Background #
When a starter fails, it may just die with no warning and you will find yourself in need of an MGB Starter Motor Replacement. This happened to me while trying to drive off a ferry, which was pretty problematic, but I got assistance for a bump start. I like to learn maintenance things and having done this before, I stopped to capture pictures and write up my process.
Step by Step #
The first step in the process is a safety thing, especially with MGB Starter Motor Replacement.
Step 1 – Disconnect Battery #
Make sure to remove the negative cable at the battery and isolate it. This will ensure that there are no electrical disasters because of the cable that goes straight from the battery positive terminal to the starter motor. It would be all too easy to be working on the positive cables at the starter motor and cause a short with a spanner or ratchet while working on the cables.
Step 2 – Raise the Car Safely #
The next step I would suggest is to plan to remove the front wheel to give you more room to work on the starter motor. As with many jobs it seems that taking things off to make room to work is often required. Loosen the lug nuts on the wheel before you jack the car up – I’ve made this omission a few times and it is hard to remove them when the wheel can freely spin, unless you have an impact wrench. Also, and not unique to this process, make sure that you position the floor jack carefully on the front cross member. Make sure that one of the lips of the shoe is tucked behind the rear edge of the cross member. This will help ensure that the car cannot slip off the jack while you put in the jack stands.
Step 3 – Remove Cables from Starter Motor #
Next up I removed the cables from the starter motor. There are 2 smaller cables with slip on spade connectors on the solenoid of the starter. On my car, which has a starter relay, a larger connector for a white with brown wire but also a second smaller connector for the white with green wire.
If you don’t have a color wiring diagram for your car see this other article. You can take advantage of the resource available from Advance Auto Wire and use the Stock Schematics page to locate a PDF with color wiring diagrams. In addition, there is a half inch nut holding on the much thicker and solid brown wire connections and the direct cable from the battery. The post on which these are placed may be soft brass material – so be careful to remove the nut squarely. Once all the wires are disconnected you may want to move them out of the way. There is not much room to get the starter out.
Step 5 – Remove Top Mounting Bolt #
With the wires removed, I suggest to return to the engine bay and remove the top bolt. This is a 9/16th socket or wrench and the bolt is a coarse thread. Don’t get the bolts mixed up. They are both 9/16th but the bottom one is a fine thread.
Step 6 – Remove Bottom Bolt #
The bottom bolt is somewhat hard to get to but if you use a long extension, it will give you room to get onto the bolt squarely and have some room to work the ratchet to get the bolt out. With luck once started you may be able to use your hand to get the bolt out with the extension which is less tedious than the ratchet.
Use one hand to hold the starter motor in place as you fully remove the lower bolt. The starter may come down right away or may need a little “jiggle” to get started.
Step 7 – Remove the Starter Motor #
Now you can try and maneuver the starter motor around to get it out. I don’t remember exactly how I got it out. There were some attempts, some naughty words and eventually I think I pushed the rear end upwards and then brought the starter down nose first – there is very little room. It might be easier if you have a helper to bring it up from the engine bay. The starter is very heavy – plan accordingly!
Once you get the starter out, you can check some of the visible ring gear on the fly wheel. While you won’t be able to see all of it without rotating the engine this might be something to check it you were having issues of slipping or a dead spot potentially.
Step 8 – Installing The New/Replacement Starter Motor #
You can then reinstall your replacement starter motor. I started from underneath the car and worked the replacement into position. This is going to be a bit of a juggle. You will want to have the starter in one hand and the lower fine thread bolt in the other and get that lower bolt started. This may be a combination of fingers and/or the long extension by hand to get it started. Get it snugged up enough to hold the starter in place and then you can move to the engine bay and get the top coarse thread bolt started and tightened. Make sure any bracket that was on the top bolt is also in place and tighten this fully.
Now return underneath and fully tighten the lower bolt. Now you can reinstall the wires. I suggest getting the big brown wires in place on the bottom solenoid connection. Be careful with putting on the securing nut to ensure no damage to the threads. You may need to hold these in place while tightening. Because,you need to keep them facing down or in whatever direction you may need to keep access to the 2 spade connections clear for the other wire(s). In my case there are 2 but as mentioned these were different sizes, so you shouldn’t have an issue getting these wires onto the right spades on the starter solenoid.
Step 10 – Optional Rubber Boot #
Lastly, as my 77 is very original, I have a plastic/rubber cover boot for the starter motor. This keeps the elements out and covers the wires and 90% of the starter motor. This is the last thing to put back in place and is also a bit of a fiddly job. This has to be squashed between the frame and engine block and then carefully brought into position. Once this is done you can carefully reinstall the negative battery cable and do a test. Hopefully all is well, as it was for me, and the starter cranks the engine over. Now you’ll be back in business having completed your own MGB Starter Motor Replacement. It’s really not too bad.
Hopefully this is helpful to understand an MGB Starter Motor Replacement.
Other Materials #
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