of the fan housing. Now you must reach in behind the fan housing and feel for engagement of the ring end of the wrench with the nut. This technique requires some contorting of sorts for the larger frame owing to the presence of the engine cover. There is not much room back there either for muscular forearms. I find that palming the handle in close proximity to the ring end so that the index finger can find the ring helps immeasurably in trying to fit the ring over the nut. Once found, the handle can be repositioned to maximize the breaking loose force by using the index finger as a pivot. Remember, the thread is right hand, so position the wrench to favor the farside of vertical because you will be pulling the wrench toward you to loosen the nut. There is always the danger that the site has been previously visited by disciples of Bruce Jennings and that is where the long handled series wrench will be to your advantage. Ready? Pull. If you are lucky, the nut will break free of the holding torque. You will then be able to back it off with a few more engagements of the wrench, and then with the fingers. Be careful not to drop the wavy washer. If you do it will likely migrate to the most inaccessible crevice in the engine cooling tin and render it irretrievable with the engine in the car. If you are just changing the starter motor, leave it. No harm will come. Just put a new one on when you reinstall the starter motor with the "helper" bolt [see below]. If the nut does not come off, do not worry, for help may be within earshot.

If removal of the starter motor was the task, solicit a second pair of hands. If you are removing the engine, go on to the other top bolt. This bolt occupies a mirrored position of the starter motor bolt about the vertical centerline of the engine and is much easier to access because the reach is less and there is no fan inlet interference. What works for the starter motor bolt will work as well for this bolt except that the aspect of the wrench handle slope can favor either the transmission or the engine. With just the right position you can actually see the nut, but it is just as easy to feel for it since you have more or less homed in on the position on the nearside now from attempts at the other bolt. It is incredible what the mind will remember and commit to muscle memory after a few tries and with practice, the wrench will go on there as easily as latching on to the #3 spark plug.

On either bolt, especially if you are attempting this for the first time, feeling for the cloaked nut can be quite a challenge. Patience is likely to wane and in these instances you can wedge your shoulder under the engine cover and lean your chest against the fan housing and arch your head and stretch your eye into an artificially lighted space behind the fan housing to view the nut while simultaneously working you hand and wrench into position to capture the nut. All this, of course, has a better success outcome if approached from the left side.

Well, both bolts are turning and the nut is not getting any looser. What to do? Here is where the extra set of hands will help if you do not have the helper bolts installed. You can actually do this yourself, but crawling in and out from under the engine and transmission starts to get old—like most of us. Starting with the more difficult of the two- the starter motor bolt- the second person is sent under the car to attach a restraining device [weapon/tool of choice] to prevent the head of the nut from turning while the person that solicited the help remains on top to loosen the nut. For this operation I use the short handle series double box wrench previously mentioned to restrain the head of the bolt from turning. If you are the bottom person, I have found the best position to launch an attack on the head of the nut is to lie coincident with the longitudinal axis of the car with your feet in the direction of forward travel. From this position it is possible to reach over the transmission with the tool in the left hand and with the17mm end extended, engage the head of the bolt. Use your index finger as before to aid in guiding the ring end onto the head. Once engaged, the person on top can try to loosen the nut while the person on the bottom keeps the wrench engaged until it rotates and stops. After it stops, continued turning of the nut by the person on top results in the nut coming loose. This procedure can be repeated for the other nut. It is far easier because you do not have as far to reach, there are fewer obstacles in the path of tool engagement, and because you can actually see the head of this bolt without body contortions, neck strain, eye stretch and the like. Artificial light is a plus here, but not necessary. If you know where all the fasteners go and which ones they are, you can change an engine and transmission on the side of the road by the light of an overhead street lamp. I should mention that I have often removed the clutch cable and bracket at the transmission to gain better access due to the close proximity of the cable to the chassis. I was never able to reach the bolt head by a route that passed beneath the installed cable. My arms were just too big then and even today. To avoid all this hassle with the upper bolts in the future [and this was circa 1962] I made a simple modification to the head of each bolt. This modification provides a protuberance that acts as a stop and prevents the bolt from turning after the bolt rotates and causes the stop to bear upon a reaction surface. The proportions of the stop on each bolt prevent turning in either direction once the stop bears against the reaction surface and without compromise to axial movement.

When you are in a remove/replace mode for either the starter motor or the engine, a good time to install helper bolts is during the replace mode. Just toss the existing ones aside and replace with the bolts shown in the Figures below. Once installed it becomes a one man operation to loosen or tighten the troublesome nuts on the upper bolts. Install the engine at your convenience and button it up by yourself. Crawling under to push the bolts through is a snap because you know where they are and how to access them now. One caution though. It is sometimes tricky to fit the starter motor bolt regardless if the design. You will find it an expedient if you start the bolt through the starter motor and work them both together into the assembled position prior to piloting the starter motor into final position.

The photos below show the bolts in use. They are easy to make if you have the inclination and the requisite tools. But, they are not expensive [$10 on your doorstep, USA] and the ones that I offer are grade 8.8, have matching head stampings, are Zn plated and embody a stop pin that is Zn plated steel. They make a great stocking stuffer.

Try them. You will like them—guaranteed!

Ab Tiedemann a.k.a. The Hermit
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Helper bolt in loosening mode
Photo by Ab Tiedemann

Helper bolt in tightening mode
Photo by Ab Tiedemann

Helper bolt in loosening mode on starter side
Photo by Ab Tiedemann

Helper bolt in tightening mode on starter side
Photo by Ab Tiedemann